M U1> Tnh cy thit ca ti:Cng vi s pht trin ca khoa hc k thut, ngnh cng ngh ch bin thy sn cng pht trin vt bc v ng gp mt phn khng nh vo vic pht trin nn kinh t t nc. Tuy nhin, cng ngh ch bin thy sn pht trin bn cnh nhng thun li nh ch bin ra cc mt hng thy sn c cht lng cao, m bo v sinh an ton thc phm phc v cho xut khu v tiu th trong nc cn c bt li l lng ph liu thy sn thi ra rt nhiu lm nhim mi trng. Mt trong nhng ngun ph liu thi ra l v ca cc ng vt gip xc nh tm, cua, gh... Ngun ph liu ny hin nay ch yu dng lm thc n chn nui hay lm phn bn nn hiu qu kinh t rt thp. Mc tiu t ra cho cc nh cng ngh l nghin cu tn dng t a nhng thnh phn c trong ph liu thy sn nhm nng cao hiu qu kinh t ca chng v trnh c nhim mi trng do chng gy nn.Trong cc mt hng thy sn c gi tr kinh t th cc mt hng thy sn ng lnh t gip xc chim t 70 - 80% cng sut ch bin. V vy, lng ph liu t v gip xc do cc nh my thy sn thi ra kh ln khong 70.000 tn / nm. Ngun ph liu ny cha mt lng ln chitin - l nguyn liu quan trng cho cng nghip sn xut chitosan v cc sn phm c gi tr khc.Chitosan l mt dn xut ca Chitin, n l mt polyme hu c ph bin trong t nhin v c ng dng trong nhiu lnh vc khoa hc cng ngh. Mt trong nhng ng dng ca chitosan l lm mng mng bao gi thc phm. Trong thc t sn xut hin nay, vt liu chnh dng bao gi thc phm l mng nha PE (polyethylen), p. (polyprothylen). Tuy nhin dng cc vt liu ny bao gi thc phm th c mt s" hn ch l thi gian phn hy chng ko di, kh x l v gy nhim mi trng. V vy, ngi ta nghin cu dng mng chitosan bao gi thc phm thay th cho bao PE, p. nhm hn ch nhim mi trng do rc thi l cc polyme tng hp.Mng Chitosan c kh nng khng khun, khng nm, khng sinh c t, gi nc tt cho thc phm trong qu trnh bo qun nhng mng Chitosan kh t tin nn dng n bao gi thc phm cha em li hiu qu kinh t. Vic nghin cu phi trn Chitosan vi cc cht khc nhm to ra mng Chitosan c bn cao, gi thnh ph hp dng lm bao gi thc phm l vn ang c quan tm hin nay.C nhiu nghin cu dng Gelatin ch to mng bao thc phm v ngun Gelatin di do, gi thnh thp li c kh nng to mng cao, khi s dng lm mng thc phm n lm tng gi tr cm quan, hn ch qu trnh gim trng lng do bc hi nc. Tuy nhin, mng Gelatin yu v mt c hc, khng bn khi gp mi trng nc, d b vi khun, nm tn cng nn kh nng bo qun i vi thc phm thp.Vic nghin cu kt hp gia cc polyme t nhin sn xut mng bo qun thc phm c thc hin nhiu nh mng chitosan vi xenlulose, chitosan vi alginate, chitosan vi tinh bt, vv... c th to nn mt s tnh cht mi ca mng. Tuy nhin cc nghin cu ny cng cn m rng vi cc polyme khc v k thut to mng cho tng hn hp polyme l rt khc nhau v phc tp i hi s u t nghin cu nhiu trc khi tnh n kh nng thng mi ha sn phm.Mng chitosan khi phi trn vi cc gelatin to nn mt s" tnh cht mi ca mng nn c th lm thay i mt s tnh nng ca mng chitosan nh tnh khng khun, khng nm... nn trong lun vn ny nghin cu b sung thm Natri benzoat nhm tng cng kh nng khng khun ca mng chitosan phi trn gelatin.Chnh v vy, vic thc hin ti Nghin cu ch to mng Chitosan - Gelatin ng dng lm bao b thc phm nhm to ra mng bao thc phm va c tnh khng nm, khng khun, kh nng gi nc cho thc phm va c gi thnh hp l Vit Nam hin nay l vn c ngha thc tin rt ln.2> nsha khoa hoc ca ti: Xc nh c nng Chitosan, nng Gelatin, nng Natri benzoat ph hp c th to ra mng mng va p ng c cc yu cu lm bao gi thc phm va c gi thnh ph hp. a ra cng thc phi trn ti u cho quy trnh sn xut thch hp i vi mng Chitosan - Gelatin s dng lm bao gi thc phm. Xc nh c nhng bin i v cht lng v dinh dng ca sn phm c ng i dng fillet trong qu trnh cp ng v bo qun ng.3> ngha thc tin ca ti: Dng mng Chitosan - Gelatin bao gi thc phm thay th cho mng nha PE, p. v mng mng bao gi t Chitosan c tnh khng khun v chng mt nc cho thc phm rt tt. Gp phn gii quyt lng ph liu thy sn c ngun gc t v gip xc t cc x nghip ch bin thy sn ng thi nng cao gi tr kinh t ca cc loi ph liu thy sn so vi vic ch dng chng lm thc n gia sc hay lm phn bn.Chng 1: TNG QUAN1.1 TNG QUAN V CHITOSAN:1.1.1 Cu trc phn t ca chitosan:Chitosan l mt amino polysaccarit, c hnh thnh t qu trnh tch gc acetyl ca chitin bng x l bng xt c. Chitosan c pht hin ln u tin bi Rouget vo nm 1859. Cng thc cu to ca chitosan gn ging nh chitin v xellulose nhng khng ging v chitin ch tan trong mt s t h dung mi, m in hnh l Lithium Chloride-Tertiary Amides, chitosan th d tan trong cc axt hu c, thng thng dng axit acetic nn c nhiu ng dng hn chitin.

Hnh 1.1 : Cu trc chitin, chitosan, xellulose

1

Chitosan l mt polyme hu c c cu trc tuyn tnh t cc n v - D - glucosamin lin kt vi nhau bng lin kt - 1,4 Glucozit. Chitosan l sn phm c sn xut t chitin sau khi x l chitin trong kim c nng (qu trnh deacetyl ha Chitin) [34], [43].

NH2CHtTOSANNHCCHa JnCHITIN

NH3+CHTOSAN

Hnh 1.2: S qu trnh deacetyl ha chitin.1.1.2 Cc loai nguvn vt liu sn xut chtin v chitosan chnh:Chitin v chitosan c th c chit rt t nhiu ngun nguyn liu nh t v tm cua, to, nm, vi khun v su b. Ngun ph thi tm, cua, gh, nang mc trong qu trnh ch bin thy sn l ngun nguyn liu sn c, nhiu, cha hm lng chitin, chitosan cao.Bng 1.1: Thnh phn ha hc ch yu ca cc nguyn liu chnh sn xut chitin v chitosan ( Muzzarelli, 1997)Nguyn liuThnh phn

mProtitTroLipitChitin

Cua

/. Callinectes sapidus4,52456212,9

2. Chinonecetes opilio29,1940,61,3526,65

3. Portunus trituberculatus12,910,357,90,317,1

Tm

1. Penaeus monodom9,126,829,30,534,9

Phn v gip u ngc9,742,820,81,236,5

Phn v

2. Pandalus borealis23,533,914,730,0

Tm cng9,2461,626,671,430

Tm sng nc ngt5,728,1444,412,5

Con moi ln44,624,71,819,9

1.1.3 Tnh cht ca chtosan:c tnh c bn ca Chitosan:Chitosan c ngun gc thin nhin, khng c, an ton cho ngi khi s dng lm thc phm, dc phm, c tnh ha hp sinh hc cao i vi c th, c kh nng t phn hy sinh hc.Chitosan c nhiu tc dng sinh hc a dng nh: kh nng ht nc, gi m, khng nm, khng khun vi nhiu chng loi khc nhau [18], [25], [29], [36], kch thch tng sinh t bo ngi v ng thc vt, c kh nng nui dng t bo trong iu kin ngho dinh dng.Tnh cht ho hoc: Chitosan l cht rn, xp, nh, dng bt c mu trng ng, dng vy c mu trng trong hay hi vng. Khng mi, khng v. Chitosan c tnh kim nh, khng ho tan trong nc v trong kim nhng ho tan d dng trong cc dung dch axit long nh axit acetic, axit propionic, axit lactic, axit citric .... Khi ho tan chitosan trong mi trng axit long to thnh keo dng. y l mt im rt c bit v phn ln cc keo polyssacharit c in tch m. Chitosan c xem nh l mt polycation c kh nng bm dnh vo b mt cc in tch m v c kh nng to phc vi mt s ion kim loi. Chitosan khi ho tan trong dung dch axit acetic long c pH = 6-6.5 to thnh mt dung dch keo dng, nh m keo Chitosan khng b kt ta khi c mt ca mt s ion kim loi nng nh Pb3+, Hg2+. Chitosan kt hp vi aldehyt trong iu kin thch hp hnh thnh gel, y l c s by t bo, enzym.Tnh cht ca chitosan ph thuc rt nhiu vo tinh khit, deacetyl ha, phn t lng v rn. Chitosan c tinh khit cng cao th cng d tan, mu sc dung dch ha tan c trong cao, c tnh kt dnh cao v c ng dng vo nhiu lnh vc hn. deacetyl ha l mt thng s" quan trng, c trng cho t l gia 2- acetamido-2-deoxy-D-glucopyranose vi 2-amino-2-deoxy-D-glucopyranose trong phn t chitosan. Kh nng thm nc ca mng chitosan c deacetyl ha thp th s cao hn so vi mng chitosan c deacetyl ha cao [58]. Phn t lng ca chitosan cng l mt thng s" quan trng [59], n quyt nh tnh cht ca chitosan nh kh nng kt dnh, to mng, to gel, kh nng hp ph cht mu [60]. rn ca chitosan ph thuc vo nhiu yu t nh ngun gc chitin, deacetyl ha, phn t lng v thng c 2 peak chnh khong 9 - 10 v 20 qut khi xc nh bng nhiu x tia X (Hnh 1.3).

20 0

Hnh 1.3. Ph nhiu x tia X ca cc loi chitosan khc nhau, a: Phn t lng thp, deacetyl trung bnh; b: nht thp, deacetyl cao c: nht cao, deacetyl ha trung bnh; d: nht cao, deacetyl ha cao Ngun: Nunthanid et al. (2001)18

Hnh 1.4: Ph hng ngoi-IR v ph cng hng t ht nhn-MNR ca chitosanWavenumbe r/cm"1Ph hng ngoi-IR ca chitin (A) v chitosan (B)

1.2 TNG QUAN VE GELATIN1.2.1 Ngun gc Gelatn:Gelatin l ch phm c to thnh t qu trnh thy phn Colagen (c loi Colagen lc un nng trong nc c th bin thnh Gelatin nh Colagen vy c nhng cng c loi phi qua bc x l mi c th bin thnh Gelatin) [23].Khi lm bin tnh collagen di tc ng ca tc nhn bin tnh nh nhit, vt l v ha hc ta thu c gelatin.1.2.2. Cu trc ca gelatin:Ging nh cu trc ca colagen, gelatin c cu trc dng chui. Chui gelatin gm nhng phn t c kch thc siu nh lin kt li vi nhau bng lin kt hydro to thnh mng li gelatin [40], [50]. Cng thc tiu biu ca gelatin l - Alanin - Glycin - Prolin - Arginin - Glycin - Glutamic - 4 Hydroxyproline - Glycin - Prolin - [60]Hnh 1.5: Cu trc phn t gelatin

NHj

Phn tch thnh phn axit amin ca mt s" loi gelatin ta c kt qu trnh by trong Bng 1.2Bng 1.2: Thnh phn axit amin ca mt s" loi gelatin [49]Tn axit aminS" lng axit amin / 1000 g gelatin

Gelatin da c chpGelatin da c tuytGelatin da c ch

Glycin317345328

Alanin120107114

Valin191918

Isoleucin12119,2

Leucin252320

Prolin124102129

Hydroxyprolin735370

Phenylalanin141314

Tyrosin3,23,51,8

Serin436941

Threoinin272525

Methionin121312

Cystin C ch c ch vi sinh vt:C ch tc dng ca axit benzoic v nhng dn xut ca chng l lm c ch qu trnh h hp ca t bo, c ch qu trnh oxi ha gluco v pyruvat. Mt khc, axit benzoic lm tng nhu cu oxi trong sut qu trnh oxi ha gluco. Benzoat tc ng lm hn ch kh nng nhn c cht ca t bo. ng dng:Natri benzoat c dng bo qun nc qu, bnh ko, mt ... Nng benzoat c php s dng trong thc phm theo khuyn ngh ca WHO l khng c qu 0,1% tnh theo khi lng ( M, FDA quy nh lng s dng trong thc phm l 0,05 - 0 ,1% tnh theo khi lng). Nhc im ca vic s dng benzoat trong vic bo qun mt s" sn phm thc phm nh mt, mt ng, tng c chua, tng t, tng qu ... l c th lm cho sn phm b thm en v d nhn bit d v.* c tnh: cc nng cho php s dng nh trn, cha c bng chng c th no cho thy tc ng khng tt n sc khe ca ngi tiu dng. Tin hnh th nghim trn ch cho thy mc s dng di lg/lkg th khng nh hng nhng khi s dng vot qu mc trn th ch bt u c biu hin co git thn kinh, mt vi trng hp c th dn n cht. i vi ngi, nu s dng cc sn phm thc phm c nng Natri benzoat cao s nh hng n thn kinh nht l i vi tr em.1.5 TNG QUAN VE C NG I DNG1.5.1 Gii thiu mt s' loi c ng ai dng:C ng i dng l ng vt mu nng. Chng c kch thc, mu sc rt a dng v gi tr kinh t cao. C ng i dng c rt nhiu loi nhng hin nay ch c 5-6 loi c ng cho sn lng ln v l i tng khai thc chnh: C ngvn (Thunnus pelanus)- C ng vy vng (Thunnus abbacares) C ngmt to (Thunnus obesus)- C ng vy di (Thunnus alaluga) C ng xanh (Thunnus thunnus)Loi c ng c sn lng lnvphnb" rng vng bin min Trung, ngNam B,c bit l vng bin KhnhHal c ng vy vng. y cng chnh li tng nghin cu trong lun vn ny.1.5.2 Thnh phn ha hoc ca c ng ai dng:C ng i dng l mt trong nhng loi hi sn c a chung v qu him trn th gii hin nay. Theo nghin cu ca y ban o to ngh c Queenland, thnh phn ha hc ca c ng theo Bng 1.4Bng 1.4 : Thnh phn ha hc ca c ngn v tnh: g/100g phn n cTTLoiNcProteinLipidGluxidTro

1C ng vy xanh - C tht 68,728,31,40,11,5

- C tht trng52,621,424,60,11,3

2C ng vy xanh phng nam - C tht 5,623,69,31,4

- C tht trng63,923,111,60,3

3C ng vy vng - C tht 74,222,22,10,11,4

4C ng vn70,425,82,00,41,4

im c bit l thnh phn lipid ca c ng i dng c hm lng cholesterol rt thp. y l u im rt ln ca c ng i dng v gp phn c ng i dng c s dng ch bin cc mn n cao cp (sashimi, sushi...)Bng 1.5: Thnh phn ha hc ca lipid c ng i dngn v tnh: g/100g ca phn n cSTTThnh phn lipidKhi lng

1Axit bo khng no (mt ni i)0,197

2Axit bo khng no (nhiu ni i)0,363

(trong c Cholesterol)(0,058)

3Axit bo bo ha0,301

Ngoi ra, tht c ng i dng cha y , cn i lng axit amin thay th v khng thay th nn c ng i dng l loi nguyn liu tuyt vi cung cp dinh dng cho c th.

Cc thnh phn dinh dng trong c ng i dng rt d tn tht trong qu trnh ch bin v bo qun nn cn c bin php hn ch tn tht cht dinh dng. Mc ch ca lun vn l nghin cu dng mng chitosan phi trn ph liu t u lm mng bao c ng i dng fillet.1.6 NG DNG CA CHITOSANChitosan v dn xut ca chng c rt nhiu ng dng trong nng nghip, cng nghip thc phm, cng nghip nh, y hc v mt s ngnh khc. Chitosan c th c bo ch ra nhiu hnh thc khc nhau: cht do, bt nhuyn, lt mng, si cht lng hoc hi xt...1.6.1. ng dung trong nng nghip: Chitosan c dng nh mt thnh phn chnh trong thuc phng tr nm bnh (o n, kh vn...), lm thuc kch thch sinh trng cy trng nh la, cy cng nghip cy n qu, cy cnh... Chitosan khng c hi, gi tc dng lu trn l, cy, lm tng ny mm ca ht, tng vic to dip lc trn l, tng kh nng m r, thc y qu trnh ra hoa kt qu v lm tng nng sut thu hoch ca cy trng. Cc nh khoa hc Nguyn Th Hu, Lm Ngc Th - trng i Hc Khoa Hc T Nhin, HQG H Ni v Nguyn Vn Hoan - trng H Nng Nghip 1 s dng cc cht c hot tnh sinh hc cao t chitin kch thch ny mm nhng ht la ging quc gia H 60 bo qun c 19-21 thng, c bit l cc ht gn nh mt ht kh nng ny mm. ng thi khi s dng cc cht c hot tnh sinh hc ny cn c kh nng kch thch cho sc sng ca ht ging cao hn, cht lng cy mm tt hn, gp phn nng cao gi tr gieo trng ca ht ging [16].Vin Khoa hc nng nghip Min Nam v Trung tm cng ngh sinh hc Thy sn cng tham gia nghin cu tc dng ca chitosan ln mt s loi ht d mt kh nng ny mm v gp phn thc y sinh trng, pht trin ca cy trng ngoi ng. Kt qu l c kh nng ko di thi gian sng v duy tr kh nng ny mm tt ca ht ging c chua v ht ging u c ve sau thi gian bo qun 9-12 thng trong iu kin bnh thng [11]. Nm 1987, Bentech c cp bng sng ch nh nghin cu dng chitosan trong vic bc nang ht ging ngn nga s tn cng ca nm trong t. Trong nhng vng m cy trng thng b nm tn cng vo h r, nu ht ging c bc nang bng chitosan s nng cao c hiu sut thu hoch ln 20% so vi khng dng chitosan. Ngoi ra, chitosan c tc dng c" nh phn bn, thuc tr su.1.6.2 ng dung trong V dc: T chitosan sn xut glucozamin c kh nng thc tin thuc khng sinh t v c th dng lm nguyn liu nui vi trng v ch thuc. Trong k ngh bo ch dc phm, chitosan c th dng lm cht ph gia nh lm t dc n, t dc dnh, cht to mng vin nang mm v cng v cht mang sinh hc dn thuc... Theo nghin cu dng chitosan lm t dc dnh trong mt s cng thc vin c dc cht d b tc ng bi cc ion kim loi nng ca Nguyn Th Ngc T, Nguyn Phc Khu v Nguyn Th Thanh Hi cho kt qu chitosan lm t dc dnh trn vin Vitamin c tt ngang PVP (dung dch cn polyvinyl pirovidin) v l tc nhn kho ion kim loi nng tng t EDTA_Na2 (Etylen Diamin Tetra Natriacetat). Chitosan c kh nng dng thay th hn hp PVP, EDTA_Na2 trong t bo thuc vin v c kh nng to mng phim trn vin, thch hp bao cc vin c thnh phn trung tnh hoc axit nh. Chitosan v cc dn xut ca n c dng lm thuc chabnh,thuchCholesterol trong mu, thuc cha vt thng, vt bng, thuc chaauddy,thuc chng ng t mu, tc dng tng cng min dch c th. Khoa dc trng i Hc Y Dc Thnh Ph H Ch Minh nghin cu thuc cha vim lot d dy t trng t ch phm ca chitosan: Gel chitosan, gel chitin, gel chitosan v Al(OH)3 [22]. Chitosan c nghin cu v bo ch thnh sn phm thuc kem cha bng Polysan [17], [19], [24]. Kho st trn sc vt thc nghim cho thy thuc ny khng c tc dng ph, khng gy d ng , li c tc dng kch thch m to iu kin cho vt thng nhanh lin, khng b nhim trng, khng li so.1.6.3 ng dung trong cng ngh sinh hoc: Dng chitsan trong c nh t bo v enzym.+ Chitin-chitosan l mt cht mang ph hp cho s c nh enzym t bo. Enzym c" nh t bo l mt cht xc tc sinh hc hot ng trong mt khng gian linh hot. Enzym c" nh cho php m ra vic s dng rng ri enzym trong cng nghip, trong y hc, khoa hc phn tch... Enzym c" nh c s dng lu di, khng cn thay i cht xc tc, nht l trong cng ngh lm schnc, lmtrongnc qu, s dng enzym c nh rt thun li v t hiu qu cao+ c im quan trng ca cc nguyn liu c s dng lm cht mang enzym l din tch b mt trn mt n v th tch hay trng lng phi rng, khng b phn gii, khng tan, bn vng vi cc yu t" ho hc, gi r, d kim. Trong cc loi polyme th chitin v chitosan tho mn yu cu trn.+ Phng php c nh enzym bao gm: enzym c dnh trn cht mang bng lin kt hp ph hay lin kt tnh in (lin kt ion), hoc lin kt vi trong li gel, lin kt ngang (Cross linking). Enzym c c" nh trong chitosan bng lin kt hp ph hay lin kt ngang qua cu n trung gian nh Glutaraldehyt hoc c khi enzym b vi trong li gel to thnh lin kt ngang gia chitosan v Glutaraldehyt. Qua nhiu nghin cu cho thy chitosan c cc c im sau:+ Chitosan l mt nguyn liu do, linh hot, n c th c nh enzym bng cc hp ph n gin, bng hp ph dng li gel hay bnglinktionquanhn t" chc nng trung gian hoc dng th vi.+ S lin kt ion NH3+ ca chitosan vi cc ion m t do khc trn enzym, l nhn t hnh thnh lin kt hp ph hay ion.Hiu sut c nh theo phng php hp ph c khuynh hng cao hn theo lin kt ion, cho php thc hin trong iu kin nh nhng.+ Khi so snh vi cc cht mang khc th chitosan c kh nng cha ng lng protein 10 - 30mg/g chitosan ...1.6.4 ng dung trong cng nghip thc phm:Chitosan c ngun gc t nhin, khng c v rt an ton cho ngi khi s dng lm thc phm [28], [33]. Chitosan c nhng tnh cht rt c trng nh c kh nng khng khun, khng nm, to mng, c kh nng hp th mu m khng hp th mi, hp th mt s kim loi nng., nn n c ng dng rng ri trong cng nghip thc phm v dng bo qun thc phm. Do chitosan c tnh khng khun, khng ho tan trong nc, trong kim, ru v aceton nhng li tan trong dung dch axit acetic long. Dng hn hp chitosan ha tan trong axit acetic long trng mng trn tm knh hay tm nilon phng ri lm kh nhit 40-60C hoc phi nng khi kh bc ra ta c mng mng chitosan. Mng mng ny c thay th polyetylen sn xut giy bng knh, lm mng bao bc thc phm cao cp hoc bc lt cc linh kin khc. Chitosan bt c tnh ty mu m khng hp th mi v cc thnh phn khc nn ngi ta ng dng n vo vic kh mu nc ung nng Ig chitosan bt cho lOOml nc ung. Chitosan dng lc trong cc loi nc p hoa qu, ru bia, nc ngt v c th ty lc cc ngun nc thi cng nghip t cc nh my ch bin thc phm nh kh nng lm ng cc th l lng, rn giu protein trong nc thi ca qu trnh ch bin tht, rau ci v cng ngh ch bin tm nh kh nng kt dnh tt cc ion kim loi nng Hg, Pb... ca keo dng chitosan. V vy cc ion kim loi trn b gi li m keo chitosan khng b keo t [33].Dung dch keo chitosan c th bc ht Gel Alginat trong vic c nh t bo nm men ln men ru v dch qu nhiu ln.1.6.5 ng dung trong mt s" ngnh cng nihip khc:* Trong cng nghip giy:Ch cn b 1 % Chitin tnh theo trng lng vo bt giy cng lm tng sc do dai ca giy, gim thi gian cn thit rt nc ra khi bt, gia tng s lng cht si trong giy. Nh cc nh my c th dng dng t cht si hn nhng vn gi c phn tt ca giy. Loi giy c ch to bng chitin d in hn loi giy bnh thng v kh rch hn khi b t nn c th c dng trong vic ch to t lt thay cho tr em, khn giy v bao giy gi hng.* Trong cng nghip dt: Chitin dng h vi, c nh hnh in hoa, mu sc. u im l lm cho vi hoa, t si bn mu, bn si, chu c c xt mt ngoi th nh p. Chitosan l nguyn liu quan trng c dng h vi chng nc. Ho tan chitosan trong dung dch CH3COOH long 1,5% dng vi acetat nhm v axit stearic em sn trn vi, khi kh to thnh mng mng chc bn chu c nc, chng la, cch nhit, chu nng v chng thi, vi ny c s dng sn xut vi bao dy in, nhng dng c bo h trong sn xut, nghin cu. T chitin c th sn xut ra si chitin theo phng php sn xut si keo dnh hoc acetat xellulose ri cho tc dng vi cs2 ch thnh Sulfonate. Sau qua nhng qu trnh lc ty bt thnh si chitin... Si chitin c u im l chu c axit, nh sng, khng c hL.Nhng khuyt im l kh nhum, gi thnh cao. Dng trong m phm:Chitosan dng lm cht ph gia, lm kem bi mt, thuc lm mm da, lm tng kh nng ho hp sinh hc gia thuc v da, ch to thuc nh hnh tc, kem bi da lt mt.T nm 1969: chitin d c dng nhiu trong k thut bo ch m phm. Vi hng ng n trong kem v thuc bi ngoi da lm cho kem c li v nhng hng khc ang th nghim n trong vic bo ch thuc tr st v sn mng tay. Chitosan c cho thm vo trong thuc gi u lm cho nc long hn bng cch kho cc ion Fe, Ca,v Mg li vi nhau.* Dng trong phim nh v mt s ngnh cng nghip khc:Phim chitosan c nt cao, khng tan trong nc, axit nhng tan trong axit long nh axit acetic .Chitosan c dng lm mc in trong cng ngh in.Chitin - chitosan lm tng bn g trong cng ngh ch bin g.Hng k thut ca Matsushita cn dng chitosan trong vic ch to my phtthanh.Chitosan cn dng trong x l nc thi cng nghip, n c kh nng to phc vi kim loi nng c hi, dng lc trong nc sch tiu dng, thanh lc nc nhim cht c hi v cht phng x do chitosan kho cht cc ion kim loi nh: Hg, Pb v Uranium.1.7 TNH HNH NGHIN cu NG DNG CA MNG CHITOSAN1.7.1 Nghin cu trong nc:Tc gi ng Th Anh o v Chu Trn Dim i (Khoa Cng Ngh Ho Hc V Du Kh - Trng i Hc Bch Khoa TpHCM) nghin cu ch to mt s mng bn thm polysaccaride nh CMC, Chitosan dng bao gi bo qun nhn trong mi trng c nng C2 cao hn mi trng kh quyn [7]. Kt qu l nhn c bao gi bng mng bn thm vn gi c gi tr thng phm sau 45 ngy bo qun (ko di thi gian bo qun nhn ln gp 3-9 ln so vi cng iu kin bo qun khng c bao b).Cc nh khoa hc thuc Trng i Hc Khoa Hc T Nhin nghin cu dng mng mng Chitosan ch ra cc dng sinh hot hng ngy nh cc, bt, da thc n, giy gi ko dng mt ln th thy sau khi s dng ch cn b chng vo trong thng rc c nc l chng t phn hy trong mt thi gian ngn [13].Tc gi Bi Vn Min v Nguyn Anh Trinh (Khoa cng ngh thc phm trng i Hc Nng Lm) nghin cu dng Chitosan to mng bao gi thc phm [2], [12]. Mng Chitosan c tnh khng khun, tnh gi nc dng bao gi cc loi thc phm ti sng giu m nh c, tht... ng thi, b sung ph gia l cc cht ho do (Ethylen Glycol - EG, Polyethylen Glycol - PEG) tng tnh do dai v n hi cho mng. Cc tc gi ng dng mng ny bao gi xc xch th thy rng ngoi vic gip cho sn phm xc xch c hnh dng p lp mng Chitosan ny cn c tc dng khng lm mt mu v mi c trng ca xc xch.Cc tc gi ny cng nghin cu dng v bc Chitosan bo qun cc loi thy sn ti v kh [1]. Bo qun c ti bng Chitosan hn ch c hin tng mt nc v tn tht cht dinh dng ca c khi cp ng v sau khi r ng. i vi thy sn kh nh c kh, c mc ... th tin hnh pha dung dch Chitosan 2% trong dung dch axit acetic 1,5%. Sau nhng c kh v mc kh vo dung dch c pha, lm kh bng cch sy nhit 30c c qut gi. Sn phm thu c c th bo qun tt nhit bnh thng. Ty theo m ca c v mc m sn phm c thi gian bo qun khc nhau, vi m 26 - 30%, c kh bo qun c 83 ngy, mc kh 85 ngy cn m 41 - 45% th c kh gi c 17 ngy, mc kh gic 19 ngy. Tc gi Chu Vn Minh, Phm Hu in, ng Lan Hng, Trnh c Hng, Hong Thanh Hng nghin cu dng mng Chitosan bo qun hoa qu ti [3], [4] th thy dng mng Chitosan bo qun th thi gian bo qun hoa qu ko di hn so vi hoa qu ch c bo qun lnh. Kim tra s" lng vi sinh vt th thy hoa qu c bo qun bng mng Chitosan c kh nng khng khun rt tt.1.7.2 Nghin cu ngoi nc:Krasavtsev v cc cng tc vin nghin cu ng dng mng Chitosan lm bao gi bo qun c v cc sn phm t c [45]. Ngi ta dng Chitosan c chit rt t cc ngun ph liu thy sn khc nhau nh tm, cua, gh ln lt lm mng mng bao gi c th thy mng Chitosan chit rt t v tm c dy, bn ko, n hi cao nht. Mng Chitosan gip cho sn phm gi nc rt tt v gi c cc c tnh t nhin ca sn phm.Attaya Kungsuwan v cc cng tc vin nghin cu s dng dung dch Chitosan (ho tan 5g Chitosan trong 500 ml axit acetic %) lm bao gi bo qun c [27] th thy c c bo qun bng mng Chitosan ko di thi gian bo qun ti 2 thng trong khi c khng c bo qun bng mng Chitosan th thi gian bo qun ch ko di ti a 1 thng trong cng mt iu kin bo qun.Blaise Ouattara v cc cng s nghin cu dng mng Chitosan bao gi tht th c th c ch c s pht trin ca cc vi sinh vt gy thi ra nhm ko di thi gian bo qun tht v cc sn phm t tht [29].Lopez - Caballero v cc cng s nghin cu dng hn hp chitosan- gelatin bao gi bo qun ch c th thy sau 20 ngy bo qun mi v ca ch c hu nh khng bin i nhiu v cc tnh cht khc nh cng, c kt, mm do ... hu nh khng i [ 39]Sobral v cc cng s nghin cu cc tnh cht c l ca mng Gelatin nh hng bi ngun gc Gelatin v cht to do sorbitol. C th l khi tng hm lng sorbitol th tnh ngn cn thot hi nc ca mng gim [40]. nh hng ca nng Gelatin s dng to mng v cc cht to do khc nhau nh glycerol, PEG v EG c nghin cu vi nhiu nng khc nhau t 10 n 30 g/100 g Gelatin [26], [32]. Vic nghin cu tnh cht ca mng to t hn hp Gelatin v mt s" polyme khc cng c thc hin nh kt hp Gelatin vi carrageenan, tinh bt, alginate cho php chng ta thay i tnh cht c hc, l hc ca mng, lm mng c bn thch hp, kh nng chu c hi m tt hn, ph hp hn cho vic ng dng trong thc phm, thng c m cao [35].1.8. GII THIU CHUNG V MNG CHITOSANMng mng chitosan c mt vai tr ht sc quan trng, dng n bao bc thc phm s hn ch kh nng mt nc cng nh khng s pht trin ca vi sinh vt ca thc phm trong qu trnh bo qun lnh .Chitosan c tc dng lm bt ng cc t bo vi trng ng vt hoc thc vt hay cc enzym. l tnh khng khun, khng nm (chitosan b sung vo thc n gia sc s kch thch s pht trin ca vi khun Bifido Bacterium trong rut, vi khun ny to ra enzym lactaza cn thit cho s tiu ho v cn tr s sinh trng ca cc vi sinh vt khc). C ch khng khun ca chitosan vn cha chc chn. Tuy nhin mt vi suy on tin cy xut kin rng:

Hnh 1.7 : Phn ng to phc gia ion Cu++ v phn t chitosan (theo Kaminski v Modrjewska, 1997)- Chitosan s ly i t cc vi sinh vt ny cc ion quan trng v d nh ion Cu++. Nh vy vi sinh vt s cht do mt cn bng cc ion quan trng .

Ngn chn ph hoi chc nng mng t bo Gy ra s tng hp ca polyelectrolyte vi polyme mang tnh cht axit trn b mt t bo vi khun.Nh vy vic dng mng chitosan bao bc thc phm c th ko di thi gian bo qun, gim s thi hng do kh nng khng khun, khng nm ca n.Mng mng chitosan c th ng dng rng ri trong ngnh cng nghip bao gi, bao b thc phm v n c th thay th PE sn xut giy bng knh bao bc thc phm cao cp. c bit mng mng chitosan cn c kh nng bo qun thc phm v thc phm ti sng. Ngoi ra ngi ta s dng chitosan lm mng mng ph trn tri cy tng thi gian bo qun.Mt khc hin nay nhim mi trng l vn bc xc ang c quan tm ca ton cu, ang tm mi cch khc phc, nh lng rc thi, nc thi cng nghip ...Trong vt dng bao b t PE, PVC,... m hng ngy thi ra mi trng mt lng rt ln v vic x l n rt phc tp, gy nhim mi trng trm trng, ngoi ra nh hng n sc kho con ngi. Chnh v vy vic ng dng mng mng chitosan trong cng nghip bao gi l ht sc quan trng .

Chng 2 I TNG V PHNG PHP NGHIN cu2.1 I TNG NGHIN cu2.1.1 Nguyn liu chnh:i tng nghin cu l chitosan c chit tch t v tm s sau khi qua cng on kh khong bng axit HC1, kh protein v deacetyl ha bng NaOH m c. Chitosan nghin cu c cung cp bi trung tm ch bin i Hc Thy sn. Cc ch tiu cht lng ca chitosan nguyn liu: Mu sc, trng thi: trng, dng mnh. m: 11% Hm lng tro: 0,9% nht: 300 cps deacetyl (DD) : 95% tan:99,8% (trong axit acetic 1%)2.1.2 Nguyn liu phu:Nguyn liu ph c s dng trong ti dng phi trn vi chitosan l gelatin v natri benzoat. Gelatin: sn phm do Php sn xut - c phn phi ti Vit Nam ti cng ty ha cht Thi Ha - 138 T Hin Thnh qun 3 TPHCM.Cc ch tiu cht lng ca gelatin: Mu sc, trng thi : mu vng nht, dng bt mn. tinh khit: 99%- m: 12% ha tan: 100%trongnc nng(trn 30C). Natri benzoat:Cc ch tiu cht lng ca Natri benzoat: Mu sc, trng thi : mu trng, dng tinh th. tinh khit:98%2.2 PHNG PHP NGHIN cu2.2.1 Phng php tao mng mng chitosan phi trn gelatin v natri benzoat:Mng chitosan - gelatin c to ra bng phi trn chitosan (DD = 95%, M = 9.105 - 106 Dalton) vi gelatin theo t l phi trn l 0/100, 80/20, 60/40, 40/60, 20/80, 0/100. B sung natri benzoat 0,05%; 0,1%; 0,15%; 0,2% ri ha tan trong dung dch axit acetic 1 %. Sau , dung dch ny s c rt vo khun mica c din tch 30 cm X 30 cm. Da vo nguyn l bc hi, sau mt thi gian l 2 - 3 ngy ta thu c mng mng trn tm mica. Tin hnh tch khun v em mng mng i bo qun v xc nh cc ch tiu c l.2.2.2 Xc inh cc ch tiu c lv:2.2.2. Xc nh cc tnh cht c l ca mng nh sc cng ca mng (Tensile strength - TS), gin ca mng (Elongation - E) c tin hnh o ti phng th nghim ca trung tm k thut tiu chun o lng cht lng 3 - Quatest 3 trn my o Instron Model 5566 theo phng php th ASTM D 882 - 02.Cc mng ny c gi trong mi trng c nhit v m n nh trong thi gian 24h trc khi tin hnh o. Mi trng phng th nghim c nhit l (253)c v m l (55 5) %.2.2.2.2 Xc nh kh nng thm nc ca mng ( water vapor permeability -WVP)Phng php xc nh kh nng thm nc ca mng c xc nh nh sau: cc loi mng chitosan phi trn ph liu c v khng c b sung cht khng khun thu c em kim tra kh nng thm nc phi c gi trong iu kin n nh v nhit v m (t = 25 3c, cp = 55 5%) trong thi gian l 24h. Sau thi gian ny em cc mng nay i cn v ghi nhn li khi lng ca tng mng (ni|) ri c ngm trong nc trong thi gian lh. Sau lau kh tng mng bng giy ht nc v cn li khi lng ca tng mng (m2). Kh nng thm nc ca tng mng s c tnh theo cng thc sau:m2- m ]wc = X 100(%)m,Trong :wc l kh nng thm nc ca mng (%)ni], m2 ln lt l khi lng ca mng trc v sau khi ngm trong nc (mg).2.2.2.3 nh gi mu sc, trng thi ca mng:Mu sc v trng thi ca mng c nh gi bng phng php cm quan.2.2.3 Phng php kim tra kh nng khng khun ca mng: ri51. r201Phng php kim tra kh nng khng khun ca mng c tin hnh nh sau: Ct mt mu nh mng c ng knh 17mm t cc mng cn kim tra. Thanh trng mi trng nui cy (mi trng MHA - Mueller Hinton Agar)ri rt mi trng vo da petri. cy 0,1 ml dch cha vi sinh vt vi lng 105106cfu/ml (trong ti ny cn kim tra kh nng khng khun ca mng i vi 4 loi vi sinh vt l Staphylococcus aureus, Salmonella typhmurium, Escherichia coli, Vibrio parahaemolyticus vo mi trng nui cy ri t tng mu mng ln trn mi trng. t da petri trong t m nhit 37c trong thi gian 24h. Tin hnh o vng khng khun xung quanh mu, vng khng khun l vng trn sch (clear zone) xung quanh mng. ng knh vng khng khun to thnh phi > 17mm th mi kt lun mng c tnh khng khun.2.2.4. Phn tch ph hng ngoai ca mng:Ph hng ngoi ca mng c phn tch ti phng th nghim trc thuc trung tm phn tch th nghim TPHCM. Bc sng ca tia hng ngoi s dng t 500 - 4000 cm'1. My d s dng l my TGS (Tri - Glycine - Sulfate).2.2.5. Phn tch ph nhiu xa tia X:Ph nhiu x tia X c phn tch ti Vin Ha Hc Du Kh trn my nhiu x tia X - Model XPERT PRO (Philips).21

2.2.6 Phng php b" tr th nghim la chon t l ph trn chtosan - gelatin t u:Hnh 2.1: S b tr th nghim la chn t l phi trn chitosan-gelatin -benzoatChitosan / Gelatin T l 100/0; 80/20; 60/40; 40/60; 20/80; 0/100To hn hp Chitosan / Gelatin c nng Ho tan trong dung dch axit acetic 1 %

To mng mngLm kh nhit phngXc nh cc ch tiu

31

44

Mu scSc cng gin thmKh nngPh hngPh

caca mngca mngnc cakhng khunngoinhiu x

mr)2MPa)(%)mng (%)ca mngtia X

Bo qun0 tun2 tun4 tun8 tun6 tun

Chon auv trnh t uKt qu thu c 30 mng mng nh sau:CG 1: mng chitosan - gelatinvit lphi trn l100/0.CG 2: mng chitosan - gelatinvit lphi trn l80/20.CG 3: mng chitosan - gelatinvit lphi trn l60/40.CG 4: mng chitosan - gelatinvit lphi trn l40/60.CG 5: mng chitosan - gelatinvit lphi trn l20/80.CG 6: mng chitosan - gelatinvit lphi trn l0/100.CGB 1-1: mng chitosan - gelatin vi t l phi trn l 100/0 b sung 0,05% Natri benzoat.CGB 2-1: mng chitosan - gelatin vi t l phi trn l 80/20 b sung 0,05% Natri benzoat.CGB 3-1 : mng chitosan - gelatin vi t l phi trn l 60/40 b sung 0,05% Natri benzoat.CGB 4-1 : mng chitosan - gelatin vi t l phi trn l 40/60 b sung 0,05% Natri benzoat.CGB 5-1 : mng chitosan - gelatin vi t l phi trn l 20/80 b sung 0,05% Natri benzoat.CGB 6-1 : mng chitosan - gelatin vi t l phi trn l 0/100 b sung 0,05% Natri benzoat.CGB 1-2: mng chitosan - gelatin vi t l phi trn l 100/0 b sung 0,1% Natri benzoat.CGB 2-2 : mng chitosan - gelatin vi t l phi trn l 80/20 b sung 0,1% Natri benzoat.CGB 3-2 : mng chitosan - gelatin vi t l phi trn l 60/40 b sung 0,1% Natri benzoat.CGB 4-2 : mng chitosan - gelatin vi t l phi trn l 40/60 b sung 0,1% Natri benzoat.CGB 5-2 : mng chitosan - gelatin vi t l phi trn l 20/80 b sung 0,1% Natri benzoat.CGB 6-2 : mng chitosan - gelatin vi t l phi trn l 0/100 b sung 0,1% Natri benzoat.CGB 1-3: mng chitosan - gelatin vi t l phi trn l 100/0 b sung 0,15% Natri benzoat.CGB 2-3 : mng chitosan - gelatin vi t l phi trn l 80/20 b sung 0,15% Natri benzoat.CGB 3-3 : mng chitosan - gelatin vi t l phi trn l 60/40 b sung 0,15% Natri benzoat.CGB 4-3 : mng chitosan - gelatin vi t l phi trn l 40/60 b sung 0,15% Natri benzoat.CGB 5-3 : mng chitosan - gelatin vi t l phi trn l 20/80 b sung 0,15% Natri benzoat.CGB 6-3 : mng chitosan - gelatin vi t l phi trn l 0/100 b sung 0,15% Natri benzoat.CGB 1-4: mng chitosan - gelatin vi t l phi trn l 100/0 b sung 0,2% Natri benzoat.CGB 2-4 : mng chitosan - gelatin vi t l phi trn l 80/20 b sung 0,2% Natri benzoat.CGB 3-4 : mng chitosan - gelatin vi t l phi trn l 60/40 b sung 0,2% Natri benzoat.CGB 4-4 : mng chitosan - gelatin vi t l phi trn l 40/60 b sung 0,2% Natri benzoat.CGB 5-4 : mng chitosan - gelatin vi t l phi trn l 20/80 b sung 0,2% Natri benzoat.CGB 6-4 : mng chitosan - gelatin vi t l phi trn l 0/100 b sung 0,2% Natri benzoat.Cc mng mng thu c ny s c xc nh cc ch tiu sau: Ch tiu 1 (CT1): Sc cng ca mng. Ch tiu 2 (CT2): gin ca mng. Ch tiu 3 (CT3): Kh nng thm nc ca mng (WVP - water vapor permeability) Chtiu 4(CT4):Mu sc v trng thi ca mng. Chtiu 5(CT5):Kh nng khng khun ca mng i vi 4 loi vi khun lStaphylococcus aureus, Salmonella typhmurium, Escherichia coli, Vibrio parahaemolyticus. Chtiu 6(CT6):Phn tch ph hng ngoi ca mng. Chtiu 7(CT7):Phn tch ph nhiu x tia X ca mngMi ch tiu c kim tra 3 ln, kt qu cui cng l gi tr trung bnh ca 3 ln kim tra (p dng i vi cc CT1, CT2, CT3, CT4, CT5)

2.2.7 B" tr th nghim dng mng chitosan phi trn phu liu ti u bo qun sn phm c ng ai dng fillet:T 30 mng mng thu c sau khi em xc nh cc ch tiu chn ra c 2 mng mng ti u l mng CG3, CGB3-2. Dng 2 mng mng ny th nghim bao gi sn phm fillet c ng i dng.

_ - Nhit - 10c Thi gian 45 ngyBo qun

Xc nh mt s" ch tiu: Tng s vi khun hiu kh b mt. Hm lng histamin. Kh nng hn ch tn tht cht dinh dng.Hnh 2.2: S b" tr th nghim dng mng mng ti u bo qun c ng idngSn phm fillet c ng i dng mua ti cng ty XNK Nam Trung B - ng 23/10 Nha Trang. Phi m ho nhit sn phm trong sut qu trnh ch hin k t khu tip nhn nguyn liu cho n khi fillet ra sn phm nhit khng c vt qu 4c nhm hn ch s pht trin histidine thnh histamin.

Bng 2.1: K hiu cc mu fillet c ng i dng nghin cuSTTChun b cc mu fillet c ng i dngK hiu mu

1Fillet c ng i dng khng bo qun, khng bao gi.Mb

2Fillet c ng i dng khng bao gi, cp ng v bo qun - 10 trong thi gian 45 ngy.Mf)C

3Fillet c ng i dng bao gi bng mng CG3 , cp ng v bo qun - 10 trong thi gian 45 ngy.M,

4Fillet c ng i dng bao gi bng mng CGB 3-2, cp ng v bo qun - 10 trong thi gian 45 ngy.M2

2.3 PHNG PHP X L S LIU THC NGHIMS" liu thc nghim c x l theo phng php thng k ton hc trn phn mm tin hc MS Excel 2000 [5].Chng 3 KT QU NGHIN CU V THO LUN3.1 XC NH NNG PHOI TRN CHITOSAN V GELATIN Ti u3.1.1 Kt qu xc nh cc ch tiu c l ca cc loai mng mng thu c:3.1.1.1 Kt qu nghin cu:Mc ch ca ti l sn xut ra mng chitosan phi trn gelatin c cc tnh cht u vit ca mng chitosan nh kh nng khng khun, khng nm, chng mt nc cho thc phm trong qu trnh bo qun v c gi thnh ph hp, ta tin hnh phi trn chitosan/gelatin cc t l phi trn 100/0, 80/20, 60/40, 40/60, 20/80, 0/100. tng cng kh nng khng khun ca mng, ta phi trn thm natri benzoat cc t l 0,05%; 0,1%, 0,15%; 0,2%.Sau khi to thnh mng mng kh tin hnh xc nh cc ch tiu c l ca mng nh sc cng ca mng (MPa), gin ca mng (%). Kt qu o c trnh by trong bng 4.1 phn ph lc 4.CQ 100 -I

CG1 CG2 CG3 CG4 CG5 CG6 Mu kim tra3.1.1.2 Nhn xt v tho lun: Ch tiu bn ko:- Theo chiu dc:

Hnh 3.1: th biu din sc cng ca cc loi mng chitosanphi trn gelatin.Trong cc mng chitosan phi trn gelatin em i kim tra sc cng, mng c G3 c bn ko cao nht (80,7 MPa) v mng CG6 c bn ko thp nht (51,6 MPa). Mng chitosan ch b sung ph liu l gelatin c sc cng tng dn theo t l b sung Ch/G l 100/0 (61,3 MPa), 80/20 (71,8 MPa), 60/40 (80,7 MPa) v bt u gim dn khi tng nng gelatin ln l Ch/G l 40/60 (60,3 MPa), 20/80 (52,2 MPa), 0/100 (51,6 MPa). So vi mng chitosan khng b sung gelatin (CG1), mng c b sung gelatin c sc cng tng hn. S d nh vy l do chitosan khi kt hp vi gelatin s xy ra tng tc gia nhm NH3+ ca chitosan vi cc nhm tch in m trong phn t gelatin lm cho sc cng ca mng tng ln.

Tc gi Qurashi v cc cng s (1992) nghin cu phi trn polyvinylpyrrolidone (PVP) b sung vo mng chitosan cng theo t l phi trn 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 th thy bn ko ca mng c phi trn PVP gim dn khi t l phi trn PVP tng ln [48]. Mng c bn ko cao nht l mng Ch/PVP l 100/0, bn ko ca mng gim dn khi t l phi trn Ch/PVP tng dn v bn ko thp nht l mng 20/80.

Mu kim tra

Hnh 3.2: th biu din sc cng ca cc loi mng chitosan phi trn gelatin c b sung natri benzoat 0,05%Theo kt qu o sc cng ca mng chitosan phi trn gelatin c b sung cht khng khun Natri Benzoat 0,05% trnh by trong th 3.2, ta thy rng sc cng o c cao nht l mng CGB3-1 (51,1 MPa) v thp nht l mng CGB6-1 (33,3 MPa). Mng chitosan phi trn gelatin c b sung Natri Benzoat 0,05% c sc cng tng dn theo t l b sung Ch/G l 100/0 (50,3 MPa), 80/20 (50,8 MPa), 60/40 (51,1 MPa) v bt u gim dn khi tng nng gelatin ln l Ch/G l 40/60 (44,5 MPa) 20/80 (43 MPa), 0/100 (33,3 MPa).

Mu kim tra

Hnh 3.3: th biu din sc cng ca cc loi mng chitosan phi trn gelatin c b sung natri benzoat 0,1%Theo kt qu o sc cng ca mng chitosan phi trn gelatin c b sung cht khng khun Natri Benzoat 0,1% trnh by trong th 3.3, ta thy rng sc cng o c cao nht l mng CGB3-2 (55,4 MPa) v thp nht l mng CGB6-2 (33,1 MPa). Mng chitosan phi trn gelatin c b sung Natri Benzoat 0,1% c sc cng tng dn theo t l b sung Ch/G l 100/0 (54,4 MPa), 80/20 (54,7 MPa), 60/40 (55,4 MPa) v bt u gim dn khi tng nng gelatin ln l Ch/G l 40/60 (48,2 MPa), 20/80 (40 MPa), 0/100 (33,1 MPa).

M u kim tra

Hnh 3.4: th biu din sc cng ca cc loi mng chitosan phi trn gelatin c b sung natri benzoat 0,15%Theo kt qu o sc cng ca mng chitosan phi trn gelatin c b sung cht khng khun Natri Benzoat 0,15% trnh by trong th 3.4, ta thy rng sc cng o c cao nht l mng CGB3-3 (38,9 MPa) v thp nht l mng CGB6-3 (23,2 MPa). Mng chitosan phi trn gelatin c b sung Natri Benzoat 0,15% c sc cng tng dn theo t l b sung Ch/G l 100/0 (32,2 MPa), 80/20 (34,4 MPa), 60/40 (38,9 MPa) v bt u gim dn khi tng nng gelatin ln l Ch/G l 40/60 (28,4 MPa), 20/80 (24,4 MPa), 0/100 (23,2 MPa).

CGB1-4 CGB2-4 CGB3-4 CGB4-4 CGB5-4 CGB6-4 Mu kim tra28.426.6

Hnh 3.5: Biu din bn ko theo chiu dc ca cc loi mng chitosan phi trn gelatin c b sung natri benzoat 0,2%Theo kt qu o sc cng ca mng chitosan phi trn gelatin c b sung cht khng khun Natri Benzoat 0,2% trnh by trong th 3.5, ta thy rng sc cng o c cao nht l mng CGB3-4 (28,4 MPa) v thp nht l mng CGB6-4 (16,2 MPa). Mng chitosan phi trn gelatin c b sung Natri Benzoat 0,15% c sc cng tng dn theo t l b sung Ch/G l 100/0 (25,8 MPa), 80/20 (26,6 MPa), 60/40 (28,4 MPa) v bt u gim dn khi tng nng gelatin ln l Ch/G l 40/60 (22,7 MPa), 20/80 (19,3 MPa), 0/100 (16,2 MPa).

Kt lunT kt qu o sc cng ca cc mng chitosan phi trn gelatin c b sung cht khng khun Natri Benzoat theo t l 0,05%; 0,1%; 0,15%; 0,2% trnh by t th 3.1 - 3.5 ta thy rng sc cng ca mng khng nhng ph thuc vo hm lng gelatin m cn ph thuc vo nng cht khng khun b sung vo. Sc cng ca mng tng khi tng nng cht khng khun t 0,05% ln 0,1% nhng khi nng cht khng khun b sung vo cao hn (0,15 - 0,2%) th sc cng ca mng li gim. iu ny c th l gii rng do s b sung thm Natri Benzoat, cc phn t cht ny cnh tranh gc NH3+ ca phn t chitosan lm thay i cu trc chitosan lm cho lin kt gia chitosan v gelatin thay i dn n bn ko theo chiu dc ca mng chitosan phi trn gelatin c b sung Natri Benzoat gim.Kt qu ny ph hp vi nghin cu ca tc gi nh Cagri v cc cng s (2001) l cc tc nhn khng khun thm vo s lm thay i cc tnh cht c l ca mng [59]. Pranoto v cc cng tc vin (2005) nghin cu b sung mt s tc nhn khng khun nh du ti, potassium sorbate, nisin vo mng chitosan th cng thy cc tc nhn khng khun ny lm thay i cc tnh cht c l ca mng v nng cht khng khun phi trn vo cng cao th sc cng ca mng cng gim [41 ]. iu ny ph hp vi kt qu nghin cu ca lun vn ny.Nu so snh sc cng ca tng loi mng chitosan phi trn gelatin vi mng c b sung cht khng khun theo cc t l phi trn khc nhau ta c kt qu trnh by trong Bng 3.1Bng 3.1 : So snh sc cng ca mng chitosan - gelatin vi mng chitosan - gelatin - benzoat.^XT l Ch/G Mc gim (%js\100/080/2060/4040/6020/800/100

Mng c b sung Natri Benzoat 0,05%16,617,136,638,117,634,4

Mng c b sung Natri Benzoat 0,1%9,710,731,332,823,335,8

Mng c b sung Natri Benzoat 0,15%46,643,851,760,453,255,1

Mng c b sung Natri Benzoat 0,2%57,256,664,868,363,168,6

Theo kt qu trnh by trong bng 3.1 ta thy mng c b sung cht khng khun cng nhiu th sc cng ca mng cng gim. S d nh vy l do nng cht khng khun cng cao s xy ra tng tc gia nhm - NH2 ca chitosan vi nhm chc nng ca tc nhn khng khun gp phn ni lng cu trc mch lm cho bn ko theo chiu dc ca mng gim.

I 15 =1.32.8 Ch tiu gin ca mng - %2.72.32.12.2

s 1 0.0 CG1 CG2 CG3 CG4 CG5 CG6 Mu kim traHnh 3.6: th biu din gin ca cc loi mng chitosan c phitrn gelatin.Trong cc mng chitosan phi trn gelatin em i kim tra gin, mng CG3 c gin theo chiu dc cao nht (2,8%) v thp nht l mng CG6 (1,3%). gin theo chiu dc ca mng gim dn khi t l gelatin b sung vo tng dn. T l gelatin b sung vo cng cao th gin theo chiu dc ca mng cng gim.Kt qu ny ph hp vi nghin cu ca cc tc gi Qurashi v cc cng s (1992) nghin cu phi trn polyvinylpyrrolidone (PVP) b sung vo mng chitosan cng theo t l phi trn 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 th thy gin ca mng c phi trn PVP gim dn khi t l phi trn PVP tng ln. Mng c gin cao nht l mng c t l phi trn Ch/PVP l 100/0, gin ca mng gim dn khi t l phi trn Ch/PVP tng dn v gin thp nht l mng 0/100.45

47

2.8

2.32.2

1.9/CS

-1IIIIIa 1 R oaaO'1s 0.5 0

CGB1-1 CGB2-1 CGB3-1 CGB4-1 CGB5-1 CGB6-1

Mu kim traHnh 3.7: th biu din gin ca cc loi mng chitosan phi trn gelatin c b sung Natri benzoat 0,05%.Theo kt qu o gin ca mng chitosan phi trn gelatin c b sung cht khng khun Natri Benzoat 0,05% trnh by trong th 3.7, ta thy rng gin o c cao nht l mng CGB1-1 (2,8%) v thp nht l mng CGB6-1 (1,9%). gin theo chiu dc ca mng gim dn khi t l gelatin b sung vo tng dn. T l gelatin b sung vo cng cao th gin theo chiu dc ca mng cng gim.

2.5

12

JD

S

i1.5

CQ

oc1

o

ng knh vng khng khun (mm)

- i vi Staphylococcus aureus0

- Escherichia coli0

- Salmonella typhmurium0

Vibrio parahaemolyticus0

Mu sc v trng thi ca mng:

- 0 tun- Trng trong, dai chc.

- Sau 8 tun- Hi ng, dai chc

Mng CGB3-2 c t l phi trn Ch/G l 60/40 c b sung Natri benzoat nng 0,1% vi cc thng s c trnh by trong Bng 3.10 sau:Bng 3.10: Cc thng s" ca mng CGB3-2Tn mngCc ch tiuCGB3-2(T l phi trn Ch/G l 60/40 c b sung Natri Benzoat nng 0,1%)

Sc cng ca mng (MPa)55,4

gin ca mng (%)2,0

Kh nng thm nc - Water vapor350

permeability (%)

** ng knh vng khng khun (mm)

- i vi Staphylococcus aureus19,32

- Escherichia coli17,92

Salmonella typhmurium17,97

Vibrio parahaemolyticus19,67

Mu sc v trng thi ca mng:

- 0 tun- Trng trong, dai chc.

- Sau 8 tun- Hi ng, dai chc

3.2 KT QU PHN TCH PH HNG NGOI CA MNG (FTIR - FOURIER TRANSFORM INFRARED)Tin hnh phn tch ph hng ngoi trn 2 mng mng ti u l CG2 v CGB3-2 ri so snh vi 2 mng i chng l mng CG1 (mng chitosan) v mng CG6 (mng gelatin) ta c kt qu nh sau:

8 ss?sc O^(Dnv