Microsoft PowerPoint - CHUONG 2

7/31/2019 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


2/432

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


3/433

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


4/434

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)


5/435

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


6/436


7/437

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


8/438

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.


9/439

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


10/4310

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=


11/4311

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


12/4312

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%


13/4313

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


14/4314

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


15/4315

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


16/4316

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



17/4317


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


18/4318


19/4319

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]


20/4320

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


21/4321

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)


22/4322

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


23/4323

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)


24/4324

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


25/4325

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


26/4326

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


27/4327

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


28/4328

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


29/4329

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


30/4330

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)


31/4331

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)


32/4332

Hardness :cng (N): L lc nn lnnht

p1


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


33/4333




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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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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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




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




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


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



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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).


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


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


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

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