Sơ lược về phương pháp cắt Warner

B CNG THNG TRNG I HC CNG NGHIP TP. H CH MINH VIN CNG NGH SINH HC V THC PHM Bo co thc hnh VT L THC PHM

Thc hin: Nhm 3 T 4 - DHTP4 GVHD: Th.S Nguyn c Vng

Tp. H Ch Minh, thng 3 nm 2012

B CNG THNG TRNG I HC CNG NGHIP TP. H CH MINH VIN CNG NGH SINH HC V THC PHM Bo co thc hnh VT L THC PHM

GVHD: Th.S Nguyn c Vng Thc hin: Nhm 3 T 4 - DHTP4 1. Nguyn Ng Sang 08270611 2. Nguyn Ngc S - 08244531 3. V Uyn Nhi 08094511 4. Nguyn c Thin 08105591 5. Nguyn Vnh Phc 08226371 6. Trn Minh Thi 08227101

Tp. H Ch Minh, thng 3 nm 2012

Bo co thc hnh mn Vt l thc phm Tm hiu phng php Warner-Bratzler Shear

GVHD: Th.S Nguyn c Vng Thc hin: Nhm 3 T 4 DHTP4

DANH SCH SINH VIN THC HIN

H v tn Sinh vin Nguyn Ng Sang Nguyn Ngc S V Uyn Nhi Trn Minh Thi Nguyn Vnh Phc Nguyn c Thin

M s sinh vin 08270611 08244531 08094511 08227101 08226371 08105591



NHN XT CA GIO VIN............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ............................................................................................................................................................... ...............................................................................................................................................................



MC LCLI NI U .................................................................................................................1 1 - TNG QUAN ............................................................................................................2 1.1. TNG QUAN V CU TRC THC PHM ...................................................2 1.1.1. nh ngha Cu trc thc phm ..................................................................2 1.1.2. Tm quan trng ca cu trc i vi thc phm ............................................4 1.2. TNG QUAN V MY O C L ...................................................................6 1.2.1. Gii thiu chung ............................................................................................. 6 1.2.2. Phn cng .....................................................................................................10 1.2.3. Phn mm .....................................................................................................17 1.2.4. Cc yu t nh hng n kt qu phn tch ................................................28 1.3. GII THIU MT S NG DNG CA MY O C L ......................... 29 1.3.1. ngha ca th biu din .........................................................................29 1.3.2. Cc v d v o c cu trc bng thit b ....................................................30 2 PHNG PHP WARNER-BRATZLER SHEAR ..............................................34 2.1. S lc v phng php Warner-Bratzler Shear ................................................34 2.1.1. Lch s ca phng php[] ............................................................................34 2.1.2. Nguyn l phng php ...............................................................................36 2.1.3. Mc ch .......................................................................................................38 2.1.4. Cc yu t nh hng ...................................................................................38 2.1.5. Phm vi ng dng ......................................................................................... 39 2.1.6. So snh vi cc phng php khc............................................................... 40 2.2. PROTOCOL[][] ....................................................................................................46 2.2.1. Chun b mu ................................................................................................ 46 2.2.2. Thao tc th nghim ...................................................................................... 47 2.3. KT QU TH NGHIM...................................................................................49 2.3.1. Thao tc th nghim ...................................................................................... 49 2.3.2. Kt qu th nghim........................................................................................ 53 KT LUN ...................................................................................................................56



LI NI U

thc phm l 1 trong nhng yu t tin quyt quyt nh cht lng ca thc phm: gp phn lm tng gi tr cm quan, p ng th hiu ca ngi tiu dng. Nu o c c cc yu t cu trc nh dai, gin, cng ca sn phm th vic nh gi, nh cht lng v pht trin sn phm mt cch hiu qu. Mi loi sn phm thc phm c trng bi yu t cu trc c trng. Trong , i vi sn phm tht v cc sn phm t tht (xc xch, gi ch) th dai, n hi l nhng thng s cn c xc nh nh gi cht lng sn phm. Phng php Warner-Bratzler Shear l 1 phng php dng xc nh cc thng s k trn thng qua cng c l my o c l. Warner-Bratzler Shear l mt phng php c in v c ci tin tr thnh mt trong nhng phng php thng dng nht trong o c cu trc thc phm ni chung, sn phm tht ni ring. Tuy nhin vi s lng khng l cc kin thc bit, vic la chn nhng kin thc no ph hp vo mt bi bo co thc hnh, ph hp vi nhiu i tng l rt kh khn, nn chc chn s khng trnh khi nhng thiu st. Nhm thc hin bi bo co rt mong nhn c nhng kin ng gp ca qu thy c v cc bn khc phc nhng thiu st v hon thin bi bo co hn.

T

rong lnh vc cng nghip hin i, khi m cuc sng ca ngi dn ngy cng c nng cao th vic kim tra cc tnh cht lin quan n cu trc ca sn phm thc phm ng mt vai tr quan trng. Cu trc

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1 - TNG QUAN1.1. TNG QUAN V CU TRC THC PHM1.1.1. nh ngha Cu trc thc phm C nhiu nh ngha v cu trc thc phm nh: - Cu trc l cc c tnh to s cm nhn v cc tnh cht vt l t da hay cc c quan th cm trong khoang ming, ngoi tr cc cm gic v nhit (Matz, 1962). - Cu trc l s tng hp ca cc c tnh xut pht t cc thnh phn cu trc bn trong (Structural elements) ca thc phm v cch n ghi li cc cm gic sinh l, (Sherman, 1970). - Cu trc (texture) l s biu l v mt cm quan ca kt cu bn trong (structure) ca thc phm v cch thc kt cu ny phn ng vi cc cc lc ln n, cc yu t lin quan gm th gic, thnh gic v cc cm nhn v s chuyn ng (kinesthethics), (Szczesniak, 1990). Mc d cha c mt nh ngha hon chnh v cu trc, chng ta c th xc nh cc c tnh sau y ca cu trc thc phm, l: - Cu trc l mt nhm cc c tnh cu trc vt l c ngun gc t kt cu bn trong (structure) ca thc phm. - Cu trc thuc v nhm cc c tnh vt l theo phng din c hc v lu bin hc, ch khng theo cc phng din quang hc, in t trng hay nhit hc. - Cu trc bao gm mt tp hp cc c tnh, ch khng phi l mt c tnh duy nht no. - Cu trc c cm nhn ch yu bng xc gic, thng l trong ming, nhng cc b phn khc ca c th cng c th lin quan. - Cu trc khng lin quan n cc cm nhn ha hc mi v v. - Cc i lng o cu trc c n v l hm s ca khi lng, khong cch v thi gian.2



Bng 1.1 - nh ngha mt s tnh cht cu trc thng thng ca thc phm L c tnh ca thc phm khng d b v hay ha tan trong ming, Dai (chewy) cn nhai nhiu ph v. L c tnh ca thc phm to ra cm gic c nhiu ht nh trong Bt (mealy) ming. L c tnh ca sn phm c sc bn ln khi c lc lm bin dng hay ph v. L c tnh ca thc phm c bn thp khi c lc lm bin dng. L c tnh ca thc phm, biu hin mc chng chu tng i khi c lc lm bin dng. L c tnh ca thc phm, cn s ln nhai ln n nm ln bng rng hm nghin nh thc phm (n mc c th nut c).

Cng Mm Chc

Cng gin

V cu trc l mt t hp ca nhiu c tnh vt l khc nhau nn s chnh xc hn khi chng ta ni v cc c tnh cu trc, hm ch mt nhm (mt tp hp) cc c tnh c lin quan, hn l cu trc nh l mt thng s n nht. iu ny cn c c bit nhn mnh, trnh s nhm tng cu trc l mt c tnh duy nht ca thc phm. Bng di y lit k mt s t thng c dng m t thc phm v mt cu trc. Bng 1.2 Cc c tnh dng m t thc phm v mt cu trc Cc c tnh c hc Cc thng s s cp cng gin c kt gin - dai dai nht3

Cc thng s th cp

Khi nim thng thng Mm chc cng D v vn xp gin Mm sn chc dai chai Mm bt nho dai Lng nht



n hi dnh Cc c tnh hnh hc Kch thc v hnh dng ca tiu phn Hnh dng v hng ca cc tiu phn Cc c tnh khc Hm lng m Hm lng cht bo 1.1.2. Tm quan trng ca cu trc i vi thc phm - Bn yu t chnh to nn cht lng ca thc phm l:

Do n hi Ko dnh dnh

Bt, xm, rp X, si, kt tinh

Kh m t nc Bo, bo ngy

Hnh thc bn ngoi Gm c mu sc, hnh dng, kch thc, bng b mt l cc yu t tc ng n th gic. (Preference) Gm c v (cm nhn bng mi) v mi (cm nhn bi cc Hng v (Flavor) trung khu thn kinh khu gic nm trong mi). Cc yu t ny c gi l cc gic quan ha hc. Ch yu do cc c quan xc gic cm nhn khi c s tip xc Cu trc (Texture) gia c th v thc phm. Bn cnh , cc cm nhn v chuyn ng, v m thanh (i vi cc thc phm gin) cng cng gp phn vo vic nh gi cu trc. Dinh dng Gm thnh phn cc thnh phn a lng v vi lng trong thc phm.

- Trong 4 yu t trn, 3 yu t u c gi l cc yu t cm quan do chng c nh gi trc tip bi cc gic quan. Cc yu t cm quan ca thc phm ng vai tr rt quan trng, v chng to cho ngi n cm gic ham thch v tha mn khi n.

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- Tm quan trng ca cu trc i vi mc chp nhn chung ca ngi dng i vi thc phm khc nhau, ty theo loi thc phm. Chng ta c th phn ra lm 3 nhm sau: Cc k quan trng: Trong nhm ny l cc thc phm m cu trc ng vai tr ti quan trng i vi cht lng ca sn phm, chng hn nh tht, khoai ty chin, ng cc, im tm. Quan trng: Nhm ny gm cc thc phm m cu trc l yu t cn thit, nhng khng hon ton quyt nh cht lng thc phm. V mc quan trng xp x vi hng v v hnh thc bn ngoi, nhm ny gm c cc loi rau qu, tri cy, ph mai, bnh m, ko v cc loi thc phm lm t lng thc. t quan trng: Gm cc thc phm m cu trc nh hng t n cht lng chung, gm ung, cc loi sp lng. - Trong ba yu t chnh nh hng n mc chp nhn thc phm (hnh thc, hng v, cu trc), cu trc l yu t t c ch nht. Trong nhiu nm, cu trc thc phm b coi nh so vi cc yu t khc. - Theo Szczesniak, cc yu t sau y l nhng l do chnh m cu trc thc phm t c nh gi l quan trng nh mu sc v hng v. - Ngi tiu dng thng khng mong i hay c mt yu cu no c bit i vi cu trc ca sn phm v t than phin v c tnh ny, tr khi cu trc thc phm c mt s c no n mc khng th chp nhn c. - S gii hn v t ng ca ngi tiu dng khi din t cc c tnh cu trc. Khi h ni mn ny khng ngon, ngi ta thng ngh rng do thc phm c hng v km, trong khi c th ngi n cp n cu trc hoc c hai. - Nu xy ra cc bin i v mu, mi, v th ngi ta thng ngh n kh nng thc phm hng. Ngc li, s bin i v mt cu trc khng r rt th hin rng thc phm khng an ton m ch th hin thc phm c cht lng km.

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1.2. TNG QUAN V MY O C L1.2.1. Gii thiu chung - Trong cc phng th nghim c hc vt liu, thit b o c l l mt cng c rt cn thit. N cho php thc hin cc loi th nghim ko, nn, un, ct (x) xc nh cc thng s tnh cht c hc ca vt liu cn th nghim. Ngy nay, s hin din ca cc thit b o c l tng cng vi s tng s lng cc phng th nghim ( cng ty kim nh cng trnh, phng th nghim trng i hc, vin nghin cu, nh my), khng ch tng v s lng m cn tng v hnh dng, kch thc, mu m nhng vn p ng nhng php o theo cc phng php c in v ci tin.

Hnh Cc kiu my o c l - Do c th, cc my th nghim vn nng u l thit b chuyn dng yu cu chnh xc rt cao, tnh n nh khi s dng, kh nng thc hin cc th nghim a dng trn nhiu loi vt liu khc nhau. Vic ch to cc my th nghim loi ny i hi rt cao trnh gia cng c kh, thit k v lp rp cc mch x l tn hiu6



o v iu khin in t. Bn cnh n cng yu cu ngi thit k phi c nhiu kinh nghim trong lnh vc th nghim, c bit l am him v cc tiu chun k thut c lin quan. - Ti Vit Nam phn ln cc my th nghim u c nhp khu t nc ngoi, mt s rt nh c ch to trong nc. Cc my my th nghim vn nng hu ht c nhp khu t Trung Quc vi cc dng my r tin, c tnh nng thp, cc dng my cht lng cao c nhp t cc nc tin tin thng c gi rt cao. - Thit b o c l c gii thiu y l mt sn phm ca hng INSTRON (Seri 5543) c s dng xc nh tnh cht c l ca nhiu loi sn phm khc nhau. Chng hn nh i vi cc sn phm thc phm nh cc loi tri cy, rau c qu v nhiu loi nguyn liu khc. - Thit b ny c mt c cu ti trng cht ch, s dng in th nh v c th d dng t trn cc k hay bn lm vic. - H thng ny gm hai loi c kch thc khc nhau. Loi nh c tng chuyn ng ca con trt l 500mm v i vi loi ln l 932mm. Hnh Biu tng ca hng INSTRON

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Hnh Thit k chung ca my o c l INSTRON * Cc tnh cht tin ch ca my o c l: - Cho kt qu nhanh chng v chnh xc ch trong vi giy. - C th dng cc gi tr tc dng lc khc nhau i vi tng sn phm xc nh. - C th nh gi tng im trn b mt thc phm bng cch tc dng lc vo cc v tr khc nhau. - C kh nng t ng ho bng vic lp trnh sn cc d liu v thao tc thc hin, c th kt ni vi mn hnh my vi tnh hin th kt qu thng qua cc phn mm, cng nh thit lp th s bin i cu trc thc phm theo thi gian. T ta s xc nh c cc thng s ca thc phm, gip d dng nh gi chnh xc v la chn sn phm theo c tnh mong mun. - Rt ngn chu trnh pht trin sn xut. Nghin cu sn phm bng my tm ra tnh cht thch hp nht, y nhanh qu trnh sn xut. Ngoi ra, cn c th tm c cc tnh cht mi trong thc phm cho cc ng dng thc t trong tng lai.

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* Nguyn l hot ng ca my o c l - Hot ng bng cch dng lc c hc tc dng ln sn phm, tu tng loi sn phm m ta c th dng cc lc tc dng khc nhau nh 5, 10, 20, 50, 500N vi chnh xc 2%. - Cn c vo thi gian v tc tc dng lc m ta c th xc nh c cc tnh cht ca sn phm nh cng, gin, n hi, trng n, xp, do. - Nh cm bin lc tc dng, ta chuyn tn hiu lc thnh tn hiu in v sau khi khuch i bng b vi sai, ta chuyn lc thnh tn hiu vo cho u c ca b x l kt qu o (hoc c ni trc tip vi my tnh). - Vn tc my c th t ti a l 500mm/pht. - Din tch b mt thc phm c th o c l 500mm2. - Thi gian c th o cng lc: 20 im/giy. - Kch c my: 380 400 720mm. - Nhit ca thc phm thch hp php o c chnh xc l 5 400C v m khong 20 80%.

Hnh Cc kiu my o c l trn th trng *S liu k thut ca my o c l hiu Instron Seri 5543:9



My thuc kiu bn, tun theo cc tiu chun ASTM E4, BS 1610, DIN 51221, ISO 7500/1.2.1.1, EN 10002 2, AFNOR A03 501 v mt s tiu chun quc t khc. Hng sn xut Kch thc ca my Instron M Chiu cao: 127mm Trng lng: 41kg Cc thng s ca my Ngun in s dng: 220V Tc ti thiu: 0.05mm/pht (0.002 inch/pht) Tc ti a: 1000mm/pht (40 inch/pht) Tc phn hi: 1500 mm/pht Chuyn ng ca con trt: 917mm Lc tc dng ti a: 1000N Phm vi lc o lng l 250:1 (V d nh s dng b phn o lc o xung 0.4% ca ton b cng sut m vn khng c thit hi g v tnh chnh xc) Tnh chnh xc: 0,5% Cng sut 1kN (225lbf) Khng gian th nghim dc: 1067 mm (42 inch) Ch thu nhn d liu ng b tt c cc knh d liu: 500 Hz - Bng iu khin phn cng thun tin cho cc hot ng th nghim. - Phn mm tng thch Bluehill 2. - Phng php th nghim theo tiu chun ISO. - T ng nhn bit b cm bin cho b phn o lc v cc gin k. 1.2.2. Phn cng - B phn chnh ca h thng thit b ny bao gm mt bng iu khin, vt me, mt ng c v ct n v. Con trt c t c nh ln ct n v v vt me. B phn o lc c c nh ln con trt. B phn truyn ng lin kt vi ng c (motor)10



pha di ca con trt. Khi motor quay, chuyn ng s c dn n vt me khin cho con trt di chuyn ln hoc xung ct n v.

Hnh Cc b phn chnh ca my o c l Instron - Ton b c cu ny l mt cu trc bn vng gip c nh mu th hay vt liu th nghim. Ta s dng kp t mu th vo gia bng v con trt. Khi ng c quay do lnh t h thng iu khin, con trt s di chuyn ln hoc xung, b phn o lc s o lng lc ti ca mu th. - H thng ny cng bao gm b khuch i cng sut, b bin p v cc bng mch in t. Bng iu khin c t c nh trn ct n v. Nt dng khn cp c th gip dng h thng vo bt c lc no khi c tn hiu cnh bo an ton.

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- B phn ph l gi sn phm lm bng thp khng r c b mt cng nhn cng tt. Cc b phn c t ln trn mt gi . - Tu tng loi sn phm m ta dng nhng b phn tc dng lc khc nhau: Food Testing Fixture Cch thc kim tra Thc phm

Fruits Ly mu dng ng Vegetables Nuts Flat End Probe Sets Magness Taylor Probes

Bread Gy bin dng bng lc p Candy Cheese Gels Compression Anvils Rolls Fruits Vegetables Cooked Pasta Tc dng lc ri ct thnh si Kramer Shear Cell Cubed Chicken Viscous Liquids Gels

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Fruits Vegetables Ground Meat Ct thnh si ri tc p bng cch tc dng lc Back Extrusion Cell Seafood Salad Viscous Liquids Gels

Fruits Gt bng dao nhiu li Vegetables Viscous Liquids Gels Ottawa Texture Cell

Beef Poultry Lamb Ct thnh tng ming Warner Bratzler Meat Shear Pork Wieners

Ko cng hai u Tension Grip

Raw Pasta Processed Meat

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Crackers Lm cong bng lc i xng 3 pt Flex Cookies Granola Bars Raw Pasta

1.2.2.1. Nt khi ng chnh Nt khi ng chnh t b ni ngun pha sau bn phi ca my. Khi nt v tr ON my s m v khi nt v tr OFF th my s c ngt khi ngun in. Dy ni cng hot ng nh l b chn in p chnh. 1.2.2.2. Bng iu khin

Hnh Bng v m phng bng iu khin th cng14



Bng Cc nt iu khin v cng dng Jog controls (Nt iu chnh ln xung) Nhn nt jog up hay jog down chnh con trt i ln hoc xung. Nu ta nhn v gi nt ny, con trt s bt u di chuyn chm ri nhanh dn, cho n khi ta thi gi nt. Fine position (Nt iu chnh bng tay) Nt ny gip ta di chuyn con trt i chm v chnh xc. Cun nt ln xung di chuyn con trt. Nhn nt ny chnh con trt t v tr hin thi n v tr ca khong cch cn o. Mt khi RESET G. L. Button khong cch o ny c thit lp, con trt s lun lun tr li ng v tr ny khi ta nhn nt Return AT G.L. Indicator Nt ny bt sng khi cn bo hiu con trt ng v tr. Nt ny bt sng ch rng nng lng sn sng cho my. Bt sng khi my ch ch. Bt sng bo hiu l my sn sng s dng. Nhn nt ny bt u tin hnh th nghim. Nt ny bt sng bo hiu hng di chuyn ca con trt. Nhn nt ny dng chuyn ng ca con trt khi kt thc th nghim. Bt sng bo hiu rng th nghim b dng li, nhng con trt khng tr li v

Power indicator Frame standby indicator FRAME READY Indicator START TEST button TEST IN PROGRESS indicators

STOP TEST button

TEST STOPPED Indicator

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tr ban u ca n. RETURN Button Nhn nt ny chnh con trt v li v tr ban u. Bt sng bo rng con trt v li v tr ban u.

RETURN IN PROGRESS Indicator

1.2.2.3. Nt dng khn cp (Emergency stop switch)

Hnh V tr nt dng khn cp - Nt dng khn cp l nt c mu , hnh trn kh ln c t pha trc ca my. - Ta nhn nt ny mi khi nhn thy th nghim khng an ton , khi ta nhn nt h thng s nhanh chng dng li. Khi nhn, nt dng khn cp s kha my li v ta phi thao tc tip tc bng tay my tip tc hot ng. - Sau khi x l xong s c, ta c th khi ng li my thc hin li cc th nghim. 1.2.2.4. Mt s lu - Gii hn dng chuyn ng ca con trt l mt c tnh an ton m ta nn thit lp mi khi s dng h thng o ny. Thit lp n sau khi t khong cch o, nhng trc khi bt u kim tra. - Gii hn ca con trt l 2 im dng c th iu chnh c t c nh trn thanh16



gii hn pha trc bn phi ca ct n v c th hin hnh v bn di. - im dng c cht vn ta vn cht hay th lng bng tay, ta c th di chuyn im dng n bt k v tr no ca thanh truyn ng.

Hnh Khong gii hn ca con trt

1.2.3. Phn mm 1.2.3.1. Gii thiu - Bluehill 2 cung cp mt chng trnh kim tra nguyn liu linh hot v y sc mnh, d dng s dng i vi c nhng ngi ch mi bt u hc hay cc chuyn gia. - Phn mm Bluehill 2 tip tc truyn thng c Bluehill 1 c ra mt nm 2004. Th h mi ny c cp nhp y cc phn mm c chnh sa cng cc bn v li. y l mt gii php dnh cho cc k thut vin v nh qun l ca nhng phng th nghim.17



- Phn mm Bluehill 2 chia thnh cc bng m mu gip thao tc d dng. Mn hnh p ng nhu cu i vi cc k thut ng dng cho tng phng php kim tra. Cc thng s nh l c nh c cu, thut ng kim tra, la chn n v v tnh ton c nh hnh t ng, cho php phng th nghim hot ng nhanh chng v chnh xc.

Hnh Giao din lm vic ca Bluehill - Nhng thit k v kh nng ca Bluehill 2 phn nh nn tng ng dng mnh m ca Instron, tp on pht trin 60 nm qua nh l ngi dn u trong vic kim tra vt liu. Bluehill 2 tng thch trc tip vi nhiu h thng ca instron nh 3300, 4200, 5500, 5800 - Phn mm Bluehill 2 giao din c thit k dng bng nn s dng kh n gin. N bao gm vic kim tra, phng php kim tra, bo co kt qu v h thng qun l. Bm vo bng m bn thy, ri chn mc bn mun kim tra. Rt n gin cho ngi s dng.

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- iu khin cc mc theo bng dng ct cho ra kt qu theo s trnh by nh trn mn hnh xc nh cng xut d liu v th nc lu tr. - Bluehill 2 c nhiu tnh nng vic thc hin th nghim c d dng hn v nhanh hn cho tt c ngi dng. Mt trong s l: Bng iu khin giao tip gia ngi s dng v my cho php ngi s dng thy tt c nhng g ang c p dng cho cc ln kim tra mu. Bng iu khin bao gm cc phm mm cho php s dng nhng tnh nng khc nhau. Tnh nng chn mu cho php ng b ha xem cc kt qu, ha, yu t u vo v tnh trng cho by k ln kim tra mu. Bluehill 2 i km vi s chuyn i a nng t ng chuyn i tt c cc phng php th nghim v cc tp tin d liu hin ti. Chng ta c th bt u th nghim trong cng mt ngy m ta ci t phn mm. S dng cc k thut sao chp v dn sao chp cc bng biu v th kt qu t Bluehill 2 sang cc phn mm yu thch nh Microsoft Word, Excel hay PowerPoint. Thng qua Bluehill 2, chng ta c th tn dng li ch ca cc menu khi nhn phi chut nh sao chp, dn cc thng tin hay tm nhng chi tit khc nh th, cc bng kt qu hay tnh nng ca bng. Vic nhp d liu u vo cc phng php th rt linh hot. Chng ta c th nhp vo bt k lc no: trc, trong hay sau khi th nghim. V d, ta c th nhp vo kch thc mu th nghim khi ang tin hnh cho mt mu khc. iu ny gip tit kim thi gian v gim thiu sai st u vo. Cc php o th nghim bao gm hng trm ng dng khc nhau, t c bn n phc tp theo tiu chun sn c ca Bluehill 2.

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Hnh Thao tc linh ng trc tip trn giao din bo kt qu bng chut phi 1.2.3.2. Cc cng c chc nng - Chuyn i gia cc mn hnh o Bng iu khin nm gc trn ca mn hnh v giao din phn mm Bluehill nm bn di. o Ty theo nt m ta chn mn hnh chnh, ta s thy cc thanh chc nng khc nhau l test, method, report, admin. - Test tab o Nu ta chn nt Test, c 4 mc l test, method, report, admin s xut hin v ta chuyn i qua li gia cc mc bng cch nhn vo tn ca mc .

20



- Method tab Trong mc ny c 1 thanh iu hng bn tri mn hnh. Nhn vo cc mc m ta cn sa i trong thanh iu hng ny. - Report tab v admin tab Trong cc mc ny cng c thanh iu hng bn tri mn hnh, cc mc m ta chn s c lm ni bt d dng nhn bit. Khi ta di chuyn qua li gia cc mc, c 1 bng hng dn bn phi cung cp cc thng tin lin quan n mc . - Mn hnh chnh y l mn hnh xut hin u tin khi ta khi ng phn mm v l mn hnh ta chn phng php th nghim.

21



*Chc nng ca cc nt trong mn hnh chnh: - Test Button Nhn nt ny khi ta mun tin hnh th nghim vi mu. Phn mm s trnh din mt lot cc mn hnh khc ta chn phng php kim tra, t tn cho mu v bt u th nghim. Mc continue sample gip ta m li mt file mu lm trc xem li cc thng s hoc tin hnh th vi mt mu khc. - Method Button Nhn nt ny khi ta mun chnh sa v lu li cc file phng php th nghim. phn mm s chuyn n mt mn hnh khc ta chn hoc thay i cc thng s th nghim ri lu li trn file gc hoc mt file mi. - Report Button Nhn nt ny khi ta mun chnh sa v lu li cc file phng php th nghim mu. Ta cng c th s dng cc bo co mu to ra mt bo co mi da trn cc d liu thu thp c trong khi tin hnh th nghim.22



- Admin Button Nhn nt ny khi ta mun thay i cu hnh ca h thng th nghim. - User Button Nhn nt ny thot ra khi ngi dng hin thi. - Help Button Nt ny d m h thng tr gip. - Exit Button Nhn nt ny thot ra khi chng trnh. - Thanh trng thi (Status Bar) Thanh trng thi xut hin pha di mn hnh ca phn mm. N cung cp cc thng tin v trng thi ca my cc trng hp khc nhau trong h thng th nghim. Nu phn mm ca my c kt ni vi my o c l, thanh trng thi s hin ra ch live machine. Nu phn mm ca my kt ni c vi my o c l nhng khng c mu, thanh trng thi s hin ra ch no machine. Nu phn mm ca my khng kt ni c vi my o c l nhng c mu th nghim, thanh trng thi s hin ra ch demo. Trong tnh trng no machine, ta c th lm mi th vi phn mm ngoi tr vic tin hnh th nghim vi mu, trong tnh trng Demo, h thng s s dng file d liu m phng th nghim trn mu. Nu nh khng c file mu no c m, thanh trng thi s hin ra ch sample: closed. Nu c file mu c m, ta s thy tn ca file . V d nh khi ta m mt phng php th nghim v bt u chnh sa n, du * s xut hin sau tn ca file cho n khi ta lu li file hoc lu di tn ca mt file mi. Nu ta chn23



to ra mt phng php mi, thanh trng thi s hin ra ch method cho n khi ta lu li di tn ca mt file mi. 1.2.3.3. Cch tin hnh th nghim - tin hnh mt th nghim, ta s thc hin theo cc bc sau: Xc nh phng php th nghim. Chn mu v t mu vo ng v tr. Chn phng php th nghim. t tn cho mu. Nhp v chnh sa cc thng s, d liu cn thit. Kim tra cc s liu nhp. Nhn nt START bt u th nghim. Theo di th nghim v kt qu hin trn mn hnh. Lu li kt qu th nghim nu cn. Kt thc th nghim v thot ra.

24



- tin hnh th nghim vi mt mu th mi, ta c th nhn vo nt TEST trn mn hnh chnh, chn nt NEW SAMPLE trn thanh iu hng (Navigator bar). - Lu l trc khi bt u th nghim, phi chn phng php m ta mun s dng kim tra cho mu th mi ny. - Nu nh file phng php m ta mun s dng nm danh sch Most recently used th ta ch cn chn tn ca phng php trong danh sch , ri nhn vo nt Next. - Nu nh file phng php m ta mun s dng khng nm danh sch Most recently used th ta chn nt Browse, mt ca s khc s m ra ta tm kim v chn file ph hp, sau ta chn nt Open m file. - Vng lm vic (Test Workspace)

25



Hnh Giao din Vng lm vic Bng -Tn nt v chc nng ca n trong vng lm vic Tn nt Start test Stop test Chc nng Bt u th nghim. Khi nhn nt ny, con trt trn b truyn ng s bt u di chuyn v th nghim bt u. Dng th nghim v ngng vic thu nhn d liu. Con trt s tr li v tr trn thanh truyn ng. Nu ta Return to gauge length nhn nt ny khi th nghim ang tin hnh, n s dng th nghim li trc khi con trt tr v v tr. Reset gauge length Finish sample Save sample Tr li v tr ban u ca con trt trn thanh truyn ng. Nt ny s khng hot ng khi th nghim ang tin hnh. Lu d liu li v k thc th nghim vi mu. Lu d liu li trn mt file xc nh trc khi bt u th

26



nghim. Save sample as Print Report M ra khung Save File As ta lu li trn mt file khc. In bo co.

- Nu ta nhp chut phi vo bt k u trong vng lm vic, mt menu s xut hin trn mn hnh. Cc chc nng ca cc mc trong menu ny bao gm: Chn cch b tr mn hnh. Thm mu. Xa mu. Khi phc th nghim mi nht. Loi b mu. Tnh ton li cc kt qu. - Nu ta v nhn nt finish m cha th nghim xong, my s lu v ng li, chng ta khng th m n li ngay lp tc. Tuy nhin, nu ta mun tip tc th nghim vi mu va mi ng th ta c th lm theo cc bc sau: - Nu ca s save changes to test parameters m ra, chn ci m ta mun lm tip v ta s tr li bc u tin ca quy trnh to mt mu mi. - Nu ta khng chn g c th nhn vo nt continue sample trn thanh iu hng. - Nhp 2 ln vo tn mu trn nh ca danh sch most recently used m file mu. By gi ta c th tip tc th nghim. - File mu cha tt c cc thng tin cn thit ta ti cu trc li mu. Khng c mi lin h no gia file mu v file gc ca phng php kim tra (L file m ta chn lc bt u quy trnh th nghim)

27



- iu ny c ngha l ngay khi ta chn mt phng php kim tra th nghim, mt bn copy ca cc thng s th nghim c to v lu trong b nh. Nu ta hon tt th nghim v lu li mu, cc thng s th nghim cng c lu trong . Vo ngy sau, nu ta mun xem li mu hoc thm mt vi mu th vo, ta ch cn m file mu m khng cn m file gc ca phng php th nghim. 1.2.4. Cc yu t nh hng n kt qu phn tch - Cc bc chun b mu: Khi o nhn ca sn phm thc phm, ta cn v sinh sch s b mt, lau gi , chn mu c tnh i din... - m ca sn phm khi phn tch: Sn phm khng b ho hoc b ng. - Nhit v m ca khng kh: Nn ph hp vi iu kin bo qun thng thng ca thc phm. - Tc tc dng lc, thay i tc tc dng lc ph hp vi tnh cht cn phn tch: phn tch cng cn tc dng lc trong mt thi gian ngn, ngha l tc tc dng ln. Ngc li, phn tch mm th thi gian tc dng lc di hn tc l tc nh hn. - Kch thc, hnh dng v thnh phn ca mu phn tch: V din tch ca gi sn phm c gii hn nn i vi cc sn phm c kch thc ln nh u hay da hu th cn ct nh ra trc khi em kim nghim. V hnh dng, chng ta ch c th so snh v nh gi cc sn phm c hnh dng tng ng. - V tr tip xc ca b phn tc dng lc: V tr tip xc ca b phn tc dng lc ln b mt sn phm phi thch hp vi hnh dng sn phm cn phn tch. Khi phn tch cc sn phm khng c ht hoc ht nh nh chui, to th v tr tip xc t nh hng. Trong khi i vi cc sn phm c ht trung bnh v ln nh xoi, cc, su ring, o... th khng nn mi dao ct xuyn su vo trong lp tht qu. Ngoi ra cn c cc yu t khc nh hng n kt qu phn tch nh: - chn ca mu.28



- Vt ng mu hoc dng u o s dng. - V tr t mu, trng tm ca mu. - iu kin bo qun v trnh by mu. - Vn tc dch chuyn ca u o. - Phn trm u d xuyn mu hay phn trm mu bin dng.

1.3. GII THIU MT S NG DNG CA MY O C L1.3.1. ngha ca th biu din My c l o c tt c cc thng s sau ca mu thc phm nh:

29



- cng (H): L gi tr lc kim tra ti a c th t ln thc phm bng cch dng mt pittong. - dnh (A3): L gi tr lc cn thit di chuyn thc phm c lin kt vi tay trong sut qu trnh cm nm hoc di chuyn khi rng, li v vm ming trong sut qu trnh n. - Tnh lin kt (A2/A1): l s to thnh v ph hy ca mt sn phm thc phm khi mt ti trng c thm vo n. Ti trng c thm vo 2 ln c th so snh. - gin (B): L lc ph hy thc phm trong ming. - n hi (T2/T1): L s so snh v lm v s dch chuyn khi mt ti trng c thm vo sn phm thc phm 2 ln bng cch dng 1 pittong. 1.3.2. Cc v d v o c cu trc bng thit b 1.3.2.1. Kim tra gin ca khoai rn Khoai mi rn:30



Khoai rn sau 5 gi:

- im A biu th gi tr lc kim tra v c xem nh l im chuyn t lc nh nht sang lc thm vo. - Ly gi tr im A tr i cng th ta s nhn c gi tr gin ca thc phm. gin biu th tc ng lm v thc phm trong ming. Nu gi tr gin ln c ngha l thc phm c th c ph v d dng. - Trong trng hp khoai rn th iu c ngha l gin c th cm nhn c. Cm gic mnh v gin c biu th r rng trong khoai mi rn khi gi tr gin l 1.77N so vi gin l 0.91N khi khoai c qua 5 gi sau . - Ngoi ra nh ta thy trn th, vng c rng ca cong ln n gi tr cng cc i i vi khoai mi rn, nhng i vi khoai c qua 5 gi th khng c iu . Nhng mp lm chm m ta thy trong th ca khoai mi rn cho thy nhng mnh nh ph ngoi khoai rn th rn chc.

31



1.3.2.2. Kim tra cng ca bnh quy Bnh quy sau khi mi m bao gi:

Bnh quy sau khi m bao gi 24 gi:

- y, s bin i v cng ca bnh quy sau khi m bao gi th c ghi nhn bi my o. Gi tr cc i ca trc Y (Lc kim tra) biu th cng ca bnh. V vng trong th cong ln t im bt u kim tra cho n gi tr cng th c gi l nng lng nhai. - So snh s liu ca bnh quy khi mi m bao gi v khi m c 24h, ta c nhn xt rng: Khi cng gim t 16.58N xung 12.86N th nng lng nhai gim t 13.86(N.mm) xung 6.35(N.mm). iu biu th rng s khc nhau t v cng trong bnh quy (c ngha l dng nh khng c s khc nhau v cht lng khu v) th hon ton c th nh lng c. 1.3.2.3. Kim tra n hi ca Kamaboko Kamaboko l mt dng bt nho ca c c nu chn.32



Sn phm cht lng cao:

Sn phm cht lng thp:

- cng ca Kamaboko c biu th bi trc Y (Lc kim tra) v phn lm ti gi tr cng cc i biu th do. Thng thng, Kamaboko cng ngon khi n hi cng ln. - Ly gi tr cng nhn vi lm ta s c c gi tr dng nh gi cht lng ca Kamaboko. Kamaboko cht lng cao khi m gi tr l 143.01 (N.mm) v kamaboko cht lng thp khi m gi tr l 131.18 (N.mm).

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2 PHNG PHP WARNER-BRATZLER SHEAR2.1. S lc v phng php Warner-Bratzler Shear2.1.1. Lch s ca phng php[1]2 - cng chc ca tht l mt trong nhng yu t quan trng nht nh hng n v ngon ca sn phm tht. Cc nghin cu ng ch trong th k qua u tp trung vo vic lm sng t nhng kha cnh lin quan n cng chc ca tht. h tr cho vic ny, rt nhiu nhng cng c c a ra nhm nh gi c cng chc ca tht nhiu mc , quy m v c tnh khc nhau. - Thit b o Warner-Bratzler Shear (xin c php gi tt l b kt Warner-Bratzler Shear) l mt phng php xc nh cng chc ca tht c chp nhn v dng rng ri nht hin nay. Thit k gc nguyn bn cho b kt ny c a ra bi K.F.Warner, mt nh khoa hc M vo nm 1928. Phin bn gc ch gm 1 li ct bng thp c 1 l trn nh gia nhm gip cho php gi mu tht li. Ngoi ra cn c 1 hp g c rnh, cho php li dao ct xuyn qua. Nm 1932, L.J.Bratzler, 1 sinh vin tt nghip Kansas State University, c mt vi ci tin cho b kt ny v phin bn b kt thng dng hin nay da trn nhng ci tin . - Bratzler thit lp 1 s tiu chun cho b kt ny. dy ca li dao ct phi t 0.04 inch (1.016 mm). Hp g c rnh c thay th bng thp vi rnh cho php li dao ct xuyn qua vi khong h l 0.005 inch v li dao c th xuyn qua vi rng rnh l 2.0828 mm, v tc li dao chy qua mu c chun ha mc 9 inch/pht (theo Tommy L. Wheeler, Steven D. Shackelford, and Mohammad Koohmaraie, USDA-ARS U.S. Meat Animal Research Center th vn tc ny l 200 n 250 mm/pht).

[1]

Dave McKenna: Warner-Bratzler Shear Force Measurement. Meat Science Section, Department of Animal Science, Texas A&M University.[2]

Malcolm C.Bourne, 2002: Food texture and Viscosity, 2nd Edition, Elservier Science & Technology Books.34



- Voisey v Larmond (1974) cng c mt s ci tin cho b kt ny. Hnh dng ca li dao v l trn gia li dao cng c thay i thnh dng tam gic u (gc 60 ). Cc gc ca tam gic u c bo trn vi ng knh l 2.363 mm (Tommy L.Wheeler et al.). - Kch thc mu sn phm tht cng c tiu chun ha bng cch dng nhng u core (ng knh 1,5 inch) ct song song vi chiu si c ti nn nhng khi mu bng nhau v ging nhau v hnh dng. - Ngy nay, qu trnh t ng ha cho php ngi i kim sot ton b qu trnh v thao tc th nghim thng qua my tnh. - Lc dng thc hin th nghim l tng lc cn dng ct mu tht rng 1.5 inch. Cng c lc lc c th hin di n v pound hoc kilogram. L do l ty vo c im sn phm tht m lc dng th nghim s khc nhau (v d loin steak s cn dng t lc hn so vi round steak). - Theo nghin cu ca Texas A&M University v cng chc ca tht dng phng php Warner-Bratzler shear. Kt qu cho thy, nu loin beef c gi tr ct l 7.0lbs. (khong 3.2kg) hoc thp hn, th ngi tiu dng cm thy sn phm kh cng chc ( tin cy 95%). Nu loin beef c gi tr 8.6 lbs (khong 3.9kg) th tin cy gim cn 68%. Khi so snh vi kt qu cm quan th gi tr 10.1lbs (4.6kg) mi cho tin cy l 88%.

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2.1.2. Nguyn l phng php - Phng php Warner-Bratzler Shear dng lc ct tc dng ln mu thc phm. Cng c dng trong th nghim l li dao c cu to c trng hnh ch V nhm gip xc nh cng chc (firmness/toughness) ca hu ht cc sn phm tht v sn phm t tht. - Phng php ct ny da trn nguyn l sau: khi ta cho b kt (gm 1 li dao hoc 2 hay nhiu li dao i vi phng php ct Bracle Kramer) chuyn ng chm vo mu cn kim tra, li dao s tc dng ln mu mt lc hnh thnh ba trng thi: ct, nn v ko gin chia mu ra thnh hai phn, da vo th th hin ng i ca lc tc dng ln mu ta c th bit c: cng t trc khi gy v. bn ct ca sn phm. Tnh ng u v cu trc bn trong ca sn phm.36



- im ni bt khi thc hin phng php Warner-Bratzler bng my o c l Instron l: Thit b c lm t hp kim nhm v thp khng r trnh b n mn v d dng lm v sinh thit b. C th thay th cc li ct (shear blade) khc nhau ty vo mu sn phm chng ta cn o. C th thay th cc b t dao (stationary blade). C mt b phn (container) thu thp mu sau khi ct. Bao gm loi thit b ct mu vi ng knh 24.5mm v 12.5mm. - Thit b o cu trc Warner-Bratzler bao gm mt li dao thp m Niken dy 1mm hnh ch V. Gc 60o ch V c bn knh cnh ct l 0.5mm. Li dao c mt bng phng cao gim ti a ma st khi chng i qua mu. - Li dao hnh ch V c gn vo mt thit b dn ng bng mt b phn chuyn i lm bng thp khng r. Cc li tnh c gn lin vi mt li ct nh hng. Bn di h thng t mt ci khay nh nh km. Thit k ny cung cp s lin kt ca cc b phn c nh, lu gi c mu ct v dch mu tit ra v cho php thay i mt cch nhanh chng cc mu thc phm khc. - Thit b Warner-Bratzler thc hin hot ng ct bng mt li dao hnh ch V i xuyn qua mu. Lc thc hin gi l lc ct. tnh ton lc cn thit trong th nghim th ta cn ch n bn ca mu vt. Khong lc ct i vi cc mu tht l t 20N ti 100N. Khi chun b mu, thit b khoan l (coring tool) l 1 dng37



c dng ct mu tht thnh cc khi tr bng nhau khi o. Khi coring mu, nn ct mu sao cho khi tin hnh th nghim, li dao ct c cc si c. iu ny cho php li ch V ct xuyn qua cc si c. Mc d th nghim ny khng cho bit kh nng chu lc ct chnh trong mu. Cc kt qu lp li c th t c v iu ny tng quan tt vi cc nghin cu cm quan.

2.1.3. Mc ch Phng php ny dng o dai v bn ct ca sn phm. Cc yu t ny rt quan trng, lin quan mt thit ti cu trc ca sn phm, nh hng n kh nng nh gi cht lng sn phm v th hiu ca khch hng. nh gi dai do gia cc sn phm vi nhau, v d cng mt gi tin v trng lng cng nh cc c tnh khc, nhng loi xc xch no dai do hn s c khch hng a thch chn la hn so vi loi xc xch b v t dai hn. 2.1.4. Cc yu t nh hng 2.1.4.1. Nhit Nhit mi trng l mt trong cc yu t nh hng n cu trc ca thc phm. Mu tip xc vi mi trng cng lu th cng nh hng nhiu ti trng thi ca n, mu dn c s cn bng v nhit gia mi trng v mu o. Nhit lm thay i nhanh trng thi ca mt s loi thc phm nh: chocolate, b, phomai, cc sn38



phm c cha hm lng glicerit cao,... Tuy nhin, vi cc mu s dng phng php o Warner Bratzler t b nh hng bi nhit do cu trc bn vng ca n c th duy tr tt trng thi nhit mi trng. 2.1.4.2. m m cng l mt trong nhng tc nhn lm thay i cu trc ca thc phm, cc phn t nc chui vo trong cc i phn t, lm cho khong cch gia cc chui polymer tng ln, lin kt gia cc i phn t s yu i lm cu trc sn phm mm v lng lo hn gy sai s cho qu trnh o. Hm m cng cao th sai s trong qu trnh o cng ln, mt khc thc phm c hm m thp, bn c hc cao gy kh ct hn. 2.1.4.3. Kch thc mu Kch thc mu a vo my cng nh hng n kt qu sau cng khi cho ra biu phn tch mu. Nu kch thc mu qu nh, li ct ch mi tc dng ln mu mt lc rt nh, thi gian xy ra nhanh chng, kh a ra c biu phn nh y tnh cht mu, v th kh c th nhn c mt kt qu chnh xc. Nu kch thc mu qu ln, cho ta c kt qu tt hn nhng s gy kh khn cho qu trnh ct v v sinh thit b. 2.1.4.4. V tr t mu V tr t mu chun cho ta mt kt qu tt v chnh xc, thng thng mu c t v tr chnh gia, cn bng t gy ra s sai lch v tr trong khi o, v tr t mu khng tt l nguyn nhn dn n s sai s v kt qu o, c s gy v v cu trc, lch mu ra khi v tr o, nh hng n cc thuc tnh cu trc ca nguyn liu. Ngoi ra, c trng ca sn phm tht ti l c cc s tht (cc b c). Do , ty vo hng t ca s tht so vi li dao cng c th to nn 1 s s khc bit. 2.1.5. Phm vi ng dng - Tht ti hoc nu chn - Tht b39



- Tht cu - Tht heo - Tht gia cm - Tht ch bin (Processed meats) - Xc xch - Hoa v thn cy, mt s loi rau qu - Wieners. (xc xch hun khi) - Ph mai. 2.1.6. So snh vi cc phng php khc Phng php c im Dng b kt ct kim tra ct t ca sn phm.Gm mt h thng dao ct nhiu li c gn c nh trn khung c th ct sn phm nh vic to nn mt ng sut ln ln mu thc phm. Nh ta c th nh gi c s n nh v hnh dng v kch thc ca mu. L phng php dng nn mt mu thc phm (thng khong 1cm3) hai ln ging nh hot ng nhai ca rng. nn thng t khong 70-80% so vi chiu cao mu. Theo kt qu ca phng php TPA, ta xc nh c cc tnh cht cm quan nh do, c kt, v lc mt cch khch quan.40

Phm vi ng dng - To, l, mn, o, chui v cc loi tri cy khc. - Cc loi tht: b, ln, - Cc loi ng cc, da mui, c chua, c civ cc loi rau khc. Phng php TPA thng dng o tnh cht c l ca cc loi sn phm nh: - Bnh m, bnh roll, bnh cake v mt s loi sn phm bnh nng. - Tt c cc loi rau - Ko

PP ct Kramer (nhiu dao)

PP nn TPA



- B - Tt c cc loi qu - Trng - Cc loi gel - Cc loi ht - B v margarine.

PP m xuyn

Phng php m xuyn dng o cng ca sn - Pho mt. phm tc l o kh nng chng bin dng do hoc - Ko cao su. kh nng ph hy gin lp b mt di tc dng ca mi - Ko dng gel. m. - Ko do.

- C, kem, rau qu. Dng m hnh lm bin dng cu trc v hnh dng thc phm kho st cng, tnh chu nn ca mu thc phm. L phng php s dng lc ko lm dn hay ko cng nguyn vt liu ra c s dng vi mc ch o kh nng chu ng ( bn) lc ko t ca nguyn vt liu nhm nh gi c thi hn bo qun cng nh nh gi thc nghim v c tnh cu trc ca nguyn liu trong vic ng dng nhng phng hng i tm cng thc pha trn to nn nhng sn phm a dng hn v cu trc. Cc loi tht, tri cy, rau qu, b, mt s loi bnh.

PP p n

PP ko t

Phng php ko t cha c s dng rng ri i vi nguyn liu t tri cy v thc vt, c nhiu l do dn n s hn ch ny. Trc tin, nguyn liu loi ny kh kh khn kp cc mu kim tra. Th hai, qu trnh nhai lin quan n vic nn, khng cng t khi nhai thc n t hai hm.

41



- i vi cc k s, t shear ngha l tc dng 1 lc ct mt mu c cu trc lin tc. Mu ny c cu to ng nhtbi cc n v song song (v d si c trong tht, si cellulose trong thn cy). i khi, nh k s thc phm li dng t shear vi ch bt k mt hot ng ct no gip chia sn phm ra lm 2 phn. T cut dng trong trng hp ny khng hn l shear nhng c dng mt cch thng dng trong cng ngh thc phm. S khc bit gia shear v cutting c minh ha nh sau:

- Theo hnh v, ta c th thy im khc bit gia shear v cutting-shear chnh l im tc dng lc. - Thit k nguyn mu th s ca phng php Warner l dng thit b n gin nh sau: mt li dao c l trng tam gic gia ch t 1 thanh mu dng hnh tr. Tin hnh tc dng lc bng cch h li dao xung. Lc s lm bin dng mu v thng qua cc thng s lc o c m ta xc nh c cng ca mu.

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Hnh Li dao Warner nguyn thy

Hnh Li dao Warner-Blatzler ci tin - C th hn, so snh vi cc phng php ct khc:

43



Phng php

c im - Lc ct xuyn qua mu - p dng cho sn phm tht, rau qu v cheese.

Warner-Bratzler Shear Knife/Guillotine Blade

- o dnh rng - o cng chc ca sn phm tht, x bt ca rau qu.

Volodkevich bite jaws

Wire cutter

-

Lc ct c sinh ra bng dy cng Din tch tip xc vi mu l c nh44



-

cng/chy ca b v cc phm b sa chc ca ph mai

- B dao ct t 5 n 10 li dao - p dng cho cc sn phm ht ng cc, u, tri cy.

Kramer Shear cell

45



2.2. PROTOCOL[3][4]2.2.1. Chun b mu - Mu tht sau khi nu chn (c ghi nhn nhit chn v khi lng) s c lm lnh 2 4oC qua m. nhit ny, khi tht s rn chc hn, nn khi to hnh (coring) s gip khi mu ng u, d dng t ng kch thc ng knh mong mun. i vi 1 s trng hp c bit, c th khng lm lnh qua m c th c th tun th 1 s iu kin nhit c th nh a v nhit phng (23oC). - Mu tht cn phi loi b m v xng. Cc loi cheese cn nhit ph hp trnh s tan chy, sao cho qu trnh coring t hiu qu tt nht. - Tin hnh to hnh (coring) mu bng thit b coring. Ch t mu khi coring sao cho cc chiu cc si c trng vi chiu thit b. Do , khi tin hnh ct, li dao s tc dng lc vung gc ln chiu cc si c. Tiu chun khi coring mu l ng knh mu phi t 0.5 inch (khong 1.27 cm).

Hnh Thit b coring to hnh (Thit b coring hin c nhiu dng: dng manual thao tc th cng hoc dng t ng)[3]

Tommy L. Wheeler, Steven D. Shackelford, and Mohammad Koohmaraie, 2003: WarnerBratzler Shear force protocol. USDA-ARS U.S. Meat Animal Research Center.[4]

Jeff Savell et al.: Standardized Warner-Bratzler Shear Force Procedures for Genetic Evaluation.46



Hnh Thao tc coring mu - Chun b t nht 6 mu vi v tr ly mu ngu nhin. Cn t nht 1 ming tht ln hoc 2 ming cho qu trnh ly mu ny.

Hnh Mu c chun b xong - Nu mu c lm lnh th phi duy tr nhit cho mu. Gi tr o c s l trung bnh ca nhiu ln o. 2.2.2. Thao tc th nghim - Lp li dao vo v tr v t mu ln thp. - Tin hnh chy con trt vi vn tc 200-250mm/pht.47



- Khi t mu cn ch t lm sao li dao ct ngang gia mu, khng ct phn ra. V i vi tht chn hoc ph mai, cng b mt kh khc bit do qu trnh x l nhit hoc do m khc bit. - Cc du hiu tri vi protocol ny u khng c cng nhn l phng php Warner-Bratzler Shear nh: li dao khng ging, l vung trn li dao thay v l trn, dng mu tht hnh vung, li dao ct trn nhn vung vc

Hnh Qu trnh ct mu48



2.3. KT QU TH NGHIM2.3.1. Thao tc th nghim - Th nghim ca nhm c thc hin trn 3 loi mu: Xc xch heo Vissan 35g Xc xch Xuxifarm Xc xch xuxifarm

- Thao tc c thc hin tng t nh phn trnh by mc 2.2. PROTOCOL. - Lp t thit b thch hp vi mu cn o. - t mu vo thit b. - Ci t cc thng s trn phn mm ri thc hin php o theo cc bc sau: * Tab Method: - Chn tn phng php ct (Shear-Cutting Test), Chn Save, ri nhn nt Open.

49



* Tab Control

Chn tc thc hin

- Tc thc hin chn gi tr l 20; n v l mm/mn

Chn Compressive extension

Chn qung ng i

- Chn qung ng i l 1 2 cm ty theo ng knh mu. * Tab Result - Chn nhng thng s cn xut bng kt qu.

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* Tab Graph * Tab Test Chn phng php lu trn.Chn s ng biu din trn mt th

51



t tn cho mu

t tn cho mu

- Nhn Set Balance load v Key 2 ri chn nt Start thc hin php o. *Nhng yu t nh hng ti qu trnh kim tra: - La chn v chun b mu. - Tnh cht t nhin ca mu.52



- Tng tc gia h thng my mu. - Thao tc tin hnh. 2.3.2. Kt qu th nghimSpecimen 1 to 9Specimen # 1 2 3 4 5 6 7 8 9

Compressive load (N)

4 3 2 1 0 -1 0 1 2 3 4 5 6 7 8

Time (sec)

Cc mu xc xch c o 3 ln, ln lt theo th t gii thiu phn 2.3.1. Do , th t cc mu l: Xc xch Vissan: specimen 1, 2, 3 Xc xch Xuxifarm 1: specimen 4, 5, 6 Xc xch Xuxifarm 2: specimen 7, 8, 9

53

Bo co thc hnh mn Vt l thc phm Tm hiu phng php Warner-Bratzler ShearLoad at Local Peak Maximum (Comp. extension 1 % Change) (N) -------------

GVHD: Th.S Nguyn c Vng Thc hin: Nhm 3 T 4 DHTP4Load at Maximum Comp. load (N) -3.39583 -3.2338 -3.05228 Extension at Maximum Comp. load (mm) -34.7706 -34.4297 -34.5794 Time at Maximum Comp. load (sec) 3.458 3.422 3.438

Ln lp

Specimen label Vissan Vissan Vissan

Maximum Load (N) 3.4 3.23 3.05

1 2 3

Mean Standard Deviation Minimum Maximum Median

3.226667 0.175024 3.05 3.4 3.23

---------------------

-3.2273 0.171867 -3.39583 -3.05228 -3.2338

-34.5932 0.170829 -34.7706 -34.4297 -34.5794

3.439333 0.018037 3.422 3.458 3.438

Ln lp

Specimen label Xuxifarm 1 Xuxifarm 1 Xuxifarm 1

Maximum Load (N) 2.47 2.53 2.57

4 5 6

Load at Local Peak Maximum (Comp. extension 1 % Change) (N) -------------

Load at Maximum Comp. load (N) -2.46763 -2.52724 -2.57468

Extension at Maximum Comp. load (mm) -36.8894 -37.8198 -37.8298

Time at Maximum Comp. load (sec) 3.67 3.762 3.762


2.523333 0.050332 2.47 2.57 2.53

---------------------

-2.52318 0.05364 -2.57468 -2.46763 -2.52724

-37.513 0.540053 -37.8298 -36.8894 -37.8198

3.731333 0.053116 3.67 3.762 3.762

Specimen label 7 8 9 Xuxifarm 2 Xuxifarm 2 Xuxifarm 2

Maximum Load (N) 2.67 2.52 2.57

Load at Local Peak Maximum (Comp. extension 1 % Change) (N) -------------

Load at Maximum Comp. load (N) -2.66888 -2.52217 -2.56723

Extension at Maximum Comp. load (mm) -37.2602 -38.3198 -36.3995

Time at Maximum Comp. load (sec) 3.706 3.812 3.62


2.586667 0.076376 2.52 2.67 2.57

---------------------

-2.58609 0.075152 -2.66888 -2.52217 -2.56723

-37.3265 0.961864 -38.3198 -36.3995 -37.2602

3.712667 0.096173 3.62 3.812 3.706

*Da vo bng s liu v th, ta c cc nhn xt sau:54



- C s khc bit v cng gia 2 dng sn phm Vissan v Xuxifarm. - cng ca 2 loi xc xch xuxifarm l tng ng nhau (Yield point trn th ca 2 mu xuxifarm l tng ng nhau: t 2 2.5N) - cng ca Vissan khc bit hn yield point l >2.5 3N. - bn ct ca sn phm Vissan thp hn (do thi gian extension c gi tr thp hn so vi 2 loi xuxifarm). - Cn kt hp vi cc nh gi cm quan a ra s tng quan gia th hiu ngi tiu dng vi cc gi tr o c c. V d: c th cng ca Vissan cao hn nhng th hiu li thp hn so vi xuxifarm. - Kt qu o c s khc bit gia cc ln lp c th do: trong qu trnh lm th nghim lin tc, li dao cha c chi ra sch nn b mt sn si, to ma st ln v gy sai s.

55



KT LUN

P

hng php o c l ni chung, phng php Warner-Bratzler Shear ni ring l nhng phng tin rt hu hiu v thng dng hin nay dng o lng cc gi tr lin quan n cu trc thc phm. Ty vo mi loi thc

phm, mi mc ch o lng m ta chn la phng php sao cho ph hp. Khng phi php o no cng p dng c cho tt c cc loi thc phm v khng phi thc phm no cng p dng c cho tt c mi php o. Hiu r nguyn l hot ng, mc ch o lng, bn cht ca mu thc phm th ta c th la chn ra ng phng php o cn thit tin hnh xc nh 1 cch chnh xc cc thng s cn o lng, t nh gi cht lng thc phm da trn nhng con s r rng. Ngy nay, kt hp vi cc kt qu o lng cm quan, ngi ta c th a ra s tng quan gia cc thng s o c c bng cc php o c l vi cc kt qu v nh gi th hiu nhm a ra s chp nhn ca ngi tiu dng v cc loi sn phm thc phm. Trong tng lai, khi khoa hc cng ngh pht trin, cc php o c l s cng c ci tin sao cho t c n chnh xc cao v thc phm ngy cng c nh gi ng vi bn cht tht ca chng.

56



TI LIU THAM KHO [1] Malcolm C.Bourne, 2002: Food Texture and Viscosity, 2nd Edition, Elsevier Science & Technology Books, p.134-138, 209. [2] Dave McKenna: Warner-Bratzler Shear Force Measurement. Meat Science Section, Department of Animal Science, Texas A&M University. [3] Tommy L. Wheeler, Steven D. Shackelford, and Mohammad Koohmaraie, 2003: Warner-Bratzler Shear force protocol. USDA-ARS U.S. Meat Animal Research Center. [4] Jeff Savell et al.: Standardized Warner-Bratzler Shear Force Procedures for Genetic Evaluation. [5] Nguyn B Thanh. Powerpoint Bi ging mn hc vt l thc phm. Vin Cng ngh sinh hc v thc phm. Trng i hc Cng nghip Tp. H Ch Minh. Nm 2009. [6] Morse B.Solomon, Janet S.Eastridge, Ernie W.Paroczay, and Brian C.Bowker: Measuring Meat Texture, p.480-483. [7] Trang web: www.instron.com

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