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GVHD: TS. Trng Th Minh Hnh

MC LCTrang Li m u.............................................................................................................3 Chng I: Tng quan ti liu...............................................................................5 1.1. Nguyn liu............................................................................................5 1.2. Thnh phn ho hc ca nguyn liu......................................................7 1.3. Cng ngh sy nng sn.........................................................................8 1.3.1. Cc tnh cht ho l v cng ngh sy nng sn...............................8 1.3.2. Mt s ch tiu nh gi cht lng sn phm sy...........................10 1.4. Phng php sy thng hoa v ngha ca n trong cng nghip thc phm.......................................................................................................12 1.4.1. Gii thiu v phng php sy thng hoa.........................................12 1.4.2. Cc giai on ca sy thng hoa.......................................................13 1.4.3. Tc truyn nhit...........................................................................14 1.4.4. Tc truyn khi............................................................................15 1.4.5. Thit b sy thng hoa.......................................................................16 1.4.5.1. Phn loi thit b sy thng hoa..................................................16 1.4.5.2. Nguyn tc lm vic...................................................................16 1.4.6. nh hng ca qu trnh sy thng hoa n cht lng sn phm...19 1.4.7. Nhng bin i chnh trong qu trnh sy thng hoa........................19 1.4.8. Tnh hnh nghin cu ng dng sy thng hoa trong thc phm v cc sn phm t khoai lang tm........................................................19 Chng II: i tng v phng php nghin cu...........................................24 2.1. i tng nghin cu...........................................................................24 2.1.1. Nguyn liu....................................................................................24 2.1.2. Ho cht..........................................................................................24 2.1.3. Thit b...........................................................................................24 2.1.4. Bao b bao gi sn phm............................................................26 2.2. Phng php nghin cu......................................................................26 2.2.1. Phng php vt l.........................................................................26 2.2.2. Phng php ho sinh.....................................................................26 2.2.3. Phng php ha phn tch my (xc nh hm lng cc kim loi nng)...............................................................................................31 2.2.4. Phng php cm quan...................................................................33 2.2.5. Phng php ton hc....................................................................33 Chng III: Kt qu v tho lun.......................................................................35 SVTH: L Vit Trin Lp: 02H2A

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3.1. Xc nh thnh phn ha hc ca khoai lang tm....................................35 3.1.1. Xc nh m..................................................................................35 3.1.2. Xc nh anthocyanin bng phng php pH vi sai...........................35 3.1.3. Xc nh protit bng phng php Kjeldahl......................................36 3.1.4. Xc nh gluxit tng, ng, tinh bt bng phng php Bertrand...37 3.1.5. Xc nh hm lng lipit bng phng php Soxlhet........................38 3.1.6. Xc nh hm lng x.....................................................................38 3.1.7. Xc nh hm lng cc kim loi nng..............................................39 3.2. Nghin cu sn xut khoai lang tm sy bng phng php sy thng hoa...........................................................................................................40 3.2.1. Nghin cu la chn qu trnh x l nguyn liu trc khi sy thng hoa...........................................................................................40 3.2.1.1. Quy trnh 1...................................................................................41 3.2.1.2. Quy trnh 2...................................................................................42 3.2.2. Nghin cu cc yu t nh hng n qu trnh sy thng hoa khoai lang tm..............................................................................................44 3.2.2.1. Chn yu t nh hng v hm mc tiu.....................................44 3.2.2.2. Cc bc thc hin bi ton quy hoch.......................................45 3.2.3. Ti u ha cc iu kin cng ngh sy thng hoa khoai lang tm....52 3.2.3.1. Ti u ha cc iu kin cng ngh sn phm c m nh nht v hm lng anthocyanin ln nht....................................52 3.2.3.2. Ti u ha hm a mc tiu bng phng php thot ly khi vng cm....................................................................................54 3.2.4. Thc nghim kim chng..................................................................55 3.2.5. nh gi cm quan............................................................................56 3.2.6. xut qui trnh cng ngh sn xut khoai lang tm sy bng phng php sy thng hoa quy m pilot....................................................57 Kt lun..................................................................................................................60 Hng pht trin ti.........................................................................................61 Ti liu tham kho.................................................................................................62 Ph lc

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LI M UK thut sy ng vai tr v cng quan trng trong cng nghip v i sng. Trong quy trnh cng ngh ca rt nhiu sn phm u c cng on sy kh bo qun di ngy. Cng ngh ny ngy cng pht trin trong ngnh hi sn, rau qu v cc thc phm khc. Sy thng hoa l qu trnh tch m ra khi vt sy bng s thng hoa ca nc. Qu trnh thng hoa l qu trnh chuyn trc tip t th rn sang th hi. iu kin bnh thng, m trong thc phm dng lng nn thng hoa chng cn c chuyn sang th rn bng phng php lnh ng. Chnh v vy nn cn gi l phng php sy lnh ng (Freeze Drying hay Lyophilization). y l mt trong nhng phng php sy cho cht lng sn phm tt nht. Sn phm sy thng hoa lu li rt tt cc c tnh cm quan, cht dinh dng v thi gian bo qun di lu khi c bao gi ng cch. V do gi thnh u t ban u v chi ph vn hnh cao nn t trc n nay vic p dng cng ngh sy thng hoa vo sn xut nc ta vn cn gp nhiu kh khn. Theo cc chuyn gia thng mi cho rng Vit Nam c tim nng xut khu rau, qu nhit i, v nhu cu nhp khu mt hng ny trn th gii hu nh khng hn ch. Tuy nhin xut khu ca Vit Nam vn cn nhng yu im m in hnh l sn xut phn tn, nng sut thp, cha gii quyt dt im c khu to ging, thu hoch, bo qun v ch bin rau qu xut khu cng nh khu kim dch v cng nhn ln nhau gia VN v cc th trng nhp khu. Ngoi ra, theo cc chuyn gia, phi xy dng cc vng nguyn liu tp trung cht lng cao, pht trin cng ngh bo qun rau qu ti, u t xy dng cc nh my ch bin cng sut 10.000 - 50.000 tn/nm i vi cc vng sn xut ln, pht trin cc nh my cng sut 1.000 - 2.000 tn/nm vi thit b ch yu do trong nc ch to. Bn cnh , cn a dng ho cc sn phm ch bin nh: bt qu, nc qu c c, qu ngm ng, sy kh, sy thng hoa, mt qu... nhm tng t l ch bin rau qu t 10% hin nay ln 20% vo nm 2010 v 30% vo nm 2020 [24]. Nhng nm gn y, nng nghip nc ta t c nhng thnh tu to ln. Ngoi nhu cu trong nc chng ta xut khu nng sn v ch phm ca n ng gp khng nh vo thu nhp quc dn ca c nc. Ngun nguyn liu rau c nc ta rt phong ph v r tin nhng c gi tr dinh dng rt cao. Khoai lang tm l mt v d. y l mt ging khoai lang c ngun gc t Nht Bn mi c nhp v trng nc ta v cho kt qu rt kh quan, em li thu nhp n nh cho ngi nng dn. Trong khoai lang tm c cha anthocyanin, y l mt cht mu SVTH: L Vit Trin Lp: 02H2A

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khng nhng to ra mu sc p m cn c nhiu tc dng c li i vi sc khe ca con ngi. Khoa hc k thut ngy cng pht trin, i sng ca con ngi ngy mt nng cao, nn kinh t nc ta c nhng chuyn i ng k. Trc sc p cnh tranh ln v nhng yu cu v cht lng sn phm rt kht khe mt khi ha nhp vi th gii th ngnh cng nghip sn xut ni chung v ngnh cng nghip sn xut thc phm ni ring buc phi u t thay i cng ngh sn xut nng cao cht lng sn phm, p ng nhu cu ngy cng cao ca ngi tiu dng v xut khu. Vi tt c nhng l do trn cng mong mun gii quyt u ra cho ngnh nng nghip, tng gi tr s dng ca khoai lang tm, tm hiu nghin cu p dng k thut sn xut thc phm hin i ca th gii to ra nhng sn phm c cht lng cao nn em quyt nh chn ti nghin cu tt nghip ca mnh l: Nghin cu sn xut khoai lang tm sy bng phng php sy thng hoa.

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TNG QUAN TI LIU1.1. Nguyn liu: Khoai lang c tn khoa hc l Ipomoea batatas (L.) Lamk l mt loi thc phm gn gi vi ngi dn Vit. Khoai lang l loi cy sng nhiu nm, thn c nha m. L khoai lang l mt loi rau dn d rt ngon, li mt v b. C v rau khoai lang cn l v thuc phng cha bnh c dng t lu trong dn gian, c ni cn gi n l sm nam. Theo ng y, c khoai lang tnh bnh, Hnh 1.1: C khoai lang v ngt, c tc dng bi b c th, ch kh, cng thn, kin v, tiu vim, thanh can, li mt, sng mt. Rau lang tnh bnh, v ngt, dng cha t h, km n, thn m bt tc. Ngn khoai lang luc hoc xo vi ti l mt mn n ngon, c nhiu vitamin v cht khong, giu cht x Cc nh khoa hc chng minh rng cht x trong thc phm c tc dng hn ch hp thu cholesteron trong rut vo mu, hn ch t l mc bnh ung th i trng. Theo Ty y, khoai lang c chng loi cc cht dinh dng tng i nhiu. Thnh phn ch yu l carbonhydrate tinh bt, d c c th tiu ho, hp thu v tn dng. Khoai lang c cha nhiu nucoprotein, c kh nng cn tr cholesteron lng ng trn thnh mch, trnh x cng ng mch, ng thi gi c tnh n hi ca mch mu, li cn c th trnh teo m lin kt trong gan, thn Trong khoai lang cha mt s cht c th phng bnh ung th rut kt, ung th v. Khoai lang c th thc y nhu ng rut, trnh b to bn [19]. Khoai lang tm l mt loi khoai lang c nghin cu a vo sn xut bi Vin nghin cu nng nghip quc gia Nht Bn c tn l Okinawan. y l mt ngun cht Hnh 1.2: Khoai lang tm ging mu tm tt v n nh v n c sn lng Ayamurasaki [16] ln vi hm lng anthocyanin cao [16].

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Trong khoai lang tm c cha anthocyanin y l mt hp cht thuc nhm flavonoid. Anthocyanin l cht mu t nhin c nhiu tnh cht, tc dng qu bu, bi vy n c s dng ngy cng rng ri trong cng nghip thc phm cng nh trong y hc. Trong sn xut thc phm cng vi cc cht mu t nhin khc nh carotenoid, clorofil, anthocyanin gip sn phm hi phc li mu t nhin ban u, to ra mu sc hp dn cho mi sn phm.

Hnh 1.3: Cng thc [16] v cht mu anthocyanin t khoai lang tm [17] ng thi do c kh nng khng oxy ha nn chng cn c dng lm bn cht bo. Trong y hc tc dng ca anthocyanin rt a dng nn c ng dng rng ri: do kh nng lm gim tnh thm thnh mch v thnh t bo nn c s dng trong trng hp chy mu, hoc c nguy c chy mu, do c kh nng chng oxy ha nn c s dng chng lo ha, hn ch s gim sc khng do s suy gim ca h thng min dch, nh c tc dng chng tia phng x nn c th h tr cho c th sng trong mi trng c nhng bc x in t. Vi nhiu c th qu bu anthocyanin cn c dng chng d ng, vim lot do nguyn nhn ni sinh hay ngoi sinh, khng nhiu loi vi khun kh tiu dit, tng chc nng chng c ca gan, ngn nga s nhim m gan v hoi t m gan, iu ha lng cholesterol trong mu, trnh nguy c tc nghn x va ng mch, phc hi trng lc tim, iu ha nhp tim v huyt p, iu ha chuyn ha canxi, lm gim au do tc dng co tht c trn, lm gim cc m xut huyt nh trong bnh tiu ng. Ngoi ra anthocyanin cn c th c nhiu ng dng khc do cc phn ng a dng ca chng trong cc enzyme v cc qu trnh trao i cht khc nhau, chnh v vy vic quan tm n thc phm giu anthocyanin ngy cng c tng cng v n c li cho sc khe con ngi [2]. SVTH: L Vit Trin Lp: 02H2A

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nc ta khoai lang tm ch yu c trng Lt v mt s tnh min Nam nh: An Giang, Vnh Long, Kin Giang cho sn lng kh ln em li thu nhp n nh cho nng dn cc tnh ny. Tuy nhin a s ngi tiu dng hin nay vn cha c thi quen s dng khoai lang tm trong khu phn n hng ngy mt mt v n cha ph bin trn th trng v ngi tiu dng cha bit c gi tr dinh dng ca khoai lang tm. Mt khc khoai lang tm cng ch c nhiu vo ma v nht nh ch khng c quanh nm. Do vy vic chn khoai lang tm lm nguyn liu trong ti nghin cu ny s gp phn lm tng gi tr s dng ca khoai lang tm ng thi to ra mt sn phm thc phm mi p ng nhu cu tiu dng ca ngi tiu dng. 1.2. Thnh phn ho hc ca nguyn liu: Bng 1.1: Thnh phn ha hc ca khoai lang (tnh cho 100g sn phm) [22] Sn phm Thnh phn Nc (g) Lipit (g) m (g) Tng Gluxit (g) ng Tinh bt X (g) Khong (mg) Ca P Fe Caroten Vitamin (mg) B1 B2 PP C C ti 68 0,2 0,8 28,5 4 24,5 1,3 34 49,4 1 0,3 0,05 0,05 0,6 23 11 3,6 1,4 48 54 Khoai lang kh 11 0,5 2,2 80 2,6 2,8 Rau khoai lang 91,9

Bng 1.2 : Cc axt amin c trong protein ton phn (tnh theo 16g N) [12] SVTH: L Vit Trin Lp: 02H2A

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Thnh phn Arginin Histidin Lysine Trytophan Phenylalanin

Hm lng 2,9 1,4 1,3 1,8 4,33

Thnh phn Methionin Threonin Leucin Isoleucin Valin

Hm lng 1,7 3,8 4,8 3,6 5,6

Ngoi cc thnh phn ha hc trn trong khoai lang tm cn c cha mt thnh phn quan trng l anthocyanin to nn gi tr v dinh dng cho c khoai lang tm. Cht mu ny gm cc dng mono hoc di-acylated ca cyanidin (YGM-1a, -1b, -2 and -3) v peonidin (YGM-4b, -5a, - 5b and -6) [16]. 1.3. Cng ngh sy nng sn [7]: Sy l mt trong nhng khu quan trng trong cng ngh sau thu hoch, ch bin v bo qun nng sn. Sy nng sn l mt qu trnh cng ngh phc tp. N c th thc hin trn nhng thit b sy khc nhau. ng vi mt loi nng sn ta cn chn ch sy thch hp nhm t nng sut cao, cht lng sn phm sy tt v tit kim nng lng. 1.3.1. Cc tnh cht ho l v cng ngh sy nng sn: 1. Phn loi nng sn: Nng sn v cc ch phm ca n rt a dng. Vi tnh cht l mt i tng sy ta c th chia nng sn Vit Nam ra lm my dng sau y: - Dng ht: la, ng, cc loi u, lc v c ph - Dng c: khoai lang, sn, khoai ty Khi sy cc nng sn loi ny thng tin hnh di dng lt hoc si. - Dng qu: chui, m, mn Khi sy cc loi ny ngi ta vn nguyn c qu hoc ch bc v nh chui. - Dng rau, l: su ho, ch, thuc l Khi sy cc loi nng sn ny thng nguyn dng (thuc l) hoc bm nh (bp ci). - Dng tinh bt hay nh tng hoc pur. y l nhng ch phm t nng sn. Sy cc sn phm ny thng dng cc loi sy phun hoc sy tng si. 2. Tnh cht ho - l ca mt s nng sn: SVTH: L Vit Trin Lp: 02H2A

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- m ca vt sy: Trong k thut ngi ta s dng hai khi nim m: m tng i v m tuyt i t. m tng i l s kg m cha trong 1 kg vt liu. m tuyt i l t s gia lng m trong vt liu v thnh phn kh ca n. T nh ngha ta c:Ga Ga .100 , % = Gk + Ga G Ga Ga t = G = G - G .100 , % k a

=

G : khi lng ca sn phm. Ga: khi lng m cha trong G kg sn phm. Gk: khi lng ca vt liu kh trong G kg sn phm. Vt liu sy trong khng kh s ht m hoc nh m t n trng thi cn bng m vi mi trng. m ca vt sy lc by gi gi l m cn bng. Nh vy, m cn bng ca mt sn phm ph thuc vo cu trc ca sn phm v m ca khng kh. Do , nu sn phm sau khi sy c bo qun hoc lu mi gia cng tip tc th chng ta ch sy ti a n m cn bng. - Cc tnh cht nhit vt l ca nng sn: Trong cc tnh cht nhit vt l ca nng sn thng dng khi tnh ton nhit qu trnh sy l nhit dung ring v h s dn nhit. Nhit dung ring ca nng sn cng nh ca vt liu m ni chung tnh theo cng thc: C (100 ) + C a . Cv = k100

Ck: nhit dung ring ca vt liu kh. Ca: nhit dung ring ca m. : m ca vt liu. Xc nh h s dn nhit nng sn ni ring v vt liu m ni chung rt phc tp, c th c hai gi tr: h s dn nhit ca mt ht hay h s dn nhit ca khi ht. Trong thc t ta thng dng h s dn nhit ca khi ht v. H s dn nhit v ch yu ph thuc vo chnh bn thn v cu trc ca mt ht, mt khi ht, nhit v m ca vt liu. Do h s dn nhit ca vt liu m c dng: v = f(t, , ). 1.3.2. Mt s ch tiu nh gi cht lng sn phm sy [6]: Cht lng sn phm l mt khi nim rng. Chng hn, ch tiu sinh hc ho l, cu trc c hc, thnh phn ha hc v cc vi lng v.vphi m bo trong qu SVTH: L Vit Trin Lp: 02H2A

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trnh sy. Tuy nhin trong thc t ta xt cc ch tiu qua mt vi c trng quan trng nht. - Hnh dng, kch thc v th tch sn phm: Cc sn phm sy thng dng kh, dng ngm nc tr li (sau khi ngm) hay dng nu chn u phi ng nht v hnh dng v ging nhau v kch thc. Hnh dng ca sn phm ph thuc vo mc ch s dng. V d: c rt sy kh dng cho cc loi sp (canh) khc nhau: sp hn hp, nc canh c th dng dng ht, dng qun c, dng si, nhng nu dng lm gia v thng dng dng bt. Th tch l c tnh th ba xc nh phm vi s dng ca sn phm sy. Sn phm kh ging nhau v hnh dng, kch thc nhng c th khc nhau v th tch. Vi hnh dng v kch thc ging nhau th th tch ca sn phm sy cn ph thuc vo loi nguyn liu, hm lng cht kh, phng php sy (th tch sn phm sy thng hoa khc vi sn phm sy bng phng php nhit p sut bnh thng) v iu kin ch bin. S xut hin cc c tnh khc nhau ca sn phm sy c th lm thay i iu kin ng gi sn phm. V d: trn u cc thnh phn theo khi lng nhng khc nhau v th tch s dn n s thay i v mu sc ca sn phm. - Mu sc: Mu sc l mt trong nhng tnh cht quan trng ca thc phm sy kh. Ring i vi mt s sn phm th c ngha ln hn c c tnh ca v, phi tun theo nhng nguyn tc thng mi quc t, cc loi thc phm kh ch c bn ra th trng sau khi trng cu kin bng cc mu chun. Tnh cht v cht lng ca sn phm khng c php khc bit so vi tnh cht v cht lng ca mu chun. Mt trong nhng c im l mu sc. Mu m nht, mu cht, hoc c s khc bit v mu sc dn n h hi ln cho cht lng sn phm. i vi cc sn phm mu trng c th bin i thnh mu vng, , en, xm; i vi sn phm mu c th b bin thnh mu vng, gch nu, i vi sn phm mu xanh c th thnh mu vng hoc mu xanh en. Vic kim tra mu sc cn tin hnh y t nguyn liu ban u, trong qu trnh bo qun, lm sch nguyn liu, chn lm ngui, sy v bo qun thnh phm, cng nh trc khi em s dng. - Nng v, cht thm v cc cht khc: Mi v v ca sn phm kh thng c nh gi sau khi ngm nc tr li, nu chn v lm ngui n nhit thng. Nguyn tc c bn ca ngi sn xut cng nh ngi tiu th sn phm l: cht lng ca sn phm phi c kim tra thng xuyn sau khi a chng v trng thi thch hp s dng.

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- Nng ng v mui: Trong cc c im cht lng cc loi bt, hoa qu... th ng, axt, mui ng vai tr c trng v v ca sn phm. Trn c s phn tch chun ngi ta xc nh hm lng phn trm ca cc cht tng ng vi khi lng cht kh ton phn. Nhng khu cn kim tra s thay i mi v v nng cc cht trong qu trnh sn xut nh sau: sau khi vn chuyn, bo qun, lm sch v bn ngoi bng hi nc hay bng xt, chn, lm ngui, sy v kim tra thng xuyn hay nh k trong thi gian bo qun sn phm. - S ngm nc: Mc v thi gian ngm nc l mt trong nhng yu cu c bn v kinh t v thi gian chun b sn phm n lin. Mc thm nc hoc ht nc cho ta bit kh nng ca sn phm sy kh tng khi lng ln bao nhiu ln sau khi cho thm nc. i lng ny l c s cho php tnh ton vi cc khi lng cn thit trn vi cc thnh phn khc v khi lng gia v. V phng din s dng sn phm th thi gian ngm nc l yu t rt quyt nh bi v bit c n ngi ta c th ra mi thi gian chun b mn n t sn phm sy . Mc v thi gian ngm nc ca sn phm ph thuc vo tnh cht ca nguyn liu (m g hay m xp), iu kin bo qun, ch sy thch hp. Bi vy phi kim tra cht lng sn phm trong sut qu trnh sn xut. - m: m cui cng cn li trong sn phm sy l mt c tnh k thut quan trng i vi kh nng bo qun v hiu sut thnh phm. - Tp cht c hc v ho hc: Cc sn phm sy c th bo qun bng cc phng php khc nhau, trong qu trnh bo qun c th ln cc tp cht c hc hoc ho hc. Bi vy yu cu t ra l gii hn hm lng cc tp cht . V d: hm lng khong, tro khng ho tan trong axt, aren, thic ch... i vi hnh ty i khi ngi ta quy nh lng xenluloza. - Ho cht dng trong sn xut: Ngi ta c th dng cc ho cht khc nhau x l nguyn liu nhng khu cn thit trong sn xut. Yu cu ca cc ho cht ny khng lm nh hng n cht lng sn phm v khng c hi i vi c th con ngi, hm lng ho cht cn li phi nm trong khong gii hn cho php. - Nhng tp cht v phn t l:

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Mun gii quyt vn tp cht i hi phi t chc tt qu trnh sn xut nh k kim tra bao b v thng xuyn kim tra kho tng v.v... Tp cht c th gy nguy him n sc kho, c nhiu tp cht khc nhau: , knh, g, kim loi, t, su b, du vt ca loi gm nhm. Tt c nhng cht khc khng phi l thc phm u phi tuyt i loi tr khi cc sn phm sy. Cn tp cht thc vt thng l cc loi c di hoc cc sn phm kh khc nhng hm lng khng c vt qu 0,2%. Nhng phn t l l nhng phn ca nguyn liu khng phi i tng sy. V d: r, phn gc, thn, rut qu, ht v, l, v cy, phn rau v qu hng... Cng cc th k trn cn phi ni n nhng phn t l do qu trnh sn xut a li, nh cc phn t bn cn st li trn b mt nguyn liu do ra khng sch hay nhng phn t b bin mu. - Nhng yu cu v vi sinh vt: Rau qu sy s l nhng thnh phn ca cc loi sp, nc st cc gia v lm kem v cc hn hp nc qu. Ngoi ra rau qu sy cn cho vo cc sn phm hp, cng nghip tht, sn phm thc phm, thc n ngui, sn phm ca cng nghip bnh ko. Do v phng din vi sinh vt, rau qu sy phi bo m tt c cc yu cu c quy nh do cc c quan y t v cc x nghip t ra. Gii hn cho php s lng v loi vi sinh vt ph thuc vo phm vi s dng sn phm sy. 1.4. Phng php sy thng hoa v ngha ca n trong cng nghip thc phm: 1.4.1. Gii thiu v phng php sy thng hoa: Phng php sy thng hoa hay sy lnh ng (Freeze Drying hay Lyophilization) do k s G.I. Lappa-Stajenhexki pht minh nm 1921. Sy thng hoa l qu trnh tch m ra khi vt liu, m trng thi rn (bng, nc ) thnh hi khng qua trng thi lng. iu kin bnh thng, m trong thc phm dng lng nn thng hoa chng cn c chuyn sang th rn bng phng php lnh ng. Mun vy phi sy vt liu trong mi trng c chn khng cao (p sut tuyt i t 0,11,0 mmHg), nhit sy c th t ti -180C. Phng php ny bao gm 2 giai on l lm lnh ng v sy kh bng chn khng thp. C 2 h thng ny u hot ng rt tn km nn c s dng tng i hn ch. N ch thng c s dng sy cc sn phm c gi tr cao, nhng sn phm m khng th sy c bng phng php khc. Bn cnh , khng phi bt k nguyn liu no cng u c th sy c bng phng php ny, c bit l nhng loi c cu trc d b h hi trong qu trnh lnh ng [6]. y l mt phng php sy nhanh (ADF: Accelerated Freeze Drying) c p dng rng ri

SVTH: L Vit Trin

Lp: 02H2A

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M sy cc loi nguyn liu t tin nh tht gia sc, gia cmNgoi ra n cn c s dng sy cc loi sn phm khc nh: c ph, gia v, trong dc phm 1.4.2. Cc giai on ca sy thng hoa [6]: Qu trnh sy thng hoa gm 2 giai on: - Giai on lm lnh ng: giai on u tin ca qu trnh sy thng hoa l lm lnh ng sn phm. Qu trnh lm lnh ng thc hin bng hai cch. Cch th nht thc hin trong thit b lm lnh ng thng thng hoc nit lng lm lnh ng sn phm bn ngoi bung sy thng hoa. Cch th hai l vt sy t lnh ng ngay trong bung sy thng hoa khi bung sy c ht chn khng. Sn phm cn c lm lnh ng rt nhanh hnh thnh Hnh 1.4: S 3 pha ca nc [18] cc tinh th bng nh t gy h hi n cu trc t bo ca sn phm. i vi nhng sn phm dng lng, phng php lm lnh ng chm c s dng bng to thnh tng lp, cc lp ny to nn cc knh gip cho hi nc dch chuyn d dng. - Giai on thng hoa: giai on k tip l tch nc trong sut qu trnh sy tip theo lm kh sn phm. Nu p sut hi nc c gi di 4,58mmHg (610,5 Pa) v nc dng bng, khi sn phm c cung cp nhit th bng rn s thng hoa trc tip hi m khng b tan chy. Hi nc tip tc c tnh ra khi sn phm bng cch gi cho p sut trong bung sy thng hoa thp hn p sut hi nc trn b mt ca bng, ng thi tch hi nc bng bm chn khng v ngng t n bng cc ng xon rut g lnh, cc bn dt lnh hoc bng ha cht. Khi qu trnh tip din, b mt thng hoa di chuyn vo bn trong sn phm ng lnh, lm cho sn phm c sy kh. Nhit lng cn thit dch chuyn b mt thng hoa (n nhit thng hoa) c truyn n sn phm do s dn nhit hoc do vi sng cung cp. Hi nc di chuyn ra khi sn phm qua cc knh c hnh thnh do bng thng hoa v c ly i. Nh vy, nu khng tnh qu trnh mt m trong phng php vt m t lnh ng trong bung sy khi ht chn khng th sn phm c sy trong hai giai on: trc tin do qu trnh thng hoa xung khong 15% m v sau do bay SVTH: L Vit Trin Lp: 02H2A

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hi ca phn nc khng ng bng n 2% m bng qu trnh nh m ng nhit. Qu trnh nh m ng nhit t c bng cch nng nhit my sy ln gn nhit mi trng xung quanh trong khi vn gi p sut thp ging nh qu trnh sy cc thit b sy chn khng thng thng. ng cong sy: Hnh 1.5 l ng cong sy v ng cong nhit ca vt sy trong qu trnh sy thng hoa trong vt sy t lnh ng trong bung sy. Khi ht chn khng, p sut trong bung sy gim xung, m t do bay hi mnh lm gim nhanh nhit ca n xung n nhit ng bng tb (ng A-B). Qu trnh ng bng ca m c ta nhit nn nhit ca vt sy tng ln mt cht (ng B-C). Qu trnh Hnh 1.5: ng cong sy v nhit sy trong sy thng hoa thng hoa m din ra khc vi qu trnh sy th nht (tc sy khng i) trong sy i lu l nhit tng ln mt t theo thi gian sy (on C-D dc ln). iu c gii thch l lp su bn trong vt sy cn c m ang ng bng. Giai on sy tip theo l giai on bay hi m lin kt, nhit ca vt sy tng nhanh. Trong mt s sn phm (v d nc p tri cy, dch chit c ph c c), s hnh thnh nn trng thi thy tinh trong qu trnh ng bng gy ra nhiu kh khn cho vic di chuyn hi nc. V vy, cht lng cn c ng bng dng bt (phng php sy thng hoa bt: vacuum puff freeze drying), hoc l nc p tri cy sy cng vi phn tht (ci). C hai phng php u to nn cc knh dn nh hi nc c th thot i c. phng php th ba, nc tri cy sau khi ng bng c nghin thnh cc, nh sy nhanh hn v cho php kim sot kch c ca ht bt tt hn. Tc sy ph thuc phn ln vo tnh cn tr nhit ca sn phm v mc thp hn vo cn tr dng hi (dch chuyn khi) ra khi b mt thng hoa. 1.4.3. Tc truyn nhit: C ba phng php truyn nhit n b mt thng hoa: nhit truyn xuyn qua cc lp bng, nhit truyn qua lp kh, truyn nhit bng vi sng.

SVTH: L Vit Trin

Lp: 02H2A

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Nhit truyn xuyn qua cc lp bng: tc truyn nhit ph thuc vo dy v dn nhit ca lp bng. Khi qu trnh sy xy ra, chiu dy ca lp bng gim xung v tc truyn nhit tng ln. Nhit b mt ca thit b cp nhit c gii hn trnh lm tan bng. Nhit truyn qua lp kh: tc truyn nhit n b mt thng hoa ph thuc vo chiu dy v din tch b mt ca sn phm, dn nhit ca lp kh v chnh lch nhit gia b mt sn phm v b mt bng. Khi p sut bung sy khng i nhit ca b mt bng duy tr khng i. Lp kh ca sn phm c dn nhit rt thp (tng t nh vt liu cch nhit) v v th gy ra s cn tr ln i vi dng nhit. Khi qu trnh sy tip din, lp ny tr nn dy hn v s cn tr nhit tng ln. Lm gim kch thc nguyn liu v tng chnh lch nhit s lm tng tc truyn nhit. Tuy nhin, sy thng hoa nhit b mt b gii hn n 40 - 65 0C trnh s bin tnh protein v thay i ha hc khc, c th lm gim cht lng ca sn phm. Truyn nhit bng vi sng: nhit c to ra trn b mt bng v tc truyn nhit khng b nh hng bi dn nhit ca bng v cht kh hay dy ca lp kh. Tuy nhin, nhit vi sng kh kim sot v c nguy c b tnh trng qu nng cc b dn n s tan chy bng. 1.4.4. Tc truyn khi: Khi nhit truyn ti b mt thng hoa, nhit v p sut ca bng s c tng ln. Hi nc di chuyn xuyn qua cht kh n vng c p sut hi thp trong bung sy. p sut 67 Pa, 1 g bng hnh thnh 2 m 3 hi v do my sy thng hoa cn phi ly i hng trm mt khi hi trong 1 giy qua cc l hng ca cht kh. Cc yu t kim sot chnh lch p sut hi nc l: - p sut trong bung sy. - nhit ca thit b ngng t hi, c hai cn thp n mc chi ph cho php. - nhit ca bng b mt thng hoa, cn cng cao cng tt nhng khng tan chy. Trong thc t m bo tnh kinh t, p sut bung sy thp nht vo khong 13 Pa v nhit thit b ngng t thp nht l khong -35 0C. V l thuyt, nhit ca bng cn nng ln mc ch va di im ng bng. Tuy nhin, trn mt nhit ti hn nht nh, gi l nhit sp (collapse temperature), cu trc sn phm s b ph hy ngay lp tc. Trong thc t v th tn ti nhit ng bng ti a, nhit ngng t ti thiu v p sut bung sy ti thiu v nhng thng s ny kim sot tc chuyn khi. Trong qu trnh sy, m h xung t mc ban u rt cao trong vng lnh ng n mc thp hn lp kh, ph thuc vo p SVTH: L Vit Trin Lp: 02H2A

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sut hi nc trong bung sy. Khi nhit chuyn qua lp kh, quan h gia p sut trong bung sy v p sut trn b mt l: Pi = Ps +kd ( ts ti ) b.s

Trong : Pi: p sut ring phn ca hi nc b mt thng hoa, Pa; Ps: p sut ring phn ca hi nc b mt, Pa; kd: dn nhit ca lp kh, W.m-1K-1; b: thm ca lp kh, kg.s-1.m-1; s: n nhit thng hoa, J.kg-1; ts, ti: nhit b mt v b mt thng hoa, 0 C. Thi gian sy c tnh bng cng thc sau: x 2 (M 1 M 2 )s Td =8k d ( t s t i )

Trong : td: thi gian sy, s; x: chiu dy sn phm, m; : t trng ca cht kh, kg.m3; M1, M2: m ban u v m cui cng. Ch rng thi gian sy t l vi bnh phng dy sn phm, do gp i chiu dy sn phm s ko di thi gian sy gp 4 ln. 1.4.5. Thit b sy thng hoa: Cc thit b sy thng hoa bao gm mt bung chn khng c cha cc khay ng sn phm v thit b un nng cp n nhit thng hoa. Cc ng xon rut g lnh hoc cc bn dt lnh c s dng ngng t hi nc trc tip thnh bng. Chng c gn vi thit b t ng lm tan bng gi cho b mt ca cc dy xon rut g c trng ti a cho vic ngng t hi nc. iu ny l cn thit bi v phn ln nng lng u vo c dung lm lnh ng cc thit b ngng t v v th tnh kinh t ca sy thng hoa c xc nh bi hiu sut ca thit b ngng t: Hiu sut =N i t g h a h th n o N i t cn la la n th b n g tu h ta h n m h i t g n

V bm chn khng dng tch i cc thnh phn hi khng ngng t. 1.4.5.1. Phn loi thit b sy thng hoa: - Thit b sy thng hoa gin on. - Thit b sy thng hoa lin tc: gm thit b sy thng hoa bng ti to ht kh ng lnh, thit b sy thng hoa bng ti rung to ht bng phun, thit b sy thng hoa vt ti. 1.4.5.2. Nguyn tc lm vic: S nguyn tc thit b sy lnh ng bao gm bung sy thng hoa, bung ngng t, h thng lm lnh v bm chn khng. Bung sy thng hoa: bung sy thng hoa gm nhng khay cha sn phm ng thi cp nhit trc tip cho sn phm thng hoa. SVTH: L Vit Trin Lp: 02H2A

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Hnh 1.6: S nguyn tc lm vic ca qu trnh thng hoa [18] Bung ngng t: Hi m thot ra t bung sy i sang thit b ngng t. Thit b ny c tc dng lm ngng t hi m v lm ng bng do thit b ngng t c lm lnh bng dung dch nc mui c nhit -100C - 400C. Trn thnh ng truyn nhit ca thit b ngng t lun lun c mt lp bng (tuyt) lm gim hiu qu ca qu trnh truyn nhit, do phi lun lun lm sch b mt truyn nhit hoc dng hai thit b ngng t lm vic thay phin nhau hoc gn vi thit b t ng lm tan bng nng cao hiu qu lm vic. Dng bnh ngng s lm nh s lm vic ca bm chn khng. Bm chn khng: Bm chn khng c nhim v ht kh to chn khng ban u cho bung thng hoa v trong thi gian sy c nhim v ht ht kh khng ngng to ra trong qu trnh lm vic ca thit b. H thng lm lnh: Nhim v ca h thng lm lnh l lm lnh sn phm n nhit yu cu v lm lnh bnh ngng ngng t v ng bng hi m thot ra, to iu kin duy tr chn khng v ch lm vic trong h thng. Qu trnh lnh ng vt sy c th thc hin bng hai cch: - Dng my lnh ng hoc nit lng lm lnh ng vt sy bn ngoi bung sy thng hoa rt ngn thi gian. - Vt sy t lnh ng ngay trong bung sy thng hoa bng cch ht chn khng.

SVTH: L Vit Trin

Lp: 02H2A

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Hnh 1.7: S cu to hm sy thng hoa [6]

Hnh 1.8: H thng hm sy thng hoa dng trong cng nghip [20]

SVTH: L Vit Trin

Lp: 02H2A

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1.4.6. nh hng ca qu trnh sy thng hoa n cht lng sn phm: Sn phm sy thng hoa lu li rt tt cc c tnh cm quan, cht lng dinh dng v thi gian bo qun di khi c bao gi ng cch. Cc cht d bay hi khng b cun vo hi nc sinh ra trong qu trnh thng hoa m b mc li trong khung sn phm. Kt qu l 80 90 % mi c gi li. Kt cu ca sn phm c tt: t b co ngt v khng b hin tng cng v. Cu trc xp cho php qu trnh lm t tr li nhanh chng v hon ton, nhng n d v v cn bo v trnh b h hi c hc. Ch c nhng thay i nh v cht lng protein, tinh bt v cc hydrocacbon khc. Tuy nhin cu trc xp ca sn phm c th cho oxy xm nhp v gy oxy ha lipit. V vy, sn phm phi c bao gi trong kh tr. Nhng thay i ca thiamin v axit ascorbic trong qu trnh sy thng hoa mc va phi v s tht thot ca cc vitamin khc khng ng k. Tuy nhin, s tht thot cc dinh dng do cc qu trnh chun b trc khi sy, c bit l qu trnh chn hp rau c th nh hng ng k n cht lng ca sn phm sy thng hoa. 1.4.7. Nhng bin i chnh trong qu trnh sy thng hoa: y l nhng bin i ch yu do qu trnh lnh ng. - Nhng bin i ha hc, sinh ha trong qu trnh lnh ng: - Khi lm lnh ng nc trong dch bo ng bng lm bin tnh prtt. - Hot ng ca enzyme gim nhng khng b nh ch. - Vi vi sinh vt do nc trong c th b ng bng hon ton nn s sng b nh ch hon ton. Vi sinh vt a phn s cht 90 95%, nhng mt s s chuyn sang trng thi tim sinh. - Ngoi ra trong qu trnh lnh ng cn xy ra bin i nhit l hc. - Nhng bin i xy ra trong qu trnh lnh ng: Ch yu l s bay hi m dn n lm gim khi lng t nhin, lm kh sn phm. Tc lnh ng c coi l mt tham s nh gi cht lng sn phm trong qu trnh ng lnh hoc sy thng hoa. Tc ng lnh khc nhau tc ng n qu trnh phn b li nc trong sn phm khc nhau do nh hng n cht lng sn phm ng lnh cng nh ng hc ca qu trnh thng hoa. 1.4.8. Tnh hnh nghin cu ng dng sy thng hoa trong thc phm v cc sn phm t khoai lang tm: Sy thng hoa trong thc phm l mt lnh vc nhn c nhiu s quan tm ca cc nh khoa hc v nhng u im vt tri ca n. Trn th gii c cc cng trnh nghin cu v sy thng hoa nh:

SVTH: L Vit Trin

Lp: 02H2A

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- Nm 1998, cc tc gi M. K. Krokida, V. T. Karathanos v Z. B. Maroulis c nghin cu: S ph thuc ca cc iu kin sy thng hoa vo tnh co rt v thm nc tr li ca cc sn phm nng nghip. Nghin cu ny ni ln s khc nhau v tnh co rt, tnh thm nc tr li ca to, c rt, khoai ty, chui khi c sy thng hoa cc nhit v p sut khc nhau [14]. - Nm 2004, cc tc gi Yeu-Pyng Lin, Jen-Horng Tsen, V. An-Erl King c nghin cu: S ph thuc ca bc x hng ngoi i vi qu trnh sy thng hoa khoai lang. Trong ti ny cc tc gi cho thy vic kt hp bc x hng ngoi vo sy thng hoa lm gim thi gian sy khi so snh vi cc phng php sy khc nh: sy bng khng kh, sy thng hoa [13]. - Nm 2006, cc tc gi Luanda G. Marques, Maria C. Ferreisa, Jos T. Freice c nghin cu: Qu trnh sy thng hoa acerola (Malpighia glabra L.). Trong cc tham s nh: m sn phm, hm lng vitamin C, s co rt ca sn phm c kim tra trong qu trnh sy thng hoa qu acerola. Cc tc gi cng nghin cu n s khc nhau ca thi gian sy cng nh cc tham s trn ca cc mu c lm lnh ng vi cc phng php khc nhau nh: lm lnh trong nit lng, nit kh v ca cc mu c kch thc khc nhau [15]. Ring nc ta cng c nhiu ti nghin cu khoa hc v sy thng hoa p dng vo cc sn phm thc phm nh: - Ch bin cm gc sy thng hoa ca TS. Trn c Ba v tp th, trng i hc dn lp Vn Lang [29]. - Sy thng hoa cc c sn ca V Thy Thy Chung, lp K7, trng i hc dn lp Vn Lang [28]. - Nghin cu sy thng hoa c sn c c tnh sinh hc v thit k lp t my sy thng hoa pilot BS-2, Nghin cu trin khai sy thng hoa nc ct da ca V Duy Khm,lp K5, trng i hc dn lp Vn Lang [28]. - Nghin cu sy thng hoa tm, nghu ca Trnh Th Hng Thanh, lp K6, trng i hc dn lp Vn Lang [28]. - Nghin cu cc yu t nh hng n qu trnh ng kh rau qu ca Hong N Thu San, lp 99H2A, trng i hc Bch khoa Nng. Trn th gii c rt nhiu cng ty nhiu nc khc nhau p dng cng ngh sy thng hoa vo sn xut. V d: Trung Quc c cc cng ty: Beijing Yshiyuan Food Co., Ltd; Ningbo J&D International Trade Co., Ltd; Shandong Tonghai Food Co., Ltd; Damin Foodstuff (Zhangzhou) Co., Ltd; Xinghua Natural Foods Co., Ltd; Sinochem Qingdao Co., Ltd; Oriental (Zhangzhou) Co., Ltd; Qingdao Farmland Food Co., Ltd; Qingdao Xinmeixiang Foods Co., Ltd; Guangzhou Abana Co., Ltd; SVTH: L Vit Trin Lp: 02H2A

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Thi Lan c cc cng ty: Cha-Liang Co., Ltd; Thiptipa Co., Ltd; Philippines: Amley Food Co., Ltd; Taiwan: Howenia Enterprise Co., Ltd [27]. nc ta hin nay ch c cng ty Asuzacfoods l cng ty duy nht s dng cng ngh sy thng hoa trn mt hng rau qu [24] v cng ty Acecookvietnam vi nhng gi sp chit xut t tht v cc loi rau c qua cng ngh sy thng hoa [25]. Cc sn phm sy thng hoa rau qu hin nay trn th trng th gii kh phong ph. V d : khoai lang tm, xoi, to, khoai ty, du ty, nm, bp, chui, u nnh, khoai m, b ng, cn ty, nho, ci bp, ht d, gng, khoai s, hnh ty, ti, ht ng cc, u H Lan, b xi, vin rau, u h, qu kiwi[30]

Khoai lang tm FD

Qu o FD

Bp FD

Chui FD

Qu kiwi FD

Xoi FD

u h FD

Vin rau FD

Khoai ty FD

Da FD

Du ty FD

To FD

Nm FD SVTH: L Vit Trin

u H Lan FD

B xi FD

Mitchuba FD Lp: 02H2A

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B ng FD

u nnh FD

To gai FD

Rau Spinage FD

Hnh 1.9: Cc sn phm sy thng hoa (FD) [21], [23] Nht Bn kt qu s pht trin ca ngnh cng nghip thc phm v ung s dng khoai lang tm l hin nay c nhiu sn phm thc phm qua ch bin c bn trong cc ca hng ti cc nh ga, phi trng, khu du lch KyushuOkinawa [16].

Hnh 1.10: Cc sn phm ung ng dng t khoai lang tm [16] Ring i vi khoai lang tm nc ta th ch yu hin nay c trng xut khu dng c ti sang cc th trng nh Nht Bn v Ty u.

Hnh 1.11: Thu hoch khoai lang tm trang tri anh Ba Ho [26] u im ca thc phm sy thng hoa so vi cc loi thc phm sy bng phng php khc: SVTH: L Vit Trin Lp: 02H2A

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- Thc phm thng hoa c th ct gi bnh thng trong nhiu nm iu kin kh hu nhit i. - Khi lng sn phm nh nn thun tin trong vn chuyn. - Khi hon nguyn tr li th thc phm ng kh phc hi nguyn vn tnh cht ti sng, mu sc v c hng v ban u. - Sn phm sau khi sy thng hoa c cht lng cao, khng lm bin cht albumin. - Khng xy ra cc qu trnh vi sinh, bo ton lng vitamin trong qu trnh sy rau qu. - Gi nguyn th tch ban u ca vt liu nhng xp hn nn d hp ph nc tr li dng ban u. - Kt cu ca sn phm tt, t b co ngt v khng c hin tng cng v - Thi gian sy nhanh. - Thi gian bo qun lu di nu thc phm cha trong bao b chng m v khng ph thuc vo iu kin bn ngoi. Nhc im ca phng php sy thng hoa: - Gi thnh thit b cao, tiu hao nng lng ln nn gi thnh sn phm cao. - Vn hnh phc tp, thao tc k thut cao. Qua phn tch trn ta thy sy thng hoa l mt phng php sy c rt nhiu u im. y l mt trong nhng phng php tt nht i vi cc sn phm sy kh. Nhng gi thnh t chnh l nguyn nhn ch yu khin t trc n nay phng php ny ch c p dng sy cc loi thc phm t tin v khng th sy bng phng php khc. Tuy nhin, i sng ca con ngi ngy cng c nng ln theo m nhu cu c s dng nhng loi thc phm c cht lng cao v an ton cho sc kho ngy cng tr nn ph bin. Chnh v vy m em mnh dn p dng phng php ny trong nghin cu ca mnh vi mong mun c vn dng nhng k thut hin i c hc to ra nhng sn phm mi p ng th hiu ca ngi tiu dng; m rng vic s dng cc thit b phc v cho nhu cu hc tp v nghin cu.

CHNG II

I TNG V PHNG PHP NGHIN CUSVTH: L Vit Trin Lp: 02H2A

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2.1. i tng nghin cu: 2.1.1. Nguyn liu: Nguyn liu nghin cu l khoai lang tm (purple sweet potato) c ngun t Lt mua ti ch Ha Khnh- Nng. Chn nguyn liu vi nhng tiu chun nh sau: - Mu: v v bn trong c mu tm. - Hnh dng b ngoi: da trn, c khng b Hnh 2.1: Khoai lang tm lm i try xc, khng su bnh, cha mc mm. tng nghin cu 2.1.2. Ho cht: - Dung dch Feling A, Feling B, dung dch st (III) sunfat, dung dch KMnO4 0,1N, NaOH m c. - Cn tuyt i, HCl m c, dung dch m pH = 1 (KCl v HCl), pH = 4,5 (CH3COONa v HCl). - H2SO4 c, NaOH 40%, dung dch NaOH 0,1N, dung dch chun H2SO4 0,1N, hn hp cht xc tc CuSO4: K2SO4 (1:9). - Ete du ha. - Dung dch KOH 10%, dung dch CH3COOH 2%. - Dung dch Hg(NO3)2 hay Hg(CH3COO)2 nng 10-2M - Kaliclorua bo ha - Axit clohydric 1:1 (~5M) - Dung dch chun: Dung dch gc Zn2+ = 1g/L, Cu2+ = 1g/L, Cd2+ = 1g/L, Pb2+ = 1g/L. 2.1.3. Thit b: - My phn tch m MB45 Thy in. - T lnh ng MDF-382 ca hng SANYO - Nht Bn. - My sy ng kh ALPHA 2-4 ca hng CHRIST c. - My ng gi chn khng t ng J-V002 ca hng New Diamond Vac - Triu Tin. - My ly tm MIKRO 22R ca hng Hettick Zentifugen - c. - My so mu 6305 ca hng Jenway. - My so mu UV/VIS - DR 2400 ca hng HACH M. - My cc ph xung vi phn CPA - HH3, Vin Khoa hc v k thut Vit Nam.

SVTH: L Vit Trin

Lp: 02H2A

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Hnh 2.2: My phn tch m MB45

Hnh 2.3: My ng gi chn khng t ng J-V002

Hnh 2.4: T lnh ng MDF-382

Hnh 2.5: My ng kh ALPHA 2-4

Hnh 2.6: My so mu 6305

Hnh 2.7: My ly tm MIKRO 22R

SVTH: L Vit Trin

Lp: 02H2A

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Hnh 2.8: My so mu UV/VIS - DR 2400

Hnh 2.9: My cc ph xung vi phn CPA - HH3

2.1.4. Bao b bao gi sn phm: S dng loi bao b PE. Kch thc 18 x 26cm. 2.2. Phng php nghin cu: 2.2.1. Phng php vt l (xc nh m): S dng my phn tch m. Nguyn l: My phn tch m bng n halogen s dng xc nh hm lng m ca bt k cht no cn phn tch. Hot ng ca thit b da trn nguyn tc o trng lc bng nhit: khi bt u o my s xc nh khi lng mu trc ri nhanh chng lm nng bng b phn lm nng ton b bng halogen v lm bay hi m. Trong sut qu trnh phn tch, thit b tip tc xc nh khi lng ca mu v hin th kt qu. Sau khi hon tt lm kh sn phm, kt qu hin th gm: thnh phn phn trm m, phn trm cht rn, khi lng hay phn trm khi lng thu c. Dng sc nng lm bay ht hi nc trong thc phm. Cn trng lng thc phm trc v sau khi sy kh, t tnh ra phn trm nc c trong thc phm. Cch tin hnh: i vi mu phn tch l khoai lang tm ti th thi mng, i vi mu khoai sau khi sy cn nghin nh. Cc mu phi cn khi lng c lp sn trong chng trnh phn tch ca my phn tch m. Sau b mu vo my, ng np li v nhn Start/Stop. Kt qu phn kt qu v tho lun. 2.2.2. Phng php ho sinh (xc nh anthocyanin, gluxit tng, ng t do, protit, lipit, x, tinh bt): Xc nh anthocyanin bng phng php pH vi sai [3]: Nguyn l: Cht mu anthocyanin thay i theo pH. Ti pH = 1 cc anthocyanin tn ti dng oxonium hoc flavium c hp th cc i, cn pH = 4,5 th chng li SVTH: L Vit Trin Lp: 02H2A

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dng carbinol khng mu. o mt quang ca mu ti pH = 1 v pH = 4,5 ti bc sng hp th cc i so vi hp th ti bc sng 700 nm. Da trn cng thc ca nh lut Lambert-Beer: lg Trong : lgI0 = .l.C I

I0 c trng cho mc I

nh sng yu dn khi i qua dung dch hay cn gi l mt quang, k hiu l A, I: cng nh sng khi i qua dung dch, I0: cng nh sng chiu vo dung dch, C: nng cht nghin cu, l: chiu dy ca lp dung dch m nh sng i qua, pH = 1 : h s hp th phn t. Hm lng anthocyanin xc nh theo cng thc:A.M .K .V a= , g (*) .l

pH = 4,5

Trong : A = (Amax_pH=1 A700nm_pH=1) (Amax_pH=4,5 A700nm_pH=4,5), vi Amax, A700nm: hp th ti bc sng cc i v 700nm pH = 1 v pH = 4,5; a: lng anthocyanin, g; M: khi lng phn t ca anthocyanin, g/mol; l: chiu dy cuvet, cm; K: pha long; V: th tch chit, l. T tnh ra c hm lng anthocyanin theo phn trm: % anthocyanin ton phn = m(100 w). 10 2 .100 % (**)a

Hnh 2.10: Mu ca anthocyanin trong khoai lang tm ti pH = 1 v pH = 4,5

Trong : a: lng anthocyanin tnh c theo cng thc (*), g; m: khi lng nguyn liu ban u, g; w: m nguyn liu, %. Cch tin hnh: - Xc nh m v chit tch anthocyanin th: Xc nh m bng my phn tch m. Qu trnh chit tch anthocyanin c thc hin theo s sau:

i vi nguyn liu ti: Nguyn liu ti SVTH: L Vit Trin Lp: 02H2A

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Ra sch bng nc, ro Cn 10g/gi lnh ng -20 0C Nghin nh Ngm trong dung mi (cn : nc t l 1 : 1 c 1% HCl) Lc qua bng thm nc Ly tm, o th tch dch trong dng lm mu phn tch i vi nguyn liu kh: Nguyn liu kh Xay nh, cn Thm nc tr li mu ti ban u Ngm trong dung mi (cn : nc t l 1 : 1 c 1% HCl) Lc qua bng thm nc Ly tm ly dch o th tch dch thu c - Xc nh bc sng hp th cc i: Ly 5 ml dch chit pha long vi dung dch m pH = 1,0 trong bnh nh mc 25 ml, qut ph hp th trong vng kh kin ( = 450 720) trn my quang ph UV VIS. Tnh ton kt qu phn kt qu v tho lun. Xc nh gluxit tng, ng t do, tinh bt bng phng php Bertrand [9]: SVTH: L Vit Trin Lp: 02H2A

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Nguyn l: - Gluxit trc tip kh oxy c tnh cht kh Cu(OH)2 mi trng kim mnh, lm cho c kt ta di th Cu2O mu gch. S lng Cu2O tng ng vi s lng gluxit kh oxy. RCHO + 2Cu(OH)2 = RCOOH + Cu2O + 2H2O - Cu2O c tnh kh oxy, tc dng vi mui st ba (Fe 3+) lm cho mui ny chuyn thnh mui st hai (Fe2+) trong mi trng axt. Cu2O + Fe2(SO4)3 + H2SO4 = 2CuSO4 + H2O + 2FeSO4 - FeSO4 c tnh kh oxy c tc dng vi KMnO4 l cht oxy ha, do dng KMnO4 chun FeSO4 mi trng axt. 10FeSO4 + 8H2SO4 + KMnO4 = K2SO4 + 2MnSO4 + 5Fe2(SO4)3 + 8H2O T s ml KMnO4 0,1N dng chun FeSO4 hnh thnh tra bng c s mg ng glucoza, maltoza, lactoza, hoc saccaroza nhn vi h s pha long ta c hm lng ng trong 100g thc phm. Cch tin hnh - Chun b dung dch phn tch: Cn khong 2g nguyn liu nghin nh cho vo bnh nn vi nc ct v 10ml HCl m c. Tin hnh thu phn trong ni cch thy n khi th ht tinh bt bng dung dch it (khng thy xut hin mu xanh khi cho mt git dch thy phn tc dng vi mt git dung dch it). Lm ngui ri trung ha axt bng NaOH m c ri NaOH 1% cho n pH = 5,5 6,0 (th bng giy qu). Lc u v lc thu ly dung dch cho vo bnh nh mc 100 ml. Tin hnh kh tp cht bng cch cho 5 ml dung dch km feroxyanua 15%, lc u, yn 2-3 pht. Tip theo thm 5 ml km axetat 30%, lc mnh. Cho thm nc ct va 100 ml, lc u v lc qua giy lc c dung dch phn tch. - Xc nh hm lng ng: Cho vo bnh nn 250ml 10ml dung dch Feling A, 10ml dung dch Feling B, 10ml mu dch chun b. un si hn hp trong 3 pht, sau khi si dung dch phi c mu xanh bic. lng yn, lc tch phn dch lng mu xanh sao cho lng kt ta Cu2O cn li phn ln nm trong bnh nn. Cho nc si vo bnh nn v tip tc gn lc vo phu cho n khi nc trong bnh ht mu xanh. Trong qu trnh gn lc ch trnh ng kt ta ri vo phu v lun gi mt lp nc un si trn mt kt ta trong bnh nn v trn phu. Ho tan Cu2O trong bnh nn v trong phu bng st (III) sunfat trong mi trng H2SO4. Lc v ra ht kt ta bm trn giy lc thu c dung dch. Chun dung dch thu c bng dung dch KMnO4 0,1N cho ti khi xut hin mu hng nht bn vng trong 15 giy. c s ml KMnO4 0,1N dng v em tra bng 3 [tr

SVTH: L Vit Trin

Lp: 02H2A

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225, 9] c lng ng glucose, lactose, maltose hoc ng nghch o theo yu cu. Tnh ton kt qu phn kt qu v tho lun. Xc nh protit bng phng php Kjeldahl [9]: Nguyn l: V c ha thc phm bng H2SO4 m c v cht xc tc. Dng mt kim mnh (NaOH hoc KOH) y NH3 t mui (NH4)2SO4 hnh thnh ra th t do. nh lng NH3 bng mt axt. Cch tin hnh: Cn tht chnh xc khong 0,5g nguyn liu cho vo bnh Kjeldahl vi 10ml H2SO4 m c v khong 5g cht xc tc CuSO4:K2SO4 (1:9). nghing bnh Kjeldahl trn bp v un t t. Nu thc phm cha nhiu nc, un cho n khi nc bc hi v hnh thnh khi trng SO 2. Khi bt tan, un si cho n khi dung dch trong sut khng mu hoc c mu xanh l ca CuSO4. ngui, chuyn dung dch v c ho vo bnh cu ca my ct m, ra bnh Kjeldahl 2 ln vi nc ct nc ra chuyn c vo bnh cu. Trung ho bng NaOH 50% vi ch mu metyl da cam. Ct ko hi nc v nh lng gin tip NH3 bng cch NH3 ho tan vo mt th tch H2SO4 0,1N xc nh, sau khi ct ko hi nc ht NH3 chun H2SO4 tha bng NaOH 0,1N. Tnh ton kt qu phn kt qu v tho lun. Xc nh lipit bng phng php Soxlhet [9]: Nguyn l: Dng ete nng ha tan tt c cht bo t do trong thc phm. Sau khi bay hi ht ete, cn cht bo cn li v tnh ra hm lng lipit trong 100g thc phm. Cch tin hnh: Sy kh nguyn liu n khi lng khng i. Cn tht chnh xc 5g nguyn liu c nghin nh, cho vo bao giy c sy kh. Ch gi mu phi c b rng nh hn ng knh ng tr v chiu di ngn hn chiu cao ng chy trn. t bao giy vo tr chit. Lp tr chit vo bnh cu v gn ng sinh hn. Bnh cu c sy n khi lng khng i ngui trong bnh ht m v cn bit khi lng. Qua u ng sinh hn dng phu cho dung mi vo tr chit sao cho mt lng dung mi chy xung bnh cu v mt lng trn phu chit cn ngp mu. Dng bng lm nt u ng sinh hn. M nc lnh vo ng sinh hn. t bnh cu vo ni cch thy, iu chnh nhit sao cho chu k trch ly hon lu ca dung mi t t 5 8 ln trong mt gi. Chit trong 8 12 gi cho n khi trch ly hon ton ht cht bo. Th bng cch ly vi git ether cui ng xiphng nh ln giy lc, dung mi bay hi khng li vt du loang th kt thc. Cho ether chy SVTH: L Vit Trin Lp: 02H2A

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xung ht bnh cu. Ly bnh cu ra t vo t hotte cho bay hi ht ether ri cho vo t sy nhit 100 105 0C trong 1,5h. ngui trong bnh ht m, cn xc nh khi lng. Tnh ton kt qu phn kt qu v tho lun. Xc nh hm lng x: Nguyn l: Xenluloza l cht x b cn li sau khi cc gluxit khc nh tinh bt, lignin v cc sc t, cc tp cht b thy phn bi axt v kim. Sau khi lc, ra sch x b ny, sy kh n khi lng khng i v nung thnh tro, tr hm lng tro tnh c lng xenluloza trong mu. Cch tin hnh: Khoai lang tm c nghin mn, sy n khi lng khng i. Cn 5g cho vo bnh tam gic 500ml c lp ng sinh hn kh. Cho vo 50ml nc ct, thm vo 10ml dung dch HCl m c, un si k cho n khi tinh bt b thy phn hon ton, th im kt thc thy phn bng cch chm mt git dung dch thy phn ln lam knh, nh vo vi git thuc th Liugon n mt mu xanh. Ly bnh tam gic ra khi bp, lc qua giy lc ly b. Ra b nhiu ln bng nc ct. Dng bnh tia nc chuyn ht b vo li bnh tam gic dng trn. Thm vo bnh cu 10ml KOH 10%. t bnh cu ln bp, un si 20 30 pht na. Ly ra lc qua giy lc khng tro, ly b. Ra b nhiu ln bng nc ct. Sau ra 3 ln bng dung dch CH3COOH 2% ri bng cn tuyt i. Sau khi ra, b c mu trng trong l c. t giy lc v b vo a Petri ri a vo t sy 105 0C trong 2h, ly ra ngui trong bnh ht m v cn. a giy lc v b vo chn nung, chn c nung trong l nung 400 500 0 C, ngui v cn trn cn phn tch. Tin hnh nung b trong l nung nhit 450 0C n khi lng khng i. Ly ra ngui trong bnh ht m v cn chn nung cha tro sau khi nung. Tnh ton kt qu phn kt qu v tho lun. 2.2.3. Phng php ho phn tch my (xc nh hm lng cc kim loi nng): Nguyn l: Cc kim loi Zn, Cd, Pb, Cu c lm giu trn in cc than siu vt hay than thy tinh vi mng thy ngn Insitu, tc l mng thy ngn c kt ta ln b mt in cc ng thi vi cc nguyn t cn xc nh. Dng o c

SVTH: L Vit Trin

Lp: 02H2A

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trong dng xung vi phn t l thun vi nng cc kim loi quan tm trong dung dch. Cch tin hnh: - Ph mu: c c mu dung dch phn tch chng ti ly 1g khoai lang tm ti nghin nh cho vo bnh tam gic, thm vo 5 ml dung dch H2SO4 m c v 5 ml dung dch HNO3 m c. t bnh tam gic ln bp in un si. Qu trnh ph mu c tin hnh trong t ht kh c cho n khi dung dch tr nn trong th ngng un, ngui hn ri ly ra lm dung dch phn tch. - Phn tch mu trng: Ly 40 ml dung dch nc ct vo bnh in phn. Thm vo : - 0,1 ml dung dch Hg2+ - 0,1 ml dung dch HCl - 0,1 ml dung dch KCl bo ho Tin hnh in phn iu kin sau: - Phng php: xung vi phn (DDP) - Th ban u (U1): -1,1V - Th cui (U2): 0,2V - Th in phn (Ustriping): -1,1V - Thi gian in phn: 120s - Thi gian ngh (Urest): 10s Cc thng s khc c mc nh (khng nn thay i). Ph thu c khng c cc pic l (tr pic thu ngn ti th ~ 0,1-0,2V), c th bt u php phn tch mu thc. Nu c, cn tr ng nn khi tnh ton kt qu o. - Phn tch mu thc: a. in phn: - i vi phn tch ch, ng, cadimi: - Thay nc ct bng mu thc cn phn tch, tin hnh cc bc nh vi mu trng. - Ring thi gian in phn, c th thay i t 120-300s tu thuc vo nng mu (vi mu c nng cht cn phn tch thp, cn tng thi gian in phn). - Th nh pic: + ng: -0,3V 0,05V + Ch: -0,4V 0,05V + Cadimi: -0,6V 0,05V + Km: -0,90V 0,05V SVTH: L Vit Trin Lp: 02H2A

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Ngoi cc bc in phn nh trn, trong dung dch phn tch cn cho thm 0,1 ml CH3COONH4 12M. Nng mu c xc nh bng phng php thm chun. Cc bc thm chun c tin hnh nh sau: b. Thm chun: - nh bng in cc bng giy lc. - Thm trc tip 0,1 ml mi dung dch chun kim loi cn phn tch vo dung dch va in phn. - Ghi ph theo cc bc nh in phn mu. Kt qu c trnh by phn kt qu v tho lun. 2.2.4. Phng php cm quan: nh gi mu sc, kh dn, mi v ca sn phm sy. Mu sc, hnh dng sn phm l mt trong nhng ch tiu hng u i vi sn phm sy v n nh hng ln n gi tr cm quan, th hiu ca ngi tiu dng. tin hnh nh gi cm quan dng php th th hiu cho im theo thang cng v y l php th cho ta nh gi c mc a thch ca ngi tiu dng v sn phm khch quan nht. 2.2.5. Phng php ton hc: - Tin hnh cc th nghim theo phng n quy hoch trc giao cp I TYT 2 3 nghin cu nh hng ca ba yu t: nhit lnh ng v nhit sy, thi gian sy n cht lng sn phm vi 2 hm mc tiu: hm lng anthocyanin v m sn phm. - Ti u ha thc nghim. Cc bc tin hnh ca phng php TYT 2k: - Chn yu t nh hng. - Chn mc cc yu t. - Xy dng 2k th nghim cn thit. - Tin hnh lm th nghim theo ma trn. - Chn dng phng trnh hi quy. - Kim tra ngha h s b. - Kim tra tng thch gia phng trnh hi quy v thc nghim. - Vit phng trnh hi quy. Quy hoch phng n ti u: - Dng cng c Tools - Solver (chc nng m rng ca Exel) tm gi tr ti u cho tng hm mc tiu. - Dng phng php thot ly khi vng cm (gii vi ngn ng lp trnh Pascal) tm iu kin cng ngh ti u ca hm chp a mc tiu m v hm lng anthocyanin. SVTH: L Vit Trin Lp: 02H2A

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CHNG III

KT QU V THO LUNSVTH: L Vit Trin Lp: 02H2A

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3.1. Xc nh thnh phn ha hc ca khoai lang tm: Ty thuc vo ngun gc v chng loi khoai lang tm m thnh phn ha hc c th dao ng khc nhau. Do nguyn liu mua v lm th nghim c xc nh mt s ch tiu ban u nh: m, anthocyanin, protein, gluxit, lipit, x, cc kim loi nng. 3.1.1. Xc nh m: Mu sau khi chun b nh phn 2.2.1 chng 2 c xc nh m 3 ln trn my phn tch m ly kt qu trung bnh. Kt qu c th hin bng 3.1. Bng 3.1: Kt qu o m ca nguyn liu Ln o m, % Ln 1 67,85 Ln 2 68,05 Ln 3 67,68 Trung bnh 67,86

3.1.2. Xc nh anthocyanin bng phng php pH vi sai: Sau khi tin hnh qut mt quang ca dung dch cha anthocyanin cc bc sng t 400-700nm trn my so mu UV/VIS DR 2400 chng ti thu c kt qu hnh 3.1.

Mt quang (Abs)0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 4.5 5 5.5 6 6.5 7

7.5 (nm)

Hnh 3.1: th xc nh bc sng cc i ca anthocyanin trongkhoai lang tm

SVTH: L Vit Trin

Lp: 02H2A

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Qua th cho thy ph hp th ca dch chit t khoai lang tm nm trong khong bc sng 510 540nm, v vy c th thy rng cc dch chit ca mu khoai lang tm rt giu anthocyanin. Bc sng hp th cc i ca anthocyanin trong khoai lang tm xc nh c l 524nm. Xc nh hm lng anthocyanin: o mt quang ca cc mu nghin cu ti cc bc sng hp th cc i 524nm v bc sng 700nm, pH = 1 v pH = 4,5, t p dng cng thc (*) v (**) mc 2.2.2 ta tnh c hm lng anthocyanin trong nguyn liu. Kt qu c th hin bng 3.2. Bng 3.2: Kt qu xc nh anthocyanin trong nguyn liu Mt quang, Abs Ln o Ln 1 Ln 2 Ln3 Trung bnh pH = 1 max 700nm 0,202 0,278 0,354 -0,017 -0,031 -0,045 pH = 4,5 max 700nm 0,192 0,180 0,168 0,002 0,001 0,003 Hm lng anthocyanin, % 0,058 0,06 0,062 0,06

3.1.3. Xc nh protit bng phng php Kjeldahl: Tnh kt qu: Tin hnh xc nh 3 ln ri ly kt qu trung bnh. Mi ln xc nh ly khong 0,5g nguyn liu, cch tin hnh nh mc 2.2.2 chng 2. Hm lng nit ton phn theo phn trm tnh bng cng thc: Nit ton phn (g/100g) =0,0014 ( N - n) .100 P

trong : N: s ml H2SO4 0,1N cho vo bnh nn trc kt hp vi NH3. n: s ml NaOH 0,1N dng chun H2SO4 tha. P: trng lng mu th tnh bng g. Mun tnh ra protit nhn kt qu nit ton phn vi 6,25. Kt qu c th hin bng 3.3.

Bng 3.3: Kt qu xc nh protein, nit ton phn SVTH: L Vit Trin Lp: 02H2A

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37 Ln 1 Ln 2 10 9,9 0,4654 0,03 0,188


Ln 3 10 9,84 0,4375 0,0512 0,32

Trung bnh 10 9,83 0,4720 0,0497 0,311

N, ml n, ml P, g Ni t ton phn, % Protein, %

10 9,75 0,5132 0,068 0,425

3.1.4. Xc nh gluxit tng, ng t do, tinh bt bng phng php Bertrand: Tnh kt qu: Cch tin hnh nh mc 2.2.2 chng 2, xc nh 3 ln ly kt qu trung bnh. Hm lng ng ton phn biu th bng ng glucose hoc ng nghch chuyn (g) trong 100g nguyn liu c tnh bng cng thc:X= G1.100 . pha long G.1000

trong : G1: trng lng ng nghch chuyn hoc ng glucose (mg) tng ng vi s ml KMnO4 0,1N c bng 3 [tr 225, 9]. G: trng lng nguyn liu cn lc u, tnh bng g. 1000: chuyn t mg sang g. Lng tinh bt = lng glucose x 0,9. Kt qu c th hin bng 3.4. Bng 3.4: Kt qu xc nh gluxit tng, ng t do v tinh bt Ln 1 G, g V KMnO4, ml G1, mg Gluxit tng, % ng t do, % Tinh bt, % 2,0033 17,9 60,67 29,19 2,92 26,27 Ln 2 2,0611 17,1 57,67 28,78 3,04 25,74 Ln 3 2,0038 18,5 63 29,36 2,86 26,5 Trung bnh 2,0227 17,83 60,45 29,11 2,94 26,17

3.1.5. Xc nh hm lng lipit bng phng php Soxlhet: Tnh kt qu: SVTH: L Vit Trin Lp: 02H2A

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Sau khi tin hnh xc nh 3 ln nh mc 2.2.2 chng 2 chng ti ly kt qu trung bnh tnh hm lng lipit c trong nguyn liu. Hm lng phn trm cht bo tnh theo cng thc: X=M1 - M 2 .100 , % m

trong : M1: khi lng bnh cu, g M2: khi lng bnh cu v lipit sau khi trch ly v sy kh, g m: khi lng mu ban u, g Kt qu c th hin bng 3.5. Bng 3.5: Kt qu xc nh lipit Ln 1 m, g M1, g M2, g X, % 4,5862 56,9904 57,0023 0,26 Ln 2 4,3904 65,0795 66,0684 0,24 Ln 3 4,6883 60,7294 62,0575 0,28 Trung bnh 4,55496 60,9331 61,7094 0,26

3.1.6. Xc nh hm lng x: Tnh kt qu: Cch tin hnh nh mc 2.2.2 chng 2, xc nh 3 ln sau ly kt qu trung bnh tnh hm lng x c trong nguyn liu. Lng x c trong mu tnh theo cng thc: m - m 2 - m3 .100 , % X= 1 m trong : m1: khi lng b sau khi sy, g m2: khi lng tro v chn nung sau khi nung, g m3: khi lng chn nung, g m: khi lng mu, g Kt qu c th hin bng 3.6.

Bng 3.6: Kt qu xc nh x

SVTH: L Vit Trin

Lp: 02H2A

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39 Ln 1 Ln 2 2,0611 0,8547 21,6915 20,8751 1,4


Ln 3 2,0038 0,8482 21,1105 20,8876 1,44

Trung bnh 2,0227 0,8473 20,4454 19,8304 1,42

m, g m1, g m2, g m3, g X, %

2,0033 0,8390 18,5342 17,7285 1,42

3.1.7. Xc nh hm lng cc kim loi nng: Tin hnh phn tch cc kim loi nng theo qui trnh nh mc 2.2.3 chng 2. Trong cc kim loi Zn, Cd, Pb, Cu c xc nh trn my cc ph xung vi phn CPA-HH3. Kt qu c th hin bng 3.7. Bng 3.7: Kt qu xc nh kim loi nng Tn ch tiu Zn Cd Pb Cu n v mg/kg mg/kg mg/kg mg/kg Thit b th Cc ph CPA-HH3 Cc ph CPA-HH3 Cc ph CPA-HH3 Cc ph CPA-HH3 Kt qu 8,637 0,012 0,482 1,420

Theo kt qu kho st cho thy hm lng mt s cc kim loi nng (Zn, Pb, Cu, Cd) trong khoai lang tm nm di mc gii hn ti a cho php theo quyt nh s 867/ 1998/ Q-BYT ca B Y t (ph lc 2). Thnh phn ho hc ca nguyn liu c tng hp li bng 3.8.

Bng 3.8: Kt qu tng hp thnh phn ha hc ca khoai lang tm trong 100g nguyn liu ti SVTH: L Vit Trin Lp: 02H2A

n tt nghip

40


Thnh phn ho hc Nc Anthocyanin Protein Glucid Lipit X Zn Kim loi nng Cd Pb Cu Cc thnh phn khc Tng

Hm lng 67,86 0,06 0,311 29,11 0,26 1,42 0,8637 0,0012 0,0482 0,1420 0,978 100

n v g g g g g g mg mg mg mg g g

Nhn xt: Theo kt qu kho st cho thy trong khoai lang tm c cha nhiu thnh phn dinh dng. Trong , hm lng anthocyanin xc nh c l kh cao khi so snh vi cc loi khoai lang khc (0,06%). Ngoi ra, hm lng cc kim loi nng cng nm di mc gii hn ti a cho php theo quyt nh s 867/ 1998/ Q-BYT ca B Y t. 3.2. Nghin cu sn xut khoai lang tm sy bng phng php sy thng hoa: 3.2.1. Nghin cu la chn qui trnh x l nguyn liu trc khi sy thng hoa: Trong qu trnh x l nguyn liu trc khi sy thng c cc khu nh: chn hp, x l ha cht. y l nhng nhn t chnh nh hng n hiu qu sy. Qu trnh chn hp em li nhng bin i ha l c li cho s thot m trong nguyn liu. Di tc dng nhit trng thi keo bin i, m thc vt mm ra, t bo trng n, khng kh thot ra, cht nguyn sinh ng t tch ra khi mng t bo, lm thm ht ca t bo tng ln. Do vy khi sy nc thot ra d dng. i vi rau qu giu gluxit qu trnh chn hp lm tng xp, i vi rau qu c lp sp mng lm mt lp sp to ra vt nt nh trn b mt. Ngoi ra qu trnh chn hp cn c tc dng tiu dit vi sinh vt, v hot cc enzym. Nhng ha cht thng s dng trong x l nguyn liu l: axit xitric, axit sunfur, mui sunfit, cht to nh tng (monostearat, glyxerin, albumin), CaCl2. Axit xitric c tc dng lm km hm s bin mu phi enzym. Axit sunfur, mui SVTH: L Vit Trin Lp: 02H2A

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41


sunfit c tnh kh mnh, tc dng vi nhm hot ng ca enzym oxy ha (ascobinaza, peroxidaza) lm chm cc phn ng sm mu, ngn nga s to thnh melanoidin, n nh vitamin C. Cht to nh tng c ng dng trong k thut sy mng bt, tng cht lng sn phm sy. CaCl2 lm chm li qu trnh sm mu, ngn nga hin tng nhn trong qu trnh nu chn, ci thin tc hi nguyn v tng cng ca sn phm hi nguyn (to phc pectat canxi) [6]. Tuy nhin mt tri ca cc qu trnh x l trn hoc l lm tn tht cc cht dinh dng ca nguyn liu hoc l li trong sn phm nhng thnh phn khng c li cho sc khe ca con ngi. S tn tht cc cht dinh dng c th khc nhau ng k trong cc qu trnh chun b trc khi sy, cc iu kin ca qu trnh sy thng hoa nh: nhit lnh ng, nhit sy, thi gian sy cng nh iu kin bo qun. Tuy nhin i vi rau qu s tht thot cc cht dinh dng xy ra trong qu trnh chun b thng vt xa so vi qu trnh sy. V d: tht thot vitamin C trong qu trnh chun b sy to (dng khi) l 8% do qu trnh ct gt, 6% do chn hp, 10% do qu trnh nghin pu r v 5% do qu trnh sy [6]. Do vy nghin cu la chn ra quy trnh x l hp l nhm gim ti thiu nhng tn tht dinh dng do qu trnh chun b gy ra ng thi tng hiu sut ca qu trnh sy l mt hng i cn thit. 3.2.1.1. Qui trnh 1: S qui trnh: Khoai lang tm

Ra sch ro Ct thnh khi hnh ch nht 10x10x30mm Chn Thuyt minh qui trnh: - Khoai lang tm phi t nhng tiu chun nh phn 2.1.1 chng 2. - Ra sch: nhng c khoai lang tm t tiu chun s c loi b ht t ct bm trn v c. SVTH: L Vit Trin Lp: 02H2A

n tt nghip

42


- Tip theo dng dao ct thnh khi hnh ch nht c kch thc 10x10x30mm. Qu trnh ny yu cu phi tin hnh nhanh trnh s tc dng ca cc enzyme oxy ha lm bin mu sn phm. Trong cng nghip qu trnh ny c thc hin bng my ct. - Chn: trn c s tham kho cc ti liu [13], [14] chng ti tin hnh cc th nghim kho st c th trn nguyn liu khoai lang tm. Sau khi chn xong tin hnh xc nh mt s ch tiu ca bn thnh phm nh: m, hm lng anthocyanin v nh gi cm quan. Kt qu th hin bng 3.9. Bng 3.9: Kt qu xc nh m, hm lng anthocyanin v nh gi cm quan sau chn Nhit nc chn, 0C 90 Thi gian chn, pht 3 m, % 67,65 Hm lng anthocyanin, % 0,223 nh gi cm quan

B mt ngoi kh, chn khng u. B mt ngoi kh, 90 5 67,70 0,226 chn u, mu m. B mt kh, mu 90 7 67,74 0,220 nht, qu chn. Sau khi tin hnh x l nguyn liu theo quy trnh 1 chng ti nhn thy cht mu anthocyanin tht thot vo nc chn kh nhiu. Do vy chng ti tip tc chuyn sang kho st theo qui trnh 2. 3.2.1.2. Qui trnh 2: S qui trnh: Khoai lang tm Ra sch ro Ct thnh khi hnh ch nht 10x10x30mm Hp Thuyt minh qui trnh: - Khoai lang tm lm nguyn liu cng loi vi quy trnh 1. - Ra sch: ging quy trnh 1. - Ct thnh khi hnh ch nht: ging quy trnh 1. SVTH: L Vit Trin Lp: 02H2A

n tt nghip

43


- Hp: khoai lang tm sau khi c ct thnh dng khi hnh ch nht s c hp nhng thi gian kho st khc nhau. Sau khi hp xong chng ti tin hnh xc nh mt s ch tiu ca bn thnh phm nh: m, hm lng anthocyanin v nh gi cm quan. Kt qu th hin bng 3.10. Bng 3.10: Kt qu xc nh m, hm lng anthocyanin v nh gi cm quan sau hp Nhit hi nc, 0C 100 100 100 Thi gian hp, pht 3 4 5 m, % 67,85 67,76 67,80 Hm lng anthocyanin, % 0,228 0,23 0,225 nh gi cm quan Mu cha chn, cng, b mt cn m. Mu chn, khng qu mm, b mt t. Mu qu chn, mm, mt vi mu b b.

Da vo kt qu thu c cho thy s tn tht anthocyanin khi x l theo quy trnh ny t hn so vi qui trnh 1, quan st cc hnh 3.2, 3.3 chng ta c th thy c iu ny.

Hnh 3.2: Mu khoai lang tm langchnsau hp Hnh 3.3: Mu khoai sau tm T cc kt qu kho st theo trn chng ti a ra qui trnh x l nguyn liu tt nht nh sau:

Khoai lang tm Ra sch SVTH: L Vit Trin Lp: 02H2A

n tt nghip

44 ro


Ct thnh khi hnh ch nht 10x10x30mm Hp T = 4 pht t = 100 0C Nhn xt: - Hm lng anthocyanin trong bn thnh phm sau x l xc nh c l 0,23 % tng ln vt tri hn so vi trong nguyn liu ti l 0,06 %. Nh vy qu trnh x l khng nhng v hot c cc enzym oxy ha, lm chn nguyn liu, tng hiu qu cho qu trnh sy m cn lm tng anthocyanin tng gi tr dinh dng ca sn phm. S d nh vy l do trong qu trnh x l nhit tinh bt b h ha, cc t bo b ph v to iu kin gii phng anthocyanin. 3.2.2. Nghin cu cc yu t nh hng n qu trnh sy thng hoa khoai lang tm: Vi mc ch l nghin cu nh hng ca cc yu t cng ngh n qu trnh sy thng hoa khoai lang tm chng ti tin hnh ti u ho cc thng s k thut ca cng ngh sy thng hoa bng cc th nghim. tin hnh cc th nghim kho st cc yu t nh hng n cht lng ca khoai lang tm sy ti s dng phng php ton hc v y l cng c gip chng ti gim bt s th nghim m vn c th xc nh c iu kin cng ngh thch hp. 3.2.2.1. Chn yu t nh hng v hm mc tiu: Trong cng ngh sy thng hoa cht lng sn phm chu tc ng ca nhiu yu t nhng y chng ti chn 3 yu t: - Z1: nhit lnh ng, 0C - Z2: nhit sy, 0C - Z3: thi gian sy, gi i vi sn phm sy th c rt nhiu ch s nh gi cht lng ca n nhng trong ti ny chng ti chn m v hm lng anthocyanin lm hm mc tiu: - Y1: hm mc m ca sn phm, % - Y2: hm mc tiu hm lng anthocyanin ca sn phm, %

SVTH: L Vit Trin

Lp: 02H2A

n tt nghip

45


Trong iu kin cng ngh nht nh mc tiu t ra l m sn phm cng thp cng tt v hm lng anthocyanin cng t tn tht cng tt. V vy chng ti biu din mi quan h gia cc yu t nh hng v hm mc tiu nh sau: Y1 = f( Z1, Z2, Z3) Y1 Min Y2 = f( Z1, Z2, Z3) Y2 Max 3.2.2.2. Cc bc thc hin bi ton quy hoch: Chn phng n quy hoch: xc nh hng i ca ti v nhanh chng tin ti min ti u ti chn phng n quy hoch trc giao cp I (TYT 2k) thc nghim yu t ton phn hai mc, k yu t nh hng. T qu trnh kho st v tham kho cc ti liu [13], [14], [15] chng ti chn mc quy hoch cho 3 yu t nh sau: - Nhit lnh ng (Z1): -60 -30 0C. - Nhit sy (Z2): 30 45 0C. - Thi gian sy (Z3): 6 10 gi. T chc cc th nghim trc giao cp I: Theo [1] s th nghim trong phng n l 2k = 8 (k = 3) v 3 th nghim ti tm, iu kin th nghim c ghi bng 3.11. Bng 3.11: Cc mc ca cc yu t nh hng Cc mc Mc trn (+1) Mc c s (0) Mc di (-1) Khong bin thin Z1, C -30 -45 -60 150

Cc yu t nh hng Z2, 0C 45 40 35 5

Z3, h 10 8 6 2

T cch chn phng n v iu kin th nghim, chng ti xy dng ma trn thc nghim theo bin m v tin hnh th nghim theo ma trn. Kt qu bng 3.12.

Bng 3.12: Ma trn quy hoch vi bin o TYT 23 v kt qu thc nghim STT Bin thc Bin m y1 y2

SVTH: L Vit Trin

Lp: 02H2A

n tt nghip

46 Z2, 0C 45 45 35 35 45 45 35 35 40 40 40 Z3, h 10 10 10 10 6 6 6 6 8 8 8 x1 + + + + 0 0 0


Z1, 0C 1 2 3 4 5 6 7 8 9 10 11 -30 -60 -30 -60 -30 -60 -30 -60 -45 -45 -45

x2 + + + + 0 0 0

x3 + + + + 0 0 0 4,48 3,8 5,69 4,64 5,58 3,84 7,95 4,98 4,78 4,97 4,68 0,168 0,158 0,19 0,186 0,215 0,195 0,233 0,200 0,203 0,197 0,194

Trong : - x1: nhit lnh ng, 0C. - x2: nhit sy, 0C. - x3: thi gian sy, gi. - y1: m ca sn phm, %. - y2: hm lng anthocyanin ca sn phm, %. Xy dng m t ton hc cho hm mc tiu m ca sn phm: - Chn phng trnh hi quy: Phng trnh hi quy c dng: y = b0 + b1x1 + b2x2 + b3x3 + b12x1x2 + b13x1x3 + b23x2x3 + b123x1x2x3 (3.1) trong : b0: h s hi quy. b1, b2, b3: h s tuyn tnh. b12, b13, b23: h s tng tc i. b123: h s tng tc ba. - Tnh h s b: V phng n c chn l quy hoch trc giao cp I, theo [1] cc h s b trong phng trnh hi quy (3.1) c xc nh theo cng thc sau:1 bj = N

( xu =1

N

ju

yu )

vi: j = (1, k)

SVTH: L Vit Trin

Lp: 02H2A

n tt nghip 1 bij = N

47iu


( xu =1 N u =1

N

x ju ) yu x ju xku ) yu

i j = (1, k) i j k = (1, k)

(3.2)

bijk =

1 N

( x

iu

T s liu thc nghim bng 3.12, p dng cng thc (3.2) ta tnh c cc h s b: b0 = 5,12 b12 = - 0,2 b1 = 0,805 b2 = - 0,695 b3 = - 0,4675 b13 = - 0,3725 b23 = 0,1825 b123 = 0,1075

- Kim nh mc ngha ca cc h s b trong phng trnh 3.1: Cc h s c kim nh theo chun Student (t)tj = bj Sb j

(3.3)

- So snh tj vi tp(f). trong : tp(f) l chun Student tra bng ng vi xc sut tin cy p v bc t do f, f = n0 1 bj: h s trong phng trnh hi quy chn. Sbj: lch ca cc h s bj Nu tj > tp(f) th h s bj c ngha. Nu tj < tp(f) th h s bj b loi khi phng trnh. - Xc nh Sbj: trong : S2 th

S bj =

2 S th N

(3.4)0 u

l phng sai ti hin =

( yu =1

n

- y0 )2

(3.5)

f

f: s bc t do, f = m -1 = 2. m: s th nghim ti tm, m = 3. xc nh phng sai ti hin ti dng 3 th nghim ti tm: y = 4,780 1

; y2 = 4,97

0

; y = 4,68

0 3

vi

y0 =

yu =1

3

0 u

= 4,81

3

Thay cc gi tr vo cc cng thc (3.4), (3.5) ta c: SVTH: L Vit Trin Lp: 02H2A

n tt nghipS 2 = 0,0217; thS2 = bj

48


0,002713; S bj = 0,052082 kim nh theo chun Student (t) ta thay h s bj, Sbj vo cng thc (3.3) ta c cc gi tr tj: t0 = 98,30652 t12 = 3,840098 t1 = 15,4564 t13 = 7,152183 t2 = 13,34434 t3 = 8,97623 t23 = 3,50409 t123 = 2,064053

Tra bng 2, [ 1, tr 152] ta c tp(fth) = t0,05(2) = 4,3 Do t12 < tp(fth), t23 < tp(fth), t123 < tp(fth) nn cc h s b12, b23, b123 loi ra khi phng trnh. Vy phng trnh hi quy ca m sn phm c dng: y1 = 5,12 + 0,805x1 - 0,695x2 - 0,4675x3 - 0,3725x1x3 (*) - Kim nh s ph hp ca phng trnh hi quy vi thc nghim: S tng thch ca phng trnh vi thc nghim c kim nh theo chun Fisher (F).2 Sd F= 2 Sth

(3.6)u

2 Trong : Sdl phng sai d =

(Yu= 1

8

- Yu ) 2

(3.7)

f d

Yu: gi tr thc nghim th nghim th u c ghi bng 3.12. Yu : gi tr theo phng trnh ng vi iu kin th u. f d = N- l = 8 - 5 = 3, N: s th nghim, l: s h s c ngha trong phng trnh hi quy. 2 Thay cc gi tr vo cng thc (3.6), (3.7) ta c: S d = 0,2263 ; F = 10,42857 Tra bng 4 [1] ta c F1-p(f1, f2) = F0,95(3,2) = 19,2 vi f1= N 1 = 3, f2 = m-1 =2 Ta c F < F1-p. Vy m hnh ton hc chn ph hp vi thc nghim. Phn tnh ton xem mc 3.1 ph lc 3. Phng trnh hi quy trn c dng tuyn tnh, c 3 yu t l nhit lnh ng, nhit sy, thi gian sy u nh hng n m ca sn phm. Vy phng trnh hi quy ny m t c l trong cc khong ca cc yu t chn khi gim nhit lnh ng, tng nhit sy, tng thi gian sy th m ca sn phm s gim. iu ny c th gii thch nh sau: khi nhit lnh ng cng thp tc l mc lnh ng cng su s lm cho nc trong nguyn liu chuyn thnh trit SVTH: L Vit Trin Lp: 02H2A

n tt nghip

49


hn do sau giai on sy chnh, m cn li s t hn, cn khi sy nhit cng cao v thi gian sy cng di th n nhit thng hoa cp cho sn phm cng ln do vy m trong bn sn phm s c tch ra nhiu hn. - Biu din cc yu t tng tc i vi m trn th Matlab: biu din mi quan h bng th thng qua phng trnh hi qui ta phi bin i v dng cha m ha nh sau: Thay cc gi tr: X1 = L, X2 = S, X3 = T; X10 = L0 = -45; X20 = S0 = 40; X30 = T0 = 8 ta c : x1 =L +45 ; 15

x2 =

S - 40 ; 5

x3 =

T -8 2

Thay cc gi tr x1, x2, x3, vo phng trnh hi qui (*) ta c : y1 = 5,12 + 0,805.T -8 2 L +45 S - 40 T -8 L +45 - 0,695. - 0,4675. - 0,3725. . 15 5 2 15

biu din hm y 1 trn th khng gian 3 chiu ta c nh mt trong 3 yu t l nhit lnh ng, nhit sy, thi gian sy. biu din s nh hng ca nhit sy v thi gian sy n m sn phm ta c nh L = -45 0C v c phng trnh :S - 40 T -8 y1L = 5,12 - 0,695. - 0,4675. 5 2

Tng t biu din s nh hng ca nhit lnh ng v thi gian sy n m sn phm ta c nh S = 40 0C v c phng trnh : y1S

= 5,12 + 0,805.

L +45 T -8 L +45 T - 8 - 0,4675. - 0,3725. . 15 2 15 2

V biu din s nh hng ca nhit lnh ng v nhit sy n m sn phm ta c nh T = 8 gi v c phng trnh:L +45 S - 40 y 1T = 5,12 + 0,805. - 0,695. 15 5 Dng phn mm Matlab (phn 4.1 ph lc 4) biu din y1L , y1S , y1T ta c cc th hnh 3.4a, 3.4b, 3.4c.

SVTH: L Vit Trin

Lp: 02H2A

n tt nghip

50


Hnh 3.4a: nh hng ca nhit sy v thi gian sy n m sn phm

Hnh 3.4b: nh hng ca nhit lnh ng v thi gian sy n m sn phm

Hnh 3.4c: nh hng ca nhit sy v nhit lnh ng n m sn phm ngha: Vi nhng th ny trong nghin cu cng nh trong sn xut ta c th kim sot s nh hng ca cc iu kin cng ngh n m v hm lng anthocyanin ca sn phm mt cch nhanh chng . V d: hnh 3.4a ng vi nhit lnh ng l -45 0C ta c th xc nh c m ca sn phm ti nhit sy v thi gian sy bt k trong khong kho st mt cch d dng bng cch t nhit sy v thi gian sy dng cc ng thng ln mt phng biu din hm lng m s c mt im trn mt phng ny. T im ny dng mt ng thng ln mt phng m ca h trc ta khng gian 3 chiu ta s xc nh c m ca sn phm. Xy dng m t ton hc vi hm mc tiu hm lng anthocyanin: - Chn phng trnh hi quy: Phng trnh hi quy c chn theo phng trnh 3.1 mc 3.2.2.2. Cc h s b1, b2, , b123 c tnh theo s liu thc nghim hm mc tiu hm lng anthocyanin (y2) v theo cng thc (3.2). Kt qu tnh cc h s b trong phng trnh hi quy ca hm anthocyanin: b0 = 0,193125 b12 = - 0,000875 b1 = 0,008375 b2 = - 0,009125 SVTH: L Vit Trin b13 = 0,004875 b23 = -0,003375 Lp: 02H2A

n tt nghip

51


b3 = - 0,017625 b123 = 0,002375 - Kim tra mc ngha ca cc h s b trong phng trnh hi quy: Cc bc kim tra tng t nh i vi cc h s b trong phng trnh hi quy hm mc tiu m. Kt qu tnh cc tj: t0 = 119,1994 t12 = 0,540062 t1 = 5,169163 t2 = 5,632073 t13 = 1,465882 t23 = 2,083095

t3 = 10,87839 t123 = 1,465882 Sau khi kim tra mc ngha ca cc h s b ta c: t12, t13, t23, t123 < tp(fth) = t0,05(2) = 4,3 nn cc h s b12, b13, b23, b123 u b loi ra khi phng trnh. Vy phng trnh hi quy ca hm lng anthocyanin trong sn phm c dng: y2 = 0,193125 + 0,008375x1 - 0,009125x2 - 0,017625x3 ( **) - Kim nh s ph hp ca phng trnh hi quy vi thc nghim: Cc bc kim tra cng tng t nh i vi hm mc tiu l m. Thay cc gi tr vo cng thc (3.4), (3.5), (3.6), (3.7) ta c: S 2 =0,000021; th 2 2 S bj = 0,000002625 ; S bj = 0.001620185; S d = 0,000111 ; F = 5,277778 Tra bng 4 [1] ta c F1-p(f1, f2) = F0,95(3,2) = 19,2 vi f1= N 1 = 3, f2 = m-1 =2 Ta c F < F1-p. Vy m hnh ton hc chn ph hp vi thc nghim. Phn tnh ton xem mc 3.2 phn ph lc 3. Phng trnh hi quy trn c dng tuyn tnh, c 3 yu t l nhit lnh ng, nhit sy, thi gian sy u nh hng n cht lng ca sn phm m trc tip l hm lng anthocyanin. Trong cc khong ca cc yu t chn khi tng nhit lnh ng, gim nhit sy, gim thi gian sy th hm lng anthocyanin s tng. S d nh vy l v: khi lnh ng mc cng thp th cc tinh th hnh thnh trong bn thnh phm cng t khng gy bin dng, rch t bo do trong qu trnh thng hoa anthocyanin trong t bo khng b cun theo hi m ra ngoi. Mt khc, anthocyanin l mt hp cht d b ph hy bi nhit v nh sng do vy khi sy trong iu kin nhit thp v thi gian ngn s tn tht anthocyanin hn. - Biu din cc yu t tng tc i vi hm lng anthocyanin Tng t nh cch biu din cc yu t tng tc i vi m ca sn phm ta cng biu din c s nh hng ca cc yu t nhit lnh ng, nhit sy, thi gian sy n hm lng anthocyanin ca sn phm trn th khng gian 3 SVTH: L Vit Trin Lp: 02H2A

n tt nghip

52


chiu. Nhng th ny cng c ngha trong nghin cu v sn xut tng t nh nhng th ca m. Chng trnh v phn 4.2 ph lc 4. Kt qu c th hin hnh 3.5a, 3.5b, 3.5c.

Hnh 3.5a: nh hng ca thi gian sy v nhit sy n hm lng anthocyanin

Hnh 3.5b: nh hng ca thi gian sy v nhit lnh ng n hm lng anthocyanin

Hnh 3.5c: nh hng ca nhit lnh ng v nhit sy n hm lng anthocyanin 3.2.3. Ti u ho cc iu kin cng ngh sy thng hoa khoai lang tm: 3.2.3.1. Ti u ha cc iu kin cng ngh sn phm c m nh nht v hm lng anthocyanin ln nht: Sau khi c phng trnh hi quy ca m sn phm v hm lng anthocyanin ca sn phm chng ti tin hnh ti u cc iu kin cng ngh sy thng hoa thu c sn phm c m nh nht v hm lng anthocyanin l ln nht. nhanh chng tm ra cc gi tr ti u chng ti s dng cng c Solver tm gi tr cc tr ca tng hm (ph lc 5). Kt qu c th hin bng 3.13 v 3.14. Bng 3.13: Kt qu sau khi ti u hm mc tiu m bng Solver SVTH: L Vit Trin Lp: 02H2A

n tt nghip

53 Bin thc


Bin m Z3, h 10 x1 x2 + x3 +

Z1, 0C -60

Z2, 0C 45

y1min, % 3,525

Nhn vo bng 3.13, kt qu ti u bng Solver trng vi th nghim th 2 vi cc iu kin cng ngh: nhit lnh ng -600C, nhit sy 450C, thi gian 10 gi v xc nh c m nh nht l 3,525 %. Ti iu kin cng ngh ny chng ti xc nh c hm lng anthocyanin ca sn phm theo hm y2 l 0,158 %. y cha phi l hm lng anthocyanin cao nht. V vy chng ti tin hnh tm iu kin cng ngh ti u thu c sn phm c hm lng anthocyanin cao nht. Bng 3.14: Kt qu sau khi ti u hm mc tiu hm lng anthocyanin bng Solver Bin thc Z1, C -300

Bin m Z3, h 6 x1 + x2 x3 -

Z2, C 35

0

y2max, % 0,228

T bng 3.14 chng ti nhn thy kt qu ti u bng Solver cho iu kin cng ngh trng th nghim th 7 vi iu kin cng ngh tng ng l: nhit lnh ng -600C, nhit sy 350C, thi gian sy 6 gi v hm lng anthocyanin t gi tr cao nht tm c l 0,228 %, Ti iu kin cng ngh ny chng ti xc nh c m ca sn phm theo hm y1 l 7,46 %, sn phm cha t m nh nht. Qua cc kt qu ti u trn cho thy iu kin cng ngh m hm lng anthocyanin t max th m khng th t min v iu kin cng ngh lm cho m nh nht ta li khng th c hm lng anthocyanin ca sn phm ln nht. Nh vy khng th tm c iu kin ti u tha mn mt lc hai mc tiu nghin cu bng phng php ny. Do vy, chng ti tin hnh ti u ha hm a mc tiu bng phng php thot ly khi vng cm tm ra mt nghim tha hip. 3.2.3.2. Ti u ha hm a mc tiu bng phng php thot ly khi vng cm: Qu trnh sy thng hoa khoai lang tm c c trng bi hai phng trnh (*) v (**) mc 3.2.2.2. Hai phng trnh ny th hin s tc ng ca cc yu t cng ngh n m v hm lng anthocyanin ca sn phm khoai lang tm sy. Khi c s thay i ca b ba s liu (x1, x2, x3) trong bng 3.12 th cho cc gi tr thc nghim y1, y2 khc nhau v y1min, y2max cng khc nhau. SVTH: L Vit Trin Lp: 02H2A

n tt nghip

54


Vi mc ch sn xut ra c sn phm khoai lang tm sy c m thp nht v hm lng anthocyanin cao nht nhim v ca chng ti l phi ti u ha hm a mc tiu tm gii php cng ngh thc tin tt nht cho c hai hm mc tiu, ng thi nng cao tnh ton din v tnh thuyt phc cho kt qu thu c. Theo kt qu ti u mc 3.2.3.1 ta thy khng th c mt nghim chung cho c hai phng trnh t c y1min, y2max m ch tm c nghim tha hip (x1, x2, x3) cc gi tr y1, y2 nm gn y1min, y2max. tm c nghim tha hip chng ta c th dng phng php chp tuyn tnh. Tuy nhin trong phng php ny chng ta phi tin hnh thm cc th nghim leo dc tm iu kin ti u sau khi c hm chp a mc tiu. gim bt s th nghim, rt ngn thi gian nghin cu chng ti p dng phng php thot ly khi vng cm trong t hp chp phi tuyn. Ni dung ca phng php [5]:y2

y2max

ykt

A T O

x

2

B

y1min

1

y1

Hnh 3.6: th th hin ni dung ca phng php Trong : y1min, y2max l cc gi tr ti u ca hm y1, y2 gii bng Solver ykt: hiu qu khng tng, ykt = {y1opt, y2opt} x: min cm Min T (din tch AOBykt): phm vi tm kim ti u ca R(x) 1: gii hn trn ca hm y1 2: gii hn di ca hm y2 T mi bi ton xy dng mt hm mc tiu chung: 1 y1 1 ( y1 ) = 1 y1kt 0

y1(x)

1 1

SVTH: L Vit Trin

y2(x) > 2

Lp: 02H2A

n tt nghip

55


y2 2 y (x) < 2 ( y 2 ) = y2k t 2 Hm mc tiu t hp chp R(x) tnh theo cng thc: 0 R(x) = (x). (x)2 2 1 2

max Bi ton c gii theo phng php lun phin tng bin ca (Gauss Seidel) vi ngn ng lp trnh Pascal. ngha: R(x) max, tc l cc i ha khong cch (thot cng xa min cm th cng gn im khng tng). Dng bi ton: Tm nghim ti u xopt sao cho Ropt(x) = R(xopt) = max R(x), x x. Sau khi chy chng trnh vi 200 vng lp nh phn ph lc 6 chng ti thu c kt qu bng 3.15. Bng 3.15: Kt qu sau khi chy chng trnh tng hp t ph lc 6 X1 ti u, 0C -60 X2 ti u, 0C 44,95 X3 ti u, h 6 y1 ti u, % 3,7219 y2 ti u, % 0,2005

Nhn xt: Theo kt qu trn, iu kin ti u (nghim tha hip) tm c u nm trong khong chn v cc gi tr y1ti u = 3,7219 v y2ti u = 0,2005 cng nm gn vi gi tr ca y1min = 3,525 v y2max = 0,228. Do vy, c th kt lun rng kt qu trn hon ton chp nhn c. 3.2.4. Thc nghim kim chng: Sau khi tm c nghim tha hip cho c hai hm mc tiu m v hm lng lng anthocyanin trn, chng ti tin hnh lm th nghim ti cc iu kin cng ngh tng ng kim chng. Theo kt qu ti u mc 3.2.3.2, th nghim kim chng ng c thc hin vi cc thng s k thut sau: - Nhit lnh ng: -600C. - Nhit sy: 44,950C. - Thi gian sy: 6 gi. V trong thc t khng th c c nhng thng s trn nn chng ti lm trn cc thng s nh sau: - Nhit lnh ng: -600C. - Nhit sy: 450C. - Thi gian sy: 6 gi.

SVTH: L Vit Trin

Lp: 02H2A

n tt nghip

56


Sau khi c mu kim chng chng ti tin hnh xc nh m v hm lng anthocyanin ca sn phm so snh vi kt qu tm c theo phng php ton hc. Cc th nghim c lp li 3 ln v kt qu c th hin bng 3.16. Bng 3.16: Kt qu th nghim kim chng Ln 1 m, % Anthocyanin, % 3,72 0,198 Ln 2 3,78 0,202 Ln 3 3,75 0,203 Trung bnh 3,75 0,201

Nhn xt: T kt qu thc nghim ti iu kin ti u chng ti nhn c sn phm c m l 3,75 % v hm lng anthocyanin l 0,201 %. Kt qu ny cho thy chng ta khng th tm c mt iu kin cng ngh m ti cho ta sn phm c m bng y1min = 3,525% v hm lng anthocyanin t gi tr ca y2max = 0,228 %. Tuy nhin, cc gi tr tm c cng gn tha mn gi tr ca y1ti u, y2ti u. Do vy, c th kt lun rng tin cy ca phng php ti u l kh cao v iu kin tt nht sy thng hoa khoai lang tm l: nhit lnh ng -60 0C, nhit sy 45 0C, thi gian sy 6 gi. Cui cng, kim tra cht lng sn phm khch quan hn chng ti t chc mt cuc th nghim nh gi cm quan i vi mu kim chng. 3.2.5. nh gi cm quan: y l mt sn phm mi, bit c mc a thch ca ngi tiu dng chng ti t chc ra mt hi ng nh gi cm quan th hiu 60 ngi bao gm cc bn lp 02H2A, 03SH, 05MT trng i hc Bch Khoa Nng. Th nghim c t chc ti phng th nghim nh gi cm quan ca b mn Cng ngh thc phm thuc Khoa Ha, chia lm 3 lt th: 2 lt mi lt 28 ngi v 1 lt cho 4 ngi cn li. Trong , sn phm s c nh gi mc a thch v mu sc, kh dn, v v mc a thch chung trn thang 9 im theo phiu hng dn mc 7.1 ph lc 7. Kt qu c tng hp bng 3.17.

Bng 3.17: Tng hp kt qu nh gi cm quan t phn 7.3 ph lc 7 im mc a thch v mu sc 8,01 im mc a thch v kh dn 6,71 im mc a thch v v 6,23 im mc a thch chung 6,5 Lp: 02H2A

im trung

SVTH: L Vit Trin

n tt nghip

57


bnh Nhn xt: Theo kt qu nhn c i chiu vi thang o ca phiu hng dn th nghim mc 7.1 ph lc 7 ta thy: - Sn phm ny c ngi tiu dng kh thch. - Ngi tiu dng rt thch mu sc ca khoai lang tm sy. iu cho thy khoai lang tm sy theo phng php ny bo tn gn nh nguyn vn anthocyanin. - V kh dn v v ca sn phm cng c ngi tiu dng tng i thch. - V y l sn phm hon ton t nhin trong qu trnh ch bin hon ton khng b sung mt gia v v ph gia no nn cha c ngi tiu dng nh gi cao. Nhng sn phm ny s rt tt cho nhng ngi n king v hn ch ti a cc cht bo v rt c li cho sc khe v hn ch c cc ha cht c hi cng nh cung cp cho con ngi mt lng anthocyanin qu gi cng vi cc cht dinh dng c sn trong khoai lang tm. 3.2.6. xut qui trnh sn xut khoai lang tm sy bng phng php sy thng hoa quy m pilot: Da trn nguyn tc lm vic ca qu trnh sy thng hoa v kt qu nghin cu chng ti xut qui trnh cng ngh sy thng hoa khoai lang tm nh sau: Qui trnh sn xut khoai lang tm sy thng hoa quy m pilot:

Khoai lang tm Ra sch

SVTH: L Vit Trin

Lp: 02H2A

n tt nghip

58


Ct thnh khi hnh ch nht 10x10x30mm Hp T = 4 pht Lnh ng -60 0C Sy t = 45 0C T = 6 gi Lm ngui, phn loi ng gi Sn phm Thuyt minh qui trnh cng ngh: Khoai lang tm dng sn xut khoai lang tm sy phi t nhng tiu chun nh phn 2.1.1 chng 2. Nguyn liu sau khi ra sch c a vo my ct ct thnh nhng khi hnh ch nht c kch thc 10x10x30mm. Tip theo, khoai lang tm c hp trong cc ni hp iu kin p sut bnh thng trong khong thi gian l 4 pht. Qu trnh hp kt thc, khoai lang tm s c dn u a i lnh ng nhit -60 0C. Sau khi t nhit yu cu khoai lang tm s c chuyn ngay vo my sy thng hoa thc hin qu trnh lm kh sn phm nhit 45 0C trong 6 gi. Sn phm sau khi sy kh c lm ngui trc khi ng gi nhm trnh hin tng m hi trong bao b dn n lm h hng sn phm. V sn phm sy thng hoa c cu trc xp d b oxy xm nhp gy ph hy lipit do cn phi c bao gi trong kh tr. Qu trnh bao gi c thc hin nh my ng gi chn khng t ng vi bao b PE c kch thc 18x26cm. Mi gi thnh phm c khi lng khong 50-70g.

SVTH: L Vit Trin

Lp: 02H2A

n tt nghip

59


KT LUNSau qu trnh thc hin ti ny chng ti rt ra c nhng kt lun nh sau: SVTH: L Vit Trin Lp: 02H2A

n tt nghip

60


1. kho st c thnh phn ca khoai lang tm. y l mt loi thc phm rt b dng, hm lng cc kim loi nng nh Zn, Pb, Cd, Cu u di mc gii hn cho php ca B Y t. c bit cn cha mt hm lng kh cao dc cht anthocyanin (0,06%). 2. la chn c quy trnh x l nguyn liu thch hp trc khi sy thng hoa: nguyn liu qua qu trnh hp iu kin p sut bnh thng trong 4 pht s gim ti thiu tn tht v anthocyanin v tng hiu qu cho qu trnh sy. 3. Bng phng php ton hc kt hp vi thc nghim chng minh c cc iu kin cng ngh ca qu trnh sy thng hoa nh: nhit lnh ng, nhit sy, thi gian sy nh hng rt ln n m v hm lng anthocyanin ca khoai lang tm sy. Trong cc khong kho st, khi gim nhit lnh ng, tng nhit sy, tng thi gian sy th m sn phm s gim xung cn hm lng anthocyanin s b tn tht nhiu hn. N c biu hin qua 2 phng trnh hi quy: - y1 = 5,12 + 0,805x1 - 0,695x2 - 0,4675x3 - 0,3725x1x3 - y2 = 0,193125 + 0,008375x1 - 0,009125x2 - 0,017625x3 4. iu kin tt nht i vi qu trnh sy thng hoa khoai lang tm l: nhit lnh ng -60 0C, nhit sy 45 0C, thi gian sy 6 gi. iu kin ny sn phm thu c c m l 3,75 % v hm lng anthocyanin l 0,201 %. 5. Qua iu tra th hiu cho thy sn phm ny ch c ngi tiu dng nh gi tng i cao. iu gip chng ti c nh hng c th to ra sn phm khoai lang tm sy hon thin hn. 6. xut c quy trnh cng ngh sn xut khoai lang tm sy thng hoa quy m pilot.

HNG PHT TRIN TI1. Kho st ton b thnh phn ha hc ca khoai lang tm sau khi sy. 2. Tip tc nghin cu hon thin sn phm khoai lang tm sy ngon hn thch hp vi nhiu i tng ngi tiu dng. SVTH: L Vit Trin Lp: 02H2A

n tt nghip

61


3. Tip tc nghin cu cc iu kin k thut v thit b trong cc cng on ca qui trnh cng ngh sn xut khoai lang tm sy thng hoa quy m phng th nghim. 4. Nghin cu nh hng ca chiu dy, hnh dng nguyn liu n hiu qu ca qu trnh sy thng hoa v cht lng ca sn phm. 5. M rng nghin cu sn xut mt s sn phm sy thng hoa trn nhng nguyn liu rau qu khc.

TI LIU THAM KHO1. Nguyn Cnh (1993), Quy hoch thc nghim, i hc Bch Khoa TP. HCM. 2. Hong Th Kim Cc (2004), Nghin cu thu nhn v ng dng anthocyanin trong thc phm, Trng Cao ng lng thc- thc phm Nng. SVTH: L Vit Trin Lp: 02H2A

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62


3. Hong Th Kim Cc, Phm Chu Hunh, Nguyn Th Lan, Trn Khi Uyn (2004), Xc nh hm lng anthocyanin trong mt s nguyn liu rau qu bng phng php pH vi sai, Tp ch khoa hc v cng ngh, i hc Nng, 3(7), 47-54. 4. Trn Bch Lam, Tn N Minh Nguyt, inh Trn Nht Thu (2004), Th nghim ha sinh thc phm, NXB i hc quc gia TP. HCM. 5. Nguyn Th Lan (2006), Bi ging quy hoch thc nghim, i hc Bch Khoa Nng. 6. ng Minh Nht (2006), Gio n k thut sy nng sn thc phm, i hc Bch Khoa Nng. 7. Trn Vn Ph, L Nguyn Dng (1991), K thut sy nng sn, NXB Khoa hc v k thut. 8. Nguyn Xun Phng (2003), K thut lnh thc phm, NXB Khoa hc v k thut. 9. Phm Vn S, Bi Th Nh Thun, Bi Minh c (1975), Kim nghim lng thc thc phm, NXB Khoa hc v k thut. 10. L Ngc T (2000), Ha sinh thc phm, NXB Khoa hc v k thut. 11. H Duyn T (1991), K thut phn tch cm quan, Tng cc tiu chun o lng cht lng. 12. Vin dc liu (2004), Cy thuc v ng vt lm thuc Vit Nam-tpII, NXB Khoa hc v k thut. 13. Yeu-Pyng Lin, Jen-Horng Tsen, V. An-Erl King (2004), Effect of far-infrared radiation on the freeze-drying of sweet potato, Journal of Food Engineering, 68, 249-255. 14. M. K. Krokida, V. T. Karathanos v Z. B. Maroulis (1998), Effect of Freezedrying Conditions on Shrinkage and Porosity of Dehydrated Agricultural Products, Journal of Food Engineering, 35, 369-380. 15. Luanda G. Marques, Maria C. Ferreisa, Jos T. Freice (2006), Freeze-drying of acerola (Malpighia glabra L.), Chemical Engineering and Processing, 46, 451457. 16. Ikuo SUDA, Tomoyuki OKI, Mami MASUDA, Mio KOBAYASHI, Yoichi NISHIBA, Shu FURUTA (2003), Physiological Funtionality of PurlpleFleshed Sweet Potatoes Containing Anthocyanin and Their Utilization in Foods, JARQ - (Vol. 37 No. 3 ). 17. Http://www.tradekey.com/index.html? action=feedback_post&uid=269387&return_url=/sellofer_view/id/133435.htm. SVTH: L Vit Trin Lp: 02H2A

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18. Http://www.rpi.ed/dept/chem-eng/Biotech-Environ/DOWNSTREAM/fig2.htm. 19. Http://www.vinamit.com. 20. Http://www.niroinc.com. 21. Http://xinmeixang.en.alibaba.com/group/50034177/Freeze_Dried_Vegetables.ht ml 22. Http://www.quangngai.gov.vn/quangngai/tiengviet/chuyennganh/soyte/133481_ 946/#top#top. 23. Http://www.asuzacfoods.com.vn/sp.html 24. Http://www.rauhoaquavietnam.vn 25. Http://www.acecookvietnam.vn/index.php? option=com_content&task=blogsection&jd=12&Itemid=175&lang=vi. 26. Http://www.sggp.org.vn/phongsudieutra/thang12/nam2004/30473images/image s37654_29B.jpg. 27. Http://www.alibaba.com/manufacture/229c3pthf/Frozen_Dried_Fruit.html. 28. Http://www.dhdlvanlang.edu.vn/news/tintucsukien.aspx?id=265. 29. Http://www.doste.hochiminhcity.gov.vn/tintuc/news_detail.asp? period_id=1&cat_id=344&news_id=1117. 30. Http://jd-trade.en.alibaba.com/group/50160209/Frozen_Dried_Food.html.

PH LC 1 (Xc nh anthocyanin trong khoai lang tm) 1.1. Pha dung dch m pH = 1: + Ly 25 ml dung dch gc HCl 0,2M. + Ly 67 ml dung dch KCl 0,2M (14,9g/l). + nh mc thnh 100 ml. SVTH: L Vit Trin Lp: 02H2A

n tt nghip

64


1.2. Pha dung dch m pH = 4,5: + Ly 400 ml dung dch CH3COONa 1M (136g/l). + Ly 240 ml dung dch HCl 1N (83ml/l). + nh mc thnh 1000 ml. PH LC 2 Mc gii hn ti a cho php ca mt s kim loi nng v c t trong sn phm rau ti (Theo Quyt nh s 867/ 1998/ Q-BYT ca B Y t) STT 1 2 3 4 5 6 7 8 9 10 11 TN NGUYN T V C T Asen (As) Ch (Pb) Thy Ngn (Hg) ng (Cu) Cadimi (Cd) Km (Zn) Bo (B) Thic (Sn) Antimon Patulin (c t) Aflattoxin (c t) Mc gii hn (mg/ kg) 0.2 0.5 1.0 0.005 5.0 0.02 10.0 1.8 1.00 0.05 0.005 150

PH LC 3 (Tnh ton cc phng trnh hi quy) 3.1. Tnh ton phng trnh hi quy ca hm mc tiu m sn phm: 3.1.1. Tnh cc h s b:1 8 1 b1 = 8 1 b2 = 8 1 b3 = 8

b0 =

(3,8 + 4,48 + 4,64 + 5,69 + 3,84 + 5,58 + 4,98 + 7,95) = 5,12. (4,48 - 3,8 + 5,69 - 4,64 + 5,58 - 3,84 + 7,95 - 4,98) = 0,805. (4,48 + 3,8 - 5,69 - 4,64 +5,58 +3,84 - 7,95 - 4,98) = -0,695. (4,48 + 3,8 + 5,69 + 4,64 -5,58 -3,84 - 7,95 - 4,98) = -0,4675.

SVTH: L Vit Trin

Lp: 02H2A

n tt nghip1 (4,48 - 3,8 - 5,69 + 4,64 8 1 b13 = (4,48 - 3,8 + 5,69 - 4,64 8 1 b23 = (4,48 + 3,8 - 5,69 - 4,64 8 1 b123 = (4,48 - 3,8 - 5,69 +4,64 8

65


b12 =

+5,58 -3,84 - 7,95 + 4,98) = -0,2. +5,58 -3,84 + 7,95 - 4,98) = -0,3725. -5,58 -3,84 + 7,95+ 4,98) = 0,1825. -5,58 +3,84 + 7,95 - 4,98) = 0,1075.

3.1.2. Tnh cc chun Student tj:y0 =

yu =1

3

0 u

= y10 + y20 + y30 = 4,78 + 4,97 + 4,68 = 4,81.0 u

3

Sth2 = Sbj =

( yu =12 th

n

- y0 )2

=

fS = Nb00,0217 8

1 ( 4,78 4,81) 2 + (4,97 4,81) 2 + (4,68 4,81) 2 = 0,0217. 2

[

]

= 0,052082. t1 = S = bj

t0 = S = bj

5,12 0,052082 0,695 0,052082

= 98,30652; = 13,34434; = 3,840098; = 3,50409;

b1

0,805 0,052082 0,4675 0,052082

= 15,4565 = 8,97623 = 7,1521830,1075 0,052082

t2 = S b

b2j

=

t3 = S b t13 = S bb13j

b3j

= =

t12 = S b

b12j

= =

0,2 0,052082 0,1825 0,052082

0,3725 0,052082

t23 = S b

thuyet minh

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