1. RH B CNG THNG TRNG I HC CNG NGHIP TPHCM VIN CNG NGH SINH HC - THC PHM BI TIU LUN MN : CNG NGH SN XUT UNG TI : CNG NGH SN XUT NC QU C GVHD: NGUYN NGC THUN LP : CDTP14KA

2. DANH SCH NHM STT H V TN MSSV 1 BI TH PHNG HOA 12011882 2 L TH THU THO 12012492 3 L TH NH TUYT 12011752 4 H TH M VN 12011962 5 PHAN TH THY TRANG 12016672 6 NGUYN VN MINH 12098321 7 TRN NG LONG 12013582 8 SN NGC THIN 12011972 3. MC LC LI M U I. TNG QUAN...............................................................................................5 1. Khi nim..............................................................................................5 2. c im chung ....................................................................................5 3. Lch s...................................................................................................5 4. Phn loi................................................................................................6 II. QUY TRNH CNG NGH SN XUT NC QU C..................8 III. THUYT MINH QUY TRNH .................................................................9 1.Qu trnh chun b..................................................................................9 1.1 Nguyn liu..................................................................................9 1.2 Ra .............................................................................................10 2. Qu trnh c nhit ..............................................................................11 2.1 X l c nhit............................................................................11 2.2 p ...............................................................................................13 2.3 Lc th .......................................................................................14 3. Qu trnh ch bin...............................................................................15 3.1. Phi ch....................................................................................15 3.2 ng ha....................................................................................16 3.3 Rt hp.......................................................................................17 4. Qu trnh sau ch bin.........................................................................18 4.1 Bi kh ........................................................................................18 4.2 Ghp m......................................................................................19 4.3 Thanh trng ................................................................................20 4.4 Dn nhn, ng gi....................................................................21 5. Sn phm minh ha.............................................................................22 IV. KT LUN..............................................................................................23 4. LI M U n ung l nhu cu khng th thiu trong cuc sng ca mi ngi. Khi t nc pht trin th nhu cu ny cng cao. V th, p ng nhu cu ngy cng kht khe ca con ngi th nhiu sn phm thc phm c ra i. Gp phn a dng ha cho cc mt hng thc phm l nc ung. Ngy nay, nc ung ngoi dng nc khong ng chai thng thng nh trc y cn c nhiu loi nc ung ng chai c ch bin t nhiu loi tri cy rt ngon v b dng. L mt nc nhit i nn c nhiu u th v cc loi tri cy. Mc d c rt nhiu quan im cho rng tri cy n ti tt hn qua ch bin, th nhng trong cuc sng tt bt ngy nay ca con ngi th nc tri cy ng chai vn c nhiu ngi a chung v s tin li ca n, con ngi vn c th thng thc tri cy m mnh yu thch di dng nc ung m khng tn nhiu thi gian. Trong nhng nm gn y, ngi tiu dng ang c xu hng chn dng hng Vit Nam, loi c cht lng, gi ph hp thay cho cc sn phm nc tri cy Australia, Thi Lan cng cng loi tri cy nhit i nhng gi thnh mc. Cc hng sn xut nc gii kht cng nhn ra s thay i trong nhu cu ca ngi tiu dng v i mi v cht lng mu m, lin tc thay i c cu sn xut. Cc cng ty : Vinamilk, Tribeco, Wonderfarm tung ra th trng nhiu loi nc tri cy : to, xoi, nho, mng cu.... p ng nhu cu khch hng v cng bt u thm nhp cc th trng H Lan, Nht Bn, Hoa K, Singapore... Trn th trng hin c hai dng sn phm : nc tri cy chit xut t thin nhin v nc tri cy lm t hng liu. Loi nc tri cy lm t hng liu ch c hai thnh phn chnh l nc v ng, hng liu ch c tc dng to mi, cho cm gic ngon ming. Loi chit xut t tri cy c cha mt s vitamin v khong cht cn thit cho c th nh : -caroten, Ca, K, v pectin trong mt s loi tri cy cn gip gim cholesterol trong mu. Cc loi nc t tri cy khng ch l ngun b sung Vitamin, cc khong cht a lng, vi lng cn thit m cn l thc ung gip thanh nhit gii kht tt. Sau y, chng ta s cng tm hiu nghin cu v cng nghip sn xut nc gii kht ng vai tr quan trng trong nn kinh t quc dn cng nh cc loi sn phm ch bin khc, n gp phn lm iu ha thc phm gia cc vng, tng ngun hng xut khu trong nc. 5. I. TNG QUAN 1. Khi nim Theo Merriam Webster 1981: nc p l dch c th chit c trong c cha t bo hoc cc m. Theo Codex Alimentarius: nc tri cy l dch qu khng c ln men nhng c th ln men c, c xu hng theo mc ch tiu th chnh xc, c th t c bng cc qu trnh c ha t tri cy v c bo qun hp l bng cc phng php vt l. 2. c im chung Nhng cht c gi tr thc phm cao nht trong qu nh gluxit, axit hu c, vitamin...u tp trung dch qu. Sn phm nc p qu c cha y v cn i cc cht nn c gi tr thc phm cao. hp nc qu dng ung trc tip l ch yu, ngoi ra cn c th s dng hp nc qu ch bin ra cc dng sn phm khc nhau nh : siro qu, ru vang, nc gii kht, mt ng.... 3. Lch s Vic sn xut nc tri cy thc ra c t rt lu, thm ch c th lu i hn c ngnh nng nghip. Khi chn, hu ht tri cy s mm dn n mt m khi vic lu tr hay vn chuyn chng s to ra nhiu nc (tuy nhin nc ny thng b ln men mt phn). Phn nc c ln nhiu tht qu ny c th tch d dng ra khi ht, v v thng th chng c mi v thm ngon hn nhng phn xc cn li. Nhng ngi i sn bt hi lm ngy xa c th dng trc tip chng hay thu nht tri cy chn mm vo nhng thng khng b r r c th s dng v sau. Vic vn chuyn sm mun cng s to ra nc tri cy. Tuy nhin vo nhng ngy tri lnh, vic bo qun c th tt hn n vi gi trc khi b ln men nn s lm thay i ng k cht lng nc tri cy. Thng qua rt nhiu ln th, con ngi hc c tch to ra nc tri cy t nhiu nguyn liu liu khc nhau v quan trng h bit trnh c nhng tri cy nhn bt mt nhng li cha cht c. K thut lm cng c lao ng pht trin thc y vic lm ra nhng dng c ngm gim tri cy v thu nc tri cy. Nhng dng c ct gi thc n, k c ng nc c to ra t nhiu ngun vt liu nh dt t si thc vt, lm t g, t st, da hay rut ng vt V bn cht d b hng ca nc tri cy m yu cu t ra l s dng trong vng khng qu 24h vi tri m v lu hn vi thi tit lnh hn. Rt lnh hay ng bng l gii php thay th duy nht iu chnh tnh cht vi khun bn trong nc tri cy. S ln men nc tri cy ny l c s cho sn xut ru, h thy rng nc tri cy sau khi c bt mt cch b n c nhng tnh cht rt khc ban u. Ngoi ra nu lu tr thm vi ngy na th chng s chuyn dn sang chua thm ch s c mi v kh chu v c vng. Th gim nguyn thy ny tng c dng lm cht bo qun cho cc tri cy v rau c khc. Vi s pht trin ca ngnh nng nghip (hn 10 triu nm trc), nhng 6. v ma trng trt gn nh p ng c nhu cu lng thc, thm ch h c th trng nhng loi cy cho tri cy thch hp vi vic sn xut nc tri cy ni ring v thc ung ni chung. Nc tri cy sau khi p nu khng dng ngay s b ln men, iu ny tip tc xy ra cho n khi nhng cng ngh bo qun c ra i. Thc ra khi nim bo qun y l bo qun tri cy dng sn xut nc tri cy dng nguyn thy cho n khi cn sn xut nc tri cy. Thm ch ngy nay vic bo qun nh th l mt trong nhng cch n gin nht bo m cho cht lng ca nc tri cy. 4. Phn loi Ngi ta c th phn loi nc qu theo nhiu cch : Da vo quy m ch bin : Nc ung tri cy quy m gia nh: l nc ung c ch bin ti gia nh nhm mc ch gii kht v cung cp mt ngun dinh dng cn thit cho c th nh vitamin, khong, ng, b sung cht xngoi ra cn c tc dng thanh nhit, tiu ha thc n, li tiu Nc ung tri cy quy m cng nghip: Cng nh nc tri cy quy m gia nh, sn xut nc tri cy quy m cng nghip vi mc ch gii kht, dinh dng v cha bnh. Tuy nhin v mt dinh dng th thp hn do trong qu trnh ch bin, mt s cht dinh dng mt i nn n c dng ch yu vi mc ch gii kht. Nc tri cy ng hp rt tin li, thch hp cho cuc sng bn rn ngy nay. Da vo phng php ch bin : Nc qu t nhin: l sn phm c ch bin t mt loi qu khng pha thm ng hoc bt c ph gia no. Nc qu t nhin dng ung trc tip hoc ch bin cc loi nc ngt, ru mi. Nc cc loi qu chua khi ung phi thm ng. C 2 loi l nc p v dch qu nghin (puree). Nc qu hn hp: l sn phm c ch bin t 2 hay nhiu loi qu pha trn vi nhau. Lng nc qu pha thm khng qu 35% so vi nc qu chnh. Nc qu pha ng: l sn phm c ch bin bng cch phi ch nc qu t nhin vi syrup. Nc qu c c: Ch bin bng cch c c nc p qu t nhin theo phng php un nng (bc hi) hay phng php lnh ng (tch nc ). Nc qu c c c li tn bao b, kho hng, vn chuyn v t b sinh vt lm hng. Theo phng php bo qun Nc qu thanh trng: l dng sn phm c ng vo bao b kn v c thanh trng bng nhit (c th thanh trng trc hoc sau khi rt vo bao b). Nc qu lm lnh: nc qu dng ny c bo qun lnh hoc lnh 7. ng. Nc qu np kh CO2: l dng nc qu c np kh CO2 c ch hot ng ca vi sinh vt. Theo trng thi sn phm Nc qu dch trong: loi ny c ch bin bng cch tch dch bo ra khi m qu bng phng php p, sau c lng lc trit loi ht tht qu, sn phm dng trong sut khng c lng tht qu y bao b. Nc qu dng c: loi ny cng c ch bin bng cch tch dch bo ra khi m qu bng phng php p, sau c lng lc 1 phn. Sn phm nc qu p dng c vn cn cha mt lng tht qu nht nh trong sn phm. Nc qu nghin (nectar): dng sn phm ny c ch bin bng cch nghin mn m qu cng dch bo ri pha thm ng, acid thc phm cng 1 s ph gia khc. Nc qu khng c tht qu c hnh thc hp dn, t b bin i khi bo qun hn nc qu c tht qu. 8. II. QUY TRNH CNG NGH SN XUT NC QU C Nguyn liu Chn la, ra Qu h, khng t tiu chun X l c nhit p Lc th Phi ch ng ha Rt hp Bi kh Thanh trng Ghp m Nc qu c B p B lc 9. III. THUYT MINH QUY TRNH 1. Qu trnh chun b 1.1 Nguyn liu La chn v phn loi Mc ch: chun b Phn chia nguyn liu ng u v kch thc, hnh dng, mu sc, chn Loi b mt phn hay ton b nhng nguyn liu khng quy cch, su bnh, men mc, thi hng Thc hin v thit b Thc hin theo phng php th cng hoc bng my. C th thc hin trc khi ra hay sau khi ra s b i vi nhng tri qu bn. Nu quy nh cc ch tiu r rng cho nguyn liu nhp vo th khu phn loi c th ch mt t 3-10% khi lng. Thng phn loi v la chn theo 3 ch tiu sau Kch thc v ln: nguyn liu cn t c kch thc trung bnh ca ging pht trin bnh thng, nhng c th c kch thc qu nh hoc qu to u phi loi ra. chn: khi a vo sn xut, nguyn liu cn t n giai on chn ton phn. chn ny, lng dch bo l nhiu nht v cc thnh phn ha hc cha trong dch cng nhiu nht. Mc nguyn vn: Trong thu hoch, vn chuyn, bo qun, nguyn liu c th b xy xt, dp nt, thi ra lm gim cht lng sn phm. Hn na, nhng vt dp nt thi ra l ni vi sinh vt xm nhp v pht trin trn tri. Chnh v vy, trc khi ch bin cn loi b nhng tri b thi ra hon ton, hoc ct b nhng phn hng. Ch tiu ny ch c th phn loi bng th cng. Phn loi theo th cng La chn nguyn liu bng tay trn bng ti vn chuyn, cng nhn ng dc hai bn bng ti v la chn kinh nghim theo cc ch tiu nguyn liu t ra. Bng ti con ln c kh nng lt mi pha ca qu o nh c th d dng pht hin nhng vt h. Kch thc bng ti: 60-80cm Tc bng ti: 0.12 0.15 m/s Nguyn liu phi c dn mng la chn khng b st. Phn loi bng my My phn loi da vo kch thc v hnh dng: Nguyn liu theo bng ti ln lt i qua cc ca c kch thc thay i t nh n ln.Kch thc ny c xc nh bng khang cch gia con ln v bng ti. Nh vo chiu quay con ln m nhng qu c kch thc ng vi kch thc ca s c 10. y ra ngoi mng hng. My phn loi da vo khi lng: nh vo cn cm ng My phn c kiu ry lc: my c nhiu tng ry, c c mc khc nhau, tng trn cng mt rng nht, tng cui cng mt nh nht. H thng ry chuyn ng bng b phn chn ng. My ny dng phn loi qu c kch thc nh nh m, mn, My phn c kiu trc trn: b phn phn loi l nhng cp trc hnh cn, thng dng phn loi qu trn nh cam, chanh, bi NIR (Near Intra Red): s dng tia cn hng ngoi. Thit b ny phn loi su sc nhng tc chm. IQA (Internal Quality Analyser): o sng phn x. 1.2 Ra Mc ch - Nhm loi b bi bm, t ct theo nguyn liu v dy chuyn, gim lng vi sinh vt trn b mt nguyn liu. - Ra cn nhm mc ch ty sch mt s cht ha hc gy c hi c dng trong k thut nng nghip nh thuc tr su - i vi nhng ngun liu qu bn, ngi ta thng thc hin khu ra trc khu phn loi lm l ra nhng ch h hng, d la chn. Yu cu : - Nguyn liu sau khi ra phi sch, khng dp nt, cht dinh dng trong tri b tn tht t nht. - Thi gian ngm ra khng c ko di. - Nc ra tn t nht v phi m bo ch tiu do B y t quy nh, cng khng qu 2mg ng lng/lt, lng clo cn li trong nc trng l 3-5 mg/l. Thc hin - Ty nguyn liu v nhim bn ca nguyn liu m ta c th ra mt hoc nhiu ln, vi nhiu phng php ra tng ng thit b ra khc nhau. - Ngi ta c th ngm, vi mc ch lm nc thm t nguyn liu, lm cht bn mm, bong ra. Qu trnh ny c tng cng bng tc dng c hc (cnh khuy, c bn chi, thi kh), v tng hiu qu ngm bng dung dch kim, nhit (thng p dng i vi lp v cng, b mt x x) - Ra bng cch dng dng nc chy ko cht bn cn li trn b mt nguyn liu sau khi ngm. - Qu trnh ngm ra ch b tn tht 100o C) trong vi pht. Thit b hp c th lin tc hoc gin on. Phng php ny gip t tn tht cht kh, cht lng nguyn liu tt hn. Sau khi chn hoc hp cn lm lnh nhanh. Trong thc tin sn xut ngi ta thng chn v thao tc thun tin, thit b n gin, truyn nhit tt. Thit b Thit b dng trng, thit b dng tunnel c bng ti li, thit b hot ng lin tc trc vis, thit b hot ng lin tc bng ti My chn lin tc dng trc xon c cu to gm mt phu nhp liu, bn nc nng v vt xon ti nguyn liu c nhng trong bn nc. Tc nhn gia nhit l hi nc, ung nng trc tip dung dch chn. 13. Thit b chn 2.2 p Mc ch: Tch dch bo ra khi nguyn liu, tch b b p. Qu trnh ny c th gy hao ht 30-50% lng cht kh. Yu cu: Hiu sut qu trnh p ph thuc vo qu trnh nghin x trc . Do phi ch n nhng thng s hot ng my nghin qu trnh p uc hiu qu. Tch trit dch tri cy t nguyn liu. Tc v p lc p phi thch hp. Tin hnh: Ngi ta thng p nng (hot-break process) tng hiu sut p, chit c mt lng ln cht mu vo dch chit, c th gi c mu sc v hng v ca tri cy. Cc qu trnh h tr: xay nghin, x l dch nghin bng enzym, trch ly. T dch p, ngi ta c th ch bin nc p trong, nc p c c, mt ng jelly, nc tri cy ln men, tri cy ngm ng Thit b p: Lm vic lin tc: cho nguyn liu vo, b thi v dch p ra lin tc. Gm c my p xon c. my p tang trng, my p trc vis vi bc vis c th thay i hoc khng (hiu sut cao 80-90%). Lm vic gin on: thit b vi trc p thng ng hoc nm ngang nh: my p gi (hiu sut 40-50%), my p khung bn, my p kh nn, my p thy lc 14. Thit b p 2.3 Lc th Mc ch: Tch mt phn hay tt c cn khng tan l lng trong dch p tri cy, thng c tin hnh sau qu trnh p. Qu trnh ny hao ht khng ng k, t hn t 1 3% khi lng. Bin i : - Vt l : gim nng cht kh trong dch qu - Ha hc : gim hm lng mt s cht dinh dng trong dch qu, hm lng ng, nhng cht hp th trn b mt dch qu, gim hm lng cht x. - Ha l : gim thnh phn pha phn tn trong dch qu. Tin hnh: Ty thuc vo yu cu sn phm m ta c th p dng lc mt ln hay nhiu ln, dng tr lc hay khng dng tr lc. Tc lc ph thuc vo p sut lc, b dy lp cn. Nng sut lc ph thuc vo nhit v nht nc p. Cc qu trnh h tr: lng, ly tm, enzym Nc qu c lc trong sut, trong qu trnh tn tr c th b c tr li hoc c kt ta do cc phn t keo kt t vi nhau. Thit b: Ngi ta thng dng thit b lc ng hay lc khung bn : mng lc c lm bng cc cht c kh nng hp th cc phn t cn, c xp nht nh. Thit b lc khung bn: gm mt dy khung v bn lc ghp li vi nhau. Gia khung v bn c lp vi lc 15. Thit b lc khung bn 3. Qu trnh ch bin 3.1. Phi ch Mc ch : trn ln 2 hay nhiu thnh phn vo vi nhau nhn c sn phm cui cng. - Tng hng v ca nc p qu - To mu sc thch hp cho nc p qu - t c kh, chua thng phi ch. Bin i : - Vt l : thay i hm lng cht kh, chua ca sn phm - Ha hc : s xut hin ca nhng hp cht mi xut hin trong dung dch nc p qu. - Sinh hc : gi tr nng lng, dinh dng ca nc p qu tng ln ( do c b sung thm syrup ng) - Ha l : i vi nc p qu c, vic thm vo cc cht ln bn huyn ph, to lin kt bn vng cho pha phn tn v pha lin tc. Cho thm cht bo qun c tc dng ko di thi gian bo qun ca sn phm, pH ca sn phm thay i, thng c a v pH thch hp. - Cm quan : tng mi v ca sn phm, c th dch qu b mt i hng v t nhin ca dch qu. Thc hin: i vi nc rau qu t nhin, thnh phn ch yu l dch nc p t rau qu. sn phm t tiu chun v kh, chua thng phi ch thm dung dch ng 70% v mt lng nh dung dch acid citric c un nng. c nc qu hn hp dng t nhin, ngi ta phi trn cc lai dch qu vi nhau theo t l nht nh. Vi nc qu pha ch t dch qu p hay t bt rau qu nhuyn, t l phi ch ca dch hay puree vi syrup ng c 16. th t 20-50%. Thit b: Qu trnh phi ch c thc hin trong cc thng phi ch chuyn dng c trang b cnh khuy trn u. Cnh khuy turbine, 2 tng tng kh nng kh nng o trn. Trc cnh khuy mt u gn vi ng c, u cn li c gn vi mt bi trnh cnh khuy b lc khi quay vi vn tc ln. Bn cnh khuy c gn tm chn gim xoy phu, chng tro, tng din tch s dng.. Thit b phi trn 3.2 ng ha Mc ch : ch bin, bo qun v hon thin. Ph v, lm gim kch thc ht (thng l di 100 micromet), phn b u cc pha trong h Gip hn hp ng nht v cu trc, mi v. Gim hin tng tch pha trong qu trnh bo qun. Thc hin: p dng i vi nc qu c hoc nectar. c thc hin bng nhiu cch: ng ha p lc cao (thng dng nht), nghin keo, sng siu m. Nhit cao gip qu trnh ng ha hiu qu hn, tuy nhin n c th xy ra phn ng ha hc khng mong mun v gy chi ph nng lng ln. Thit b: Thng s dng thit b ng ha p lc cao: bao gm bm cao p v h thng to i p Bm cao p: vn hnh bi ng c in thng qua mt trc quay v b truyn ng chuyn i chuyn ng quay ca ng c thnh chuyn ng tnh tin ca piston. 17. Cc piston chuyn ng trong xylanh p sut cao, bn trong thit b cn c h thng dn nc vo nhm mc ch lm mt cho piston trong sut qu trnh lm vic. u tin, hn hp s c a vo thit b ng ho nh bm piston, bm tng p lc cho h ln n 100-250bar hoc cao hn ti u vo khe hp. To ra mt i p ln h huyn ph bng cch hiu chnh khong cch khe hp trong thit b gia b phn sinh lc v b phn to khe hp. i p ny c duy tr bi mt bm thy lc s dng du, khi , p sut ng ho s cn bng vi p sut du tc dng ln piston thy lc. Thit b ng ha 3.3 Rt hp. Mc ch : hon thin - Bo qun sn phm : hn ch s pht trin v ti nhim ca vi sinh vt - Rt ngn thi gian thanh trng - Khi ng hp c th to ra chn khng trong hp, s gim p sut ni ti ca bao b trong khi thanh trng nh trnh c hin tng nt, h bao b, bt np. Bin i : - Vt l : gim p sut ni ti ca bao b. Thit b rt hp : 18. 4. Qu trnh sau ch bin 4.1 Bi kh Mc ch : hon thin, bo qun, chun b cho qu trnh thanh trng Bo qun: loi kh trong hp trc khi ghp m (gm kh ha tan trong qu trnh ch bin, trong t bo rau qu, trong khong trng bao b), t hn ch c qu trnh oxy ha, hn ch s pht trin ca vi sinh vt hiu kh cng nh hin tng n mn hp st. Chun b cho qu trnh thanh trng, v lm tng h s truyn nhit v lm gim p sut trong hp khi thanh trng, trnh bin dng, bt np, nt mi hn. Bin i : - Vt l : gim p sut ni ti trong dch qu do nng kh cao gy nn, gim kh nng nt v bao b.. Gim din tch tip xc gia pha kh v pha lng, pha kh v pha rn. Ph v lin kt gia pha kh v pha lng, pha kh v pha rn, nh loi b c kh trong pha lng - Ha hc : gim nng kh trong sn phm, gim kh nng b oxy ha ca sn phm, nh tng c thi gian bo qun ca sn phm. - Sinh hc : gim kh nng sinh trng v pht trin ca mt s loi vi sinh vt. Thc hin: Dng nhit: un nng trong ni h hay bung kn Dng phng php c hc: ht khng kh ra khi hp bng bm chn khng Kt hp: rt nng dung dch v ht chn khng. Nhit v p lc chn khng phi thch hp. Thit b bi kh chn khng : 19. 4.2 Ghp m Mc ch: bo qun v hon thin. Cch ly hon ton sn phm vi mi trng ngoi, hn ch s ti nhim vi sinh vt, m bo cho thi gian bo qun v cht lng sn phm. Thc hin: Th cng (a hp vo, ly hp ra, ghp u cn c ngi iu khin) Bn t ng (a hp vo v ly ra bng tay, ghp t ng) T ng (a hp vo, ly hp ra v ghp u hon ton t ng). Sau khi ghp m, c th kim tra kn ca hp bng 2 phng php: o Phng php ht chn khng (theo TCVN 165-64): Dng khn tm etxng chm k hp, c bit l cc mi ghp. Cho 1-3 hp vo bnh thu tinh ca mt my ht chn khng, rt nc va mi si trong 15 pht v lm ngui n 40-450C lm ngp hp. y kn bnh v cho bm chn khng hot ng, chn khng t p sut tuyt i 104N/m2. Trong qu trnh ht, ta xem c hp no c bt kh thot ra khng. Nu xut hin bt phun ra hng lot hoc phun ra u n cng mt ch th hp coi nh b h. Bt xut hin l t khng phi l du hiu ca hp h. Khng c dng nc cha si kim tra d kn v nh th, khi ht chn khng trong bnh th hp s dnh y bt v lm sai vic kim tra. o Phng php ngm trong nc nng: Ra sch hp bng nc nng v x phng, ng thnh mt lp trong chu thu tinh to c ng nc nng nhit chn khng di 850C. Lng nc nng gp 4 ln th 20. tch cc hp, mc nc phi trn mt hp t 25-30mm. Hp trong nc nng t 5-7 pht, lc u y xung di, sau lt np xung. Quan st phn bt kh nh phng php trn. Thit b ghp m : 4.3 Thanh trng Mc ch : nh ch hat ng enzyme v tiu dit vi sinh vt, bo qun sn phm trong thi gian di. Bin i : - Ha hc : mt s cht nhy cm vi nhit c th b bin i - Sinh hc : h vi sinh vt trong sn phm b v hot hoc tiu dit. - Ha sinh : v hot enzyme cn tn ti trong dch qu. Thc hin: Ty vo tnh cht cc loi sn phm m ta c th thanh trng nhiu ch nhit khc nhau: 100-120o C trong thi gian rt ngn (vi giy), hoc 85-100o C trong thi gian di hn (vi chc giy n vi pht). i vi sn phm c chua cao (pH