HOl NGH! KHOA HQC CONG NGHg SINH HOC T O A N Q U O C 2013
-NGHIEN^6t|-TA0-M"ATTG"CHlTDSTW^n^S'lN"KHANG"KHUAN U'NG DUNG ^ TRONG B A O Q U A N XOAI
Nguyin Kim Thoa', Hoa Thj Minh TiJ, Tran Thanh ThCiy, Nguyin Quoc Vi$t, L.9I Thf Hong Nhung W#n Cbng ngh$ sinh hgc, Vi$n Hin lam Khoa hgc vi-Cong ngh$ Vi$t Nam " " '
T6MTAT
Bio quin tli^ pham ii6i chung vi bao quin hoa qui n6i rieng hifn nay dang li m6t vln 6i dugc cic nhi klioa hpc quan tam ngbiSn ciiu. Hijn nay b niiAc ta, ciing vdi svr phit trien kinh te HI hgi, vifc bio quin thp: phSm bSng cic polymer co ngudn g6c dlu mo tr&
nen rit &ang d^g. Cac bao bi c6 nguon goc hoa hoc niy rat kho bi phin hiiy do vgy vifc tliii chiing ra m6i tiu&ng da giy ra o nhilm iii5i truing n ^ g ak. Mgt kiiic, hio quin hoa qui vi thuc phim bang cich sii dipig rit nhiSu cic cic hgp clilt toa hgc !i m^t tiiijc trfog lit pho bien. Ngoii vifc lim ^im chat luong thuc pham, viec lam dvmg cic hda chit nay giy inh hudng nghiem trpng Ski siic kb6e ciia nguoi tiSu diing. Be g6p phan kbic phvc cic ti^u che trSo, vifc nghien ciiu tao ta ming bao gdi thpc p l i ^ dl pbkn hi^y sinh hgc li rit can thiit vi c6 ^ nghia. Tuy nhien, d^ ning cao gia trj bao quan hoa qui, bSn canh vifc sii dyng cic ming de phfin hiiy sinh hgc, cin phii nghien c(hi cic chit bio quin an toin co ngudn g6c sinh hgc. Cic chit bao quin niy c6 klii nSng khing I^i svi xSm nhiem ciia c£: nhdm vi sinh ^ t gay hdng h(ta qui, Trong khuon ldi§ bai bio nky, chting toi nghiSn ciiu c&ch pti6i trgn nisin, mgl lo^
' ctiit Idling Idiuin dugc thu i^in tii qui trinh Ifn men vi Idiuiu lactic vi dugc diung nhin li an loan, duOc sit dvmg li chit bio quin Ihvic phim, c6 ma so Cliiu Au E234 vdi v^t lifu.chitosan di t^o thinii ming khing khuin tog dyng trong bio quin xoai Ming chitosau - nisin dugc phoi tr$o theo cong thic 2% chitosan (w/v), 1% asit axetic (vA;), 1% cKat dio h6a (v/v) va bo sung nism c6 ho?t d§ cu6i ciing li 1000 IU/ml. Milng chitosan - nisin ch^ tao dugc xac djnh co kha ning dift cao chung vi khuin Gram (+), djic bift li hai loii vi khuin gay bfnh L monocytogenes vi B. cereus. Cng dpig ming khing khuin chitosan - nisin b di^u kifn nhift df ph6ng (22 - 2S° C^ xoii^ dugc bip quin trong thfri gian 12 ngiy ma vln dim bao dugc ca diim cim quan vi chit lu^g, tmmg dirong 'v6i kit qui bio ,quin bing nhung miing thuong pMm khic. TCt nhiing kit qua ttiu n h ^ dugc bu6c diu c6 thi djnh hudng ihig dvmg ming chitosan-nisin dl bio quin hoa qui fr quy m616n ban.
Tie khoa: chitosan, ming film khing khuin, nisin, bio quin xoai
MdDAU
Myc dich cua bao bl thyc phim IS dS bSo vf thyc phSm lap&c I3c dfng lAm giim ho|c bilri doi chat dinh du-ong ti> c^c tdc nh3n ly, h6a vi sg phi hOy cOa vi sinh vfit ICF khi thu hoach ldi thirl dllm nguiri tiSu dimg sb dgng. Cic vi sinh v | l ngoai lai thu&ng xam nh|p vi phit triSn* trSn b^ mat thu:c phim trong qua trinh bio quin. Vi V do 66, dc ming bio qu^n thi^c phim cd tfnh chit khing khuSn phii Sim bio chat khing khulin dup'c khuech tin liJr li> len b^ mil Ihiirc phim giup kim ham sy phit triln vi sinh v|l trong Ih&l gian dii Mppendinl e( al., 2002). M^t trong cio lo^i polymer dugc ua chuOng nhit hi^n nay diing lim bao bl bio quin thyc pham l i polyethylene (PE) va cic co-polymer cOa nd, chO ylu
6ugc rong hgp til diu mb vi 6i dugc nginh cong nghi#p-lhyc phim si> dyng tren 50 nim, Cic log! polymer niy c6 uudilm l i gii thinh r§, Unh chat 1;^ h6a l6t, lhu|n ti#n cho gia cong bao bi nhung cic v|t lifu niy l^i cd nhu^c dilm I6n nhit I i khflng c6 khi nana phin hiiy sinh hgc, do do chting tfin lai rit liu hx>ng dit giy nSn van nan m6i truing. Giai phip duy nhat hi#n nay fle giii quy$t vin ngn nay l i all ho|c til chl (Floros ef al., 2000). COng v6i dfl la sy khan hiem vi tang gii cOa diu mo khien cho u'u thl ve gii thinh cOa cic loai v|t liiu nay giam din.
o l giii quyll vln ngn mfli tsubng do dit ho|c lai chl cic loai polymer hfla hpc, hi|n nay tr§n thl gifl'i, xu hu'fl'ng tlm ra v i phit triln cic logi polymer cfl khi ning ty phin huy dang dugc tip trung nghiin ci>u. Polymer sinh hgc dug'c djnh ngliTa l i cic v i i lifu cfl nguin gic tCr cic ngu6n nguySn li$u tii tgo sCr dung trong vigc tgo bao bi bao quin thuc phim.
Cic polymer sinh hpc co the dugrc chilt-xuit tivc tilp ho^c tach tCr sinh kh6l, vl' dy' nhu tirih bgt, polysaccharide v i cellulose, chitosan/chilln v i cac protein nhu casein va gluten (Wilfred., 2009), Gin fliy sy tiin bfl ve mgt cflng nghg cho phip tgo ra cic ming film Kr polymer sinh hgc theo cich thi>c gia cflng giong nhu vfl'i polymer cfl nguon goc dlu mfl (Akiyama el al., 2003). Tuy nhifln, cic ming polymer sinh hoc vln chua dip i>ng dug'c hit cac yeu clu ciia qui b'inh bao quin do sy tgp nhilm cua cac nhom vi sinh v|l giy hflng, giy thoi Vi vgy, song song vfl'i vifc tim kilm cic vat llfu tgo bao b) cfl ngu6n gic sinh hgc, vifc tlm ra cac chat khang khuin mdi cung nhu cong thi>c phoi trgn giua cac thinh phin tgo ming d l chit khing khuin khulch tin vio thyc pham cfl dO ning dfl kim ham vi sinh vit trong thyc phim cQng l i nhifm vy quan tigng.
Hifn nay vifc nghiin cuu cic chit bio quin thyc phim cfl ngu6n goc sinh hgc - nham i>c chi.hpgl dOng hay tifiu dift vi
sinh vft nhung vin gii> dupc dgc tlnh. cim quan ban dlu cOa san phim - da tr&'thinh mii quan tam hing diu cua cic
nhi khoa hpc. Trong dfl khuynh hudng SCF dgng bacteriocin, dgc bift la nisin dang dugc chO 'j nhit. TCr nam 1969 to
chi>c FAO vi WHO d i dong y cho phip si> dyng nisin trong bao quan Ihyc phim (Delves, 2005), Nisin trfl' thanh khing
sinh chuyf n bift d l bio quin thyc phirn, l i chat bio quan sinh hoc cfl ma quic t l l i E234, cfl gii trj si> dyng cao, khic
phyc dupc nhO'ng nhugc dilm cOa cic phugng phip khic (Batdorj et al., 2006). Ngoai ra nisin efln nhilu uu diim khac
nhif: phgm vi i>ng dyng khi rfng li> cac san phim tugi sing nhu thJt ci, tn>ng, sira... din cac thyc phim ISn man,
dflng h9p, binh ml. nufl'C ulng...; khSng lam thay dli cam quan, khflng lim biln dii chll lugng, khflng d i Igi du lugng
trong tfiyc phim; khing inh hu&na lfln si>c Wide con ngudi, c6 khi ning phin hCry trong eg thl con ngufl'i (Cotter e( a/.,
2005). Oiu nhOng nim 80 cOa thl kJ tiubc, da c6 nh&ng nghifin cu-u tim cich dua nlsIn, mfl Iogi bacteriocin cfl tfnh
Hiing khuin vio cac ming bao gfli thyc pHSm nhim kiim soit cac vi sinh vft giy hflng v i giy bfnh cfl trong thyc
phim (Han at al.. 2000). Theo nghiSn t^u cila Cutter v i cfng sy, si> dyng ming PE gan nisin cfl hifu qui bao quin
thyc phim lit hon so vdi vifc phun v i tlm nisin len b l mgt thuc pham, nguyen nhin la do nisin khulch tan ra tCr tir Ifin
b l m|it thyc phim. giOp cho vifc bio quin thyc phim tit hen. Tuy nhien trong qui trinh bio quin; nisin din din bj mit
hogt tlnh do bj hit hogt. hofc bj phin huy, hofc bj pha loing vio thyc phim. Coma v i cfng sy (2001) da lim each kll
hgp nisin, axil stearic v i hydroxypropylmethylcellutose (HPMC) d l igo ra mang an dugc cfl khi nang khing khuin va
HOI NGH! KHOA HQC C O N G NGHE SINH HQC T O A N Q U 6 C 2013
c h i n g Igi q u i trinh m i t n u d e cua ttiyc p h i m . K i t q u i thu d u g c m i n g nisin-HPMC cfl k h i nang k h i n g r i t l i t hai l o i i Listeria innocua v i Staphylococcus aureus (Appendin ef al., 2002).
NGUYEN L i e u VA P H l f a N G P H A P Vgt l i f u
C h l p h i m nisin dgng long "c6 hogt d f 6000 IU/ml d u g c s i n x u i t tO chiing Lacfococctrs lactis sub. lactis V L S H 10.1, t h u f c Phong C6ng nghe sinh hgc v g l Hfu, V i f n Cflng n g h f sinh hgc.
Chitosan t h u o n g p h i m d u g c mua t u cflng ty T N H H K&H V i f t Nam, 91 N g u y i n HOu C i n h , Phufl-ng 22. Q u f n Blnh Thgnh, T P HCM (do deacelyl hfla 98%).
Xoai d u g c thu h i i tr^rc t i l p tip v u d n cay cOa c i c h f nflng d i n tgi x i i C l N h u l , TCr Liem, H i Ngi, d a m bao khflng sD dyng c h l l b i o quan n i o khac.
P h t r o n g phap
Phirong phap tpo mang chitosan: Chitosan 2 % (w/v) d u g c hoa tan trang 1 % dung dich axit (v/v) tai 70°C, sau d f l t i l n h i n h bo sung 1 % c h i t d i o hfla tai 7e°C. l i l p tyc b i sung 1 % glycerol trong tong t h l tfch 20 m l . Hfln h u p dung djch trfin d u g c chfnh pH ve cac g i i trj pH 3 , 4 v i 5 tnrdc khi d u g c do v i o dTa petri co d u d n g kinh 15 c m , s a u dfl t i l n h i n h d i khfl m i n g 48 h tgi n h i f t dg phflng. M i n g tgo ra d u g c bao q u i n d dieu k i f n kho-frirdc khi t i i n h i n h c i c thf nghiSm l i l p theo.
Xic djnh khi ning hba tan eua ming chitosan: Ming film chitosan tgo ra dugc cat theo kich t h u d c 5 cm x 5 c m . Sau khi c i n trgng l u ^ g ban d i u cua m i n g b i o q u i n kho, m i n g d u g c n g i m v i o n u d e k h i i ion trong 24 h tgi n h i f t dg phflng.
sau dfl logi bfl n u d e . Mang d u u e - s i y khfl 6- 100''C trong 24 h, t i l n h i n h c i n mang de x i c ^ n h trong l u p n g hao h y t cOa m i n g , tCr dfl co t h l x i c djnh d u g c % k h i i l u g n g c i c t h i n h phan khflng bj dao hfla v i bj hfla tan trong n u d e v i c f l the lya chgn d u g e logi axit v i pH thlch h g p cho v i f c tgo m i n g .
Phtrong phip xic djnh khi nang khing khuan cOa ming: dugc x i c djnh theo nguyfin t i e k h u l c h t i n tren dTathgch.
Chiing k i l m dinh Lactobacillus plantanim JCM 1149 d u g c nufli tmh qua d i m (12 h) trong mfli tnj-dng MRS Iflng d 30° C (ODBIM = 1.28). Mfli t r u d n g MRS b i n Iflng (efl chCra 0,6 % agar) d u g c k h i i triing 6-121° C trong 30^ phiit. Sau khi lam Ignh d i n n h i f t d f khoang 37 - 40* C, bd sung 0.5% (v/v) djch h u y i n phil vi k h u i n chung k i l m djnh, lac d l u v i d l r a dTa petri cfl d u d n g kinh D = 15 cm (25 ml/dta). Mang chitosan - nisin kich t h u * c 0,5 cm x 0,5 cm dUgc d f t trfin b i mgt dTa thgch , gitp trong 4 ° C trong k h o i n g 4 h, sau dfl tien h i n h 0 d 37°"C v i x i e djnh d u d n g kfnh vflng khang k h u i n , Phuomg phip bio quin xoit. X o i i d u g e thu h i i t r y e t i l p trfin c i y ICP e i e h f nflng d i n d u g c l i m sgch bang khan g i i y m i m v i bgc b i n g giay ban. Phan x o i i v i o c i c Io, moi lfl cfl 30 q u i . Lfl d l i chCrng i m : x o i i d l nguyen, khdnq bgc m i n g ; 16 d l i chdng d u o n g : m i n g bgc chi cfl chitosan. khflng b l sung nisin. D i n h d i u v i theo dfli s y b i l n fff ng ve cam quan ciia q u i (can ngng, m i u sac, d f n h i n eOa q u i . d f chin) b cac 16 doi chCrng v i t h i n g h i f m s a u 10 n g i y d n h i f t d f phdng v i 30 ngay d n h i f t d f 4° C,
K ^ T QUA V A T H A O L U A N
Lipa chpn d u n g m o i axit p h i i h p p d l h d a tan v i tcio m i n g c h i t o s a n
Chitosan l i m f t polysaccharide mgch t h i n g d u g c caii tgo I d cac p h i n t u D-glucosamine (don vj deacelyl) v i chOng d u g c n l i vdi nhau b i n g c i c m i l liSn k i t p-l ,4-glycoslde. Chitosan khflng lan trong n u d e , dung djch k i l m va phan Ifl'n.
c i c dung mfli hO'u CCT nhung Igl c d kha n i n g tan trong dung djch axit hiiu ccr v i vfl c o . Tuy nhifin d l d i m b i o c h i t iugng b i o quan eung n h u c h i t l u g n g dinh d u d n g cila hoa qua, chiing tfli da chgn b i n logi axit hij'u e g d u g c si> di,i,ng l i m dung mfli de hfla tan chitosan va tgo m i n g l i axit lactic, propionic; axetic v i formic. K i t q u i d u g c trinh b i y d B i n g 1 cho t h i y khi s u dgng axit' lactic d i hfla tan chil05an,'qua trinh deo hfla khdng t i t , vi t h l m i n g bj tan ra h o i n l o i n khi cho v i o n u d e , Tnang khi dfl d pH t h i p (pH 3) eac m i u hfla tan chitosan b i n g ajdt formic, propionic v i axetic , chitosan d u g c hoa tan t i t , m i n g tgo ra cd d f bfin vi>ng h o n tgi pH AvaB.Ct m3u chitosan d u g c hfla trong axil axetic r i i chlnh v l pH 3, mang chitosan tgo ra cfl tdi h o n 85% t h i n h p h i n d u g c d i o hfla v i chl c d 13,2% trpng l u g n g c i c t h i n h p h i n bj hfla lan v i o n u d e , day l i k i t q u i tgo mang tot n h i t trong c i c m l u t h l n g h i f m . Ti> k i t q u i nghifin CCPU t r f n chting tfli chpn lya cdng thdc axU axetic ( 1 % v/v) d i hfla tan chitosan khi tgo m i n g . Dung djch chitosan tgo ra p h i i cfl p H < 3 .
B i n g 1. Lya chpn dung mol axit thich hop d l hoa tan v i t^o mang chitosan
Mang film
2% chitosan 1% glycerol
pH
3 4 5
Axit tactic 100 100 100
%
Axil axetic
h^t tan trong nu&c • Axit fonnic 13,2 ±0,3
25,4 ±0.5 64,6 ±0,6
31,9 ±0,5 71,0 ±0,3 79,5 ±0,6
/\xit propionic 24,1 ±0.5 63,9 ± 0,6 100 L y a c h g n c h i t deo hda d l t g o m i n g c h i t o s a n
Ba logi c h l l dSo hfla d u g c s u dyng song song trong nghifin c i i u tgo mang l i n l u g t l i PEG 600; sorbitol v i glycerol, Chitosan 2 % d u g c hfla tan trong axit axetic 1 % tgi TO^C, roi dieu chinh v l pH 3. T i l n h i n h b l sung mfim c h l l deo h o a v d i ndng d f 0,4; 0,8; 1 v i 1,5%. Kha nang tgo m i n g d u p c d i n h g i i thflng qua d f day cua m i n g . Hfin h g p 20 ml d u n g djch tren duge d l v i o dfa petri cd d u d n g kinh 15 cm, sau dfl t i l n hanh d l khd 48 h tgi n h i f t d f phdng (Hlnh 1). M i n g chitosan tgo ra d u g c x i c djnh dg d i y b i n g micrometer.
K l l q u i do d f day ciia m i n g cho t h i y v i f c b l sung cgc c h i t deo hda se l i m l i n g do d i y cua m i n g , cflng t h d c m i n g e h i
HQI Mf^HI ^^rib. Hnr ri^Mr; NPJHF SINH HOC T.QAN OI K^C ?ni rt
cfl 2% chitosan m i k h d r ^ b i sung chit"f<^~h(Sa-rhf) m j n j r n dp r l i y mdng nhat (3,00 x 10"' mm), tnang khi dd cflng thdc m i n g 2% chitosan + 1,5% PEG 600 cd d f d i y n h i t kfch thudc len tdi 4.62 x 1 0 ^ mm. O i n g ... thdi cfl fill thay ^ f e tang n i n g df.
c h i t dec hda tCr 0,4% d i n 1,5% ty le thufn vdi d f d i y cua m i n g . Trong so 3 logl c h i t d i o dugc nghien c d u thl glycerol cho dg day ciia mang thap nhit, NghiSn cdu ciia Wiles v i c f n g s y (2000) di chi ra r^ng dp d i y ciia m i n g i n h hirdng r i t nhieu tdi s y
Hlnh 1. Mang chitosan dugc tcio ra tip cac c5ng thi>c:
- 2 % Chitosan + 1 % a)dt axetic +1%glycerol(A)
~2%Chrtosan + 1 %axit axetic + 1K PEG 600 (B) - 2 % Chitosan-<-1 %axit axetic + 1%sortiitol(C)
trao d l i qua Igi ciia COz, Na v i hoi n u d e phla trong v i n g o i i m i n g . B i i vdi m i n g polysaccharide q u i trinh t h o i t hoi nude sfi l i m giam,ip l y c ciia hui n u d e I f n b l m f t m i n g . Tuy nhifin, v i f c lya chpn c h i t deo hda thfch hgp c f n phy thufc v i o nhieu y l u t i va myq^dfch s d dyng ciia m i n g . Theo nghifin cdu cOa Jiang va Han (1986) do glycerol efl tlnh ph^n eye cao hon sorbitol cho nfin khi s d dyng b cOng m g l n i n g dp thl mang tgo ra cfl k h i n i n g t h o i t hgi nirdc cao hgn, trong khi dfl vfl'i PEG, v i f e tgo ra c i u tnic dgng mgng l u d i cung sS l i m tang c i c linh c h i t co 1;^, cung n h u k h i narig t h o i t hgi n u d e cOa m i n g . Do v f y , lya chgn glycerol v i PEG l i e h l ^ d f o hda cho q u i h-lnh tgo m i n g cd u u t h l hun so vdi sorbitol.
B i n h gia k h i nang k h i n g k h u i n ciia m i n g c h l t o s a n - n l s i n c h l tgo
T d nhung k i t qua t r i n , chiing tdi da lien h i n h che tgo mang khang k h u i n chitosan - nisin si> dung c h l pham nisin dgng djch ed nong dg 6000 IU/ml vdi cdng thuc phoi che n h u da mfl t i d p h i n phuorig p h i p . Dung djch chitosan ~ nisin d u g c d l v i o dTa pelH cd dudng kinh 15 cm, sau dfl t i l n h i n h d l khd mang 48 h tgi nhift dg phflng. M i n g chitosan khfl tgo ra cd kleh thudc 0,5 cm x 0,5 cm b i o quan d 4° C d u g c chyp kinh hien vi quel d i xem k h i n i n g p h i n t i n ciia nisin (xlng nhu t h u nghifm kha n i n g k h i n g k h u i n ciia nfl v d i c i c chung vi k h u i n k i i m djnh Gram (-) n h u E. coll, S. typhimurium v i c i c chiing vi k h u i n Gram (+) n h u S. aureus,L. monocytogenes, B. cereus vi L. plantarum. K i t q u i xac djnh kha nang khing k h u i n ciia m i n g chitosan nisin c h l tgo d u g c the hien d Hlnh 2. B i n g 2 v i Hlnh 3
S ' sir J A ' • " • • " • S f
'?
'= '_ •"_
Hinh 2. Hlnh Snh SEM ciJa ming.chltosan o> mSu khong bo sung r
Hinh 3. V6ng khang vl khuan L. plantarum JMC1149 (A) va vong khang vl khuan t monocytogenes (I chitosan- nlsIn
Bang 2. Kha n3ng kh:ang khuan cCia mang bhitosan - nisin c h l t^o
Vi khuin Gram (-) Vi khuin Gram {+)
B. cereus 24,8+0,2
K i t qua nghlSn cdu cho t h i y . nisin cfl kha n i n g phan t i n tucmg doi dong d l u tren d i f n tich m | l p h i n g c i c mang chitosan v i alginate sau Wii th\rc h l f n q u i trinh c i n m i n g . m i n g chitosan-nisin cd kha nang diet r i t i l l l i t ca c i c chiing
HOI N G H L ^ ^ ^ o c C O N G N G H $ SINH HQC J£n
vi k h u i n Gram (+) k i i m dinh, dac-bj% ^ a l chung vi k h u i n g i y b f n h k f f l p n ^ g j ^ - f ^ , nhdng k i t qua n i y , co the thay lifim nang ( 0 ^ j n j n g khang k h u i n chltosan^iisisL^o « & e ^ ^ j ^ v i h o a q u i ' LPng d u n g m i n g c h i t o s a n - n i s i j j ^ ^ q u ^ n x o a i
Chiing toi da l i i n hanh nhOng ^ . t § g ^ g b i o q u i n xoai «iu hogch d cac J© '^^'^0^*';^*. u * ^ 6 1 X o ^ ' ^'^'^1 chia v i o c i c Id de bao quan & , f ! t i i ^ | ^ . e j n g (22 - 25" C). C i c lfl thf n g H f ^ ^ d u C f f t ' i & t ^ y a c i c thSng sfl n h u to'gng l u g n g , m i u sac, d f t c h i i ^ ^ u ^ K l t q u i sau 12 n g i y , t o i n b i * ^ ! ^ * ' ® * ' i ^ l k h f n g b i o q u i n bang m i n g ) da chin v a thoi, ^%n^tif^^ cfl r i t n h i l u c h i m den (Hlnh 4 ) . O l f l * ^ ^ * ^ * ' ' ! 4 ^ m ' - c h i cd chitosan, khflng bo sung nisin), xoai c f l i ^ l u j ^ j t n i a t n u d e h o n ( b l mgt f l nhan) i ^ ' . ^ * 3 I N ^ V i 5 , 2 f l % so v d i trgng l u g n g ban dau, hjy nhifin c a c ^ ^ o m j & ^ n xuat h i f n v i 7 0 % so q u i v i n t^ " ( ^ ^ ' ' - " ^ i ^ n i J ^ B I f m i t nude ciia xoa" dao ddng 5 10% k l ^ g j s ^ f s n d l m d e n v i t i l f c h i n d i u 10% •- • ' • J ™ ^ '
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TAl LI^U THAM K H A O
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Cotter PD. Hill C, Ross P (20O5), Bacterlocins: developiilg innate immun'i^for food. Nat Rev Microbiol 3-J77-7BB.
Cutter CN, WilletJL, and Siragusa GR (2001), Improved antimlcrabial acfivity of nisin incorporated polymer films by fomiulation change and addition of food grade chelator. Left A^pf MIcrobld. 33(4).25 - 328.
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Polymer Physics Z^{B):^2TS•^28•\. .
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PREPARATION OF AN ANTIMICROBIAL CHiTOSAN - NISIN FILM USING IN THE MANGO C O A T I N ' G STORAGE
Nguyen Kim Thoa*, Hoa Thl Minh Tu, Tran Thanh Thuy, Nguyen Quoc Viet, Lai Thi Hong Nhung Institute of Biotechnology, Vietnam Academy of Science and Technology
SUMMARY
Food preservation in general and fiuit storage in particular are now focused in many of studies. Along with the socio-economic development, food is used to pacldng by oil-derived polymers which are degraded diEGcui^ and caused serious environmental pollution Moreover, usmg a h u g e o f cheiliical compounds infoodandfiruit preservations are very poUular in V i e t n a m ¥ o w a d a y s . ^ addition to reduce the quality oflhe food, the abuse offhese chemicals has aSected severely on the health of consumers. In order to overcome these limitations, the study on a biodegradable food packaging membrane is generated necessarily and meaningfiUly.
Besides this membrane, it is important to study a s a f e ^ preservative bio-agents which are resistant to the inaction of inside and outside tnicrooi^anisms caused damage to the fruit In this paper, w e have investigated a film preparation which is combined between cliitosan and nisin, an antimicrobial product obtained fivm lactic- bacteria fermentation applying in mango preservation.
Nisin is confirmed as a safe additive and used as a common food preservative which has European E number E234. This film is prepared^as^foliowjng recipe;_25ii,cbitosan.Cw'YX-l% a x e t i c . . axit (v/v), 1% plasticized agent (v/v) and-nisin in the-final—
concentration of 1 OM fU/ml, W e have demonstrated the antimicrobial activity of this film against the positive Gram bactena strains, especially two pathogenic bacteria L monocytogenes and B. cereus. Finally, this film is applied to mango preservation whicH resulting in good sliape and quaUty in 12 days at room temperature (22 - 23°C) which is equal as preservation by other commercial membranes. From this primary results, we would like to expand the application of the chitosan - nisin for mango preservation in bigger scale.
Keywords: antimicrobial membrane, chitosan, food preservation, iacfococcus lactis sab lactis, nisin
•Author for correspondence: Tel; +84-4-37567103 ; Email- [email protected]
