nguyen lieu san xuat thuc pham

8/14/2019 Nguyen Lieu San Xuat Thuc Pham

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I HC NNG

TRNG I HC BCH KHOAKHOA HA K THUT

BI GING MN HCNGUYN LIU SN XUT THC PHMM s mn hc: 1071163

S tn ch: 2

Gio vin ph trch: GVC ThS Trn Xun Ngch

Nng - 2007

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Chng I - Mt s khi nim mu ...........................................................11.1. Thc phm.............................................................................................11.2. Ph gia ...................................................................................................1

1.3. Nguyn liu thc phm .........................................................................1Chng II Nhm nguyn liu rau qu .......................................................22.1.Thu hi v ti .................................................................................22.2. Mt s thnh phn ha hc lin quan n cht lng rau qu.............32.3. Gii thiu mt s loi rau quin hnh..............................................8

Chng III Nhm nguyn liu sc sn, thy sn ....................................123.1. Tht v cc sn phm tht ...................................................................123.2. Mt s thnh phn ha hc v cu trc lin

quan n cht lng ca tht ..............................................................123.3.Trng gia cm .....................................................................................15

3.4. Nguyn liu sa..................................................................................173.5. Mt s loi ph phm sc sn, thy sn ............................................18Chng IV Nhm nguyn liu lng thc...............................................19

4.1. Cu to v thnh phn ha hc ca ht cc .......................................194.2. Gii thiu cc loi ht cc ch yu ....................................................214.3. Cu to v thnh phn ha hc ca c lng thc.............................23

Chng V Nhm nguyn liu du mv tinh du..................................245.1. Nhm nguyn liu du m.................................................................245.2. Nhm nguyn liu tinh du................................................................49

Chng VI Ngm nguyn liu ch, thuc l, c ph, ca cao.......................

6.1. Nguyn liu ch......................................................................................6.2. Nguyn liu c ph.................................................................................6.3.Nguyn liu thuc l ...............................................................................6.4. Nguyn liu cacao ..................................................................................


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Chng I: MT S KHI NIM CBN

1.1. Thc phm :

L vt phm t nhin dng th, n l hoc qua ch bin, phc hp, n c, thamn nhu cu ca ngi s dng nh :

- Cung cp cc cht dinh dng: protein, gluxit, lipit, vitamin, khong - An ton cho sc khe .- To cm gic ngon, th v (vn ha m thc ).- Ph hp vi thi quen, truyn thng: ca c nhn , gia nh, vng , min , quc gia,

chu lc.1.2. Ph gia :

L cc ch phm t nhin hoc tng hp ha hc , khng phi thc phm , dc avo thc phm mt cch c thc hin nhng mc ch k thut nht nh .

Hin nay ngi ta chia ph gia lm 2 loi chnh :- Ph gia thc phm :cn lu li trong thc phm dng nguyn th hoc dn xut

nhng m bo an ton cho ngi s dng. Loi ny bao gm 6 nhm chnh l: cht boqun, ph gia dinh dng, ph gia to mi thc phm, ph gia to mu thc phm ,cht tocu trc v cc ph gia khc .

- Cht h trk thut :khng c lu li trong thc phm sau khi thc hin xong chcnng k thut. Loi ny bao gm 19 nhm chnh l: cht chng bt, cht xc tc, tc nhnlm trong v trlc , cht lm bn mu, tc nhn lnh, tc nhn chng vn cc, cht bi trn,cht cnh enzim, cc enzim, dung mi , tc nhn lm bin i s kt tinh , tc nhn kt t, nha trao i ion ,tc nhn chng dnh khun , tc nhn chng vi sinh vt , kh trdng

trong bao gi thc phm , cht ty ra v lm rng lng th, cc cht dinh dng cho vi sinhvt v cc cht h trk thut khc .

1.3. Nguyn liu thc phm :L nng sn thc phm t nhin dng th , n l hoc qua ch bin , phc hp,

trong mt s trng hp c thn c, tha mn nhu cu ca ngi s dng nh :- n c vi t cch l mt thc phm .- Yu tu vo ca cng ngh sau thu hoch (ct gi , d tr ,ch bin ).- Hng ha lu thng trn th trng .C mt s cch phn loi nguyn liu thc phm , chng hn :

Nu da vo thnh phn ha hc , thnh phn dinh dng ch yu , ta c cc nhm :

- Nhm nguyn liu giu protein: tht , c , trng , u tng ,- Nhm nguyn liu giu lipt : u phng , da , c du, o ln ht.- Nhm nguyn liu giu tinh bt: cc loi ht cc (la m, la , ng , cao lng ,

k) v c c bt (khoai ty , sn , khoai lang , sn dy ).- Nhm nguyn liu giu cc cht ng: ma , c ci ng, tht nt, cc loi qu

chin .- Nhm nguyn liu tinh du :bc h , s , qu , hng nhu - Nhm nguyn liu ha sinh : ch , ca ph , thuc l , ca cao .

Nu da vo ngun gc sinh vt v t nhin , ta c cc nhm :- Nhm nguyn liu ng vt.

- Nhm nguyn liu thc vt .- Nhm nguyn liu sinh vt bc thp: rong to, nm n .


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- Nhm khong vt: nc ngt , mui n -Nu da vo c tnh ca dy chuyn cng ngh ch bin thc phm (gi l c tnh

cng ngh ) ta c cc nhm :Nhm nguyn liu cho cng ngh bo qun lnh v lnh ng .

- Nhm nguyn liu cho cng ngh hp .- Nhm nguyn liu cho cng ngh ch bin lng thc .- Nhm nguyn liu cho cng ngh ch bin ng bnh ko.- Nhm nguyn liu cho cng ngh ch bin cc sn phm ln men .- Nhm nguyn liu cho cng ngh khai thc - ch bin du mv tinh du .- Nhm nguyn liu cho cng ngh ch bin cc sn phm ha sinh.Trong bi ging ny, chng ti kt h p cc cch phn loi trn chia nguyn liu

thc phm thnh nm nhm chnh sau y :- Nhm nguyn liu rau qu.- Nhm nguyn liu sc sn - thy sn.- Nhm nguyn liu lng thc.- Nhm nguyn liu du mv tinh du.- Nhm nguyn liu ch, c f, thuc l, ca cao.

Ring nhm nguyn liu sn xut ng saccaroza l ma v c ci ng mangtnh cht c th, gn lin vi cng ngh sn xut nn chng ti khng xem xt n trong

bi ging ny.

Chng II : NHM NGUYN LIU RAU QU.2.1. Thu hi v ti:

- Thu hi: rau qu phi ng chin ca n.+ chn thu hi : rau non ( x lch, u h lan ).

+ chn sinh hc : dng lam ging.+ chn k thut : chui gi xanh, u gi xanh, c chua gi xanh.Qu trnh sng ca rau qu sau khi thu hi :

+ Duy tr ti sng: mc d ngun cung cp cht dinh dng khng cn nhngtrong khong thi gian gii hn nht nh, rau qu vn gic ti. Rau qu thu hicng non th cng gic ti lu.

+ S mt nc: do t nhin (m tng i ca khng kh, nhit ), do cngbc (lm ho), u lin quan n trng ca m t bo thc vt s dn n hin tngho.Ty theo dc tnh ca rau qu m c th ho hi phc ( ti) c v ho khng hi

phc ( ti). Rau qu ho trong mt chng mc nht nh c th s dng c ( ho bt

buc trong cng ngh ch bin ch, chn rau qu) tuy nhin gi tr nguyn liu hay mt hngc th khng cao.

+ S h h p: trong qu trnh chn ca rau qu din ra s ng ha t nhin:

(C6H10O5)n + n H2O n C6H12O6 (1)Tip C6H12O6 + 6O2 6H2O + 6CO2 + Q1 (2)

C6H12O6 2C2H5OH + 2CO2 + Q2 (3)

Phn ng (2) lm hao ht cht kh trong iu kin hiu kh ( h hp hiu kh)Phn ng (3) l phn ng ln men trong iu kin ym kh, tip c th tip din cc

phn ng phn hy su xa hn.

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Nu nhit phn ng b tch t (b rau cht , xp rau qu qu cht,khng thng thong )s lm bin i cc cht mu ( clorofin, flavonoit, caroteloit, antoxian) ng thi vi qutrnh phn hy lm cho rau qu b a ri b nu v h hng .

- Cht lng chung ca rau qu :bao gm ti v hm lng cht kh ha tan trongnc chit rau qu . c bit nu rau qu la nguyn liu trong cng ngh sn xut nc rauqu ( trong, c, nc rau qu c c ), cng ngh sn xut ru vang ( nho , da , to,chui )2.2. Mt s thnh phn ha hc lin quan n cht lng rau qu.2.2.1. Cc cht gluxit:

L thnh phn cht kh ch yu trong rau qu, va l vt liu xy dng t bo, vatham gia vo cc qu trnh trao i cht ch yu. gluxit cng l ngun d tr nng lngcho cc qu trnh sng ca rau qu ti khi bo qun

sinh nng lng ca 100g rau ti qu sng l khong 25 - 40 kcal ,ca 100g quti l khong 50 - 70 kcal .

Thnh phn glu xit ch yu trong cc loi rau qu l khc nhau , chng hn trong khoaity , chui xanh l tinh bt , trong rau l xenluloza , trong u l tinh bt v ng , trongqu chn l ng .

- Cc cht ng :+ Ch yu l ng t do ( ha tan trong dch t bo ) cc dng D-glucoza,

fructoza, saccazoza .+ ng kt h p trong phn t tinh bt xenlulozo, hemixenluloza, pectin v cc

glicozit .+ Tt c cc loi ng u tan trong nc v ha tan cng tng khi tng nhit

.V vy khi lm chn rau qu , tt nht l dng bin php chn bng hi nc gim tntht ng do ha tan .

+ Cc loi ng u c tnh ht m mnh , nht l fructoza .Trong khng kh boha hi nc ( %100= ) , fructoza c th hp th ti 30% nc , glucoza :15%, saccaroza:13% ( theo khi lng ng ) .Do i vi cc sn phm rau qu cha nhiu ng (mt kh , rau qu sy kh ) cn bo qun trong bao b kn trnh ht m .

+ Khi nng ng trong nguyn liu v sn phm qu cao ( xoi ct, nho chnmt ong, cc loi mt ) th ng c th b kt tinh. V vy cc lai qu dung ch bincc loi mt nhuyn, bnh ko cn c axit thch hp, nu khng phi b sung thmaxit chng kt tinh ng.

+ Khi bo qun rau qu ti hoc trong qu trnh chn ti trn cy, ng saccarozab chuyn ha dn dn thnh ng kh di tc dng ca enzim invertaza, cn trong qu

trnh sng thc vt th li din ra s tng hp saccaroza tng kh v s thu phn tcc polysaccarit khc.+ Cc rau qu c cha ng khi bun nng lu nhit cao s xy ra hin

tng caramen ho. l qu trnh dehydrat ha ( mt nc) dn dn to thnh cc snphm trung gian c mu v mi thm giai on u ( mi rau qu chin, nu) nhng nhit cao v thi gian lu th s sm mu cng nhanh, to vng.

S sm mu cc sn phm rau qu khi ch bin cn do tc dng ca ng kh vi ccaxit amin ( phn ng malanoit) to ra cc melannoidin lm gim cht lng ca sn phmv mu sc v mi v.

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Phn ng melanoit xy ra mnh nht khi t l gia cc axit amin v ng kht

khong 1:2. Trong s cc cht trung gian to thnh c nhm aldehyt lm cho sn phm cmi khc bit i khi c tc dng tt ( lm thm ha ) nhng nhn chung nu ch bin nhitkhong nhit 100 120OC (khong nhit thng thng un nng, c c, lm


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chn, hm nh v thanh trng ) v nht l trong thit b h th thng c mu sm, mi vkm t nhin, tn tht nhiu ng v axit amin

- Tinh bt:Trong rau qu, ht tinh bt c kch thc v hnh dng khc nhau ty thuc lai rau

qu, mc gi chn, thi gian bo qun tm thi.Kch thc ht tinh bt cng ln (trn 20m ) th c, qu cng b, xp khi nu chn (

n c bi). Cc loi qu, ht, c lu ( c lu nm khng nh d; ht; c; qu bo qunlu ngy) kch thc ht tinh bt gim dn s trnn qunh (do), sng khi nu chn nh:sn, khoai lang, u xanh, u en.

Trong cc loi rau qu, hm lng tinh bt tng nhanh trong qu trnh gi nhng khichn th hm lng tinh bt gim nhanh chng do s chuyn ha thnh ng.

V d: Chui tiu xanh gi cha 1518% tinh bt , 12% ng nhng khi chn honton ch cn 12% tinh bt v 1620% ng.

- Xenluloza: c cc phn v ( v qu, v ht, v t bo) v cc m nng ( thn,cnh, gn l, li).

Xenluloza l mt polysaccarit gm 20.000 100.000 phn t glucoza. Cc phn txenluloza hnh si di lin kt vi nhau bng cu hydro (H-O-H) thnh b si gi l mixen,nhiu mixen lin kt vi nhau thnh chm si. Gia cc chm si c cc cht gian bo lhemixenluloza, protopectin, lignin, cutin, chng ximng ha gn kt cc chm sixenluloza li vi nhau lm cho m v qu rn chc v rau qu cng khi cn xanh.

mt s loi rau qu c cu truc xenluloza phn t di, lin kt mng cht ch, dyc s c tnh bo v cc cht dch bo khng b men tiu ha tc dng, chng km gitr tiu th trc tip ( n khng ngon) v ch bin cng nghip nn phi gt v, t li, ctmt (da ), tc x ( u qu), ch, p, ly tht qu v nc rau qu ( da, chui, cam,nho)

Khi vn chuyn v xp d, bo qun rau qu, xenluloza c tnh bo v chc ( chngd p nt khi va chm, nn p) v iu ha nhit cho khi rau qu. Khi ch bin cngnghip, xenluloza gy kh khn nh: gim hiu qu truyn nhit khi un nng - lm ngui,cn tr qu trnh ch v ng ha, lm gim cng sut thit b gy c. Tuy vy, khixenluloza ng vai tr l cht trlc khi p, vt nc rau qu.

- Hemixenluloza : cn gi l bn (na) xenluloza (bn x) tn ti cng vi xenlulozanhng km bn hn xenluloza v mt ha hc, c th b thy phn bi dung dch axit yuhay kim yu. Ngi ta li dng kh nng ny bc v qu, c bng phng php hahc) dng kim, axit hay cht oxi ha mnh).

Monosaccarit ch yu to nn mch polymer phn t hemixenluloza l ng pentoza,

khi thu phn s to ra cc ng arabinoza v kxiloza. Hemixenluloza (pentozan) khng bthu phn trong ng tiu ho ca ngi do chng cng nh xenluloza khng c gi trv mt dinh dng, chng ch c tc dng nng cao nhu ng rut. Tuy vy, mng ( mngtre, mng ty) 2 thnh phn ny to nn khoi khu (n ngon)

- Pectin: l h p cht gluxit cao phn t vi phn t lng nh hn xenluloza vhemixenluloza. Trong rau qu pectin ng vai tr quan trng trong qa trnh trao i ncv s chuyn ho cc cht giai on gi chn. Pectin tn ti hai dng: dng khng hatan l protopectin ( tin pectin) v dng ho tan l pectin.

+ Protopectin thng tn ti song song vi xenluloza v hemixenluloza, khng tantrong nc nhng d b thy phn bi enzyme pectinaza hay axit chuyn ha thnh

pectin. Protopectin to nn rn chc ca rau qu khi cn ti xanh. Trong qu trnh chnca qu th protopectin chuyn thnh pectin ha tan lm gim cng lc lin kt thnh tbo v v m nng nn qu b mm dn. Khi chu tc ng ca nhit 8085OC v


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trong mi trng axit ca qu th Protopectin c th chuyn ho thnh pectin ha tan lmcho rau qu b mm.

+ Pectin l cht khng mu, khng mi v, d tan trong nc. Dung dch pectin c tnhkeo ln, nht v bn ca keo pectin gy kh khn cho nhiu qu trnh ch bin nhlm trong, lc, c c nc rau qu.

Trong phn t pectin c cc nhm cacboxyl t do (-COOH) mang in tch m. Dovy keo pectin l keo m nn d b kt ta bi cc cation kim loi, cc keo dng tothnh cc pectat. y l phn ng cbn ca qu trnh t lm trong nc qu, ru vang,

bia.Tnh cht c trng ca pectin l to gel (to ng) ngay nng thp (11,5%) khi

c ng trong mi trng axit yu ( 60% ng v 1% axit xitric). Tnh cht ny cng dng trong sn xut ko mm, bnh, mt do.

Trong qu trnh ln ln v gi chn ca qu, hm lng pectin bin i lin tc, thngl t cao nht khi chn ti. Sau gim dn v b demetoxy ha ( kh nhm -OCH3) vdepolyme ha ( phn ct mch pectin).2.2.2. Cc axit hu c.

To cho rau qu c v ni bt hn bt c thnh phn no, cac axit hu ccng thamgia vo cc qu trnh oxy ha - kh nh cc thnh phn d tr khc( gluxit, lipit) v qatrnh h hp ( chu trnh Krebb). V vy sau mt qu trnh bo qun lu di, gi tr cm quanv khu v ca mt s loi qu b gim i rt nhiu (cam, to).

Trong rau qu, cc axit hu cch yu tn ti dng t do v thng thng mi loirau qu ch cha mt vi loi axit hu cch yu. Do c mt s axit hu cc ngungc thc vt c pht hin, thu nhn v t tn ca loi thc vt . V d: trong h qu cmi citrus( cam, chanh, qut) axit hu cch yu l axit citric, cng c th gi theo tnqu chanh (lemon) l axit limonic.

Trong h qu nho(vino) axit hu c ch yu l axit vinic ( hay axit tantric). Trongcng ngh ch bin rau qu, axit hu clm tng gi tr khu v, chng hi ng, tng ng ca mt v bnh ko mm, tng kh nng tit trng, to axit v pH mi trngthun li cho qa trnh ln men.

chua ca rau qu ph thuc vo hm lng axit, pH ca nc chit v hmlng ng trong . Ngi ta a ra ch sng/axit (ch s/A) m t tng quanny.

V d: Hm lng ng trong nc da hoa Vnh Ph l 15,8%, axit l 0,51%. Vy/A =31

S hi ha chua ngt c th tnh ton trn csch s/A ti thiu bt u gy cm

gic v chua-ngt. Chng hn i vi dung dch ng saccaroza v axit citric:(/A)min=0,58/0,015 = 25,3Tuy nhin chua ngt cn ph thuc vo cc loi ng v axit trong rau qu nn ch

s/A cng thay i, chng hn.Ch s/A V trong cc loi qu

2530 Khng thy v chua ( chui, u )1020 Chua nh ( cam)510 Chua( bi chua)


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c to thnh t cc monosaccarit (hexoza, pentoza) lin kt vi cc hp cht hu ckhc nh ru, axit, aldehyt, phenol Theo kiu este, phn khng phi l gluxit gi laglucon.

Nhiu loi glicozit to cho rau qa co mi thm c trng c mi thm c trng vphn ln l gy vng. Glicozit cn l cht d tr, i khi cn l cht bo v (khngsinh thc vt) v khi thy phn s gii phng ra phn aglucon c tnh cht st trng.Glicozit c phn ln lp v v ht, trong m nc c t hn. Trong thi gian bo qun (h qu citrus, khoai ty) iu kin khng thch hp: lm lnh ng, gia nhit, b chiusng, b ny mm th glicozit hnh thnh v tch t li nhiu nht khu vc chn mmhoc c th chuyn vo dch bo. Tuy nhiu glicozit s b ph hy dn dn khi gia nhitlu hoc b bay hi.

Nhn chung, glicozit gy vng v c ( tr glicozit trong hoa houblon sn xutbia) nn trong ch bin cn hn ch v loi b. Trong rau qu, thng gp cc glicozit sauy: hesperidin, naringin, limonin, solanin, amidalin, manihotin, xinigrin, xinanbin,capsaixin, apiin.

- Hesperidin: C nhiu trong v v m bao che h qu citrus, khng c vng, chot tnh ca vitamin P, khi b thy phn s gii phng ra ng ramnoza, glucoza v nhmaglucon l hesperizin. Trong v chanh non c neohesperizin c v rt ng.

- Naringin: C trong v ci v dch qu h citrus gy vng khi qu cn xanh. Khiqu chn, naringin b thy phn thnh ng ramnoza, glucoza v aglucon l naringonenkhng c vng.

- Limonin: c vng trong h qu citrus, bn thn limonin khng ng nhng vngxut hin khi kt hp vi axit citric. Phn ng ny xy ra khi cu trc t bo (tp bi, cam)

b ph v(ch, p, vt, nhai ), khi lm lnh ng, khi qu b h thi.- Solanin: thng gp trong h c, trong khoai ty solanin c trong v v phn tht st

v c. Do phn ln solanin s b loi khi gt v, hm lng solanin trong khoai tykhng nhiu lm (0,01%) nhng khi ny mm, khi c ha xanh do tip xc vi nh sngmt tri th hm lng solanin tng nhanh. Tp trung nhiu chn mm, lp v xanh lmcho khoai bng v c, khng cn dung lm thc phm c. Tuy vy nhng c khoai kh b thi hng (do solanin c tnh st trng v cn trng, chut ph hoi). Solanin trongcc loi c gy vng v nga ( c bit hm lng glicozit trong nhm c c dc rt cao,gy cht ngi).

- Amidalin: cha trong ht cc loi qa hch nh m, o (23%), mn (0,96%), hnhnhn (2,53%). dng nguyn cht amidalin c cu trc tinh th, vng, ha tan trongnc v ru. Trong s ny th ht hnh nhn c gi tr thc phm rt cao bi vng, thm

ngon c bit, cc ht cn li l v thuc bc.- Manihotin: c nhiu v in hnh trong sn, tp trung phn v ci, c bit mt sging sn ( sn ng) c hm lng manihotin ln trong phn tht c nn khng dung nti c. Manihotin khi b thy phn s gii phng ra HCN gy ngc khi n sn.

- Xinigrin, xinanbin, capsaixin v apiin: gy ra cc v cay du n cay xc trong ccnhm rau v rau gia v nh: ci xanh, c ci, hnh, ti, rau mi (ng), th l, t, h tiu.2.2.4. Cc hp cht polyphenol:

Hm lng cc hp cht polyphenol trong rau qu tuy rt nh: 0,10,2% nhng phbin v ng vai tr quan trng trong qu trnh trao i cht v nng lng ca thc vt.Nhm cc cht polyphenol ha tan trong nc c nh hng ln n nguyn liu v bn

thnh phm trong qu trnh ch bin rau qu:- Kt hp vi Fe to nn mui Fe(III) mu xanh en, vi Sn, Zn, Cu th polyphenol vantoxian to ra cc mu khng t nhin. V vy cc dng c, thit b, ch bin rau qu nn


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lm bng thp inox hoc nhm.nht l i vi mt s loi qa cha nhiu polyphenol(chui, hng o, m).

- D b oxy ha bi xc tc enzim polyphenoloxydaza (EPPO) to ra cc sn phm trunggian t nu n . Qu trnh ny xy ra rt nhanh v l nguyn nhn ch yu lm sm murau qu khi ch bin chc nh khi gt v, ch, nghin, thi. chng li hin tng smmu ny, cn phi c cc bin php nhm chng tc dng ca oxy hoc ph hy h EPPOtrong rau qu nh: ngm nc, ngm trong dung dch NaHSO3,xng SO2, chn.

- C tc dng ln trong sn xut nc rau qu v ru vang do c kh nng kt ta viprotein (to mui tanat protein khng tan) v vi cc cht keo t nhin khc (keo protein,keo pectin) t lm trong sn phm.

- ng vai tr quan trng khi bo qun rau qu v polyphenol iu chnh cc c tnhsinh l quan trng ca thc vt nh trng thi ng v kh nng t khng khun. Khi rauqa b tn thng (st, gy, ong chm, vi sinh vt k sinh) t bo ca chng s t to nncc hp cht phenol mi hoc cc hp cht phenol sn c s b oxy ha lm tng kh nngkhng khun v nm mc. Trong mt s trng hp, s oxy ha cc hp cht phenol s trittiu cc t bo khu vc b thng tn ( to nn m so) cng vi cc vi sinh vt k sinhti . Tnh cht ny gi l phn ng t v linh cm ca thc vt, n tng t vi hintng thc bo trong ng vt.2.2.5. Cc cht mu:

Chia thnh 2 nhm: ha tan trong cht bo l chlorophyll v carotenoid, ha tan trongnc l flavon v antoxian.

- Chlorophyll: c mu xanh lc v chng khng hp th mu ny m li phn chiu n mt thy c. Sc t chlorophyll (dip lc t) ng vai tr quan trng trong qu trnhquang hp, l ngun ch yu to nn cc hp cht hu cv l ngun duy nht ti to oxycho sinh quyn.

Trong cng thc phn t ca chlorophyll c bn nguyn t N kt hp vi 1 nguyn tMg trung tm. Khi b gia nhit lu hoc trong mi trng axit , ion H+ s thay th ion Mg2+ trung v chuyn sang mu vng l. Do bo v mu xanh t nhin ca rau qu khich bin, cn gia nhit nhanh ( chn, hp) hoc gia nhit trong mi trng kim hay muiaxit phn ly mnh nh NaCl. Nu thay Mg2+ bng Cu2+ sc phc cht mu xanh lc

bn, phn ng ny c dng lm tiu bn thc vt khi nghin cu ( x l mu thc vt vidung dch CuSO4).

- Carotenoid: to cho rau qu c mu vng, da cam, , ph bin nht l cc loicarotene, licofin v xantofin.

+ Caroten c nhiu c rt, gc, c chua, o, mn.

+ Licofin to mu c chua v mt s qu khc.+ Xantofin l sn phm oxy ha carotene to nn mu vng rc r ca l, v quchui, da, u , mu ti mnh to, vi, chm chm.

Cc carotenoid l provitamin A ( tin vitamin A) quan trng trong ng k nht ltrong du qu gc.

- Flavon v antoxian: y l cc cht mu trong nhm glicozit to cho rau qu c muvng, da cam, tm v, l, tht qu nh: mn , du, da , rau dn, bp ci tm, tat.

Gc ng trong nhm cht mu ny l glucoza v ramnoza, cn aglucon l flavonolv antoxianidin.

S chn ca qu l qu trnh tch t antoxian. Khi un nng lu trong nc, antoxian bph hy mt phn. Trong mt s loi rau qu, khi ung nng antoxian tc dng vi Sn chomu xanh lp mt. Do ng hp c trng thic cc loi qa c nhiu antoxian nh


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mn, du, bi s c tc dng tt v mu sc. Vi Al antoxian cho mu tm, vi Fe sto mu xu cho nn y l cc kim loi c hi cho qu trnh ch bin rau qu giu antoxian2.2.6. Cc hp cht nit.

ng vai tr quan trng trong qu trnh trao i cht v dinh dng bao gm nitprotein v nitkhng phi protein .

- Cc hp cht nit ,amoniac ,amit v cc axt amin ng vai tr quan trng khi sdng dch qu ch bin ru vang v nm men dng ha cc dng nitny khi ln men.Dch chit rau qu cng cha y cc axit amin khng thay th nn gi tr dinh dngca rau qu cng cao .

- S bin hnh protein c th xy ra khi rau qu bo qun lu , in hnh l cc loiu ht , khoai ty , khoai lang , sn .Tuy nhin s bin hnh ch xy ra mc thp ,

protein cha b ng t m ch b gi ci , kh nng trng nc v ht nc gim.Nhng loi nguyn liu ny khi ch bin nhit ( nu chn , hm nh ) s sng, km n, luchn .2.2 .7. Cc cht bo .

Tp trung nhiu trong ht, mm ht v c trong phn tht quin hnh nht l qub, gc v thng i km vi sp to thnh mng mng bo v ngoi v. Trong thnh phncht bo ca rau qu thng c hai axit bo no l palmitic v stearic, 3 axit bo khng no loleic, linoleic v linolenic.2.2.8. Cc vitamin

Thc vt c th t tng hp c hu ht cc vitamin, d rau qu l ngun thcphm cung cp vitamin quan trng.

- Vitamin C (axit L-ascorbic): c nhiu nht v ph bin trong cc loi rau qu, tn ti2 dng: dng kh l axit L-ascorbic t do, dng oxy ha l axit dehidro ascorbic, c haidng ny d dng chuyn ha thun nghch v u c hot tnh sinh ha mnh.

c bit trong mt s loi rau h ci nh bp ci, sp lcn tn ti mt dng th 3 caaxit ascorbic dng lin kt vi protein gi l ascobigen c nhiu trong bp v l non.

Tnh cht quan trng nht ca vitamin C l d b oxy ha bi cc tc nhn nhit ,khng kh, nh sng. Do , bo v vitamin C trong qu trnh ch bin rau qu cn c cc

bin php dit men, bi kh, chn khng ha. Vitamin C c bo v tt trong dung dchng m c ( xir). Cc mui Fe v Cu ph hy vitamin C ( Cu c trong thnh phn caenzim ascobinoxydaza l enzim oxy ha ph hy vitamin C). V vy cc thit b nu rau qunn ch to t thp khng r.

Do tnh cht d b oxy ha nn vitamin C l cht chng oxy ha t nhin cng nh thng ( vitamin C b sung cho cc thc phm d b oxy ha nh du m, hp)

.- Vitamin P: thng i km vi vitamin C, c tc dng tng h v bo v ln nhau- Caroten ( provitamin A): c nhiu trong c rt, gc. Hin nay du gc l sn phmcung cp vitamin A quan trng.

2.2.9. Cc enzim:- ng ch hn c l h enzyme oxy ha-kh (oxyreductaza) gm cc enzim:

peroxydaza, EPPO c hot tnh oxy ha mnh v bn nhit. Nu ch bin s b rau qubng nhit trong thi gian ngn, chng hn nh chn th h enzim ny c th tm ngnghot ng nhng trong qa trnh tng tr, bo qun tm thi trn dy chuyn cng nghchng c th phc hi hot tnh. y cng l nguyn nhn gy nn nhng bin i khng cli v mu sc v mi v. V vy trong ch bin cn c bin php c ch hoc nh ch hot

tnh cc enzim ny.- Enzim pectinaza c tc dng phn gii pectin


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- Enzim phosphataza: Xc tc qu trnh thy phn v tng hp cc glucozophosphat -l cc cht trung gian quan trng ca qu trnh h hp v ln men

- Enzim proteaza: Xc tc s thy phn protein. Cc ch phm enzim proteaza thc vtc nhiu ng dng trong ch bin thc phm v y hc.

V d: t nha u thu c ch phm papain, t da thu c ch phm bromelainng dng trong sn xut ru vang, lm mm tht, sn xut nc mm, thc n gia sc.2.3. Gii thiu mt s loi rau quin hnh.

- Nu phn loi rau qu theo vng kh hu:+ Nhit i: da, chui, u , xoi, vi, nhn, chm chm. Sn lng ln nht l da

v chui.+ Cn nhit i: Cam, chanh, qut, hng, mn, o, nho, ci bp. Sn lng ln nht

l cam.+ n i: du ty, sp l, mng ty, l.- Nhm qu dng lm rau gm c: c chua, bu b, da chut, mp, u a.- Nhm sinh dng: c phn s dng lm thc phm l thn, l, r, c: khoai ty, c

rt, ci bp, su ho, sp l, hnh ti, mi, nm n.- Nhm qu gm c:+ Qu c mi( citrus): cam, chanh, qut, bi.+ Qu 1 ht ( qu hch): o, m, mn, to, vi nhn, chm chm.+ Qu nhiu ht: u , i, mt, su ring.+ Qu nc: khng c ht hay l ht khng pht trin nh chui, da.Di y ta ch xem xt 1 s loi rau qu c gi tr kinh t ln v c dng nhiu

trong ch bin thc phm.2.3.1. Da: (Bromeliaceae - ananas).

C ngun gc ng Bc M La Tinh, hin nay l loi quc sn cc nc nhiti, l n hong ca cc loi qu.

Da c nhiu ging, hin nay nc ta trng 3 nhm sau y:- Da ta ( ananas comosa): qu to nhng hng v km- Da ty ( hay da hong hu-ananas comosa queen): nhp ni t nm 1913, qu b

nhng thm ngon.- Da khng gai ( hay da c bnh - ananas comosa cayenne, da cayenne): qu rt

to, c thn 2,5kg/qu.V thnh phn ha hc, trong qu da ti c 7288% nc, 815,5% ng,

0,30,8% axit hu c. Thnh phn ng trong da ch yu l saccaroza( 70%), cn li lglucoza v fructoza; axit hu cch yu l axit xitric. Ch tiu cht lng quan trng ca

da l thnh phn nc p da gm: hm lng cht kh, hm lng ng, axit, chtkhong, nht l khi dng da l nguyn liu sn xut nc da ( t nhin, c c) ru vangda.

Cc mt hng da: hp qu ( khoanh, ming, r qut) nc ng (compost) dalnh ng, da sy, mt, nc da c c, ru vang da.

Ph liu da ( v, li, mt, chi) l nguyn liu sn xut ch phm bromelain.2.3.2. Chui.

Bao gm nhiu ging: chui tiu, chui ng chn thu hi ca chui l chui xanhgi c bo qun tm thi ri em gim chn trong kh quyn iu chnh ( hn hp khngkh vi C2H4, v C2H2). T chui xanh c th sn xut ra tinh bt chui c gi tr thc phm

cao ( dung sn xut bnh ko , thc n king).Thnh phn chnh ca chui chn l ng 10 19%, axit 0,2 0,5%.


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Cc mt hng chui: lnh ng, chui sy (lt, p nguyn qu), pur chui, bnh ko, hp qu - nc ng, vang chui.2.3.3. Nhm qu c mi (citrus).

y l nhm qu nhit i v cn nhit i c trng cc nc a Trung Hi (Italy, Nam T, Php), Hoa K, Nht, Vit Nam , Cuba, Chu phi.

- Cam ( citruc auranticum).V bng, v ngt, hng thm, t s. nc ta c mt s ging cam ngon ni ting

nh: X oi ( Ngh An), B H ( Bc Ninh), cam Canh.- Chanh ( citrus medica - limon)

V mng, bng, nhiu nc. Trn th gii ni ting nht l ging chanh qu hi dica Italy.

- Bi ( citr grandis):Qu trn, ln nht trong h citrus. Trn th gii c Cuba vi cc ging bi ngon ni

ting. nc ta cng c nhiu ging bi ngon nh: oan hng ( Tri m - Ph Th ),Phc trch (H Tnh), Nm roi ( Vnh Long), Bin Ha (ng Nai).

- Qut (citrus reticulata)Qu trn, dt, d bc v. nc ta c nhiu ging qut ngon ni ting nh Thanh Tr

( H Ni), Lai vng (ng Thp vi ging qut hng).- Qut ( citrus Japonica):Qa trn, nh thng chn vo dp tt, l 1 cy cnh quan trng.

Nhm qu c mi c s dng trong cng ngh ch bin thc phm vi cc mt hngnh: hp nc qu, mt ( cam, qyt, qut), bnh ko, vitamin pp, nuc gii kht v btgii kht (dng bt hay vin si bt), chic xut axit citric. V chanh, bi, cam l nguynliu tinh du v pectin, cng ngh pha ch ri mi (cam, chanh).

2.3.4. Xoi (Mangi fera indica)Qu nhit i rt ngon, sn lng hng nm trn th gii ng th 3 sau da v chui,

ngun gc n , Malaixia. Hin nay cc nc Chu phi, Thi Lan, Vit Nam trngnhiu xoi. Vit Nam c cc ging xoi ct, xoi tng Cam Ranh (Khnh Ha),

Nam b,Cc mt hng t xoi gm c: noc qu, d hp qu - nc ng.

2.3.5. Vi , nhn, chm chm.y l nhm qu ngon trong vi ( litchi chinensis) c trng cc tnh pha bc (

Hi Dng, Hng Yn, Bc Giang), chm chm (nephelium lappaceum) c trng cctnh Nam B (ng Nai, Bn Tre, An Giang, Kin Giang), nhn ( Euphoria longan) ctrng nhiu ni ( Hng Yn vi ging nhn lng ni ting, Nam b vi ging nhn tiu da

b).Cc mt hng t nhm qu ny gm c: hp qu nc ng (chm chm, nhn),nhn sy (long nhn), vi sy, ru vang.2.3.6. M, mn, o, to.

y l nhm qu hch c trng ph bin trn th gii , ngon nht l cc vng khhu cn nhit i v n i. nc ta c mt s ging qu ngon nh mn tam hoa (TyBc ), mCha hng (H Ty), o Sapa, to mo (Sn tr cc tnh Ty Bc).

Cc mt hng t nhm qu ny gm c: to sy, msy tm mui - nc ng (xumui ), ru mi, ru vang.2.3.7. C chua (solanum licopersicum tomato).

Ngun gc Peru, c trng lm rau t th k XVI Chu u. Hin nay c chua lcy rau c sn lng ln nht c trng khp ni trn th gii, trong c chua n ic sn lng v phm cht tt hn.


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Thnh phn cht kh (6 -8%) l ch tiu cht lng quan trng nht ca qu c chua.ccmt hng c chua bao gm nc qu ( t nhin, c c), bt c chua, mt qu, hp.2.3.8. Da chut (cucumis sativus).

Cn gi l da leo, c ngun gc tn .Thnh phn cht kh trong da chut ti ch khong 5% gm ng: 3%, protein:

0,8%, xenluloza: 0,7%.Da chut c phm cht tt l loi qu nh, v mu vng, thnh dy, c rut, t ht,

ng > 2%.Da chut dng mui chua, hp da chut dm dm.

2.3.9. Bp ci, ci tho v supl.y l cc loi rau thuc h ci, c nhiu ging nhng ch c 3 ging trn l c gi tr

trong ch bin cng ngh. Ngun gc ca h ci l vng a Trung Hi, l th rau cnnhit i v n i. Bp ci v ci tho c phm cht tt phi cun cht l dy, suplc hoa chin.

Cc mt hng t cc loi rau ny bao gm: bp ci, ci tho mui chua, bp ci sykh, hp rau t nhin, hp spl- tht.

2.3.10. C rt (Daucus carota).L th rau cn nhit i v n i, trong thnh phn cht kh c: ng: 8%, protein:

1,5%, xenluloza: 1,2%. C y cc vitamin v cht khong quan trng, c bit lcaroten v st.

C rt c dng trong sn xut hp rau t nhin, nc p c rt, bt c rt.2.3.11.u H Lan (Pisum sativum).

Phn s dng l qu cn non cha 5% protein, 5 -8% ng , 3 -5% tinh bt, 0,2 -0,4% lipit, 1,5 -2% xenluloza. y l loi rau giu m nht. u H Lan dng sn xut hp rau t nhin, xp u, u sy.2.3.12. Mng ty (asparagus officinalis).

y l lai cy tho lu nm cc nc n i (Php, Anh, H Lan,). Mng ty llai thn non ngn, thnh phn ha hc c 0,41% ng, 1,95% protein, 0,10% li pit,carotene, vitamin C.

Mt hng sn xut t mng ty gm: lnh ng, hp, mng ty sy.2.3.13. Mng tre (Bambusa).

L mng ca tt c cc loi tre, na. Trong thnh phn ha hc ch yu l xenluloza,mt t ng, protein, caroten, glicozit (khi ch bin phi loi b glicozir bng cch luctrong nc hay ln men chua). Mng tre c dng sn xut cc mt hng nh: mngkh, hp rau t nhin, hp tht gia cm.

2.3.14. Nm n.C 5 loi c ngha kinh tc thu hi v gieo trng l: nm rm, nm m, nm bong, nm hng v nm mc nh.

- Nm rm (volvariella esculenta): pht trin trn rm rkhong nhit 28 42oc.Qu th nm mu trng ng c s dng sn xut cc mt hang: nm mui, lnh ng, hp rau, nm sy.

- Nn m(Agaricus campester) c nui trng trn ph liu nng nghip cc ncChu u (li ng). Qu th nm hnh trn, mu trng dng sn xut cc mt hng lnhng, hp rau.

- Nm hng (Leutinus edodes): c thu ht (t nhin) hoc trng trn thn cy g

si, dvng cao min Bc Vit Nam, min Nam Trung Quc, Min in. Tai nm munu, hng v thm ngon, l mt hng tiu dng, ch bin v xut khu c gi tr cao.


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- Nm bo ng: c trng trn th gi th l mn ca. Hi nay ngi ta trng thnhcng nm n v c nm linh chi trn gi th ny.

- Cc loi mc nh: mc trn cc loi cy mc: xoan, sn, mn ca.Nhn chung cc loi nm n c l thc phm qu, hng v thm ngon, gi tr dinh

dng cao, v th ngh trng nm v ch bin nm ang rt c trin vng.2.3.14. Cc loi rau thm v rau gia v.

- Rau gia v s dng ph bin cc nc phng ty l: l nguyt qu (cng nghhp) v ht mi ( t sn xut ra loi gia v mustaque (m tc) rt thng dng).

- H hnh ti (Liliaceae)+ Hnh (Allium) gm nhiu ging: hnh hoa (Allium fistulosum), hnh ty (Allium

cepa): mi thm c bit ca ging hnh d c cha tinh du vi thnh phn ch yu l allindisulfur, ngoi ra cn c fitin, mt alcaloit l fitonxit gy v cay c bit, cc vitamin nhmB,C.

Hnh l gia v trong hu ht cc sn phm tht, c, m n lin, bn, phn lin.+ Ti (Allium Sativum) gm nhiu ging: ti ta, ti ty (allium porrum).

Thnh phn ch yu ca tinh du ti l alixin cng l mt phitonxit c tc dngkhong khun rt mnh.

Ti cng l gia v trong hu ht cc sn phm tht, c, m n lin, bnh phng tm.+ C kiu (Allium fisum): l nguyn liu sn xut mt hng c kiu mui.- H tiu: y l gia v cn rt nhiu sn phm ch bin. Hin nay Vit Nam ang dn

n sn lng tiu c th gii vi cc sn phm tiu s, tiu en rt ni ting ca cc vngnh Vnh Linh (Qung Tr), Ph Quc (Kin Giang), Ty Nguyn.

- t: c hai loi: mt loi v cay c dng nh l gia v vi cc sn phm nht kh,bt t, cary (n ), mt loi khng cay (t ngt) c dng nh l mt loi rau.

Chng III. NHM NGUYN LIU SC SN. THY SNNhm ny bao gm: tht v cc sn phm tht gia sc, gia cm v thy sn (c, tm,mc,), trng gia cm (vt, g, cun ct), sa ( b, tru) v mt s loi ph phm caqu trnh git m, ch bin c gi tr cng ngh cao nh: ni tng, da, huyt, xng.3.1. Tht v cc sn phm tht.

Gia sc, gia cm v thy sn ti sng c a vo h thng git m v ch bin phitri qua cc bc sau:

- Kim tra dch t, th y: c tin hnh trong sut qu trnh chn nui, nh bt, thumua, git m v ch bin cng ngh. y l khu bt buc nhm bo m cht lng sn

phm, ngn nga v x l dch bnh.- Phn hng (c) :+ Theo mc bo tt, ti sng t cc yu cu k thut cho cng ngh ch bin.+ Xc nh hng s dng.+ nh g c khi thu mua.- Git m:+ i vi gia sc: tru, b, ln, cu, d.Tm ra gy chong ly tit co lng, lt da ly ni tng x thtlm sch bo qun tam thi.

+ i vi gia cm: g, vt, vt xim, ngng, iu.Tm ra gy chong ly tit chn nc nng, nc si vt lng ly ni

tng lm sch bo qun tam thi .+ i vi c gm c cc loi:

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1. C nguyn con, t nhin nh mi nh bt ln (tu, thuyn, ao, h nui).2. C nguyn con nhng rt ht cc ni tng bng cch m moi.3. C bu, m bng, loi b ni tng, vy, ui.4. Fillets (phi l): phn tht ln hai bn hng c.+ i vi tm:

Ra sch phn loi vt u bc v, b gn bo qun tm thi .+ i vi mc:

Ra sch loi b ni tng lm sch, phn loi bo qun tm thi .3.2. Mt s thnh phn ha hc v cu trc lin quan n cht lng ca tht .

Thnh phn cu trc ca tht (sc sn, thy sn) l t l 3 lai m c, m lin kt vm m, n ph thuc vo c th con vt, gii tnh, mc bo, tui git tht v tng b

phn ca sn phm tht. Gi tr dinh dng cao nht v ngon nht l phn m c( tht nc),thp nht l m lin kt, m mlm cho tht c v bo v c gi tr nng lng cao.

- M c: c gi tr ch bin cng ngh cao vi mioglobin l cu t ch yu quyt nhmu sc ca tht nc, chng hn trong tht b, tht c ng ( phn mu sm) mioglobin quytdinh 90% mu sc ca tht. Nhm ngoi ca mioglobin l cc heme trong nguyn ttrung tm ni cc heme c th l Fe (tht c mu) hoc Cu, Zn ( tht mu trng tht g,mc, tm). Trng thi oxy ha ca nguyn t trung tm Fe cng nh bn cht ca cc

phi t ni vi n ( O2, NO2-, CO, CO2) l nguyn nhn lm thay i mu sc ca tht khi

bo qun v x l cng ngh. in hnh l s bin hnh ca protein bi nhit: 50oC thtvn gic mu sc, khong 50 70oC tht trng ra v thot dch c mu, trn 70oC thtc mu nu ca sc t feri mioglobin. Nu thay Fe bng NO2

- ( mui tht bng nitrit) sc phc rt bn mu, c ng dng trong sn xut lp xng, xc xch.

Phn tht nc c nhng gi tr cng ngh sau y:+ Nhm mt hng gi ch: bao gm: gi la, ch qu (Vit Nam), lp xng, xc xch,

cc loi nem, ch hi sn (c, tm, mc). sn xut ra nhm mt hng ny tht phi c ti tt gn nh tuyt i ( tht mi git m, tht cn nng).

+ Nhm mt hng hp: ln, b, cu, pat.+ Nhm mt hng sy kh: tht b, ruc tht, thy sn kh (tm, mc)- M lin kt: s lng ca chng c nh hng trc tip ti gi tr dinh dng v mc

mm mi ca sc tht, trong collagen v elastin l 2 protein chim qu na tng lngprotein ca m lin kt.

+ Colagen c trong xng, da, gn, sn, h thng tim mch. N l mt protein hnh sikhng n hi c l do cc cu ng ha tr gia nhm - NH2 ca gc hidroxilizin vichc aldehyt ca gc lizin. ng vt non, cc cu ng ha tr ny tng i khng bn,

d b phn hy bi tc pH, nhitng vt gi, cc cu ny c thay th bi cc linkt khc bn hn lm tng dai cng ca tht. c bit colegen c kh nng tng tc vitanin ( phn ng thuc da) lm tng dai, mm, mn ca da thuc.

Trong qu trnh cha ca tht ( cha ha sinh) collagen ch b bin i cht t. trng thi t nhin colagen b enzim pepxin v colagenaza thy phn 1 phn ( s lm mmtht bi enzim), ch sau khi bin hnh nhit ( tht chn bi nhit) mi c tripxin,chimotripxin v cacboxy peptitdaza (cc enzim trong dch tiu ha) thy phn trit . Khigia nhit n 55oC phn t collagen b co ngn i 1/3, khi ti gn 61oC th co ngn i 1/2,khi nhit gn 100oC th collagen b ha tan v to ra gelatin (s keo ha hay s gelatinha (gelatinization), nhit cao 115 125oC v p sut cao th s gelatin ha xy ra rt

nhanh. Galentin c tnh to keo, to gel v kh nng gi nc rt tt.Vn gelatin ha c nhiu ngha quan trng:

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1. Tnh to keo c p dng trong cc sn phm tht nu ng, gi b nh gi th, gida, nem.

2. Cng ngh sn xut gelatin thc phm v cng nghip (keo da, vy, vy)3. Cng ngh sn xut bng b t da ln, mt s sn phm thc phm truyn thng rt

ni ting.4. Cng ngh sn xut mt s mt hng c gi tr thc phm v tiu th cao (m v)

nh: vy c nhm, c mp, yn so, bong bng c (lm thc phm v ch khu phu thut).5. Cng ngh ch tc cc loi thuc cao cha bnh t xng, sng mng: cao kh, cao

trn, nai.+ Elastin l protein c mu vng, c nhiu thnh ng mch, dy chng, t sng,

c tnh n hi. Khi nu trong nc, elastin ch b trng m khng ha tan, bn vi cc tcnhn ha hc v phn ln cc enzim proteaza, ch b thy phn mt phn bi papain.

- Tc(miofibrin): chim trn 50% lng protein ca ctht, c chia lm 2 phn:+ Protein gy nn hiu ng co rt ca cnh miozin, actin.+ Protein iu ha s co rt ca cnh tripomiozin, tropomin, - actinin, - actinin,

protein M, protein C.Tcb gim ha tan trong khong nhit 4060oC do gin mch polypeptit vb keo t. Khi nhit cao trn 75oc th xy ra phn ng kh sulfua to ra H2S l nguynnhn lm en tht hp, to mi.

- Protein ca thy sn: ctht c cng nh ttht gia sc, gia cm nhng cng c nhngc im khc nhau l:

+ Hm lng m lin kt trong cc thp hn, chim 3 -10% tng lng protein.+ Nhit gelatin ha ca cc thp hn tht hng chc .+ Cc si cc ngn hn (cvi cm) ctht v c t chc thnh cc lp mng.+ Hin tng cng xc v chn ti ca c din ra nhanh hn so vi tht: 5 giv 30 gi

0

o

C. Sau khi thy sn cht, pH gim t t 7 xung cn 6,2 -6.5 nnt khng bn so vivi sinh vt, rt nhanh bn hng.Khi ngm thy sn vo nc m, nc mui trong mt thi gian ngn (cha thy

sn bt u phn hy) s c mt lng dch trong t chc c tht ha tan ra m ngi ta gi l cht ngm, cht rt hay nc bi.

Lng cht ngm s nhiu hn thy sn cp thp ri gim dn thy sn cp caohn: sa > mc >trai, s > tm > c. Cht ngm c mi vc trng lm tng kh nng tiuha, tuy nhin chng rt d b vi sinh vt gy thi ra lm gim kh nng bo qun, gim

phm cht nguyn liu ( ti tt). Khi ch bin thy sn bng phng php ln men (snxut nc mm, cc loi mm) th tc phn gii l do tnh cht v s lng cc cht

ngm ra quyt nh mt phn. Thnh phn cht ngm ra ca thy sn c chia lm 3nhm:1. Trimetyl amin (TMA) v Trimetyl aminoxit (TMAO):

CH3 CH3 N CH3 v O = N CH3

CH3 CH3

TMAO c mi thm ti rt r chu c trng cc thy sn ti sng, ngi ta chorng mc ngun gc t mi trng nc.

TMAO d b kh thnh TMA bi mt s loivi khun nh micrococus, achromobacter, flavobacter, pseudomonas

15


17/86

nhit cao TMAO phn gii thnh dimetylamin (DMA) v HCHO. Khi thy sn bn thi TMAO c th b phn gii ln lt thnh mono mentyl amin (MMA) ri n NH3.

TMA c mi tanh c trng ca a s thy sn t lc bt u cht.2. Betain :

CH3CH3 N CH2 C = OCH3 O

C rt t trong sc sn v c, c nhiu trong cc loi nhuyn th v chn t nh mc,cua, c, tm. Betain c mi thm ti d chu, dng khan nc (khng ngm nc) tonn lp phn trng p v thm trn mnh cc loi mc kh (trong 1kg mc ng kh c 16g

betain). Do trong ch bin mt hng mc kh t nhin ngi ta phi phi v mcln phn.

3. Cc cht khc nh: axit amin t do, taurin, bazpurin, glutation, cc sn phm phngii cui cng nh (NH2)2CO, NH3, c bit trong cc loi c sn (nhm, ui) hm lnghai cht cui cng ny kh cao n 2g% to nn mi khai thi. Mt s cht hu c khckhng cha nitnh glycogen, axit lactic, axit sucxinic, trong glycogen v axit sucxinicto mi thm thy sn ti sng.

16

3.3. Trng gia cm:Trng gia cm chn nui bao gm cc loi: g, vt, ngan (vt xim), ngng, cun ct

c dng vo cc mc ch: lm thc phm (n ti, p trng vt ln); ch bin cng ngh:trng mui, trng lnh ng, bt trng p n; sn xut thuc cha bnh (vac xin, thuc) .

Khi lng ca mt s loi trng: g/qu: g: 60 65, vt: 60 80, ngng:150 170,cun ct: 10 15.

Cu trc ca t qu trng l hnh elip: mt u nhn mt u t, bao gm:1- Lp mng protein ngoi v2- V cng3- Mng trong4- Bung hi5- Lng trng6- Dy chng7- Mng non hon8- Lng 9- a phi

89

3

21

4

6

7 5Bng 1 - Thnh phn ha hc trung bnh ca trng g, %

Cc phn T l Nc Protein Lipit Gluxit KhongTrng nguynRut trngLng trngLng V trng

10090603010

65.574884710

121318162

1112

0,03340

0,50,70,80,60

110,90,51,188


18/86

- Mng ngoi v l lp tiu b protein dy 10 30 t tan trong nc, c tnh cht gnging nh colagen, c tc dng hn ch s bc hi nc, ngn nga s xm nhp ca visinh vt qua v vo lng trng . V th nu lau ra hay c xt lm tn thng lp mng nym khng c bin php bo v (st trng, bao gi) th vi sinh vt d xm nhp vo trng gyung hng nhanh. S tn ti ca lp mng ny l du hiu nh gi mc ti mi catrng.

- V ngoi c cu trc mng li protein trn c bm cc tinh th CaCO3 (90% khilng v), MgCO3 (1%) v Ca3(PO4)2 (1%). Trn b mt v c nhng l nh thm kh:10000 l/trng cho phi c th h hp khi p trng.

- Mng trng do cc si protein-saccarit to nn c b mt dy 70 . Khi b bin tnhnhit (luc trng) mng ny trnn dai v bn chc, d tch khi lng trng.

- Bung hi: trng va mi th mng trong dnh vo v. Sau mt thi gian, nhit ca trng gim dn, kh v hi nc trong rut trng thot ra ngoi qua cc l trn v, thtch rut trng gim i, u t ca trng, lp mng dn dn tch khi v to nn bunghi. Kch thc ca bung hi tng dn theo thi 13

- Lng trng (albumin) gm 3 lp: lp ngoi lng (23%), lp gia c (57%), lp tronglng (20%), khi b vth chnh lp albumin c gia bao ly lng .

Albumin l dch th gm cc protein hnh cu nh: ovalbumin, conalbumin,ovogolbulin, flavoprotein , ovoglucoprotein, ovomacroglobulin, avidin v mt protein hnhsi l ovomuxin. Trong albumin trng cn c 0,5% glucoza t do, y l tc nhn gy nn

phn ng lm sm mu phienzim, c th loi tr phn ng ny bng enzim glucooxidoza( c ng dng trong cng ngh).

- Dy chng cng l mt loi albumin c gi cho long lun trung tm qutrng. Nu trng lu hay trng b h hng th long trng trng v day chng b chylong (va long trng), khi long c h b di chuyn t do hoc trn ln vi long trng

trng, khi trng v th rut trng chy long, khng phn bit c long .Thnh phn ovalbumin chim nhiu nht lng trng (58,4%), n c 4 nhm SH v 2 cui sunfua S S , c kh nng to gel tt, to bt tt khi nh khuy, bt n nh khi lmlnh, lm bn bt khi gia nhit. Cc albumin c tnh khng khun (trc tip hay gin tip:to phc vi vitamin, kim loi, c t) gp phn bo v phi ca trng: albumin ti nichung l kh tiu ha, ch sau khi bin tnh nhit (luc, rn chn) mi c th tiu ha ddng, l do thnh phn ovomuxin l mt anti tripxin (enzim khng tiu ha protein) v c1 s globulin khng chu tc dng ca enzim tiu ha. C th bo qun hay s ch trng

bng cc phng php: bo qun lnh t t = 1oC, %90= trong 6 thng, bo qun trngtrong kh quyn c c 2,5% CO2 hay kh trkhc nh N2, nhng trng vo du khong,

parafin nng chy bt cc l thong hi trn v, chn trng ( lm ng t nhanh 1 lpmng protein di mng trong), bao gi kn, ch bin trng mui (dung dch NaCl,Ca(OH)2).

- Lng : gm cc ht protein phn tn trong dung dch protein, ht hnh cu ngknh 1,3 20 do 3 kiu protein lin kt vi nhau thnh mt phc bao gm: lipovitelin v

phosvitin l 2 h p phn c s, cn lipoprotein s nh vi phc qua cu ni trung gian phosvitin. Cc lipovitelin l protein nng c th tch thnh 2 dng , lipovitelin.Phosvitin l mt phosphoprotein rt giu serin ( chim 31% lng axitamin ca lng ) ckh nng c nh cc ion st. Dung dch ca lng (dch tng) bao gm livetin vlipoprotein nh. Livetin l mt protein hnh cu vi 3 dng ,, khc nhau v phn t

lng. Chng c th tch ra 2 phn: L1 c phn t lng 10 triu v L3 c phn t lng 3triu.

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19/86

Lng cha gn nh ton b lipit ca trng ch yu l triglixerit (60%), phosphatit(28%) v cholesterol (5%).

Cng mu ca lng ph thuc vo hm lng carotenoit ca thc n v iukin chn th. Gia cm nui th t nhin, n thc n t nhin th trng c long mu scp hn so vi gia cm nui theo li cng nghip.

Khi luc trng hoc dng cc x l nhit khc (rn) th lng c li mi v bi, boc trng, c bit t lng trng c th gii phng ra H2S, c th tc dng vi Fe ca lng to kt ta en FeS (vt en trn b mt lng chin).

ng ch l thnh phn axitamin ca trng rt cn i, n nh, gn nh khng phthuc vo ging thc n, iu kin nui dng gia cm, V vy trong dinh dng hc ngita coi protein trng l loi hon thin v ly n lm chun dinh dng ( cc ch s: gi trsinh hc (BV), t l hiu qu protein (PER), thang gi tr ha hc(CS), ch s axitamin cnthit (EAAI), gi tr thay th protein (PRV).3.4. Nguyn liu sa.

Trong cng ngh, ngi ta thng s dng 4 loi sa l: b, tru, cu, d.- V phng din ha l, sa l mt huyn ph cc ht keo trong nc. Cc ht bao

gm cc cu bo ng knh 3 5 cc mixenprotein ng knh 0,1 c to thnh dotrng ti gia casein vi cc protein khc, gia cc protein vi cc mui v cha tan. Ccht to ra c v mu trng ca sa (do tn x nh sng bi cc mixen protein).

- Hm lng protein trung bnh ca sa khong 30 35g/lit. Gn 80% lng proteinny tn ti dng mixen l phc gia carein vi mui canxiphosphat. Hm lng Ca trongs khong 1,2g/lit v c th tch mui Ca2+ ra khi sa bng li tm hay kt ta ng in

pI = 4,6.Trong cng ngh ch bin sa, ngi ta thng kt ta sa (ng t) bng cc phng

php sau y:+ Kt ta (ng t) bng axit: di tc dng ca axit thm vo hay axit sn c trong

sa, phc Cazein - Ca - Phosphat b ph v, cein tr nn trung ha in v ng t.phng php ny dng trong ch bin sa chua v ch bin cazein.

+ ng t bng ch phm enzim chimozin ca d dy d: trong ch bin phomat,cazein di tc dng ca emzim chimozin chuyn ha thnh paza-cazein tip tc tc dngvi Ca2+ v ng t li.

Trong cc cazein th cazein K thng c nh v ch yu trn b mt cc mixen. Khingi ta x l sa bng ch phm chimozin th gn nh ton b cazein K b thy phn trongkhi cc cazein khc khng b bin i. Nh vy bn ca mixen ph thuc vo t lcazein K.

S tn cng ca enzim chimozin ln carein K nh sau:Peracazein K khng tan Careino gluco peptit ha tanH2 N (1)

phe (105) met (106) (169)v tr tn cng ca chimozin

Chimozin cc lin kt phe (105) met (106) ca cazein K to nn cazeinoglucopeptit ho tan v para-cazein K khng tan lin kt vi mixen gc ng t li. Tuy nhinnhiu nghin cu ch ra rng sng t ch xy ra khi c trn 80% cazein K b thy phn

bi chimozin.- Mt s loi nguyn liu sa:

+ Sa b: c sn lng ln nht, ph bin nht.Sa b cn gi l sa cazein snxut ra hu ht cc sn phm sa thong dng nht hin nay nh: sa ung ti, sa chua,

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sa c nguyn cht c ng, sa bt (ton phn, tch mt phn b hay tch ht b (sagy), b v phomat.

Mt lt sa b c hm lng b3,8% c sinh nng lng 540 calo, tng ngvi 0,5kg tht nc, 8 9 qu trng, 2kg rau u, 100g go, m hoc 1,5kg hoa qu.

+ Sa tru: c tnh cht gn ging sa b, sn lng ng th 2 sau sa b. sa trudng sn xut ra loi phomat mm do hm lng cazein cao.

+ Sa cu: c mu trng hi vng , v hi cht, giu vitamin c bit l provitaminA.Sa cu rt thch hp sn xut phomat v nhiu mt hng c gi tr.

+ Sa d: ph bin cc nc chu phi, c mu trng, v hi chat, d bo qun hn sab trong mi trng nhit cao.

Bng 2: Thnh phn ha hc trung bnh ca mt s loi sa, %Vt nui Nc Lipit Lactoza Cazein Protein khc KhongBTruDCu

87,580,586,880,6

3,88,05,0

8,0

4,74,54,3

4,8

2,74,23,3

4,6

0,50,70,7

1,1

0,700,840,85

0,863.5. Mt s loi ph phm sc sn - thy sn.

- Huyt: khi git m gia sc, gia cm lng huyt thu c l 3,5% khi lnh contht, trong huyt c khong 17% protein nn c th coi l 1 dng tht lng. C thchng ng (hm tit) bng cc cht ph gia nh NaCl, natri xitrat.

Huyt nguyn + Cht chng ng

Khi bng Khi b khng ng

19

Huyt thanh Huyt khi Hng cu Huyt tng

Hng cu Fibrin Hemoglobin Cht m (khong)

Cng ngh ly huyt v lm sch huyt khi sc tht (sc sn, thy sn v c) c ngha c bit quan trng bo m cht lng tht ti sng cng nh tht ch bin, boqun tip theo. V nu sc tht cn huyt (huyt lu hoc huyt ng) s lm xu mu sc

sc tht, tht d b bin cht do hot ng ca vi sinh vt v do ha sinh.So vi protein ca trng th protein ca huyt thiu izolxin v metiomin. Trong huytc gn 200 loi protein, tr albumin v mt vi protein vi lng nh c hot tnh enzimnh lisozim, - amilaza th tt c nhng protein cn li u thuc nhm gluco protein.

Fibrinogen l tnh cht ca fibrinogen, l cht lm cho mu ng, phn t ca n rt s, rt di. Khi mu ng, mng fibrin khong tan c to ra t fibrinogen di tc dngca trombin l mt enzim proteaza c trong mu di dng tin trombin khng hot ng.Tin trombin c hot ha nhtromboplatin, ion Ca2+ v cc yu t phc hp khc ( c tnht 8 yu t trong proconvertin l yu t chng bnh a chy mu (bnh mu khngng) c gi l vitamin K).

Hemoglobin l protein ch yu ca huyt cu t trong nguyn t Fe nm trung tmv bn nhn heme nm nh ca mt t din. i lc gia hemoglobin vi oxy b hn i


21/86

lc gia oxy v mioglobin do s chuyn oxy t hemoglobin ca mu (HHb- O2) nmioglobin ca ctrong vng tun hon ca mu.

Trong qu trnh x l nhit, mu ca hemoglobin b bin i do b oxy ha. Cc tcnhn nh l CO, - NO2, - NH2 lm bin mu hon ton ca mu.

Trong cng ngh huyt c dng nhum mu mt s sn phm gi tht, sn xutbt huyt.

- Gan: l b phn quan trng nht trong chuyn ha vt cht ca hot ng sng. Tonb cht dinh dng tiu ha t rut non u thm vo mu v i n gan t gan siuha, phn phi cc cht dinh dng ny cho ton b cth, gan cn c chc nng khc,d trng di dng glycogen v iu ha lng ng trong mu. Khi git m gia sc,gia cm, ty theo yu cu mt hng (nht l cc sn phm gia cm) m ngi ta c th gili gan, tim, m cng vi ton b thn gia cm. Trong cng ngh ngi ta s dng gan nhsau:

+ Gan ngng: c gi tr cng ngh cao nht. Mt s nc trn th gii chn nui loingng ch yu ly gan gi l ngng gan. Mt hng ni ting nht t ngan l pat ganngng t nhin v pat gan ngng vi nm.

+ Gan ngan (vt xim): c ch chn nui trong nhng nm gn y ly gan(Php, Hungari).

+ Gan ln: l nguyn liu sn xut mt hng pat gan.+ Gan b: t c gi tr thc phm nhng c dng nhiu nht trong sn xut thuc

cha bnh, dch thy phn gan b dng sn xut dch truyn (m) y t.+ Mt s loi gan c nh thu, nhm, ui, mp c s dng trong sn xut du gan

c.- D dy v rut: c dng ch bin mn n (b lng) nhng trong cng ngh

ngi ta s dng trong cc lnh vc sau:+ Dch d dy: l nguyn liu thu nhn mt s ch phm enzim quan trng nh

pepsin t d dy ln, chimozin t d dy b.+ Rut non ca ln, d, cu dng nhi tht khi sn xut xc xch, lp xng.

Chng IV. NHM NGUYN LIU LNG THC

20

4.1. Cu to v thnh phn ha hc ca ht cc.4.1.1. Cu to ca ht cc .

Tt c cc ht cc u c 3 phn chnh: v, ni nh v phi.

- V: ty thuc cu to v m ht ccc 2 loi: loi ht trn (v mm) v loi v tru.Loi ht trn nh: ng, k.Loi v tru nh: la, la m, i mch.

Cu to ht la1 - v tru ; 2 - lp cm (alrng)

7

53

1

2

4

6

3 - ni nh ; 4 ru5 - l p ng ; 6 phi ; 7- my

V l lp bo v cho phi v ni nh khi b cc tc ng t bn ngoi. Vc cu

to t mt s lp t bo. Khi ht cn xanh th cc t bo ny cha nguyn sinh cht vdip lc t (chlorophyll). Khi ht chn th nhng cht ny chuyn dn vo ni nh, lc


22/86

21

t bo tr nn trng rng li thnh t bo c cu to ch yu t xenluloza,hemixenluloza v cht khong (v tru ht la c cc tinh th SiO2 nn rt th rp). Nhvy trong v hu nh khng c cht dinh dng nn cn phi tch sch v khi ch bin(cng on xay).

- Lp alrng v ni nh: sau lp v l lp allng (cn gi l lp cm) gm t 1 - 3lp t bo hnh ch nht hay hnh vung. Chiu di lp alrng ph thuc vo loi ht,ging ht v iu kin canh tc (ht chu hn, rung kh c lp alrng dy hn ht chunc, rung nc).

Thnh t bo lp alrng c cc cht cha nit v c bit l cha hu ht lngdu bo (lipit) ca ht (vi ng th lng du ny tp trung ch yu phi), in hnh nhtl la. V th cm go l nguyn liu chit p ly du cm c g tr thc phm cao.

Ngoi ra trong lp cm cn cha hu ht cc vitamin nhm B ca ht.Sau lp alrng l khi t bo ln thnh mng c hnh dng khc nhau, khng c th

t, y l phn ni nh, ni d tr cht dinh dng ch yu ca ht. Phn ln tinh bt vprotein ca ht u tp trung ni nh v th loi ht no c t l ni nh cng cao th cgi tr cng ln, t l thu hi khi ch bin cng cao.

- Phi ht: c phn cch vi ni nh bi lp ng. Lp ny ng vai tr quan trngkhi chuyn cht dinh dng t ni nh vo phi nui cy non, v th n c cu to

bi cc t bo sp xp thnh mt mng thm thu cht dinh dng ha tan.Phi l phn pht trin thnh cy non khi ht ny mm, n bao gm 2 phn chnh l

mm phi (pht trin thnh thn v l non) v r phi (pht trin thnh r). Thnh phnch y ca phi gm protein, gluxit ha tan v lipit, c bit trong phi ng lipit chimti 40% cht kh. V thy l nguyn liu chit p ly du phi ng. Nh vy trong

phi c nhiu cht dinh dng, phi li mm, m cao hn ni nh nn d b vi sinh vtv cn trng ph hoi. Mt khc lipit trong phi c cu to ch yu t cc axit bokhng no nn d b oxy ha (i kht). V vy ngi ta thng tch phi ng d boqun v ch bin v sau.

Bng 3 - T l khi lng tng phn ca la, ng v la m, %.Loi ht V Phi Ni nh

LaNgLa m

16,0 27,05,0 8,5

15,0 49,0

2,0 2,510,0 15,02,2 3,2

7279 8377 82

4.1.2. Thnh phn ha hc ca ht cc.Bao gm cc nhm cht hu cnh: gluxit, protein, lipit, enzim, vitamin, axit hu

c, cht mu, cc cht v cl khong (tro) v nc.

Bng 4 Thnh phn ha hc trung bnh ca ht cc, %.Loi ht Nc Gluxit Protein Lipit Xenluloza TroLaLa m

Ng

131414

60,068,767,9

6,712,010,0

2,11,74,6

8,82,02,2

5,41,61,3

Bng 5 Thnh phn ha hc tng phn ca la, %B phn ht Protein Tinh bt ng Xenluloza Pentozan Lipit Tro

Ton b ht

Ni nhV v phi

10,07

12,9141,30

69,00

79,82Vt

4,32

3,5425,12

2,76

0,152,46

8,10

2,729,74

2,24

0,6715,04

2,18

0,455,31


23/86

22

Alrng 28,70 Vt 4,18 16,2 36,56 7,78 10,51

Bng 6 Thnh phn ha hc trung bnh ca ng, %

B phn ht Protein Tinh bt ng Lipit TroNi nhPhiV

9,418,83,7

86,48,27,3

0,6410,800,34

0,8034,501,00

0,3110,100,84

ng ch l cc vitamin tp trung nhiu phi v lp alrng. V vy khi xay xt

(go, la m) ng thi cng tch b phn ln lng vitamin ny. Gi tr thc dng cago lt (go nguyn cm) mt phn l do lng vitamin ny quyt nh. Ngoi ra thnhphn khong phn b khng u trong ht, phn ln tp trung lp v, alrng v phikhong 6 8%, trong ni nh c rt t khong 0,4 0,6%. V th tro (khong) l ch scbn nh gi cht lng cc sn phm lng thc (phn hng bt m, cc loi bt vtinh bt). Nu tro cng thp ngha l s tch v v phi cng trit , cht lng sn

phm cng tt, t th hn cng cao.4.2. Gii thiu cc loi ht cc ch yu.4.2.1. La (Oryza Sativa L).

La l cy lng thc chnh ca gn na dn s th gii, c ngun gc ng Nam

t 3000 nm trc Cng nguyn. Hin nay hu ht cc nc du c trng c la trmt s nc cc bc.C khong 20 ging la khc nhau trong c ngha kinh t hn c l loi la trng

(khc vi la mc hoang di gi l la tri mc theo ma nc ni Nam b Vit Nam,min nam Campuchia, min trung Thi Lan). Loi la trng ph bin nht hin nay trn thgii c chia thnh 2 nhnh: nhnh n v nhnh Trung - Nht, trong nhnh n ht di, nhnh Trung - Nht ht to nhng ngn hn. Trn th trng th thc go nhnh nc a chung hn nhnh Trung - Nht, thc go t ph bin hn thc go np.

Cc ch tiu cht lng ca la nh sau (c th p dng cho cc loi ht cc khc mc thch hp):

- ti (mi) ca ht: c nh gi bi thi gian ht thu hoch cho n khi em ixay xt. ti c th hin cc mt: tnh trng ni nh (khng b mc, mc, v l,ny mm, mu sc l), tnh trng khi ht trong kho, trong bao b (mc v s lng mt,trng b).

- tp cht: 2 nhm tp cht nng (sn, si, vn kim loi) v tp cht nh (rm rc,ht lp, bi).

- v: yu t quyt nh t l thu hi go khi xay.- m: ch tiu cht lng ca la v go.- trng trong: ni nh la ty loi ging v iu kin pht trin m c th trng

trong, na trng trong hay c hon ton. Thng th thnh phn ni nh trng trong c

hm lng amilo cao hn, cng ln hn thnh phn ni nh trng c c hm lngamilopectin cao hn, cng thp hn. Trong cng ngh xay xt, la c ni nh trng


24/86

trong cao v phn trng c cng xa tm ht th khi xay xt t bt gy, t l thu hi gonguyn cao.

Thng thng khi sn xut go th tch mt khong 86% cht bo, 73% khong, 15%protein, 70% vitamin nhm B, 6% tinh bt, 82% xenluloza. gi li mt phn cht dinhdng, c bit l vitamin, ngi ta dng phng php gia cng nc nhit chuynmt phn vitamin t lp cm vo ni nh. Go thu c gi l go (hay go sy) c thc xay xt k nhng vn bo m hm lng vitamin. Nhc im ca loi go ny lmu sc hi vng, v nht hn go thng.

Go l nguyn liu thay th trong sn xut bia, l nguyn liu chnh trong sn xutru c sn (ru Mao i, Thiu Hng Trung Quc, Sak Nht Bn, ru Vn, ruBu , ru Cn Vit Nam), trong sn xut cc sn phm thc phm truyn thngnh: tng, bn, bnh ph, min, bnh trng, bnh phng, ko m xng, cm.4.2.2. La m (Triticum aestivum L).

y l cy lng thcc din tch trng v sn lng ln nht, c khong 20 dng lam bao gm cc ging: la m mm, la m cng, la m Anh, la m Ba Lan v la mln, trong bao hai ging la m mm v cng l ph bin nht. Sn phm thng mica la m bao gm ht la m v bt m.

Hai thnh phn quan trng nht trong la m v bt m l tinh bt v protein. Trong protein bao gm 4 loi chnh: albumin (5,7 11,5%), globulin (5,7 10,8%), gliadin(40 50%) v glutenin (34 42% tng lng protein). Nh vy 2 loi gliadin v gluteninl ch yu chim n 70 85% tng lng protein ca bt m. Khi nho bt mc d 2

protein ny khng ha tan trong nc nhng li ht nc, trng n to thnh mt khido n hi gi l gluten. Vi la m tt thong thng hm lng gluten ti chimkhong 20 25% khi lng ht.

Gluten c ngha rt ln trong cng ngh sn xut bnh m v cc cng ngh khc cs dng bt m (bnh bisque, m n lin, spaghetti, vn thn, bnh bao). Khi phn btrong bt nho, gluten to thnh mng n hi, dai, c kh nng gi kh, phng ntt. Nhvy cht lng gluten quyt nh cht lng ca bnh m v cc sn phm khc c s dng

bt m.Cht lng gluten c th hin cc ch s sau: mu sc, kh nng hut nc,

n hi v cng t, bn ban u v s thay i th tch gluten khi nng (bnh).- Mu sc: quan st m sc gluten ngay sau khi tch bng nc. Gluten tt c mu trng

ng i khi hi vng, gluten xu mu xm, ti.- Kh nng ht nc: chnh l m ca gluten ti ngay sau khi tch bng nc, gluten

tt th c kh nng ht nc cao (tnh theo lng nc c ht bi 100g gluten kh).

- n hi: l tnh cht rt quan trng ca gluten v n biu hin kh nng gi kh cabt nho, c xc nh bng cch cn 4g gluten ti, v trn ri c nhit thngsau 30 pht.nu n ngn tay vo vin gluten ri th ra nu n phng tr li v tr c lgluten tt, nu phng chm hay khng bng v tr c l gluten xu.

- cng t: cng c trng cho kh nng gi kh ca bt, c xc nh bng diko t ca 2,5g gluten ti.

+ Gluten c cng t km: 8cm+ Guluten c cng t trung bnh: 8 15cm+ Gluten c cng t cao: >15cm

- bn ban u ca gluten c c trng bi n hi v cng t ban u v

sau khi tch gluten 2 3h.

23


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24

- S thay i th tch gluten khi nng: l ch sc trng cho nca gluten. Vivin gluten ti 2,5g em nng trong l 160 165oC trong 30 pht. Nu gluten tt th thtch tng gp i, nu gluten xu th tng t, khng tng thm ch b chy.

La m v bt m l nguyn liu trong cc cng ngh sau: sn xut ru etylic,nguyn liu thay th trong sn xut bia, ru uytxki, bnh m, m n lin, bnh bisqui,

bnh bao. Ring gluten l nguyn liu sn xut bt ngt bng phng php ha gii doc hm lng axit gluten cao (30 35% tng lng protein ca gluten), l nguyn liu tohnh ca cc mn n chay, ca cc sn phm gi tht.4.2.3. Ng (Zea mays L).

C ngun gc Trung M t 3000 nm trc Cng nguyn. Ng c nhiu ging khcnhau v hnh dng bp, hnh dng v kch thc ht, bao gm mt s ging chnh nh: ng, ng rng nga, ng bt, ng sp (ng np), ng n, ng ng.

V mt cu to, ht ng cng c 3 phn chnh: v, ni nh v phi.Bng 7 - T l khi lng tng phn ca mt s loi ng, %

Loi ngCc phn ca ht Ng Ng bt Ng rng nga

Ni nhPhiV

80 908 13

1,5 6 0

79 8310 14

5,0 5,5

81 8410 12

5,0 5,3

Bng 8 Thnh phn ha hc trung bnh ca cc loi ng, % cht kh

Loi ng Protein Tinh bt Lipit KhongNg bt

Ng rng ngaNg Ng spNg ngNg n

11,3

12,212.312,913,814,3

64,2

61,566,061,631,259,9

7,2

7,77,97,8

14,46,36

1,05

1,161,281,101,371,33

Trong ng c 1,6 2,7% xenluloza, 1,5 5% ng, 1 6% dextrin, 7% protein,trong ng vng c 0,3 0,9 mg% provitamin A.Trong ng c nhiu vitamin nhm B, E, Dv C.

Protein ca ng gm c nhm: albumin, globutin, glutelin v prolamin. Trong

prolamin nhiu hn c v c gi l Zein (ly theo tn la tinh ca ng Zea mays L) vcng c kh nng to gluten nhla m.Ng c gi tr cng ngh rt coa, c th ch bin thnh 200 loi sn phm khc nhau nh:ng mnh, bt ng, bong ng, hp, ru, bia, nc gii kht, mch nha, cng ngh dt(t vi), keo dnh trong sn xut pin kh.4.3. Cu to v thnh phn ha hc ca c lng thc.

Khoai ty, khoai lang, sn, dong ring, c mi, sn dy l nhng loi c lng thcph bin.4.3.1. Khoai ty (Solanum tuberosum L).

c du nhp vo nc ta trong thi gian cha lu (u th k 20), c trng ch

yu cc tnh pha bc t Ngh An tr ra. Theo ln v trng lng c cc loi: trung


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bnh 50 100 g/c, to: 100 150 g/c, nh: 25 50 g/c, kch thc ht tinh bt : 1 -120 , hnh bu dc, hm lng tinh bt trung bnh 8 30%.Khoai ty l nguyn liu sn xut cn etylic, tinh bt khoai ty, khoai ty chin.4.3.2. Khoai lang (Batatas edulis chois).

c trng cc nc nhit i. Trn th gii v nc ta c nhiu ging khoai langngon nh Nht Bn, Trung Quc, L Cn (Gia Lai), Duy Xuyn (Qung Nam).Thnh phn ch yu ca khoai lang l tinh bt, ty thuc ging v mc gi ca khoai,kch thc ht tinh bt 5 50 . Khoai lang cha nhiu ng 5 10%, ch yu l ngglucoza. Enzim trong khoai lang c nhiu loi nhng ch yu l amylaza, v vy khi boqun khoai ti, amylaza thy phan tinh bt thnh ng lm cho khoai ngt them ngthi lm hao tn cht kh ca khoai.

Trong m khoai cn c cc polyphenol v cht mu nn rt d gy bin mu trongqu trnh ch bin khoai.

Khoai lang l nguyn liu sn xut khoai lt kh, mch nha, tinh bt, hp,axitaxetic (dm n), axit xitric, sn xut ri etylic, h vi, sn xut pin.

4.3.3. Sn (Manihot utilissima pohl).Ngun gc t Nam Mc trng nc ta t th k 19 ti cc vng t i, trungdu v min ni gm nhiu loi nh: sn d (cn gi l sn tu hay sn ng), sn vng (cngi l sn ngh), sn (cn gi l sn canh nng), sn trng. Nu phn loi theo hmlng HCN th cc loi sn c chia lm 2 nhm l sn ng v sn ngt. Sn ng chm lng HCN cao, khng dng n ti v d b say, hm lng tinh bt li cao nnch dng sn xut sn lt kh v tinh bt. Sn ngt c hm lng HCN thp, c thnti c. c t trong sn dng glicozit gi l fazeolunatin C10H17NO6, di tc dngca enzim hay axit s phn hy thnh glucoza, axeton v HCN:

C10H17NO6 + H2O C6H12O6 + C3H6O + HCN

E H+

Trong sn xut tinh bt, c t ha tan theo nc thi nn sn ng vn cho sn phmtinh bt tt, hu nh khng cn c t. Hm lng tinh bt sn ph thuc vo nhiu yu t,quan trng nht l ging v gi ca c sn khi dc. Ht tinh bt sn hnh trn, ngknh 5 35 .

Ging nh khoai lang, trong m sn cng c cc polyphenol v cht mu. Nu trongqu trnh sn xut tinh bt c s tip xc lu vi khng kh hoc khng dng cht km hmsinh mu (ph bin nht l SO2) th cc cht trn b oxy ha lm cho tinh bt khng ctrng.

Sn l nguyn liu ch bin cc sn phm sau y: sn lt kh, bt v tinh bt sn,

bnh phng tm, ko m xng, ru etylic, mch nha, bt ngt (iu ch mi trng lnmen axit glutamic), ng glucoza.

Chng V. NHM NGUYN LIU DU MV TINH DU

5.1. Nhm nguyn liu du m:Nguyn liu du mbao gm cc loi cy trng, vt nui, ng vt sn bt, nh bt m

trong mt hay nhiu cquan cu to cth ca chng c cha mt lng cht bo ng k,sn lng ln c th bng cc phng php cng nghip khai thc c lng cht

bo y vi hiu qu kinh t cao.Trong thc t c nhiu cch phn loi du m, chng hn:5.1.1. Phn loi theo ngun gc:

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26

C 2 loi:- Loi nguyn liu du mthun tu: gm cc nng sn (hng ho nng nghip) thc

s nh ht lc, kh da (copra), ht u tng, ht hng dng, ht c du, ht o lnht, ht thu du, ht tru, ht vng, ht liu ... v ng vt nh bt in hnh l c voi vc heo.

- Loi nguyn liu du mkhng thun tu: chng c th l nng sn thc s hay phphm nng nghi p, cy cng nghip, ng vt nh bt c, c cha du m c thkhai thc vi hiu qu kinh t cao.

Vd: Cm go, phi ng ( khai thc du cm, du ng) cc loi cy bng, lanh, gai,cao su ly bng, si, nha nhng ht ca chng c th khai thc du bo rt c hiu qu;cc loi bca sa vt nui (b, tru, d, cu) v mca chng: mln, du c, du gan cthu, c mp, c ui ...5.1.2. Phn loi theo c im dinh dng:C 2 loi chung cho c cc sn phm du:

- Loi nguyn liu du mlm thc phm v lm thuc cha bnh: gm tt c cc loinguyn liu v sn phm m con ngi v vt nui c thn trc ti p v ch bin thc

phm. Ngoi ra cn c mt s loi khc dng lm thuc cha bnh nh du tru lm thucty, du ng, du gc, du gan c lm cc ngun vitamin A, D quan trng, du vng lmthuc cha bng, cha vim lot rt tt ...

- Loi nguyn liu du m khng phi thc phm: gm cc loi nguyn liu v snphm khng th dng n c do trong thnh phn ca chng ngoi du bo ra cn ccha cc cht gy c, gy mu, mi, v khng chp nhn. Do a s chng c khaithc ly du dng vi cc mc ch khc trong cng nghip v i sng, ch c mt sloi du nu qua tinh ch lm gim hay lm trit thnh phn c hi hay mu sc, mi, vkhng chp nhn th cng c th dng n c nh du s, du bng, du cao su.

V th, i khi ngi ta cn gi cch phn loi ny thnh hai nhm l nhm nguynliu (v sn phm du m) thc phm v nhm nguyn liu (v sn phm du m) cngnghip (hay cng ngh, k ngh hay k thut). Trong nhm th hai ny ngi ta cn nhnmnh thm mt s loi du mmc d l thc phm nhng ch bin cng nghip th cli hn rt nhiu so vi dng n nh du da, mb, mcu, mc voi, du c.5.1.3. Phn loi theo trng thi vt l bnh thng ca du m:

Tc l xem xt trng thi ca du m nhit bnh thng (2530oC) th tn tidng lng hay c:

- Nu du m th lng th gi l du, tuyt i a s du bo ca thc vt bnhthng th lng, cho nn ngi ta cng gi du thc vt l du bo hay du. Tuy nhin c

ngoi l l mc, mgan c bnh thng th lng nn c gi l du c, du gan c.- Nu du mdng c th gi l mhay b, tuyt i a s cht bo ng vt trncn bnh thng th rn, cho nn ngi ta cng gi chng l mhay b(mln, mb,

bsa b, bsa cu ... ). Tuy nhin c ngoi l l du ca cao (du thc vt) bnh thng th rn ging nh bnn gi l bca cao.5.1.4. Phn loi da vo sbin i ca du khi tip xc vi khng kh (sto thnh

mng keo, mng sn du):C 3 loi:

- Du kh: khi tip xc vi khng kh nhanh chng to thnh mng keo bn vng nhcc loi du tru, lanh, trm ...

- Du na kh: khi tip xc vi khng kh cng to thnh mng keo vi tc chm,khng bn vng nh cc loi du: v ht iu, u tng, mng tang, ...


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- Du khng kh: Khi tip xc vi khng kh khng to thnh mng keo nh phn lncc du mthng dng.

Cch phn loi ny c p dng khi s dng du mtrong cc ngnh cng ngh snxut sn, sn mi, vecni, mc in, cht kt dnh ...5.1.5. Thnh phn cu trc ca nguyn liu du m:5.1.5.1. Thnh phn cu trc ca nguyn liu du thc vt:

Ht v qu c du l nng sn ng sau ng cc, sn lng th gii hin nay 240triu tn/nm v t khai thc 60 triu tn du.

Nc ta c 3 vng kh hu: nhit i, cn nhit i v n i ni cao nn cc loi cyc du rt phong ph, c nhng loi c trng i tr t lu nh lc, da, vng, utng, tru, s, cao su ..., mt s cy trng khc ang gy trng pht trin nh c du,hng dng, thu du, o ln ht, ca cao ... Ngoi ra cn c cc ph liu ng cc c dunh cm go, phi ng v cc loi cy rng, cy hoang di c du nh go, en, sn, vngng ...

Ht du c kch thc v hnh dng rt khc nhau, gm 3 phn chnh l: v, phi v ninh

- V:theo bn chc c 2 dng:+ V cng: da, o ln ht, tru, thu du, u tng, bng.+ V mm: lc, vng, ca cao.Tr vo ln ht (iu) l c du v nha, v c du l c du bo, cn tt c cc

loi v c ht du u cu to ch yu t xenluloza v hemixenluloza c tc dng bo vphi v ni nh bi cc tc ng chc, ho hc, vi sinh vt, trng b xm nhp lm h hiht.

mt s loi ht du cn c lp v la mng bao bc ly ni nh nh lc, vng, dachng d dng tch khi nhn khi phi sy v xt.

Trong cng ngh khai thc du, v l thnh phn v ch li c tnh ht du, tp trungnhiu cht mu (in hnh nht l nhm cht polyphenol c mu nu gy v cht trong vla ht lc) nn ngi ta phi tch b n.

- Phi ht: l cquan duy tr sinh sn ca ht, t mc ln r phi v mm phi, lmm khi gieo, m ht. mt s ht du nh lc, u tng, phi c cha cc cht gycht, ng, cht khong, enzim, nn trong cng ngh khai thc du cng phi tch b n

bo m cht lng du v kh du (c bit phi ng li l ni cha nhiu du bo).- Ni nh: cn gi l nhn ht, l phn c gi tr nht ca ht du bao gm cc m

cha cc cht dinh dng d tr cho hot ng ca ht khi ny mm v pht trin thnh cynon. Thng c th l phi nh ht thuc lp mt l mm (da, c du) hoc l t dip khi

ht thuc lp hai l mm (lc, u tng, hng dng, thu du, vng, iu ... ).Bng di y cho ta thy kch thc trung bnh ca t bo m cha du ca cc loiht du khc nhau:

Bng 9

Kch thc t bo - Loi ht M cha du

Chiu di Chiu rngLc T di p 78,5 47,6Thu du T di p 58,4 40,4Lanh T di p 33,7 13,1

Hng dng T di p 53,3 30,6u tng T di p 72,0 24,0

27


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28

Bng T di p 30,0 17,3

Qua bng 9 ta thy t bo m cha du ca lc c kch thc ln nht ri n utng v thu du, b nht l t bo ht bng v lanh. T bo m cha du c kch thccng ln th cng d b ph vv khi chu tc dng ca lc chc (nghin, khuy trn khichng sy, p du) gii phng du ra dng t do, tc l tnh cht cng ngh p du caht cng tt m in hnh l ht lc chng hn.5.1.5.2. Thnh phn cu trc ca nguyn liu mng vt:

Cng ging nhthc vt, mc tch ly trong t bo cu trc nn mca cthng vt cc lp di da, cc lp bao bc hay xen k h c, gn v dy chng (cvn catht, ctim, mng bao ngoi cc cquan bn trong nh rut non, mng tim, l lch, thn v

bng quan), mt lng ln cht bo c d tr trong gan, no, sa, trng ... mc tchly trong cc lp di da in hnh nht l ln v cc loi c voi, cn mc tch lutrong khoang bng th c hu ht cc loi ng vt nui v nh bt. Lng m tch luc khi v bo gia sc, gia cm v c nui cng c tp trung phn ln phn c thny. Nhn chung lng mdi da v trong khoang bng (cn gi l mkh v mphnhay m l) do tch lu vi s lng ln, tp trung, kh mdy nn d dng lng, lc khisc tht. Lng mny cng vi bchim t trng kh ln trong ton b lng mngvt.

Trong mt s cquan ca c voi nh cc tuyn, cc hch, trong no c cha du vmdng cc rn m ngi ta quen gi l sp c voi, mphn vai v c b cng gn gingnh vy. Mdng sp c khu vc bit c nhiu ngi yu thch.

M trong gan c tnh cht v chc nng c bit iu phi mi hot ng sinh l,sinh ho, tiu ha v hp th thc n ca cth. V th mgan (thng gi l du gan) cgi tr thc phm v dc phm rt cao in hnh l cc loi gan ngng, g, ln, b, c mp,

c ui, c thu.5.1.6. Thnh phn ho hc ca nguyn liu du m:Cc hp cht ho hc c trong nguyn liu du mrt phong ph i din cho hu ht

cc nhm hp cht hu c, chng bt ngun t mt s cht to thnh do kt qu ca qutrnh quang hp v qu trnh tch ly thc n khi tiu ha hp th. Trong cc cth trngthnh, thng qua qu trinh ng ha cc cht ca thc n s xy ra mt s qu trnh tnghp chnh v tnh u vit thuc v qu trnh no l ph thuc vo nhng nt c bit ca ht bo sng, cu trc v thnh phn ni bo quan ca t bo cht. ng thi vi qu trnhtng hp chnh to ra nhng nhm hp cht ch yu, tt nhin cn xy ra cc qu trnhtng hp nn cc cht khc.

Khi cng tng hp lipit c tng cng th cng tng hp protein li gimv ngc li. iu ny chng t gia hai cu t ny c mi lin h mt thit vi nhau saocho tng hm lng ca chng trong cth lun gimc nht nh.

Sn nh tng i v thnh phn ha hc cc hp cht c trong nguyn liu du mr rng c mt ngha quan trng trong qu trnh trao i cht khi c th sinh sn v sinhtrng.5.1.6.1. Lipit.

y l nhm h p cht quyt nh gi tr ca nguyn liu v sn phm du m, baogm cht bo v cc cht tng t cht bo. a s cc cht ny c kh nng ha tan tttrong cc dung mi hu c khng c cc nh etxng, hexan, ete du ho, ete etylic,

cloroform, benzen, toluen ... v trn thc t khng tan trong nc. T dn n kh nngc th tch chng ra khi hp cht hu cdng lin kt yu vi lipit hoc dng t do


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bng dung mi thch hp. y l csca phng php khai thc du bng trch ly dungmi.

Phn ln lipit trong du li lin kt ha hc vi gluxit v protein, khi dng bin phpha tan bng dung mi (trch ly) th khng th tch chng ra c. tch nhng lipit linkt ny cn phi sb ph vphc cht lipit protein, lipit gluxit bng cch nghin, giam , gia nhit (chng sy), khuy trn (phng php Skipin) bng cch dng ru etylichoc axeton.

- Lipit n gin (este ca axit bo): thuc nhm ny c cht bo (glyxerit) v sp.- Lipit phc tp (este ca axit bo vi cc nhm thay th): thuc nhm ny c

photpholipit, glucolipit, aminolipit v sulfolipit.-Sn phm thu phn lipit n gin v phc t p: thuc nhm ny c cc axit bo,

sterol v ru, hidrocacbon ...Ngoi tnh ho tan tt trong nhng dung mi hu ckhng c cc, lipit khi tc dng vi

kim s to thnh mui ca axit bo, tc x phng (phn ng x phng ho). lipit cng cth b thy phn bi kim, axit hay enzyme lipaza. Phn ng thu phn axit bng enzimthng xy ra trong iu kin khng thun li khi bo qun nguyn liu du mv khi bini sinh ha trong hot ng sng ca sinh vt (khi ny mm, sinh trng, sinh sn ...).

Thnh phn ch yu v c gi tr nht ca lipit l cht bo. y l este y ca ru3 chc glyxerin vi 3 axit bo nn c gi l triglixerit.

Hp cht quan trng nht ca nhm lipit phc tp l photpholipit. Cng do tnh d thyphn ca lipit cho nn trong thnh phn hn hp ca n bao gicng c axit bo t do vnhm hp cht khng b x phng ha bi kim. Nhng cht khng b x phng ha baogm cc sterol, tecpen, hidrocacbon, ru bc cao, carotenoit ...

Ngoi ra cn c cc sc t ha tan trong du mv cc dn xut cng nh sn phmthy phn ca chng.5.1.6.2. Axit bo:

Trong qu trnh tng hp cht bo ti cc t bo, bao gicng to thnh mt hn hpcc axit bo, v phng din cu to chng gn ging nhau ri kt hp vi glyxerin hnhthnh nn triglyxerit hn hp vi dng nh sau:

H2C O

HC

H2C

O

C

C

R1

O

R2

O

O C

O

R3

HC

HO

CH3

CH3C3H6

CH3

CH

CH3

CH3

Cholesterol C27H46 O y R1, R2, R3 l cc gc axit bo.

Hin nay ngi ta bit c hn 100 loi du mkhc nhau, tuy nhin s loi axit boli khng nhiu. Cc axit bo: stearic, panmitic, butyric, oleic, linoleic c trong phn ln ccloi du m. Tr mt s loi du, a s trong triglyxerit chc hnh thnh t mt vi loiaxit bo c trng cho du m:

V d: axit miristic c trong du nhn c, axit lauric c trong du da, axit oleic ctrong du lc, axit panmitic c trong mln, mb, axit rixinic c trong du thu du, axitelaostearic c nhiu trong du tru ...

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30

C hai nhm axit bo: nhm no v nhm khng no, axit bo khng no c cng thcchung l CnH2nO2 (k hiu l Cn:O). i vi axit bo khng no, tu thuc vo khng nom ta c:

Loi mt ni i: cng thc chung CnH2n-2O2 k hiu l Cn:1Loi hai ni i: cng thc chung CnH2n-4O2 k hiu l Cn:2Loi ba ni i: cng thc chung CnH2n-6O2 k hiu l Cn:3Loi bn ni i: cng thc chung CnH2n-8O2 k hiu l Cn:4Trong t nhin ch gp cc axit bo c s cacbon l chn t 2 30 (n = 2 30) nhng

ph bin nht l loi axit bo c n = 16 v n = 18Bng di y cho thy cc loi axit bo ph bin c trong cc loi du m:

Bng 10

Tn axit S nguyn tcacbon

Trng lng phnt

Khiu

C trong loi du m

Axit bo khng no CnH2nO2Axetic 2 60 C2:0Butyric 4 88 C4:0Caproic 6 116 C6:0

c trong hu ht cc loi dum

Caprilic 8 144 C8:0 du da, nhn cCapric 10 172 C10:0 du da, nhn c, bLauric

12 200 C12:0du da, nhn c, b, du c

voiMiristic 14 228 C14:0 du da, nhn c, mb, bPanmitic 16 256 C16:0 u tng, ci c, bcacao, bStearic 18 284 C18:0 mb, mlnArachidic 20 312 C20:0 du lcBehenic 22 340 C22:0 h hoa thp tLinoxeric 24 368 C24:0 du lcXerotic 26 396 C26:0Montanic 28 424 C28:0Melixic 30 452 C30:0

ph bin trong du thc vt

Axit bo khng no CnH2n-2O2Crotonic 4 86 C4:1Tiglinic 6 114 C6:1Licopodinic 16 254 C16:1

du ht ci

Oleic 18 282 C18:1Petrogenic 18 282 C18:1Cruxic 22 338 C22:1

hu ht cc loi du m

Physeteric 14 226 C14:1 du mc voiAxit bo khng no CnH2n-4O2

Linoleic18 280 C18:2

ph bin trong du kh v nakh

Axit bo khng no CnH2n-6O2


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Linolenic 18 278 C18:3Elaostearic 18 278 C18:3

ph bin trong du kh

Axit bo khng no CnH2n-8O2Parinaric 18 276 C18:4 du c trch

Trong du c ngi ta cn tm thy cc axit bo khng no dng CnH2n-10O2 (dng 5 nii) v dng CnH2n-12O2 (dng 6 ni i) vi n = 22, 24, 26, 28. Trong ng ch nht laxit clupadonic C22H34O2 (C22:5) vi cng thc cu to l:CH3 CH2 CH = CH (CH2)2 CH = CH CH2 CH = CH (CH2)2 CH = CH (CH2)2 CH = CH (CH2)2 COOH

y l thnh phn ch yu lm cho du c sn sinh mi thi (nu dng tay xt mnhvo axit ny s c mi thi ca du c), c nhiu nht trong c nhm.

Tnh cht vt l v ha hc ca cc axit bo (v do ca du m) l do s nguyn tcacbon v s ni i trong phn t ca chng quyt nh. Cc axit bo no ni chung bnvng vi cc tc nhn vt l v ho hc. Tnh cht quan trng nht ca cc axit bo khng

no l tnh oxi ha ti cc v tr ni i bi cc tc nhn khc nhau, chng hn:+ Nu tc nhn l hidro (p sut cao v xc tc thch hp) s lm bo ho (no ho)cc ni i theo cc mc khc nhau. y l phn ng cbn sn xut du hidro ha(mnhn to) nhm bin du lng gi tr thp (cha axit bo khng no) thnh mc gi trcao hn (thnh axit bo no).

+ Nu tc nhn l oxy nguyn t, ozn, nc, kim loi hot ng vi s xc tc canh sng, nhit , ca enzyme oxy ha - kh lypooxydaza sinh ra cc peroxit, chng hn:

RH2C C

HCH

(CH2)n C

O

OH + O2Lipooxydaza R CH2

HC

HC

O O

(CH2)n C OH

OPeroxit l sn phm trung gian ca s oxy ha cc axit bo khng no khi b phn hy,

cc peroxit to thnh oxit v oxy t do, t sinh ra ozon v hidroperoxit (H2O2).

R CH2HC

HC

O O

(CH2)n C OH

O

R CH2HC

HC (CH2)n C OH

OO

+ O3 + H2O2

S to ra ozon c th xy ra di nh sng cc tm. Do vy iu kin thng s iha l do c s to nn ozon trong khng kh, ozon s li oxy ha cc phn t axit khng no to thnh ozonit.

RH2C C

HCH

(CH2)n C

O

OHH2C

HC

HC

O O

(CH2)n C OH

O

+ O3

O

R

Ozonit l hp cht khng bn, d b thu phn to nn cc andehytH2C

HC

HC

O O

(CH2)n C OH

O

+ +

O

R H2O R CH2 C H

O

H C

O

(CH2)n C

O

OH

Cc andehyt li b oxy ho tip tc thnh cc axit mono v dicacboxylic tng ng:

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O2++R CH2 C H

O

R CH2 C OH

O

HO C

O

(CH2)n C OH

O

H C

O

(CH2)n C OH

O

+

Trong qu trnh du mb i, cc peroxit v oxit cng to thnh cc oxy axit :

1/2O2+ +H2OH2C HC HC

O O

(CH2)n C OH

O

RH

2C HC HC

OH OH

(CH2)n C OH

O

R

+ H2OH2C

HC

HC

OH OH

(CH2)n C OH

O

RH2C

HC

HC (CH2)n C OH

O

R

O ng thi vi s to thnh cc sn phm oxy ha, trong du mcn c th xy ra s

polyme ha vi cc mc khc nhau (tnh cht khng kh, na kh hay kh ca du m)Nhng sn phm to thnh do qu trnh thu phn v oxy ha nh trn lm cho du m

c mi v kh chu, chua, hc, ng v c th b h hng hon ton. V th trong cng ngh

ngi ta tinh ch du th hay du km phm cht (do bo qun, do s dng nhiu ln) bngcch loi b axit t do (trung ha bi kim) nng cao, phm cht ca du m, ko dithi gian bo qun.5.1.6.3. Triglyxerit v du m:

Du ml hn hp triglyxerit v cc cht tng t glyxerit song thnh phn ch yu ltriglyxerit

Tnh cht du mc quyt nh bi v tr cc gc axit nh vo glyxerit v s loiaxit cng nh tnh cht ca chng.

Cu to ha hc cc loi du m kh phc t p nhng phn ln chng chc tothnh t 5 8 loi axit bo khc nhau.

S loi triglyxerit c th c c theo s loi axit bo cu to nn chng c tnhtheo cng thc:

2

23

aan+

= trong : n l s loi triglyxerit c th c

a l s loi axit bo cu to nn triglyxerit.(V d: nu s loi axit bo c trong du m l 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 th s

triglyxerit c th c tng ng l: 1, 6, 18, 40, 75, 126, 196, 285, 405, 550).Trong du mcng c th c triglyxerit n gin (3 axit bo cng loi) nhng vi s

lng khng ng k. Mt s du mc thnh phn axit bo cho nh: du ve 50%

axit rixinic, du tru 85% axit elaostearic, du oliu, du lc 50% axit oleic, du no cvoi 60% axit physeteric. Khi lng ring du mtrong khong 900 980 kg/m3.H s khc x hay ch s chit quang l mt i lng c trng cho mi loi du m,

phn ln cc loi du mch s ny . Du mcha axit bo khng no bao

gicng c h s khc x cao hn loi du mcha nhiu axit bo no.

48.144.115

=nD

Nhit ng c ca a s cc loi du di 0oC ca cc loi mtrong khong 25 40oC.

Du mcn c tnh ha tan cc cht kh, hp th cc cht d bay hi. nhit bnhthng 100 ml du c th ho tan c 0.9 1.1 ml khng kh hoc 4 8 ml CO2. V thtrong cng ngh ch bin, ngi ta phi bi kh cho du mbng cch s dng chn khng

hoc sy nhit cao. Ngoi ra phi kn vic s dng mt s loi mnh mln, m

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c voi lm tc nhn hp th thu nhn mt s tinh du qu, hm lng nhhoa hng,hoa nhi.

Du mha tan cc cht thuc nhm lipit nh axit bo t do, cc hp cht ca axitbo, photpholipit, ru, hidrocacbon, carotenoit, sterol, tocoferol ...

Do c trng lng phn t ln nn cc triglyxerit hu nh khng b bay hi thm chtrong iu kin chn khng cao v y l csk thut ca cc bin php tinh ch du mc s dng chn khng v sy nhit cao ( tch m, bi kh, ty mu, kh mi). nhit 240 250oC th a s cc triglyxerit mi b nhit phn to thnh cc sn phm bay hic mi c bit (mi du mchy) v trong iu kin c y oxy s bt chy to thnhngn la - thi im chnh l nhit bt chy ca cc loi du m. Trong ch bin thc

phm v cng ngh ngi ta rt ch n nhit bt chy ca du m n hn nhkhong nhit s dng an ton du m, chng chy n.

Nhng tnh cht ha hc ca du mc th hin c th qua cc ch s ha hc phcv cho mc ch thu nhn, bo qun, ch bin, qun l cht lng nguyn liu v sn phmdu m, phng hung s dng du m.

Ch s axit l s mg KOH cn thit trung ha ht axit bo t do c trong 1 g dum. Nu mt loi nguyn liu hay sn phm du mno cng nhiu axit bo t do (htdu cn non, b khuyt tt, du ms dng nhiu ln ...) th cht lng ca n cng km.

Nh vy ch s axit c trng cho cht lng ca nguyn liu v sn phm du m. Vi ccloi du m thc phm ch s axit khng c vt qu 2.25, nu vt qu mc an tonny, cn phi tinh ch h thp ch s axit bng bin php trung ha bi kim v khi ch s ny c dng lm cstnh ton lng kim cn thit trung ha.

Ch s x phng l s mg KOH cn thit trung ha ht axit bo t do v x phngha ht este c trong 1 gam du m. T ch s ny cho php tnh trng lng phn t trung

bnh ca mt s axit bo v triglyxerit c trong du mcng nh tnh ton c lng kimcn thit x phng ha khi em du m sn xut x phng v cc cht ty ra.

Ch s este l s mg KOH cn thit x phng ha ht cc este c trong 1 g du m.Thng ch s ny c tnh bng hiu s gia ch s x phng v ch s axit. Trng hpdu mc ch s axit nh khng ng k hoc du mtrung tnh th ch s este s trng vich s x phng.

Ch s It l s gam It c th kt hp c vi 100 gam du m(nhm lm bo hocc ni i ca cc axit bo khng no trong du m) ch s ny khng chc trng chothnh phn ha hc m cn ni ln c tnh ha hc (tnh khng no) ca du m. V th chs ny c ngha rt ln trong mt s ngnh ch bin v s dng du m, chng hn:

Trong cng ngh sn xut du hidro ha ( sn xut b, mnhn to), ch s It s

gip ta quyt nh mc hidro ha (no ha) khi dnh sn xut cc sn phm b, mnhn to khc nhau c tnh cht cn thit v rn, nhit nng chy, xp ...Trong cng ngh sn, vecni, sn du, thng qua ch s It ta bit c du thuc nhm

kh, khng kh hay na kh. Nh ta bit, do tnh cht ca cc axit bo khng no, nht l

cc axit bo khng no c ni i kt hp (kiuC C C C

) d b oxy ha v trng hpto thnh mng keo polyme (in hnh l du tru). Mc to thnh mng keo ny honton do hm lng v tnh cht cc axit bo khng no quyt nh v ngi ta gi l tnh chtkh ca n.

+ Nu du mc ch s It di 85 th thuc loi khng kh

+ Nu du mc ch s It 85 130 th thuc loi na kh+ Nu du mc ch s It 130 246 th thuc loi kh v kh nhanh.

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Ch s peroxit l s gam It c gii phng khi cho dung dich KI tc dng vi 100gam du mnhtc dng ca peroxit c trong

+ +H2O+H2C

HC

HC

O O

(CH2)nC OH

O

R

H2C

HC

HC (CH2)nC OH

O

R

O

2KI 2CH3COOH I22CH3COOK++

Cc peroxit hnh thnh trong qu trnh oxy ha gy h hng du. Do ch s peroxitc trng cho mc h hng du mdo b oxy ha (du mb i kht).

Ngoi ra, trong cng tc nghin cu khoa hc v cht bo, ngi ta cn a ra mt sch s khc nh ch s Reisl Meisl, ch s polens, ch s gener, ch s rodan, ch s axetylnh tnh v nh lng mt s thnh phn axit bo ring bit c trong du mv nguynliu du m.5.1.6.4. Sp:

Rt ph bin trong ht du vi t l nh 2.5 3% chng thng trn lp v, c tcdng bo v ht khi b tc ng va chm, m, kh nng, enzyme, vi sinh vt xm nhp.

V mt ha hc, sp thuc nhm lipit n gin l este ca cc axit bo phn t lngln vi ru phn t lng ln bc 1(t khi bc 2) c s nguyn t cacbon trong mch lnhn 19.

R1

H2C O C

O

R2 y R1 l gc ru, R2 l gc axit bo.Trong thnh phn ca sp thng gp cc loi axit bo sau y: stearic, oleic, xenotic,

montanic.Trong sp cn c ln mt s tp cht nh parafin, cc dn xut carotenoit t nhinlm cho sp c mu c trng.

Sp rt bn ha hc, hu nh khng b thy phn v este ha bi kim mnh, enzyme,khng c tiu ha trong cthng vt. Khi tinh luyn du th, bng cc bin php hahc khng th loi bc sp. Bnh thng, sp c kt tinh thnh nhng tinh th rt nhtrong du lng v khng b lng trong thi gian di lm gim gi tr cm quan ca du. tch sp, ngi ta dng bin php du nhit thp 7 10oC nhng tinh th sp ktlng li thnh ht ln ri tch chng ra.5.1.6.5. Lipit phc tp:

a) Photpho lipit (photphatit): l loi hp cht hu cc photpho c trong hu ht ccloi ht du, m m, ng vai tr quan trng trong vic hnh thnh mng t bo, trao iaxit bo trong t bo v to thnh cc hp cht vi protein (lipoproteit).

V mt cu to, cc photphatit l cc glyxeryl c thay th 1, 2 gc axit bo bi 1, 2gc axit photphoric cng vi nhm th X no , thng gp nht l cc photphatit c 1gc axit photphoric vi nhm th X vi cng thc tng qut nh sau:

H2C OCHOR1

HC

CH2

OCOR2

O P O

O

OH

X Nu X l hidro th photphatit s l axit photphatit, trong ht du thng tn ti dng

mui kim loi (vi lng).

Nu X l ru amin colin

NH2C

OH

H3C

H3C

H3C

CH3

th photphatit l lexitin.

34

Nu X l etanolamin H3CH2C NH2 th photphatit l xephalin


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Nu X l serin

H3CHC COOH

NH2 th photphatit l photphatidilserin.Nu X l inozit C6H6(OH)6 th photphatit l inozitolphotphatitTrong lexitin v xephatin l hai loi photphatit thng gp nht. Trong nguyn liu

du m, photphatit ch yu nm trong tng khng bo, mt phn dng t do v mt phn

nm dng lin kt vi protein v gluxit. Trong t bo, photphatit dng t do v nhng cxu hng lin kt vi lipit v gluxit. Thng thng phc cht photpholipoproteit d b phhy khi protein b bin tnh v kh khai thc du mbng trch ly dung mi.

Photphatit tan mnh trong hu ht cc dung mi hu c nh etxng, hexan, ete, benzen, cloroform, t tan trong ru etylic v hu nh khng tan trong axetol vmetylaxetat.

Mi ni ca phn t photphatit d dng b thy phn bi cc tc nhn kim, axit, enzimphotpholypza vi mc ph thuc vo phn khng bo (a nc) ca gc photphat.

Photphatit c tnh cht ca mt cht keo ho nc v ng vai tr quan trng trongvic trao i cht ca t bo. Do c tnh cha bo ha gc photphat ca gc photphatit

lm cho chng khi b oxy ha ko theo kh nng chuyn vn oxy. cht bo li khng ckh nng ny v chng khng tan trong nc v trong dch bo. V vy cht bo trong t bokhi b oxy ho phi tri qua giai on kt hp vi cc hp cht photpho tc l bc trunggian to thnh photphatit. Cng do tnh cht d b oxy ha nn photphatit c coi l chtchng oxy ha vn c ca du m.

Thnh phn axit bo ca photphatit cng khc vi glyxerit ch axit bo cho caphotphatit l axit bo no panmitic v mt lng nh axit bo c t ni i vi s nguyn tcacbon l 20, 22.

Trong cng ngh tinh ch du m c th tch photphatit ra khi du th bng binphp thu ha(hidrat ho) - tc l x l du th vi mt lng nc hay dung dch in gii

(mui, kim, axit, tanin). Lc photphatit s kt hp vi nc mt kh nng ho tan trongdu kt ta thnh cn du (cn photphatit, cn thy ha). Tuy nhin bin php ny khngc kh nng kt ta c axit photphatit v inozitphotphatit, chng c gi l cc

photphatit khng b thy ho. Photphatit dng t do sau khi tch khi du th li rt d dngb oxy ho chuyn t mu trng hoc vng nht sang vng hoc en sm. Chng nhanhchng b h hng (chua, thi).

Photphatit c gi tr thc phm cao lm cht nh tng ha quan trng khi sn xutbnh ko, bnh m, bnhn to, lm thc n gia sc. Cn ch l chi vi mt s loinguyn liu ht du v du thc phm nh lc, u tng, hng dng mi c kh nng(hm lng) thu hi photphatit thc phm. Bng di y cho bit hm lng photphatit

trong mt s loi ht du in hnh.Bng 11 Hm lng photphatit (tnh theo % lexitin) so vi khi lng tuyt i ca

ht

Tn ht Hm lng photphatit - %u tng 1.6 2.5

Nhn ht bng 1.2 1.8Thu du 0.25 0.3Lanh 0.5 0.7

Nhn ht hng dng 0.5 0.8

Lc 0.6 0.7Bng 12 Hm lng photphatit trong du theo phng php khai thc

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Hm lng photphatit trong du - %Loi duu tng bng lc hng dng

p ngui (th cng) - - 0.05 0.07 0.05 0.07p bn ckh (skipin) 1 1.2 - 0.09 0.12 0.09 0.13p sb 1.1 2.1 0.5 1.56 0.18 0.75 0.2 0.8

p kit mt ln 2.7 3.1 1.4 1.8 0.55 1.12 0.60 1.20Trch ly 2.7 4.5 2.0 2.5 0.70 1.25 0.80 1.40Du tinh luyn 0.00 0.02 0.01 0.02 0.01 0.02 vt

b) Glucolipit: l hp cht ca axit bo vi gluxit v hu nh ch c trong nguyn liudu thc vt. Gluxit c trong mi thnh phn cu trc t bo thc vt v c kh nng chuynha ha hc mnh m nn chng c th kt hp c vi lipit kiu este hay lin kt hp

ph, lin kt kiu phc cht.Mt trong nhng loi glucolipi

nguyen lieu san xuat thuc pham

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