microsoft powerpoint - chuong 2
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1
CHNG 2
CC TNH CHT LU BIN CATHC PHM(Rheology of food Products)
-Lu bin hc l mt khoa hoc nghin cu s chy vasbin dngca vt liu di tc dng ca ng sut.
- Cc nghin cu v lu bin cung cp cc thng tin lin quan ntnhcht n hi va nht ca cht lng
- Vt liu thc phm l cc cht khng hon ton lng hoc rn doo thhin tnh nht n hi, ngha l tnh cht trung gian ca thlng vathrn
- Lu bin hc vvt liu thc phm c th c m ta theo thutngbin dng n hi, lu ngnht hay lu ng do
- Cc tnh cht lu bin c chuyn sang ngn ngthng thngnh: vng chc (firmness), cng (hardness), kh cng (crispiness),gin, d gy v(brittleness), c th ko di (extensibility)
CC TNH CHT LU BIN CA THC PHM(Rheology of food Products)
Vic nghin cu nhng ng thi lu bin c ng dng trong nhiungnh cng ngh khc nhau:
- Kim tra cht lng sn phm : tnh gin, n hi, do, l in kt,
- Nghin cu mi quan h gia vi cu trc va ng thi lu bin nhmpht hin ra cc sn phm mi
- Cc tnh cht lu bin tham gia vo cc chu trnh ton rt cn thit trongtnh ton kythut (cc qu trnh truyn nhit va ng lng), ty theo sthch ca ngi tiu dng c th to nn sn phm p ng nhucu ca
h.
- Am hiu v tnh cht lu bin s gip chng ta thit k c nhng my
mc, thit b chnh xc vatit kim nng lng
- Tnh cht cu trc lin quan n cc tnhcht cm quan ca thc phm
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NG SUT V BIN DNG(Stress and Deformation)
ng sut (Stress) l lc tc dng (theo phngbt ky) trn mt n v din tch.
A
= F/AF
p
tStress = F/A [Pa, N/m2]
Phn loi ng sut
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ng sut php (nn hay ko): lc tc dngtheo phng vung gc vi b mt bdi hay th tch ca vt thay i
ng sut trt (hay ng sut tip): lc tcdng theo phng song song (tip xc) vib mt lp b mt dch chuyn so vilp pha di
ng sut tc dng ln vt th s gy nn bin dng:- Bin dng di
+bin dng Cauchy
+bin dng Hencky
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bin dng gc
khi nhothi
C hc c in phn bit rocht lng vacht rn,mi trng thi c m ta bi nhng phngtrnh khc nhau.
Cht rn c m tabi nh lut Hooke, cht lngc m tabi nh lut Newton.
Tuy nhin c rt nhiu trng thi vt cht nmgia 2 cht ny, c bit l thc phm va cc vtthsinh hc
Cht rn
nhlut Hooke
Cht lng
nhlut NewtonCht trung gian
Cht rn n hi (Elastic Solids)
Cht rn n hi c m tabi nh lut Hookean:
Di tc dng ca ngsut ko hoc ngsut nn = E* c
E: modun n hi ca cht rn (Youngs or elasticitymodule ) ( cng)
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Di tc dng ca ng suttrt
ij= G* : shear strain
G: modun trt
Di tc dng ca p sutthy tnh
P = K* K: modun khi
=V/V
V d bi tp
M un n hi ca to l 0,6.107Pa
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Bai tap1 mieng pho mai hnh khoi ch nhat co kchthc dai x rong x cao = L x W x H= 0.5 x0.4 x 0.3 inch. Dung 1 vat co khoi lng 0.1lb nen len mieng pho mai nay. Sau khi nen,mieng pho mai co chieu dai la 0.043 ft. Xacnh o cng (modun dan hoi), chieu rong,chieu cao cua pho mai sau nen. Biet t so Poisson cua pho mai la 0.25.
1 inch = 2,54 cm, 1 lb = 0,453 kg, 1 ft = 0,3048 m
S : E = Pa, W = mm, H = mm
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o bien dang cua thc pham theo chieu dai,chieu rong hoac ng knh = o bien dangcua thc pham theo chieu cao x T so Poisson
cua thc pham o
Cht rn n hi l cht b bin dng di tcdng ca ng sut hoc lc. Khi lc khng cnn tkhi phc li hnh dng ban u (Elastic)
Vt sau khi ngng tc dng lc khng khi phchnh dng ban u gi l cht do (Plastic)
Cht trung gian l cht c tnh cht nm gia E
vaP gi l Elastoplastic.C ngha l khing su t tcdng nho n c th
khiphc li hnh dng banu, khi ng su tln hn mt gia tr noo n bbindngvnhvin.
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nht - Viscosity
nht l mt i lng vt l c trngcho tr lc do ma st ni ti sinh ra gia
cc phn t khi chng c s chuyn ngtrt ln nhau.
nht c lin quan n kh nng thchin cc qu trnh bm, vn chuyn chtlng trong cc h ng ng, kh nngthc hin cc qu trnh phun, bay hi.
o nht
nht c o bng cch ghi li thigian cn thit mt lng cht lngnht nh chy qua mt ng mao qun ckch thc nht nh mt nhit nhtnh.
n v o nht: Poise (g/cm.s), Pa.s(kg/m.s), St (stock)
nht biu kin, nht ng lc hc hay nht
- nht l hmca tc trt
- nht ca cht lng Newton c xc nhtrn mt im ca ng thng
- nht biu kin ca cht lng phi Newton (H-B, B-P) c xc nh theo hnh dng cang cong
- nht ca cht lng Newton khng th xcnh t mt im duy nht trn ng cong
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nht - Viscosity
Ti sao phi o nht
-Cht lng, gi tr cm quan v mong munca ngi s dng thc phm
- s bin imusc, khi lng ring, thnhphn dinh dng, nng v pH
- nhng kin thc v nht mang li nhngthng s cho qu trnh ch bin thc phm
Cht lng Newton
C 2 tm phng, gia l cht lng, tm dic nh. Khi ta tc dng 1 lc ln tm trn, ns trt i ko theo lp cht lng chy theo. Tctrt gim dn ttrn xung di hnh thnhmt gin vc t.
Cht lng Newton
dt
dxvp =
==
=
=
dt
d
dy
dx
dt
d
dt
dx
dy
d
dy
dv
= 0=
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nh lut Newton v nht
: hsthc nghim phuthuc vo c tnh cathc phm (nht)
Cht lng m nht khng phu thuc vo tc trt gi l cht lng Newton va ngc linu nht phuthuc vo tc trt thi gi lcht lng phi Newton
=
Cht lng Newton Phng trnh bin dng tun theo ng thc NewtonHm lin hgia ng sut trt vatc trt l hm tuyn
tnh:
VD: nc, tra, c ph, bia, ru vang, cc loi ung vanc p tri cy, mt ong
Sa: l nhu tng c cha cc cc git b nho c ngknh 0,0015 0,001mm, cha 87% nc, 4% cht bo, 5%ng, 3% protein l cht lng Newton
nht ca sa tng theo hm lng cht bo, nhng ligim khi nhit tng
Du cng l cht lng Newton. Cu trc phn t ca n cmch di, chiu di mch ccbon ca cc acid bo cngln thi nht cng ln. nht ca du tng cng vimc bo ha ca lin kt ccbon ni i.
Cht lng phi Newton0
c lp vi thi gian Time independent fluid
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a s cht lng, chtkhi n gin bin itrng thi nh mtcht lng Newtontrong vng chy tng
(cc tia chy songsong vi nhau) khing sut trt va tctrt nho.
Khi ng sut trttng thi ng thi chylch ra khi ngNewton theo nhiucch khc nhau, hmca ng sut trt vatc trt l hm phituyn
Pseudoplastic (shear thinning): Khi tc trt cng tng,dc ca ng cong cng gim, nht gim cngkhuy cng long : VD: cc sn phm nh : pur chui,st to ng, nc cam p c c, kem, mu, cc loisn v sn mng tay.
Dilatant (shear thickening): Khi tc trtcng tng, dc ca ng cong cng tng,nht tng cng khuy cng c, trng n
V d : mt ong (mt s loi ring bit), tinh btng sng chim 40%
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Cht lng dng Bingham: Nu ng sut tc dng nhohn ng sut ngng (0) cht lng cha chy. Khing sut tc dng ln hn ng sut ngng (0) chtlng chy va c ng thi chy ging cht lng Newton
VD: kem nh rng, st c chua
Pseudoplastic fluids with yield stress: Khi ng sut trtvt qua gia tr ngng thi cht lng chy va c ngthi chy ging vi Pseudoplastic
M hnh Herschel - Bulkley
: shear stress (ng sut trt) (Pa)K: consistency index (chs nht): shear rate (tc trt) (1/s)
0
: ng sut ngng (l ng sut nh nht dng bt u chy)
n: index of flow behavior (chsv ng thichy), khi n thay i thi dng iu cang cong thayi
0 +=
n
k
Mta ng thi chy ca cc dngcht lng Non-newton
thng qua m hnh Herschel - Bulkley
o
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nht c lp vi thi gian Time independent fluids
Vi cht lng phi newton c lp vi thi gian,cc dng ca ng thi chy lun n nh hayc lp vi thi gian
Da vo m hnh Herschel Bulkley ta thy:- Cht lng newton, pseudoplastic (cht gia do ),
cht dilatant (trng, n) khng c ng sutngng khi c lc tc dng n chy ngay
- Nhng cht lng c nht phuthuc vo tc trt chng t n tn ti mt cu trc bntrong hthng
Khi ta tc dng ng sut lm cho n chy thitrong qu trnh chuyn ng c s b gy vaphn b li cu trc
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Pseudoplastic (cht gi do) cc im
1. Hp cht c khi lng phntln hay ht di
2. Gia cc phn t c tng tcmnh vi nhau to nn skthp bng cc lin kt thcp
3. Trong phn t c mt trc divaphn tkhng i xng doo n nh hng theo dngchy lm cho nht gim
4. Hnh dng va kch thc caht khng ng nht cho phpchng chng cht ln nhau.
5. Cc phn t ca n mm do,c th lm thay i hnh dngca chng, dn ra hoc thu lity theo lc ko
Hydroxyethyl-cellulose
Cht lng phuthuc vi thi gian Time dependent fluid
Phuthuc vi thi gian(Time dependent fluid)
Khi c nh tc trt (. = cosnt), cht cng thi chy m ng sut tng dn theotc trt gi l Rheopectic
Khi c nh tc trt (. = const), cht cng thi chy m ng sut gim dn theotc trt gi l Thixotropic
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Cht n hi nht(Viscoelasticity)
Nhng cht thuc nhm ny thhin tnh
cht ca hai nhm l cht lng nht vacht rn n hi
c trng ca nhm ny th hin haihiu ng l hiu ng Barus va hiu ngWeissenberg
Cc yu t nh hng n nht
nh hngca nhit
- Nhit cngtng thi nht ca cht
lng newtoncng gim
Cc yu t nh hng n nht
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Cc yu t nh hng n nht
nh hng ca p sut
- p sut cng tng thi nht ca chtlng newton cng tng
nh hng ca nng : t l nh hng ca khi lng phn t : t l
Cha khuy khuy
Cha khuy khuy
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Bi tpMt tm g phng c ph mt lp cht
bao ph c chiu dy l 1 mm, tm ghnh vung c chiu di x chiu rn g l :30 cm x 30 cm, dng mt lc 10 N tcng vo b mt song song vi tm g.tnh vn tc chuyn ng ca b mt tmg ? bit rng nht ca cht bao ph l50 Pa.s
Tc trt
u : vn tc di (m/s)
V
s : u = 2,2 mm/s
.
21.
)(
== yf
PHN TCH CUTRC THC PHM
Tham kho : NGUYEN BA THANHEmail: [email protected]
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Mc ch
Tm quan trng ca phn tch cu trc thc phm
Tm hiu cc khi nim, nh ngha v cu trc thcphm, cc t ng m t n cu trc thc phm.
Cc phng php phn tch cu trc thc phm: nguyntc hot ng, cu to ca thit b, chc nng, h thngx l s liu
Mi lin h gia phng php cm quan v phngphp vt l
Chn la test ng dng
Tm quan trng (ti sao chng taphi phn tch cu trc thc phm) Hng v, cu trc, hnh thc bn ngoica sn phm
l bayu t chnh quyt nh sn phm c c chpnhn trn th trng hay khng.
Cu trcthc phm l mt tnh cht hin nhin ckhch hng i hi phi c xc nh
Cu trc nh hng n s cm nhnmiv cng nhn hnh thc bn ngoi ca sn phm
L mt thuc tnh quan trng, tuy nhin, n mi cnhn nhn mt cch nghim tc trong thi gian gn y.
P DNG N l mt phn khng th thiu ca kim
sot cht lng (Quality Control)
Kim tra cht lng thit lp mtquy trnh tim nng
D on tnh lu bin ca sn phm (quytrnh pht trin)
Dng thit lp cc tiuchun cht lng
Ph hp vi n h u cu cht lng cakhch hng
Pht trin sn phm mi S tngquan vi cm quan
FACTORY
RESEARCH
CORRELATION
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Lu bin
Lu bin hc l nghin cu s bin dng v dng chy
S thay i hnh dng
Vt cht chuyn ngnh th no
Lu bin
Lu bin hc l nghin cu s bin dng v dng chy
Cht rn Cht lng
Tri cyThtBnh ko
NcTng tMayonnaiseNc ng
CU TRC THC PHM All the mechanical, geometrical and surface attributes of
a product perceptible by means of mechanical, tactileand, where appropriate, visual and auditory receptors.
Tt c nhng thuc tnh c hc, hnh hc v b mt casn phm c t h c nhn bit, nh gi bng cc cquan cm nhn c hc, xc gic, th gic hay thnh gic
(ISO 5492: 1992, t vng trong nh gi cm quan)
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Phn tch cu trc l g?
Test vt liu-Tnh n hi-Tnh cht do-Modun
Phn tchcu trc
gy v cng mm gin dai
Tnh lu bin
- nht
-Visco-elastic
cng (hardness): thuc tnh c hc cacu trc lin quan ti cng lc cn lm cho sn phm bin dng hoc c thm xuyn qua sn phm.
Trong ming, chng c cm nhn bng vicnn sn phm gia hai hm rng (cht rn)hoc gia li v vm ming (cht bn rn)
Mm (soft) : cng lc thp, vd cream cheese Chc (firm) : cng lc va phi, vd olive Cng (hard) : cng lc cao, vd ko
(ISO 5492 : 1992)
Nhng khi nim c bn Strain
Stress Strain Rate
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Lc c kt (cohesiveness): thuc tnh chc ca cu trc lin quan ti mc bin
dn g m sn phm c th chu ctrc khi gy v
(ISO 5492 : 1992)
Tnh d v (fracturability): thuc tnh c hc ca cu trclin quan ti lc c kt v lc cn lm v mt snphm thnh nhng mnh nh.
Chng c nh gi bng cch nn t ngt sn phmbng rng ca hoc bng cc ngn tay
D v vn (crumbly): mc lc thp, vd bnh nngxp
Gin (crunchy): mc lc va phi, vd to, c rt Gin (brittle): mc lc cao, vd u phng rang
Gin (crispy): mc lc cao, vd khoai ty chin Cng gin (crusty): mc lc cao, vd v bnh m Php
(ISO 5492 : 1992)
dai (Chewiness): thuc tnh c hc cacu trc lin quan ti lc c kt, cnghoc s ln nhai cn thit mt sn phmrn tr thnh dng sn sng cho vic nut
Mm, b (tender) : cng thp, vd ht unon
Chewy : cng va phi, vd fruit gums Dai (tough) : cng cao, vd tht b gi, da
heo(ISO 5492 : 1992)
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Gumminess: thuc tnh c hc ca cu trclin quan ti lc c kt ca mt sn phmmm b (tender). Trong ming, chng lin
quan n lc cn nghin n t sn phmthnh dng sn sng cho vic nut
xp gin (short) : cng thp, vd bnh quy xp Bt (mealy, powdery) : cng va phi, vd khoai ty, u
HLan kh luc St, nho (pasty) : cng va phi , vd bt nho ca ht
d nghin Dnh (gummy) : cng cao, vd gelatin thc phm
(ISO 5492 : 1992)
Nn nu nhng yu t nh hng ncu trc thc phm
Vd: mm ca tht nh hng bi thnhphn, bi qu trnh bo qun, qu trnhbin i k h i bo qun
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PRODUCTS AND PROPERTIES...PRODUCTS AND PROPERTIES...
STICKINESS
HARDNESS
GEL STRENGTH
FIRMNESSADHESIVENESSCONSISTENCYHARDNESS
TOUGHNESSTENDERNESSCONSISTENCYCHEWINESS
HARDNESSBRITTLENESS
RIPENESS
FRESHNESSBRITTLENESSSTICKINESSDOUGH QUALITY
TABLET STRENGTHCOATING HARDNESSBLOOM STRENGTHCONSISTENCY
Szczesniak (1963) chia c tnh cu trcthnh ba nhm sau:
c tnh c hc - lin quan n phn ng ca thc phm vi lcnn Thng s bc 1: hardness, cohesiveness, viscosity, elasticity,
adhesiveness Thng s bc 2 : brittleness, chewiness, gumminess
c tnhhnh hc-lin quan n kch c, hnh dngv xuhngsp xp ca nhngphn t trong sn phm, vd : powdery, gritty,lumpy, flaky, fibrous, cellular, aerated, crystalline
Nhng c tnhkhc linquan n vic tip nhn m, bo..vd: dry, moist, oily
Vic phn nhm thut ng ny chuyn bit cho tng loi sn phmnhngtrongmi trng hp c th phi da trn tnh lu bin casn phm. Trong thc nghim, bn cht thay i theo thi gian canhn thc c ngun gc t cm gic cng c cngnhn, vthuc tnhny c chia thnh hai giai on, giai on nhai banu vgiai on sau khi nhai
Sherman (1969) : Tnh cht bc mt ca thc phm: c tnhhnh hc nhc ht, phn b c, lng kh
Tnh cht bc hai-xut pht t s kt hp ca hai hocnhiu tnh cht c tl khng xc nh; Tnh cht lubin nh viscosity, elasticity, adhesion
Tnh cht bc b a c phn chia da trn cc qutrnh nh sau : Nhai : hard, soft; brittle, plastic, crisp; rubbery,
spongy; smooth, coarse; powdery, lumpy, pasty;creamy, water, soggy; sticky, tacky
S tan r: greasy, gummy, stringy; melt-downproperties
Nonmasticatory: appearance; sampling and slicingcharacteristics; spreading, creaming characteristics,pourability
One possible criticism : it is based primarily on the
rheological properties of the foods rather than on aperceptual basis
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Jowitt (1974) :
c tnh chung-structure, texture, consistency
Thut ng lin quan n tpt nhca vt cht di ngsut nn hoc ng sut ko, vd: firm, chewy, stringy,rubbery, sticky, glutinous, brittle, crumbly, crisp
Thut ng lin quan n kt cu ca vt cht Lin quan n kchc ht hay hnh dng ht, vd : smooth,
chalky, gritty, mealy Lin quan n hnh dng, s xp xp ca cc yu t kt cu.
Vd: flaky, stringy, aerated, glassy, gelatinous, spongy Thut ng lin quan n tnh cht cm gic trong ming.
Vd: body, watery, greasy, slimy, mushy, astringent,cooling
Phng php phn tch cu trc thc phm
- Phng php phn tch cm quan : cc c quan cmgic ca con ngi tm hiu, m t v nh lngcc tnh cht cm gic ca mt sn phm thc phmnh mu sc, hnh thi, mi, v v cu trc. Ngiphn tch phi tp luyn v thng nht cc thut ngcm quan.
- Phng php phn tch bng thit b :
- Phng php c bn (fundamental methods):
- Phng php thc nghim (empirical methods)
- Phng php m phng (imitative methods):
Phng php dng lc
L phng tin khoa hc dng o phnng ca mu trong nhng iu kin nhtnh
Thng s o c biu din l p hn ngca mu vi lc tc ng hoc vi khongcch p dng theo thi gian
Dng c thc hin nhng chuyn ng lnhoc xung
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Ba phng php o cu trc(ngoi phng php nh gi cm quan ra)
fundamental : S dng nhng nh ngha t b nh hng bi dng c D dng so snh kt qu gia nhng sn
phm c ngun gc khc nhau Vd : o cc tnh cht nh nht,
cng, tnh d gy ca sn phm
Empirical Dng o nhng thng s khng th biu
din c bi nh lng lu bin c bn.
Nhng k thut nyda trn ba nguyn tcc bn ca s bin dng : s un, ct v nn.
Cho kt qu nhanh v d s dng. Thng
c s dng nht trong cng nghip Chc th dng c mt vi iu kin
nht nh
Imitative
Dng c m phng cc dng tc ng cakhch hng ln thc phm
v d : bt chc hot ng ca rng.
Trong mt vi trng hp, cc kt qu onhn c t dng c phn tch c th linh vi cc gi tr cm quan, ngi t a gi lspychorhologie
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The ideal test
IDEAL
Empirical
Imitative
Fundamental
(D. Kilcast, 2001)
VVVV d mt test n gin
Hy tng tng rngngntaycabn l mt u o gn vi bn, mtloi my phntch cu trc. Nocabn ng vai tr nh mt phn mmtnhton ccthng tin t ngntay vc th ca bn.u tinngntaycabn dichuyn n b mt ca mu
Phn tch cu trcc linquann vic o cc c im c hcca mu khi mu chu nhng tcng c kim sot
VVVV d
Mt loi my phntch cu trcghili s chng lilc ca sn phm
LFRATEXTUREANALYSER
345
Mt ngntay ca bn (u o)chm vo b mt ca mu, c thca bn (b phn phntchcutrc) bt u nhn c thng tinlin quanti cc c im cutrc ca mu
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VVVV d
Khi ngntay ca bn (u o)n xung mu mnh hn, ns i xuyn qua sn phm, vc th ca bn (b phn phn
tchcu trc) s chuynthng tin chung ti no(phnmm x l) thc hin vic
nh gi c tnhtnhchtca mu
VVVV d
LFRATEXTURE ANALYSER
345
COMPRESS COMPUTE INTERPRET
Bn dichuyn ngntaycamnh(u o) tr li v tr banu v nh githng tin trongno ca bn vi ch mt thngtin y d c chn
Cu to ca thit b
Biu : nguyn tc o lc nn
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GII THIU MT S DNGC IN HNH V NGUYN
TC HOT NG
VARIABLE:VARIABLE: TEST CONFIGURATION
Lc tc ng ln xung nhiu ln TEXTURE PROFILE ANALYSIS (TPA): thit b k
thut s dng ng cong ca lc, ng cong cas bin dng phn loi cc c tnh cu trc thencht ca mu, l cu ni vi cm quan.
Chdng lc nn Vic lp li thao tc nhiu ln gip ta c th tnh ton
c cc c tnh cu trc a chc nng, c nhiu ng dng trong cng nghip
TEXTURE PROFILE ANALYSIS cng =nh ca biu lcTnh n hi = Chiu rng ca ngphc hi (hnh)
Lc c kt (Cohesiveness) = A2/A1
Tnh dnhkt (Adhesiveness) = Dintchm ca ln o u tin (A3)
Tnh d gy (Fracturability) = Ch gyu tin trong vng trn
Gumminess = Thc phm bn rnc t nh bng cng x lc c kt
Chewiness = Thc phm rn c tnhbng Hardness x Cohesiveness xSpringiness
F
t
HARDNESS
ADHESIVENESS
A2
A3
A1
SPRINGINESS
VARIABLE:VARIABLE: TEST CONFIGURATION(imitative test)
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Cc thng svcu trc(tm dch)
- gin (Fracturability, N )
- cng (Hardness, N)- kt dnh, kt cu (Cohesivement)- co dn (Springiness, m)- dnh b mt (Adhesivement, J)
- n hi, dai (resilience, J)- do (Gumminess,N)-o lc nhai (Chewiness, J)
TEXTURE PROFILE ANALYSIS
Hardness Adhesiveness Cohesiveness Compressibility Elasticity Resil ience
Fracturability Gumminess Chewiness
time
FSecond compressionFirst compression
TEXTURE PROFILE ANALYSIS Hardness
time
F
Hardness: Force required tocompress a food between themolars
Hardness = peak +ve forcef =
Force (N)
S (m2)
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Hardness :cng (N): L lc nn lnnht
p1
TEXTURE PROFILE ANALYSIS
Fracturability: la contrainte ala fracture Fracturability : Not all samples
fracture. The fracturability point isobserved as a significant peak(fall off) in the first compression.
F
f =Force (N)
S (m2)
Fracturability : gin (N): L lc btu lm nt gy thc phm. Phim 1
Phim 2
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TEXTURE PROFILE ANALYSIS
Hardness Adhesiveness Cohesiveness Compressibility Elasticity Resil ience
Fracturability Gumminess Chewiness
Adhesiveness: The work requiredto pull the food away from asurface
distance
FAdhesiveness = Negative area from first bite
Adhesivement : dnh bmt ca thcphm: L cng cn thit ko u d rakhi thc phm = area 3.
P1
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TEXTURE PROFILE ANALYSIS
Hardness
Adhesiveness Cohesiveness Compressibility Elasticity Resil ience Fracturability Gumminess Chewiness
Cohesiveness: The strength ofthe internal bonds making upthe food.
AB
Cohesiveness = B/AF
Cohesivement :c kt ca thc phm:L tisgia cng nn ln 2/ln 1 =area2/area1.
P1 P2
TEXTURE PROFILE ANALYSIS Hardness Adhesiveness Cohesiveness Compressibility Elasticity Resil ience Fracturability Gumminess Chewiness
Compressibility : The workrequired to deform the sampleduring the first compression.
distance
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TEXTURE PROFILE ANALYSIS
Hardness
Adhesiveness Cohesiveness Compressibility Elasticity Resil ience Fracturability Gumminess Chewiness
Elasticity : The extent to whicha compressed food returns toits original size when the loadis removed
Cycle = second contact first contact
Elasticity = Cycle for inelastic material cycle for food
TEXTURE PROFILE ANALYSIS
Hardness Adhesiveness Cohesiveness Compressibility Elasticity Resil ience
Fracturability Gumminess Chewiness
Resilience : How well a productregains its original position.Corresponds to the area of the firstwithdrawal divided by that of thecompression.
phc hi (resilience) ca thc phm: l khnng phc hi tr li v tr ban u.L tisarea 5/area4
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Springiness ca thc phm: L tiskhong cch nn ln 2 (distance 2)
P1
TEXTURE PROFILE ANALYSIS
Hardness Adhesiveness Cohesiveness Compressibility Elasticity Resil ience
Fracturability Gumminess Chewiness
Gumminess: The energy required todisintegrate a semisolid food so thatit is ready for swallowingGumminess = Hardness x cohesiveness
Chewiness : The energy requiredto chew a solid food until it isready for swallowing.Chewiness = hardness x cohesiveness x
Elasticity
Gumminess : do (N)
Chewiness : lc nhai (N.mm) ; N.mm = mmJ, J
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VD: s liu o ca bnhhttp://www.brookfieldengineering.com/education/applications/texture-
sponge-cake.asp
BiBinn ss:: dng u oLci xung
Nn: u o (hnh tr hoc tm kim loiphng) i xung n khi tip xc vi muv tc ng ln n mt lc
Bnh ngtFFFF
tttt
Vt ntu tin
DOWN STROKEUPSTROKE
cng
Din tch u obnghoc ln hndin t chca mu
Lci xungm thng v xuyn qua:u o i xungn khi tipxcvi b mt,khi xuyn qua vt,n to r a c lc nnv lc ct
Kim trakhi GELATIN
Lc m = nht(Tackiness) ca mu gelatin
F
t
Gitr khi (Bloom) l lc tia t c ti thi im gyra s bin dng
Din t ch =tc ng t ti sbin dng
Dintchm= sdnh kt (adhesion)ca mu gelatin
BiBinn ss:: dng u o
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Lci xung
mthng v xuyn qua: u o hnhcn i xungvtip xc vi b mt mu. Tc ng ca lc s tng khidin tchtip xc gia u o v mu tng.(b, phomai)
BiBinn ss :: loloii uu oo
c
cng
c tnhdnh kt
o phomai mmF
t
Lci xungCt (CUT) v xn (SHEAR): li dao hoc thanh cti xung n khi t ip xc, lc ct mu to ra khikhong cch u o tng.
BiBinn ss:: LoLoii uu dd
o phomai Cheddar
cng
c tnhdnh kt
F
t
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Lci xungu o hnh cu : dng u o trn nn.u o ixung n khi t ip xc vi b mt, to ra ch yu lc
nn n khi im b ct hoc n khi t kimtra ktthc.
BiBinn ss :: loloii uu oo
F
t
Kim tr a b mt pho mai Brie
cngAPPARENTMODULUS
Din tchth hinlc tc ng, thhin c
BiBinn ss:: TEST ACCESSORIESLci xung
Ct bng mt thanh kim loi: thanh kim loai cnh hot ngging nh hnh ng ct lt (slicingor cutting)
Lc ct tht heomui Reformed
Din tchth hinc ca snphm
cngModulus isgenerated frominitial slope
Tht v snphm t tht
C
Thc vt
Phomai
M phm
Lci xungCt (CUT) bng thanh WARNER-BRATZLER : sdng mt thanh c khot mt l hnh tr gia.Loi vt khot ny lm tng din tchtip xc, ktqu kim t r a s n nh hn
F
t
Vt gy u tin
cc vt gytip theo,lc gim dn.
Dintchth hinc ca snphm
Ct xc xchbng thanh Warner-Bratzler
VARIABLE:VARIABLE: TEST ACCESSORIES
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Lci xungCt (CUT) bngcng c VOLODKEVICH : nguyn tchot ng tng t nh hot ng nghin ca rng
ca. y, ngi ta quantm ch yu n nh lc
Ng cc
Tht
Tri cy vrauqu
Bnh ko
VARIABLE:VARIABLE: TEST ph
Lc ct ca mu c rt
Dintchth hin c ca sn phm
cngim
Bio-Yield
Lci xungCt kiu KRAMER : Cu trc gm cchnhxc10 tm kim loi, chng xuyn qua mt c ihpcha thc phm, nn, ct v y thc phm rangoi
Nhiu li ct xp song song c bit thchhp nh gi t nhiu phn nh ca snphm hay nh gi nhng sn phm cnhiu phn ct nhcht khc nhau, nuln
tnh cht t iubiu ca sn phmNg cc cho
ba sng
Bt nho
Go, u ch bin
Tht
VARIABLE:VARIABLE: TEST ACCESSORIES
Lci xungBACK EXTRUSION : Kiu p n hotng bng cch tc dng mt lc ln thcphm n khi thc phm chy qua mtli thot. B y ln trn theo li thot X vY trong minh ho di y.
Lc tham gia cc k phc tp
Lc ti a ph thuc v o lc nnvthi gian nn.
X Y
VARIABLE:VARIABLE: TEST ACCESSORIES
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BACK EXTRUSION: Test ny c bit thch hp vi snphm st, nht nh :
Gel mmv sa chua
Tri cy v rau cnghinMphmNc st v patDu m
Din t chmca th gyrabi khilng ca mu trnu o v bi ctnh dnh kt(adhesive).
VARIABLE:VARIABLE: TEST ACCESSORIES
F
Modulus(Gradient)
t
cng
c
Lc dnh kt
Light Mayonnaise
Standard Mayonnaise
Lci xungFORWARD EXTRUSION:o lc nncn piston trn phng c th y sn phm chyqua mt c i l c kch c chun bn di vtcha.
c s dng chort nhiu loi mu:- Gel v sn phm b n rn- Bt nho
- Tri cy v rauc nghin- Kem v sn phm chm sc tc
VARIABLE:VARIABLE: TEST ACCESSORIES
Lci xungUn ba im: Test ny o c im gy vcong ca nhiu dng vt cht khc nhau nh:
Chn cth iu chnh
Mu
u o
Biscuits
Ko
Cht do
M phm
Thc vt
Polyme
VARIABLE:VARIABLE: TEST ACCESSORIES
F
t
c tnhca son mi
dc banu
cng
Lc gimngaykhi vtb gy
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VARIABLE:VARIABLE: TEST DIRECTIONLc hng ln: Lc dnh kt (Adhesion) c tnhton t lc cn ko ginmu n kh imu vncn tip xc vi u o.
Hng n c hai c tnh m vdng
Biu th lc ko gia mu v mt vt khcmntip xc
nh lng c in, tnh ton lckoca bmt phngii ca :
Keo h
Bnh ko
Ko gm, bt nhovgel
Go v m si
F
t
VARIABLE:VARIABLE: TTEST DIRECTION
Thi g ianm phn mu vndnh vi u o
Tc ng cn ct t bmt chung gia mu v uo (Adhesiveness)
Lc cn ct t bmt chung gia mu vu o (tackiness)
C TNH DNH KT CA SA CHUA
LC KO LN: Dng lc cng, to r a s cng vko xy rabntrong bn thnvt
VARIABLE:VARIABLE: TEST DIRECTION
Mu s b gy ti khu vc c ngknh nh nht.
Hnhhc v tnhcn i ca mumang tnh quyt nh
v tr mngkhi lc cngtngln
Spaghetti
M si
Dykimloi v.v.
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Nhng yu t nh hng n ktqu o
Kch c mu chn ca mu (sample age)
Vt ng mu v(hoc) dng u o s dng V tr t mu, trng tm ca mu Hnh dng vthnh phn ca mu Qu t rnh x l mu iu kin bo qun vtrnh by mu Vn tc dch chuyn ca u o??? % u dxuynmu hay phn trm mu bin dng ???
http://www.brookfieldengineering.com/education/applications/texture-white-bread.aspDahle, L. and Sambucci, N. 1987. Application of Devised Universal Testing Machine
Procedures for Measuring the Texture of Bread and Jam Filled Cookies. AmericanAssociation of Cereal Chemists, Inc. 32, No. 7, 466-470.
Xc nh gin, c ng, k t c , dnh b m t, ph c h i, d o, l c nhai c a SP
F
B
A C D
E
G H I
K
M
N
O
P5.7
B
A CD
E
F
Xc nh gin, c ng, k t c , ph c h i,
d o, l c nhaic a SP