TRNG I HC CU LONG

KHOA KHOA HC NNG NGHIP

B MN CNG NGH THC PHM

TIU LUN MN HC PHN TCH THC PHM

XC NH HM LNG MELAMINE TRONG THC PHM

GVHD: ng Xun o

Trng Quc Khnh MSSV: 1111032039

Nguyn Th Trc Ly MSSV: 1111032049 Lp: CNTP-K11

Nin kha: 2011-2012MC LC0MC LC

2Chng I. TNG QUAN V MELAMINE TRONG SA

21.1Tng quan v sa nhim Melamine:

21.2Tm quan trng ca sa i vi i sng con ngi:

41.3Quy trnh sn xut sa:

6Chng II. PHN TCH HM LNG MELAMINE TRONG SA

62.1Tng quan cht Melamine:

62.1.1c tnh ca Melamine:

62.1.2nh hng ca Melamine n sc khe:

62.2Vai tr ca Melamine:

62.3Xc nh hm lng Melamine trong mu sa bng phng php sc k kh ghp khi ph (GC-MS):

62.3.1Nguyn tc:

62.3.2Thit b v dng c:

62.3.3Ha cht v thuc th:

62.3.4Pha ch dung dch:

62.3.5Tin hnh phn tch:

62.3.6Xc nh v tnh kt qu:

62.3.7nh gi phng php phn tch:

62.4Kt lun:

6TI LIU THAM KHO

Chng I. TNG QUAN V MELAMINE TRONG SA1.1 Tng quan v sa nhim Melamine:Gn y vic tm thy Melamine, mt cht c hi cho sc kho c trong sa v cc sn phm sa nh bnh, ko gy nhiu lo lng cho ngi dn v c cc nh qun l v an ton v sinh thc phm, v y l loi thc phm rt ph bin c nhiu ngi s dng, nht l tr em. Kim sot hm lng Melamine trong sa v cc sn phm t sa hin nay l vic cn thit bo v sc kho ngi dn.Vic thm Melamin vo sa ti Trung Quc trong thi gian gn y vi mc ch tng m gy nh hng nghim trng n sc khe ngi tiu dng. Theo thng tn x Php (AFP) ti Beijing, cho n nay gn 13.000 tr em nhp vin ti Trung Quc sau khi ung sa c cha Melamine, trong 104 tr bnh rt nng v c t nht 4 tr b t vong. Melamine c pht hin trong sa hp tr em, sau pht hin trong c sa lng ng hp,yoghurt v kem ti Trung Quc. Hm lng nhim Melamine trong khong t 0.09 mg/kg n 2.560 mg/kg.Gn y, vic nhp khu mt lng sa v nguyn liu sa t Trung Quc v cc nc khc vo tiu th ti th trng VitNamgy nhiu bt an cho ngi dn v c cho cc c quan chc nng v an ton v sinh thc phm. Melamine c tm thy trong cc loi sa v sn phm sa ang tiu th ti nc ta khng? y l vn tht s cn c quan tm. V th vic kim tra, gim st Melamine nhim trong sa v sn phm sa l iu cn thit phi thc hin nhm bo v sc khe ngi tiu dng.1.2 Tm quan trng ca sa i vi i sng con ngi:Sa cha rt nhiu thnh phn khc nhau, bao gm protein, lipid, ng lactose, cc cht khong, cc men v cc hot cht sinh hc khc.

Nu tnh theo khi lng th 1 lt sa b vi thnh phn c trng nh sau:

- Nc: 900-910g.

- Vt cht kh, bao gm:

+ Cc cht bo (37-38g) bao gm 99% l cc lipid n (glycerit) v t 0,5 n 1% l cc lipid phc.

+ Gluxit c th ca sa l ng i lactose (33-48g).

+ Vt cht cha nit (33-38g) bao gm: 80% cazein, 18% protein trong nc sa

(lactoserum) v 2% nit phi protein.

+ Sa cha nhiu khong v vitamin, thnh phn ca chng trong 1 lt sa nh sau:

Kali1,34 - 1,70gVitamin D 15 - 20 IU

Canxi1,00 - 1,40gVitamin B31 - 2 mg

Natri0,35 - 0,60gVitamin B10,3 - 1 mg

Magn0,10 - 0,15gVitamin B20,3 3 mg

Clo0,80 - 1,10gVitamin B60,3 - 1mg

Photpho0,75 - 1,10gVitamin B121 - 8 mg

Vitamin A1000 - 3000 IUVitamin C10 - 20 mg

+ Ngoi ra, sa cn cha cc nguyn t vi lng nh: nhm, brom, ng, st, flo, it, mangan, molipden, silic, km.Ni chung, sa l ngun thc phm thit yu cung cp cc cht dinh dng cn thit cho con ngi.

1.3 Quy trnh sn xut sa:

Thuyt minh quy trnh: a) Nguyn liu:+ Nguyn liu chnh: Bt sa gy, Sa ti.+ Nguyn liu ph: Du b, ng, Nc.+ Ph gia: Cht n nh .+ Mui phosphat v citrat ca Natri, Kali.b) Gia nhit chun ha:iu chnh thnh phn sa gy, du b, ng ph hp vi tng loi sn phm sa.c) Trn tun hon: Mc ch: Tn, ha tan ng u cc thnh phn, nguyn liu.

Yu cu k thut: + Nhit : 600C.+ Thi gian: 1 gi - 1 gi 30 pht.+ Thit b: H thng bn trn c cnh khuy.

d) Lc: Mc ch: Loi b nhng cn b hay tp cht c trong nguyn liu.

Yu cu k thut:

Kch thc l lc < 300 m, cn c tch ra, khng c s bin i no ca sa.

Thit b: Lc dng ti tho ri.

e) ng ha: ng ha l qu trnh x l c hc, dng lc tc dng ln cc ht bo.

Yu cu k thut: + Nhit : 700C.

+ p sut: 100-110 bar.+ Kch thc ht bo gim, cc ht cht bo phn phi ng u trong khi sa lm cho trng thi h nh tng trong sa bn hn.

Thit b: Thit b ng ha hai cp.f) Thanh trng: Mc ch: Tiu dit vi sinh vt gy bnh cho ngi v tng thi gian bo qun. Ci thin tnh n nh ca protein, to cu trc cho sn phm.

Yu cu k thut: + Nhit : 1500C.

+ p sut lm vic: 9 bar.+ Thi gian: 5 pht.+ Cht bo hon ton b nng chy v xut hin mng cream, sa sm mu (tuy nhin do lng nc trong sa kh ln nn kh quan st uc).+VSV b ph hy hon ton, c ch hot ng cc bo t.+ V hot hon ton cc enzyme trong sa.

Thit b: V trao i nhit PHE (plate heat exchanger).g) C c, lm ngui: Tng nng cht kh ca sa t nng cht kh ca dch trn ban u 23,46 % ln gi tr yu cu ca sn phm sa c (72-73%). Loi b kh ha tan trong dch sa nh qu trnh bc hi trong chn khng.

Yu cu k thut:+ Nhit : < 440C.

+ p sut: Chn khng, Sa c mu vng kem. Thit b: Thp c c hot ng p sut chn khng.

h) Kt tinh:

To iu kin cho lactose trong sa kt tinh mt cch trit .

Hon thin sn phm, gip cho sa sau c c c mt trng thi c mn.

Yu cu k thut: Nhit : 30 320C. Thi gian: nhanh, c s chuyn pha ca ng t dng ha tan thnh tinh th. Tinh th lactose to thnh tht nh v khng th pht hin khi cm quan.

Thit b: Bn cha v trng c o cch nhit v cnh khuy.

i) Chun ha: Kim tra cc tnh cht ha l ca sa nh nht, hm lng cht kh.

Yu cu k thut: + Cht bo: 8%.+ ng: 45%.

+ Nc: 27%.

+ Cht kh: 20%.

j) ng hp: Qu trnh rt v ng hp phi hn ch ti a vic sa tip xc trc tip vi khng kh cha c kh trng. Hp sa v np sa phi c tit trng trc khi ng hp. Nhit u rt: 12.5-190C. Thit b chit rt.

Chng II. PHN TCH HM LNG MELAMINE TRONG SA2.1 Tng quan cht Melamine: Melamine tn y l 1,3,5-triazine-2,4,6-triamine.

L mt baz hu c dng tinh th trng.

C cng thc ha hc C3H6N6 to thnh t 3 phn t cyanamide (CN2H2). Khi lng phn t: 126.12g/mol. Ha tan yu trong nc ( 200C, 3.1g/l). Tan chy 3500C. Nu tnh t l cc nguyn t cacbon (C), nit (N) v hydro (H) th nit chim ti 66% theo khi lng. Cng thc cu to v cng thc phn t:

Trong t nhin, Melamine l sn phm trao i cht hnh thnh trong c th ng vt c v khi n vo cyromazine. Melamine c tng hp u tin do nh ho hc c Justus von Liebig (1834). Ngy nay, vic tng hp c cng nghip ho s dng urea ((NH2)2CO), theo phn ng:

Sn phm hnh thnh l kh v dung dch, kh c ti thu hi gim thi tit NH3 v dung dch c tinh th ho cho ra 70% Melamine, 23% oxytriazines (ammeline, ammelide v cyanuric acid), 0.7% polycondensates (melem, melam v melon).

2.1.1 c tnh ca Melamine:Melamine (mu xanh) d dng kt hp vi acid cyanuric (mu ) qua lin kt hydro to kiu lin kt phn t hnh thnh mi ngi, lng ng v gy si thn.Melamine t n khng c xem l mt c cht. Nhng khi kt hp vi Acid cyanuric th n tr nn c hi. Khi Melamine kt hp vi cyanamide s cho ra Melamine cyanurate c kh gy si thn thm ch dn ti t vong.

Acid cyanuric l cht tng hp, dng nhiu trong cng nghip, c nhiu tn gi khc nhau, c mu trng, khng mi, l dn cht trong ngnh nhum vi, thuc ty, thuc dit c. Acid cyanuric hin c nghin cu i i vi Melamine, l th phm kt hp vi Melamine lm thnh mt hn hp c c tnh cao hn, gy ra cn st v ng c sa Melamine hin nay.

2.1.2 nh hng ca Melamine n sc khe: Gy si thn:

Ng c Melamine cp tnh:

2.2 Vai tr ca Melamine:

Melamine l cht c nitrogen chim 66% theo khi lng, chnh l c s cho vic thm Melamine vo sa tng hm lng nitrogen nhm thi phng l sa giu protein. V hm lng nit cao nn Melamine c nhng nh sn xut "gian di" a vo thc phm, a 1% Melamine vao trong thc phm thi lam tng ln 4,13% protein th. Mt iu cn lu tm l nha Melamine thng c s dng trong ng gi thc phm ca ngi v ng vt cng nh lm nguyn liu ch to cc dng c n ung nh tha, da... nn Melamine c th xm nhp t dng c bao gi hay dng n ung vo thc phm vi hm lng rt nh (tnh bng phn triu). 2.3 Xc nh hm lng Melamine trong mu sa bng phng php sc k kh ghp khi ph (GC-MS):Sc k kh ghp khi ph (GC-MS_Gas Chromatography Mass Spectometry) l mt trong nhng phng php sc k hin i nht hin nay vi nhy v c hiu cao, c s dng trong cc nghin cu v phn tch kt hp. Thit b GC-MS c cu to thnh 2 phn: phn sc k kh (GC) dng phn tch hn hp cc cht v tm ra cht cn phn tch, phn khi ph (MS) m t cc hp phn ring l bng cch m t s khi. Bng s kt hp k thut ny, cc nh ha hc c th nh gi, phn tch nh tnh, nh lng v c cch gii quyt 1 s ha cht. Ngy nay, ngi ta ng dng k thut GC-MS rt nhiu v s dng rng ri trong cc ngnh nh y hc, mi trng, nng sn, kim nghim thc phm

My Sc k kh ghp khi ph (GC-MS)

2.3.1 Nguyn tc:

Melamine trong mu c chit bng nc ct aceonitril. Mu c lm sch bng ct chit pha rn SPE amino, sau to dn xut bng ct bng N,O-BIS (Trimethylsilyl) trifloracetamid (BSTFA) vi 1% trimethylclosilan (TMCS) dn xut ca Melamine c xc nh trn my sc k kh ghp khi ph.

Gii hn pht hin ca phng php l 50 ppb.

2.3.2 Thit b v dng c: Micropipet. L ng mu cho my GC-MS. Giy lc th. Phu lc. Tube thy tinh nt nhm 50, 100, 150 ml. Bnh nh mc 20, 50, 100, 500 ml. Ct chit pha rn SPE amino (Strata-NH2 500mg*3ml phenomenex). My sc k kh ghp khi ph (GC-MS) c ch tim mu chia / khng chia dng (Split/Splitless Injector). Ct sc k phn tch DB-5MS, ng knh trong 0.25 mm, b dy lp phim 0.25m. Cn phn tch 4 s l (chnh xc n 0.1mg). Bp cch thy. B siu m. My lc vortex. My c quay chn khng.2.3.3 Ha cht v thuc th: Chun Melamine (Mr.Ehrenstoefer GmbH). Pyridine (Merck). Dung dch N,O-bis (trimethylsilyl) trifluoacetamide (BSTFA) voiws 1% trimethylchlorosilane (TMCS) Alltech-18089. Acetoonitril tinh khit HPLC (Merck). Nc ct 2 ln. 2,6 diamino-4-chlropyrimidine (DACP)-Sigma.2.3.4 Pha ch dung dch: Dung dch chun Melamine 600 ppm: Cn chnh xc 30mg Melamine cho vo bnh nh mc 50 ml, thm vo khong 20 ml pyridine. Ha tan ha ton v nh mc n vch bng pyridine. Dung dch chun Melamine 6 ppm: Ht 1ml dung dch chun Melamine 600 ppm cho vo bnh nh mc 100 ml, nh mc n vch bng pyridine.

Dung dch chun Melamine 600 ppb: Ht 1ml dung dch chun Melamine 6 ppm cho vo bnh nh mc 10ml, nh mc n vch bng pyridine.

Dung dch ni chun 2,6 diamino-4-chloropyrimidine(DACP) 600 ppm: cn chnh xc 30 mg DACP cho vo bnh nh mc 50 ml, thm vo khong 20 ml pyridine. Ha tan hon ton ri nh mc n vch bng pyridine.

Dung dch ni chun 2,6 diamino-4-chloropyrimidine (DACP) 6 ppm: ht 1 ml dung dch ni chun DACP 600 ppm cho v bnh nh mc 100ml, nh mc n vch bng pyridine.

Dung dch ni chun 2,6 diamino-4-chloropyrimidine (DACP) 6 ppb: ht 1ml dung dch ni chun DACP 6 ppm cho vo bnh nh mc 10 ml, nh mc n vch bng pyridine.

2.3.5 Tin hnh phn tch:a) Chun b mu:Cn 5 mg mu cho vo cc thy tinh 50 ml. Ha tan mu bng 15 ml nc ct, nh siu m cho n khi mu ng nht. Cho tt c dch mu vo bnh nh mc 50 ml, nh mc n vch bng acetonitril. Sau lc qua giy lc th. Ly dch lc qua ct SPE amino nh sau:

Hot ho ct bng 2 ml ethanol ( chy t t khng dng p sut). Cho 2 ml dung dch lc trn qua ct ( chy t t khng dng p sut). Sau khi mu qua ct dng bm chn khng ht ct cho kh hn.

Dch chit qua ct SPE c cho vo bnh c quay 50 ml. C quay ti 700C cho n khi kh hon ton. Sau cho vo bnh c quay 2 ml methanol, siu m 2 pht, chuyn lng methanol ny vo tube 15 ml c np vn, un kh nit thi kh hon ton dung dch methanol c cha Melamine. Sau thm vo tube 100 m pyridine y np k trnh bay hi.

b) To dn xut cho chun v mu:

Ly 100 m dung dch chun Melamine 0.6 ppm cho vo tube thy tinh c np vn hoc 100 m dung dch mu kim tra, thm vo 100 l dung dch DACP 600 ppb v 400 l dung dch BSTFA vi 1% TMCS. y kn l, lc u, to dn xut ti 700C-45 pht . Ly ra ngui v nhit phng. Cho vo l ng mu phn tch trn my GC-MS.

c) Phn tch trn my sc k kh ghp khi ph (GC-MS):

+ Ct phn tch DB-5MS.+ Ch tim: khng chia dng (splitless). M x kh sau mt pht. Tc chia 40 ml/pht.

+ Nhit bung tim : 2800C.+ Th tch tim: 1 l.+ Kh mang: He.+ Tc kh 1.5 ml/pht.+ p sut: 17.5 psi.+ Ch chy: ng dng (constant flow).+ Nhit ban u: 750C.+ Thi gian gi: 1 pht .+ Bc tng nhit: 150C/ pht .+ Nhit cui: 3200C.+ Thi gian gi 9 pht .+ Nhit bung chuyn 2000C.iu kin phi ph:

+ Nng lng electron: 70eV.+ Ch chy: ton ph t 40- 450 amu v la chn ion (SIM) vi 4 ion 171 ; 197; 327 ; 342.

+ Thi gian m felament: sau 8 pht.+ Nhit t cc: 1500C.+ Nhit ngun ion ha: 2300C.+ Gi tr b khuch i: 300-500V.2.3.6 Xc nh v tnh kt qu:

Xc nh s hin din ca Melamine trong mu, mu ch c coi l dng tnh vi Melamine:

+ Trong ph phi c s hin din ca c 4 ion : 171; 197; 327; 342.

+ Thi gian lu ca cht phn tch phi trng vi thi gian lu ca cht dn xut Melamine.

+ T l gia cc ion : 171/327; 197/327; 324/ 327 ca mu phn tch phi tng ng vi dn xut Melamine.

Tnh hm lng Melamin trong mu :

Hm lng Melamine trong mu c tnh ton theo phng php ni chun :

Tiu chun Melamine ca b y t l < 0.5 ppm.

Trong :Smu: l din tch o trn my.Snc(chun): din tch ni chun ca chun o trn my.Schun: din tch chun 0.6 ppm o trn my.

Snc(mu): din tch ni chun ca mu o trn my.

0.6: nng chun Melamine (ppm).0.1: th tch pyridin ha tan mu (ml).2: th tch mu qua ct chit pha rn (ml).50: th tch dung mi pha long mu (ml).Kt qu phn tch Melamine.2.3.7 nh gi phng php phn tch:

u im:

L phng php phn tch Melamine hin i nht hin nay.

nhy v c hiu cao. Gii hn pht hin ca phng php l 50 ppb.

Dng cht ni chun tng tnh chnh xc cho phn tch.

Nhc im:

Phng php ny dng cht ni chun nn nh hng n hiu sut thu hi.

Vi iu kin ca Melamine th khng phn tch c sc k khi ph trc tip nn phi to dn xut phn tch.

Gi thnh phn tch mu kh t.2.4 Kt lun:Sa l mt thc n b dng, c th dng nh mt thc ung gii khc. Li ch do sa mang li l rt ln, va cung cp nng lng, vitamin, khong cht cn thit va tng sc khng cho c th. Theo xu hng pht trin kinh t ngy cng cao trong x hi, nhu cu s dng sa v cc sn phm sa s cn gia tng rt nhiu v c v s lng ln cht lng. Hn bao gi ht vic kim sot Melamine trong loi thc phm ny phi c quan tm ng mc. Kt qu trn cho thy tnh trng nhim Melamine trong sa v cc sn phm sa tiu th ti nc ta hin nay l ng lo ngi, kt qu phn tch mu Melamine s l c s d liu gip c quan chc nng tip tc theo di, gim st trong thi gian ti nhm m bo v sinh an ton thc phm cho ngi dn.TI LIU THAM KHO1. Bi ging: PGS.TS Dng Thanh Lim, B mn Dinh dng, Khoa Chn nui Th y Trng i hc Nng Lm, Tp. HCM.

2. www.en.wikipedia.org/wiki/Melamine3. www.mz-at.de/pdf/MelamineCrisis080926.pdf 4. www.hoahocvietnam.com5. www.sachdientu.edu.vn

6. www.choluanvan.vn

7. www.tailieu.vn

8. www. dantri.com.vn/c7/s7-251646/su-that-ve-melamine.htm

9. www.tusach.thuvienkhoahoc.com/wiki/Melamine:_ng_dng_v_tc_hi

10. www.ykhoa.net/.../081001_nguyenvantuan_lieuluongmelamime.htm11. www.hua.edu.vn/khoa/cnts/index.php?option=com...task...

12. www.docsachonline.vn/.../phan-tich-ham-luong-melamine-kem-file-power...

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