MC LC

I.Mc ch chn ti1II.Tng quan v xc xch11.Ngun gc ca xc xch12.Cc loi xc xch trn th trng2III.Tng quan v nguyn liu31.Thnh phn nguyn liu32.Gii thiu nguyn liu32.1.Nguyn liu chnh32.2.Thnh phn ha hc ca tht82.3.Nguyn liu ph182.4.Ph gia, gia v v mt s tiu chun v ph gia192.5.Ph gia(Q 3742/01/BYT)24IV.Qui trnh cng ngh sn xut xc xch261.Qui trnh cng ngh262.M t qui trnh cng ngh272.1.Lm lnh272.2.R ng272.3.Ra272.4.Cn282.5.Xay th282.6.Xay nhuyn282.7.Nhi nh lng322.8.Tit trng342.9.Sy kh352.10.Lm ngui362.11.Dn nhn, v thng36TI LIU THAM KHO39

I. Mc ch chn tiTht cc ng vt mu nng cung cp cho c th nhng acid amin cn thit. So snh vi thc phm ngun gc thc vt, tht c ng ho cao, no cao. Tht chu ng c nhit khi ch bin nng v c th lm nhiu loi mn n c mi v khc nhau. Cc c im d nhn thy ny lm cho tht tr thnh loi thc n c gi tr dinh dng c bit .

Trong thi i ngy nay xc xch l mt phn ca thc phm hng ngy. mi la tui xc xch ngy cng c a chung. Nh bit trn th trng ngy nay c rt nhiu loi xc xch khc nhau nh : xc xch g, xc xch heo, xc xch cNhng tm nhng loi xc xch an ton v b dng tht khng d. Sau mt qu trnh tm hiu v nghin cu v mt s sn phm xc xch trn th trng,chng ti quyt nh chn sn phm xc xch heo tit trng lm ti ny.

II. Tng quan v xc xch1. Ngun gc ca xc xchT xc xch bt ngun t ting Latin Salsus ngha l ph nhiu mui hoc c bo qun bng mui. Xc xch c bit sm nht Odyssey hn 2800 nm trc cng nguyn. Xc xch tr nn ph bin trong nhng l hi hoang d Rome. n thi trung i, nhiu loi xc xch c sn xut khp chu u, nhng vng kh hu m p nh: Italia, Ty Ban Nha, Php th pht trin nhng loi xc xch kh, bn kh; nhng vng lnh hn th sn xut xc xch ti, xc xch xng khi v bo qun chng khng kh khn lm.Chnh ngi Trung Hoa, cch y khong 2500 nm lm ra loi xc xch kh chng ra kh, t chng ra t gi l lp xng. Vi trm nm sau , ngi Hi Lp v La M mi nm c mi xc xch v pht trin nhiu loi xc xch ngy nay chy u. Thot u xc xch nhi tit, gan ri ci thin hn nhi vi tht bm s v ct nh, sau ny mi nhi vi nh tng tht ( tht nghin mn), sau c ln men, xng khi bo qun. Chnh loi xc xch ny mi c xem c ngun gc t chu u.2. Cc loi xc xch trn th trngXc xch hin nay a s lm t tht hn hp tht heo, b, c khi l t tht g, c, tm v c xc xch chay t u nnh. Tht v gia v c nhi trong rut sc vt, xng khi hay ln men bo qun c lu.Cn bao xc xch rt a dng, c loi c nhi trong rut sc vt chng hn xc xch Frankfurter, dng rut cu. Cng c loi dng rut heo. Mt s xc xch khc dung bao collagen, lm t da b. Hai loi bao xc xch trn c th n c v cho cm gic cn st v dai. Cng ngh xc xch hin i i hi sn xut hng lot, kch thc sn phm ng u, ngi ta dng thm bao cellulose trong lm t bt g cng kh ph bin trn th trng. Loi ny khng n lun bao c.

III. Tng quan v nguyn liu1. Thnh phn nguyn liu Tht heo, m heo vy Mui n Mui Nitrat Polyphotphat Benzoat (0,05% nguyn liu) Sorbat (0,05% nguyn liu) Tinh bt bp Gia v: hnh, ti, ng, bt ngt, tiu, hng cc loi2. Gii thiu nguyn liu2.1. Nguyn liu chnh Tht ng vt c cu to t nhiu loi m khc nhau nh m biu b, m c, m lin kt, v m thn kinh; m phn theo gi tr thc phm gm m c, m m, m xng v m lin kt. Hm lng cc m v tnh cht ca chng ph thuc vo loi, ging, gii tnh, tui v mc bo ca con vt. Cc m k trn c th tch ra khi nhau mc d khng han tan v c s dng theo gi tr thc phm ca chng. Dng tht nc, m v da t gia sc git m em lm lnh hoc t tht cp ng Tht nc: thng dng phn tht i, lng v mt s phn khc trn c th (v tr s 1;2;4;5 v 8)

Tuyt i khng ln xng, da v phi loi b nhng mng m, gn, mch mu, mng c trn, vt bm.Nhng du hiu tht hng: Tht i: Tht b i khi bo qun nhit khng thch hp trong vng 24 gi u sau git, thng xy ra khi cc khi tht cn bc hi, nht l loi tht bo, xp cht vo ch m, km thong gi. Trong iu kin ny, d nh hng ti cc men ca t chc v ccqu trnh t hu trong tht rt mnh. Qu trnh ny xy ra khng c s tham gia ca cc vi khun nhng km theo s to thnh H2S v nhiu cht bay hi khc. Mu tht bin i, tht tr nn nho; tht c th b i ch v chm lt da sau khi git tht. V phng din v sinh, nh gi v x l tht i ty theo mc . cc giai on u, nn ct tht thnh ming mng ri lm thong gi. Khi bay ht mi, tht c th dng n. Nu c nhiu bin i cm quan m sau khi thang gi vn khng ht mi, tht khng c dng n.

Tht b chua: Qu trnh ny do hot ng ca cc vi khun gy nn v to thnh cc sn phm acid. Qu trnh ny hay gp nht gan v gan giu glycogen. Khi b ln men chua, tht c mu trng, mm nho, mi chua kh chu, pH t 5,4 5,6. nh gi tnh trng v sinh, nn ch l qu trnh tht chua hay i lin vi qu trnh thi. Do khi ln men chua, cc loi nm mc v men pht trin mnh, chng chuyn mi trng sang kim v ta iu kin cho vi khun gy thi pht trin. Tht b thi: Hin tng ny hay gp nht, xy ra do tc dng ca vi khun hiu kh v k kh gy thi lm bin i protein. Cc loi vi khun sau y c tc dng phn gii protein mnh: B. proteus vulgaris, B. coli communis, B. subtilis, B. mesentericus, B.sporogenes, B. perfringens, B.putrificus. Nhiu loi vi khun phn gii protein mnh c th pht trin 0oC v nhit thp hn. Thuc loi ny c cc trc khun gram m thuc h Achomobacterium, Pseudomonas v mt s men. Sn phm trung gian v sn phm cui cng ca qu trnh thi c to thnh t cc aicd amin. l indol, scatol, czezol, meccapton, ammoniac, acid carbonic, H2S c mi thi v cc acid bo bay hi.

Tht b mc : Mt trong nhng nguyn, nhn hng tht l do nhim mc. Mi trng c m cao v khng thong gi to iu kin pht trin mc. Trong tht thng gp cc loi mc Penicilinum, Mucor, Aspergillus v mt s loi khc to thnh cc khun lc mu trng, xanh sm, xanh xm hay en trn b mt. Phn ln cc khun lc nm pht trin nhit 20 25oC nhng mt s loi c th pht trin tt nhit 0oC, ngay c khi bo qun tht trong t lnh (t -7oC n -9oC) Cc loi mc thng pht trin cng vi cc vi khun gy thi v chng chuyn mi trng sang kim thun li cho s pht trin cc loi vi khun. nh gi v sinh tht nhim mc tu theo su cu s xm nhim. khi tht b nhim mc b mt, nn x l bng dung dch mui 20% hay dung dch acid acetic 3%. Ngoi cc trng hp hng tht ni trn cn gp mt s loi khc khng lin quan vi qu trnh thi. l hin tng b mt tht c mu do cc vi khun ta sc t, c mu xanh do nhim khun B. cyanogens. Tt c cc loi hng tht ny ch pht trin b mt tht. Sau khi gt b b mt, tht c th dng n. Khi tht hng c km theo qu trnh thi ra th khng c s dng.

2.1.1. M cM c c gi tr thc phm cao nht chim 35% trng lng con vt. M c bao gm t bo si c v cht gian bo.Ty vo cu to v hot ng co gin ca si c m c c chia thnh cc loi:C trn: l c co gin khng theo mun ca con vtC vn: iu khin mi c ng theo mun ca con vtC tim: l c trung gian gia c vn v c trnCc thnh phn ha hc chnh ca m c gm: Nc: 72%-75% Protein: 18%-21% Lipid: 1%-3% Glucid: 1% Khong: 1,2%-1.5% Ngoi ra cn mt s vitamine, enzym tham gia vo hot ng ca c.2.1.2. M lin ktTrong c th, m lin kt c phn b rng ri, c tc dung lin kt cc b phn li vi nhau, tham gia qu trnh trao i cht v thc hin vai tr bo v c th. M lin kt gm cc t bo v cht gian bo. Do c im ca cht gian bo m chia ra m lin kt ring, m sn, m xng v m mu.2.1.3. M mM m c to thnh t m lin kt hnh li cng vi lng ln t bo m. T bo c ng knh khang 130pm c cc nguyn t cu trc thng thng ca t bo, trung tm cha y git m.Lng m m, v tr tch ly, mu sc, mi v v nhiu tnh cht khc ty thuc vo loi, ging tui, mc bo v iu kin nui dng.2.1.4. M xngXng gm c cht nn c to ra lp b mt v cht xp bn trong. Thnh phn cht gian bo ca m sn gm: chodrominoit, acid chodroitin sunfuric, collagen v mt s protein khc. Khi un si nc, cht gian bo chuyn thnh keo trong c gelatin, muxin v mui.2.1.5. M muKhi ct tit ng vt chy ra khang 40-60%. Mu cn li tn ti mao mch ca m, cc c quan v da.Trong mu cha 16,4%-18,5% protein, 79%-82% nc, 0,6%-0,7% cht hu c phi protein v 0,8%-1% cht khang. Mu gm cc thnh phn hu hnh v huyt tng lng.2.2. Thnh phn ha hc ca thtTht c c im chung l cha nhiu nc,khong 60-75%.Protein chim 15-20% trng lng ti.Lipid trong tht dao ng nhiu. iu lin quan vi loi sc vt, mc bo v v tr ming tht.V d: -Tht ln bo,m c th ti 30%-Tht b gy, m khng qu 2%Tht cc con vt non thng c nhiu nc, t protein v lipid.Glucid trong tht c rt t. Ngoi glycogen trong cc lin kt khng c nit cn c acid lactic v inozytol. Lng acid lactic sau khi git tht l 0,05%, tht sau 24gi ln ti 0,7%.Lng inozytol tht ln l 0,45%.Khi luc tht, phn ln cc cht chit xut ra theo nc. Glycogen, glucose, acid lactic thuc nhm cht chit xut khng c nit,chim khong 1% trng lng tht .T s gia 3 cht ny thay i theo thi gian. Gi u tin sau khi git lng glycogen tht nhiu hn lng acid lactic 2,5 ln nhng 24gi sau lng acid lactic li nhiu hn gp 3 ln lng glycogen.Gi tr sinh hc ca protein cc loi tht gn ging nhau. Theo Mitchell, protein c gi tr sinh hc khong 74%, ng ha ca protein tht ln ti 96-97%. Trong tht, ngoi cc protein c gi tr ton din cn c cc protein hu nh khng c tryptophan v cystin. l collagen v elastin thuc loi sclero-protein. Chng c ch yu t chc lin kt v no. Cc loi protein ny nht l elastin rt t b tc dng ca men phn gii protein. Khi un trong nc collagen chuyn thnh gelatin,gy ng keo. Tht c mu l do myoglobin, mt protein thuc nhm cromoprotein c cu trc v c tnh gn vi hemoglobin. Cc protein khc ca tht l myosin (khong 50%), actin (khong 15%) v globulin (khong 20%).Bng 1. Thnh phn ha hc mt s loi tht thng dngTnthc phmNng lng(kcal)Thnh phn ha hc(g %)

NcProteinLipidGlucid

Tht ln nc13973,019,07,00

(Ngun: bng thnh phn dinh dng thc phm Vit Nam nm 2000)Protein khng phi l nhng hp cht duy nht cha nit trong tht. Ngoi protein cn c nhng cht chit xut tan trong nc, c mi v c hiu, lun lun xut hin trong nc luc (khong 1,5-2,0% trng lng tht), tht cc con vt gi hay gy m do thiu n th cc cht chit xut nhiu hn. Cc cht chit xut l: creatin, creatinin, carnosin, cc cht kim purin, pyrimidin, glutathion v nhng cht khc. Lng carnosin v creatin trong tht ln v ng vt c sng gn ging nhau (285 v 265mg% carnosin,288 v 300 mg% creatin).Cc cht kim purin c nhiu tht ln (86mg%).Tht ngay sau khi git khng c cc acid t do nhng lng acid t do ny tng dn theo thi gian.Tht c hu ht cc acid amin,lng acid amin cn thit vo khong 46%.Bng 2. Hm lng cc acid amin trong tht v ph tngTht ln nc

Acid amin(mg%)LysinMethioninTryptophanPhenylalaninThreoninValin

1440400230690740910

LeucinIsoleucinArgininHistidinCystinTyrosin

11909401010510202644

(Ngun:Bng thnh phn dinh dng thc phm Vit Nam nm 2000)Gi tr sinh nng lng ca tht ng vt ty theo hm lng m. Cc cht bo c t chc di da, bng, quanh cc ni tng v xng vi hm lng rt thay i. M d tr ca cc ng vt mu nng c rt t acid bo c dy ni ngn (ti C14). Acid palmitic (C16) c khong 25-30%,acid stearic (C18) , cc loi khc 16-28%. Acid oleic c nhiu nht 35-43%. Cc acid bo cha no nhiu mch kp (EFA) c khong 2-7%. m ln, cc lp ngoi c nhiu acid bo cha no nhiu ni kp hn cc lp su.Thnh phn ng ch trong cht bo ca tht l cholesterol. Khoa hc ngy nay chng minh ch n c qu nhiu cht bo cng vi lng cholesterol trn 300mg/ngy c lin quan n cc bnh tim mch.Gi tr sinh hc v ng ha cc cht bo ca tht lin quan trc tip vi bo ca con vt. Lng acid bo cha no cn thit con vt gy cm gim v lng cc acid bo no tng ln r rt. Nhit tan chy ca m ph thuc vo t s gia cc acid bo no v cha no. Nhit tan chy ca m ln l 34-440C. ng ha ph thuc nhiu vo nhit tan chy. M ln c ng ha cao nht(97-98%). Cn lu rng nhit tan chy cn ty theo v tr t chc m trong c th:m ni tng c nhit tan chy cao hn m di da.Tht cha nhiu loi mui khong cn thit cho s tn ti v pht trin ca c th, loi tht c nhiu m th lng mui khong thp hn.Bng 3. Hm lng khong v vi khong trong 100g thtThc phmCa (mg)P(mg)Fe(mg)Na(mg)K(mg)Mg(mg)Mn(mg)Zn(mg)Co(mg)Cu(mg)Se(mg)

Tht ln nc71901,0--32-2,501,119023,9

(Ngun: Bng thnh phn dinh dng thc phm Vit Nam 2000)Tht thuc loi thc n gy toan mnh v cha lng phospho v lu hunh rt cao. Hm lng st trong tht khong t 1-5mg%. Tht c kh nhiu kali v natri,lng ng k cc vi khong quan trng nh ng,km,coban,selen nng cao gi tr dinh dng ca mt s loi tht. Tht ln nc ti c ti 2,5mg km v 23,9 g selen trong 100gam.Tht l ngun vitamin nhm B rt tt,nhng hm lng thay ty loi tht. Tht ln nc c nhiu loi thianin hn cc loi khc.Bng 4. Hm lng mt s vitamin trong tht v ph tngTht ln ba ch

VitaminVitaminA(g)VitaminB1(mg)VitaminB2(mg)VitaminPP(mg)VitaminC(mg)

100,530,162,72,0

(Ngun:bng thnh phm dinh dng thc phm Vit Nam nm 2000)Trong tht cn c cc vitamin khc nh pyridoxin 1,3-3mg%, biotin 0,01 0,02mg%, acid pantotenic 1,25-2,95mg%.

Quy trnh sn xut xc xch tit trng GVHD: ThS. Nguyn Th Hin

Lp: D10-TP01+02Trang 12.2.1. ProteinL thnh phn quan trng nht trong tht, hm lng dao ng t 5-20%. Protein ca tht ch yu l protein han thin cha y cc acid amin khng th thay th (chim khang 80%) bao gm miozin, miogen, actin, mioglobin, globulin trong miozin chim ti 40% lng protein chung, l protein ch yu ca m c.Ngi ta tm ra 30 acid amin trong t nhin, trong c 20 acid amin thng c tm thy trong hu ht cc protein. Tt c cc acid amin khng tm thy trong t nhin u c th tm thy d dng trong m c, v vy protein tht c gi tr sinh hc cao. Mt nhm khc gm cc cht lin quan n protein (nhng khng phi protein tht s) nh purines, pyrimidines v nucleopeptides. y l thnh phn tan nhiu trong nc, c gi tr dinh dng t nhng chng l nhng hp cht sinh ha c th tn ti trong dch tiu ha. Chng to cho tht c mu v mi c trng. Nhng thnh phn ny c nhiu trong th gi v chng c bit nhiu trong nhng m c hot ng nhiu, n lm cho ming tht ct ra t nhng m ny s dai, cng hn.Ngoi thnh phn ca protein c myozin, actin, tropmyozin ng vai tr quan trng trong vic to nn nhng c tnh chc nng tht.2.2.2. LipidCht bo trong m c c hm lng khang 3%, m c 60-94%, m lin kt 1-3,3%, m sn 3,5%, m xng 3,8-27%, trong ty xng 87,6-92,3%, m mu 0,3%, hm lng cht bo tht ph thuc vo loi ging, gii tnh v mc bo ca con vt. Cht bo c nh hng n s cung cp nng lng, mu sc, mi v, s thm ngon v mm mi ca tht.Lipid thc phm ch yu l triglycerides trong c cha cc acid bo no, acid bo cha no c mt ni i v cha no c nhiu ni i. Nng lng cht bo cung cp gn 2,25 ln so vi glucid, protein (tnh trn cng mt n v). Ngoi nhng gi tr ny, cht bo cn ng vai tr lm cho v ca tht ncngon hn nh hng thm, mu sc, lm mm ming tht nc. Tuy nhin theo American Heart Association (AHA) v U.S Department of Argiculture khuyn co rng trong khu phn n, nng lng cung cp t cht bo khng qu 30% mi m bo v vn sc khe. Trong mt na cht bo con ngi s dng l t thc vt, mt na t ng vt v t l s dng cht bo t thc vt ngy cng tng. Ngy nay, m tr nn khng thit yu trong ba n hng ngy v vic to ra nhng con th c cha lng m thp l mc tiu hng u ca cc nh di truyn v chn ging.2.2.3. NcHm lng nc trong m c tng i cao (72-80%). Hm lng nc mi loi tht khc nhau th khc nhau v nc chim t trng ln hn cc cht khc. Nc trong tht gm c nc t do v nc lin kt. Hm lng nc trong tht gia sc, gia cm c lin quan n loi, ging, mc bo, iu kin chn nui v iu kin bo qun.Nc l thnh phn ha hc phong ph nht trong tht, n l thnh phn quan trng trong c th ng vt cn sng, nc c nhiu chc nng khc nhau nh: cn thit cho qu trnh trao i cht, iu chnh nhit , l dung mi ha tan cc cht dinh dng, Nc l cha kha trong ch bin tht, chng hn trong cc sn phm sy, xng khi s lm gim hm lng m, nng cc cht tan s tng, ngc li trong mt s sn phm dng gel nu thm vo mt lng nc thch hp s c mt sn phm c cu trc tt, gim c gi thnh.2.2.4. GlucidHm lng glucid trong m c khng nhiu (1,5%) ch yu l glycogen tp trung gan, mu trong c bp, ngoi ra cn mt s sn phm chuyn ha ca n nh glucoza (0,15%), dextrin, mantoza,2.2.5. Cc cht trch lyCht trch li ca m c gm hai loi: cha nit v khng cha nit. Glucid v cc sn phm ca chng l cc trch li khng cha nit. Cht trch li cha nit gm nhng hp cht c cha nit nhng khng phi l protein v c hm lng khang 0.9-2,5% nhng cht trch li cha nit c vai tr quan trng trong nhiu qu trnh bin i m c khi con vt cn sng cng nh sau khi git m nh tham gia vo qu trnh trao i cht v l ngun cung cp nng lng cho hot ng co rt c bp. Cht trch li to hng v thm ngon cho tht v kch thch s tit dch tiu ha.Cc cht trch li quan trng nht ca m c nh creatin, creatin photphat, acnozin, adenozin photphat,2.2.6. Mt s cht khcEnzym: trong tht c hn 50 loi enzym tham gia vo qu trnh phn gii v tng hp.Vitamin: cha nhiu vitamin nhm B nh: B1, B6, B12 v mt s vitamin ha tan trong nc nh vitamin C.Nc: lng nc trong c th ng vt tri ngc vi lng m, m cng nhiu th nc cng t. Cng mt c th ng vt v tr khc nhau th lng nc khc nhau.Mui v c: lng mui v c trong t chc c tht rt t.2.2.7. Cc bin i ca thtSau khi ra v kim tra, ng ta cho tht vo bung lnh. Ty theo iu kin nhit , ngi ta chia tht loi ngui, p lnh v p ng. Tht c ngui cc phng thong, tuy nhin loi tht ny cha c mi v tt v cc qu trnh chn cha hon thnh. Tt nht v phng din dinh dng v mi v l vic lm lnh tht. mm, chc v mi thm cu tht p lnh l do qu trnh chn ti tht. Mi c hiu v d chu cu tht chn ti l do tch lu trong cc acid glutamic, inosine, cc purin v nhiu cht khc Thi gian chn ti cu tht tu theo nhit bo qun: nhit cng cao, thi gian chn ti cng ngn. Tuy nhin v phng din v sinh qu trnh chn ti xy ra tt nht nhit 0 2oC v qu trnh chn ti kt thc trong vng 2 3 ngy. Trong thc t i khi p dng phng php rt ngn nhit 36oC trong 12 gi, sau 2 - 4oC trong 12 gi. Nhc im ca cch ny l c nhiu iu kin thun l cho s pht trin cc vi khun. Theo nhiu tc gi s chn ti tht nhit cao ch c th p dng trong nhng iu kin c bit (chiu tia t ngoi ) ngn cn s pht trin cc vi khun.Trong mt s iu kin bnh l ca con vt (mt mi, kit sc ) lng glycogen trong t chc gim, qu trnh chn ti b ri lon, lng acid lactic v phosphoric gim i trong c nn loi tht ny rt kh bo qun.Sau khi lm lnh ngi ta chuyn cc khi tht sang khu ch bin k ngh hoc vo cc bung ng lnh. Nhiu nghin cu cho thy, cc thnh phn ca tht nht l protein khi bin cht khi bo qun lu nn lm ng lnh tht khi ang cn ti nng, gim c s mt nc tht ti 20% v gim s mt protein t 15 20%ng lnh nhanh tht ang ti nng gim bt r rt cc bin i oxy ho lipid v th tht gi c mi t nhin v gi c gi tr dinh dng lu hn. Th gian vn chuyn tht ang ti nng t xng ch bin s b t nh lnh khng c qu 2 gi.Khi ng lnh t t (nhit t -8oC n -10oC), nc ra khi t bo vo cc khong gian bo sau ng li di dng tinh th ln lm bin dng t chc. Khi lm lnh nhanh (nhit -25oC hay thp hn) cc cht dch ng rt nhanh khng kp tit ra cc khong gian bo. Trong nhng trng hp na, cc tinh th ta thnh u nh v ta iu kin thun li hp thu tr la t bo khi ph . Lng mt cc cht cc cht khi lm ng lnh gii hn nhit t -4oC ti -9oC.+ Cc bin i ca tht sau khi lnh ng:Do nhit lm lnh ng ca tht khang -150C n -200C thp hn nhit ng c ca dch hot ( -150C th 87,5% nc trong t bo b ng bng), nn khi tht b cng li. ng thi do nhit thp nn nng cc cht ha tan trong nc cha ng tng ln ln 10 ln. Trong vng c dung dch ny protein b bin tnh mnh m do lc ion tng v pH thay i, lm protein b bin tnh dn n kh nng gi nc gim.Lnh ng c th lm thit hi cu trc trc t bo, khi lm lnh ng chm th cc tinh th ln to ra trong mi trng ngoi bo, lm cho p sut thm thu b hn mi trng ni bo, nc chuyn t mi trng ni bo sang mi trng ngoi bo, lc ion mi trng ni bo tng, cui cng t bo b teo nguyn sinh v protein b bin tnh.Cc yu cu k thut khi tip nhn nguyn liu tht: Trc khi a vo cp ng , v nguyn tc nguyn liu tht cn kim tra tt c cc ch tiu cn quan, l, ha, sinh theo qui nh. Nhng trn thc t, do c im ca nguyn liu nn ch kim tra phn cm quan ca nguyn liu l chnh. Da vo nhng ch tiu trn ngi ta phn tht lm 2 loi: tht ti v tht km ti, iTht tiTht km ti, i

Trng thi bn ngoi-Mng ngoi kh-M c mu sc, rn,mi v bnh thng-Gn trong, n hi bnh thng-Mt khp lng v trong-Dch hot trong

-Nht nhiu hay bt u nht-M mu ti, rn gim st,mi v i-Gn km trong v km n hi-Mt khp c nhiu nht-Dch hot c

Ch vt ct-Mu sc bnh thng,sng-Mu sc ti hn trc

rn chc v n hi-Rn chc, n hi cao, ngn tay n vo tht to thnh vt lm khng li du vt gi khi ly ngn tay ra.-Tht km ti: khi n ngn tay c th li vt nh nhng tr li bnh thng nhanh chng-Tht i: khi n ngn tay vt lm do ngn tay to thnh khng tr li bnh thng c

Ty

Nc canh un si lng-Ty tht ti bm cht vo thnh ng ty, n hi trong

-Nc canh trong, mi v thm ngon trn mt c mt lp m vi vt m to-Ty ri ra khi ng ty,mi i, mu sc ti hn hoc nu

-Tht km ti: nc canh c, mi v i, trn mt c lp m tch thnh nhng lp m nh, kh tp trung thnh lp m ln-Tht i: Nc canh c mi v i, bn, hu nh khng cn vt m na

Phn ng giy quAcidKim

+ Cc bin i ca tht trong giai on tan gi:Tht lnh ng trc khi s dng phi a vo phng r ng thc hin qu trnh r ng t nhin. y, nhit ca tht tng dn ln, v khng kh trong phng lun phin tch cc. Do c s chnh lch nhit gia mi trng v nhit bn trong tht, cc tinh th tan v mang theo mt s cht dinh dng ha tan trong nc. iu ny dn n s hao ht nh v dinh dng v khi lng tht mc d nc v dch hot mt phn c hp ph tr li bi cc t bo.Tht tan gi l mi trng tt cho vi sinh vt pht trin (v nhit ca tht tng ln, cht dinh dng tit ra), nn hn ch s lng vi sinh vt th phi em ch bin ngay sau khi tan gi. Tht sau khi tan gi th khng lm lnh ng tr li.

Cc ch tiuMc cht lng tht heo lnh ng(TCVN 4377-1993)

1.Cm quan:

a.Trng thi lnh ng:

Bn ngoi:

Bn trong:-Vung vn, ng cng,lng dnh tay. B mt kh, khi g c ting vang, c th c mt t tuyt mng trn b mt. y ca khi tht khng c lp dch mng v cc im ng nc ng bng.

-Mu hng ti c trng ca tht,chen ln mu trng c ca sa l m

b.Trng thi tan gi: Bn ngoi: -Tht

-M

-Mi,v

c.Trng thi chn: Bn ngoi: +Tht: Mu Mi V +Nc luc:

-Dai c tnh n hi, khi n ngn tay khng li du ln trn b mt tht,vt ln mt t t. Khng c hch tm ba,cc ng mu ln, m lin kt th, m bo nho, gn sn tht.-Mu hng m n mu ti c trng ca tht

-Mm, nh hnh-C mu trng c ca sa

-C mi c trng ca tht lnh ng,khng c mi chua, i,kht,v nht m c trng

-C mu hng nht-Mi c trng khng c mi l-V ngt m

+Trong,mi thm,thong c mi chua lc mi si. V ngt,c th c vng m trn b mt v c vi kt ta lng nh di y

2. Ha sinh: - pH -Hm lng NH3 -Hm lng acid bay hi -P nc luc tht vi CuSO4-Khong 5.5-6-Nh hn 35 mg/100g-0.36-0.51 ml NaOH 0.1 N-Trong cho php mt t vn c

3.Vi sinh:-TSVSVHK-E.coli-Staphylococcus-Salmonella106 khun lc/g100 khun lc/g100 khun lc/g0 khun lc/g

2.3. Nguyn liu ph2.3.1. MLp m di da c cht lng tt nht. Khng dng m vn v cc lp mng m bn trong c th. Yu cu m khng b bin mu, bin mi.M c ra bng nc nng ra tri lp m nhy v lm co khi m nn b mt m s kh khi ro. T l gia tht nc v m thng thay i rt ln nhng lng m phi m bo 97%

Hm lng cht khng tan trong nc tnh theo % khi lng cht kh