KHOA HOC C 6 N G N G H t
AIVH H U O I V G C U A D I E U KI^IV CHIET L A T R A X A I V H V A 5IJ D U M G D | C H C H I E T D E HAIM C H £ S U DIEM DEIV Q
T D M V A O X I H O A C H A T B E D Q CA
Cao Thi Kim Nguydn', Nguydn Xuin Duy^ Nguydn Anh Tuin'
T6MTAT
Anh huong cia didu kidn chidt li tri xanh (GTE) gdm nhidt do, thdi gian va ty Id nguydn lidu so vdi dung mdi chidt va sit dyng djch chidt thu dugc dd han chd hidn tuong bien den d torn the vi su oxi hoa chat beo cua flijt ca thu nging dS dugc nghidn cuu. Kdt qui chi ra ring didu kidn chidt tdi uu dd thu dugc djch chiet c6 hogt tinh chdng oxi hda cao nh^t (dua vio nSng lye khu gdc bf do DPPH) c6 th^ dat dugc nhu sau: Nhidt do 70°C; thdi gian tir 1 - 1,5 gid; t^ Id nguydn lidu/dung mdi li 1:15 (w/v) ho4c nhidt do 90"C; thdi gian 0,5 gid; ty Id nguydn Udu/dung mdi la 1:15 (w/v). Dung mdi chidt su dyng Uong ca hai trudng hgp la nuoc.
T6m dugc xit ly bing GTE cd tic dyng h ^ chd sy hinh thinh ddm den trong qui trinh bao quan l?inh d 5"C so vdi miu ddi chiing (p < 0,05). Kdt qua tuong ty cQng dat dugc ddi vdi miu thit ci dugc xii ly bdi GTE.
Thjt ca xit ly bang GTE cd tic dyng h^n chd su oxi trong qui trinh bao quan lanh d 5°C so vdi mau ddi chiing (p < 0,05). Kdt qui dat dugc trong nghidn ciiu niy chi ra tidm n^ng cua djch chidt tir la tra xanh c6 thd ling dung trong bao quin nguydn lidu thuy san sau thu hoach.
Tit khda: Hi^ tuong bi^'n den tdm. ca thu ngang. djch chiet la tra xanh. oxi hoa chat beo, tdm the.
LBATVANDE
Trong la t r i xanh chiia rat nhidu hgp chat cd hogt tinh quy, die bidt l i cac hop chit phenol v i cic din xuit 0^ Jun v i cdng su, 2009; Khan v i Mukhtar, 2007). Tri xanh li ngudn chii y^u cung cap catechin, mot chat chdng oxi hda tii nhidn, cd tac dimg khu cac goc tu do v i dugc sii dung hidu qua trong linh vuc thuc pham (Victoria va cdng su, 2010). Gan day, nhi^u nghidn ciiu da chi ra ring dich chiet tir la tra xanh cd tic dung han ch^ su hinh thanh bien den b tSm (Nirmal vi Benjakul, 2010, 2011) v i su oxi hda ch^t beo ciia thit ca (Tang v i cpng sir, 2001). Bi^n den 6 tdm la mdt trong nhiing nguydn nhan lam giam thdi han su dung cung nhu g i i tri thuong mai cua torn (Martinez-Alverez v i cdng su, 2005). Tuong b; nhu vay, oxi hda chat beo cung giy ra nhiing van de nghidm trpng lam giam g i i tri cam quan v i dinh duong ddi vdi san pham thiiy san (Ladikos and Ixmgovois, 1990).
Nghidn ciiu vd dich chid't Ii t r i xanh da duoc mot sd tie gia bao cio (Ld Ttr Hai va cdng su, 2010;
fiinh Via Dien va cong su, 2009). Tuy nhidn, trong c^ bio cio nay cic t i c gia chi chti trong d^n hieu swat tiiu hoi dich chiet thd, ham luong tanin,...chii cnuadanh gia hoat tinh chdng oxi hda ciia dich chiet
thu dupe. Ngoii ra, dung mdi chi^t su dung khdng phii la nude m i li sir kdt hpp giira dung mdi hiiu ca vdi nude theo mdt ty Id nhat dinh hoic chi dung mdi hiiu ca (Ld Tu Hai va cdng sir, 2010). Vi viy, muc tidu ciia nghidn ciiu niy li: (1) nghidn ciiu anh hudng cua cic didu kien chid't la tri xanh de thu duoc dich chi^t cd hoat tinh chdng oxi hda cao nhat str dung dung mdi l i nude; (2) thu nghidm i p dung dich chi^t thu dugc trong vide h^in che su bidn den b tdm vi oxi hda chat beo cho thit ci.
L l O Y B H VAT U$U VA PHUONG PHAP niGHIBV Ciiu 1. Nguydn, vit li§u
Li t r i xanh {Camellia sinensis var. sinensis) duoc sir dung trong nghidn ciru d d ^ g tuoi. Nguydn lidu dugc bim nhd trude khi thyc hidn qui trinh chiet. Tdm the chin tring {Litopenaeus vannamei), CO tdm 116 120 con/kg. C i thu ngang (Acanthocybium solandn), loai cd chat lugng tdt nhit, cd 4 - 4,5 kg/con. Tat c i nguydn lidu trdn dugc mua tai chp Vinh Hai, TP. Nha Trang, Khanh Hda.
2. Hda chit
DPPH (l,l-Diphenyl-2-picrylhydrazyl, do tinh khi^t > 99%), TBA CThiobarbituric axit, do tinh khi^t
> 98%), TCA CTricloaxetic axit, do tinh khi^t > 99%) va cdn 99,5°. Tit ca hda chit str dung trong nghidn ctiu thudc dang tinh khiet va phii hgp trong phia tich.
B$ mon Cdng ngh? Che bien Thiiy sin, Khoa Cdng ngh?
%c phim, Bjii hoc Nha Trang
N6NG NGHIEP VA PHAT TRIEN N 6 N G THON - KY 1 - THANG 6/2012 65
KHOA HOC C d N G N G H |
3. Phuomg phip nghidn ciru
a. Bd tri thi nghiem xic d/nh cic thdng sdtd'i uu cho qui trinh chid't
Trong qui trinh chi^t, mdt trong nhtrng myc tidu quan trgng nhit li thu dugc djch chidt cd hoat tinh chdng oxi hda cao. Hoat tinh niy chju i n h hudng bdi bdn y^u td chinh gdm: Nhidt dO, thdi gian, dung mdi chidt v i ty 1$ nguydn lidu so vdi dung mdi. Trong thyc nghidm niy, nude dugc chgn lim dung mdi chidt, ba ydu td cdn 1^ dupe nghidn ciiu nhim tim ra chd dd chidt tdi uu d^ thu duge dich chi^t cd hogt tinh chdng oxi hda cao nhit. Nhidt dd dupe bd b-i 6- ba miic (70, 80, ^QTC). thdi gian b ba miic (0,5,1, 1,5 gid), ty Id nguydn Udu so vdi dung mdi chidt b bdn miic (1:15. 1:20, 1:25. 1:30 (w/v)). Bd tri thi nghidm theo qui hoach toin phin gdm tdng cdng 36 thi nghidm dupe thi;c hidn, mdi thi nghidm duge lip l?ii hai lin. K^t qua bio cio l i gii trj trung binh.
b. Xuly ngim miu tdm, d bing dich chii'tli tri xanh
Tdm dirge cho xdc nhidt trong nude da lanh vdi ty Id di:nude:tdm la 1:1:1, cho ddn khi tdm ch^t hoan toan. Tiep theo, tdm dupe xii ly ngam trong dung dich chiet l i tra xanh vdi ty Id tdm so vdi dich chi^t Ii 1:2 (w/v) trong 15 phut. Sau dd, tdm duge vdt ra, dd rao trong 2 phiit truoc khi cho vio cic dia xdp, dimg man co PE bao hoc bdn ngoai va ti^n hanh bao quan b 5''C trong tu l^nh. Mau ddi chiing khdng xu ly ngam trong dich chi^t GTE ma thay bing nude ciing duge chuan bi trong cung didu kidn nhu trdn.
C i thu nguydn con dirge cit thinh timg khiic vdi do day khoang 3 cm (khdi lupng 151 ± 29,5 g/midng) sii dung dao cit. Sau dd, cic khua c i dupe c i t lim bdn phin bing nhau, da, g i n v i c a thjt dd dupe lo^i bd. Mdi mi^ng c i cd khdi lupng trung binh khoang 20 g/midng. Cic midng c i dupe ngim trong djch chidt l i tra xanh vdi ty l i 1:2 (w/v), trong 15 phiit, d^
rao trong 2 phut tnrde khi cho vio cic dia xdp, dung man co PE bao bgc bdn ngoai v i ti^n hinh bao quan d 5°C trong tu lanh. MSu ddi chiing cQng dugc chuln bi trong didu kidn tuong tir nhu trdn, ngoai trir dich chidt dupe thay bing nude.
c. Xac dinh khi ning chdng oxi hda cua dich chiet la tri xanh
Kha ning chdng oxi hda cua dich chiet dupe xac dinh bing ning lire khu gdc tu do DPPH. Ning lye khu gdc ttr do DPPH dugc x i c dinh theo phuong
phip ciia Fu Hui-Yin va cdng su (2002) vdi mpt su hidu chinh nhd. Khoing 20 ul ddn 140 pi djch chi^t trdn vdi nude c i t d^ dat th^ tich tdng cdng 2 ml, thdm 1 ml cdn tuy^t ddi (99,5"), lie d^u. Sau dd thdm 1 ml dung dich DPPH 0,2 mM, lie ddu va d^ ydn trong bdng tdi 30 phut. DO h i p thu quang hgc dupe do b budc sdng 517 nm (Spectrophotometer, Carry 100, Varian, Australia). Ning luc khii gdc tu do DPPH dugc x i c dinh theo cdng thiic sau: DPPH (%)
= 100 X (ACT - ASP)/ACT. Trong dd: ACT: dd hap thu quang hpc cua miu tring khdng chiia dich chi^t; Agpi Dd h i p thu quang hgc ciia mau cd chiia dich chidt.
d. Dinh gii cim quan tdm
Sir bidn den cua tdm dugc danh gia true tidp bing cim quan theo Montero v i cdng su (2001).
d. Xic dinh cic chi't phin ung vdi axit thiobarbituric (TSARS)
Cic chit phin ling vdi TBA dugc x i c dinh theo phuong phip ciia Lemon (1957) vdi mdt su hidu chinh nhd. Khoang 5 g thit tdm hoic ca da dupe xay nhuydn trgn vdi 10 ml dung djch chi^t TCA 7,5% va ti^n hanh chi^t trong thdi gian 15 phiit, sau dd loc qua giiy Igc sd 1. Phan dich Igc thu dupe trdn voi dung dich TBA 0,02 M theo ti Id th^ tich bing nhau d^ dat thd tich tong cdng la 6 ml trong mpt dng nghidm 10 ml v i giii a nhidt do sdi trong 40 phiit Sau dd lam ngugi duoi vdi nude chay d^n nhidt dp phdng truoc khi di x i c dinh dp h i p thu quang hpc d budc sdng 532 nm (Spectrophotometer, Carry 100, Varian, Australia). Ham lugng malonaldehyt (MAD) dugc tinh toin tir duong cong c h u ^ dugc xiy dung vdi ndng dd MAD tir 0,01 d^n 0,05 pM. K^t qua dugc b i o cio l i rag MAD/kg thjt tdm hoic ci. Moi phan tich dupe th^c hi^n l$p 1^ ba lin. K^t qua bao cao la gii tri bung binh.
e. Xulysdli$u
Gii tri IC50, di^m cam quan bi^n den va su oxi 1 hda chit bdo CTBARS) dugc xu ly trdn phan mem ; Statistica 8.0 (Stasoft. Tulsa, Ok, USA). Ki^m dinh Tukey dugc thtrc hi^n sau phan tich ANOVA d^ danh gii sv khac nhau vdi miic y nghia p < 0,05.
•.KfTQUAVATHAOLIIAN
1. Xic dinh c i c thdng sd tdi im cho q u i trinh chi^t l i t r i xanh
Gii ti-i IC50 ciia dich chi^t l i tra xanh (GTE) dupe thyc hidn bdi 36 di^u kidn chi^t khac nhau v^
nhi§t dd, thdi gian va ty 1$ nguydn lidu so vdi dung
66 N 6 N G NGHllP VA PHAT TRIEN NONG THON • KY 1 • T H A N G 6/2012
KHOA HOC CONG NGHE
in6i Cky hi^*^ tir TNI den TN36) dugc trinh bay trong hinh 1. Nhi^t do, then gian va ty \i nguydn li^u so v6i dung moi chiet co anh Huong d^n boat tinh chong oxi hoa ciia dich chi^t thu dupe. K^t qua nghien ciiu cho thay qua trinh chi^t du(?c thuc hi6n theo TN3 (90'C, 0,5 gio, 1:15 w/v), TN4 (70"C, 1 gia, 1:15 w/v) vaTN7 (TCC, 1 gio, 1:15 w/v) cho dich chiSit c6 gia tri IC50 th^P nhat, thap ddng k^ so voi cac di^u ki^n chiet con lai (p < 0,05). Gid tn IC50 ciia chiing tin lugt la 67, 65 va 64 nl. Ket qua phan tich ANOVA chi ra ring gia tri IC» cua dich chi^t theo TN3, TN4 va TN7 Ithong khac biet dang k^ (p > 0,05). Vi vay, co the ket lu|n rang de thu duoc dich chiet co hoat tinh chong oxi hoa Ion nhat co th^ tien hanh chi^t theo dieu ki^n TN3 hoac TN4 hoac TN7.
Mpt so tac gia khdc cung da nghien cuu di6u iuen chiet la tra xanh. Dinh Van Dien va cong su (20O9) nghien ciiu chiet hpp chat polyjihenol tu che xanh vun ling dung trong san xuat thuc pham chiic
nang. Cac tac gia nay da xac dinh duoc dieu kien chiet thich hijp ddi vol 14 tra xanh la: Nhiet do 77"C, thoi gian 42 phiit va ti le nguyen litu so voi dung moi la 1:10 (w/v). LS Tu Hai va cong su (2010) nghien cim tach chiet tanin tir la tri xanh da xac dmh duoc diiu ki^n toi im d^ chiit tanin nhu sau: Kich thuoc nguyen li^u 1 - 5 mm, ti If dung moi nuoc/etanol la 50/50, chiet b nhift do soi, thoi gian 90 phiit, ti 16 nguydn lieu/dung moi la 1:25 (w/v). Ket qua nghien ciiu ciia Amara va cong sir (2006) chi ra rang co the dat dmic hieu suat chiet la tra xanh cao nhat 6 nhiet do 95"C, thoi gian 10 phiit, ty le nguyen lieu so vol dung moi 1:40 (w/v), dung moi chiet bang nuoc. Co mpt sir khac biet giua k^t qua tim duoc cQa nghidn cuu nay so voi cdc ket qua cong bo cua cac tac gia trin; co thi la do sir khac nhau vi diiu kien chiet, dung moi chiit, ty li dung moi chiet, xu ly nguyen
\\iu truoc khi chlit.
q
- 1 -
h 1 hh
d - k' d e
0
i i , I 1 ^ b *= I I I
c c
III
Oi'fu ki^n chiet
Hinh 1. Gia tti IC51, dia djch chiA U t r i xanh dupe chiit boi nhiiu diiu ki^n khic nhau. Cic ky hif u tr6n cdt khic nhau chi ra su khic nhau ding k i (p < 0,05)
Sg. 2 Su thay ddi ch^t lupng cSm quan ciia tdm
^ ^ qua tiinh bao q u ^ lanh
Xii ly torn bing dich chidt la tra xanh (GTE) diic^theo cac didu kidn da dupe xac dinh (TN7) c6 tac dung han chd su hinh thanh ddm den trong thoi^lian bao quan lanh b 5"C. Diem cam quan bienMpn cua mau tdm dupe xii ly b i n g GTE thap Ironaang ke (p < 0,05) so V('n mau doi chun^f (hinh
^va 3). Nhin chung, drini den xuat hien ro sau 5 ngay bao quan. D|ch chiel GTE c6 lac dung han fhe sir hinh thanh ddm den a torn da duoc b ^ c a o W miit sd tac gia (Nirmal va Benjakul. 2009,"2010,
2011). Sd di dich chiet GTE cd tac dung han che bidn den a tdm la vi trong dich chidt GTE cd chiia cic chat lie chd enzym tyrosinaza, day la emzym dong vai trd quan trpng trong su hinh thanh bidn den b tdm. Mdt sd chat lic che tyrosinaza da dupe nhan didn trong dich chidt GTE nhu catechin, epicatechin, epigallocatechin, epigallocatechin gallate va epicatechin gallat (Nirmal va Benjakul, 2010); axit ferulic (Nirmal va Benjakul, 2009). Sir dung dich chidt GTE b ndng dd thich hpp cd tac dung han chd su bidn den o tdm. Theo Nirmal va Benjakul (2010) da chi ra ring tdm nguydn con
NONG NGHIEP VA PHAT TRIEN N O N G T H 6 N - KY 1 - THANG 6/2012 67
KHOA HQC CdNG NGHfi
duoe xu ly vdi GTE b ndng dd 5 g/l cd di^m cim quan bi^n den thip hon dung k^ so m^u ddi chiing.
Kdt qua nghidn cim cua dd l;\i nay cung chi ra kdt qua tuong tu.
Tuy nhidn, trong dd tai n^y da sir dung true tidp dich chidt GTE iin khdng phai thdng qua quJi trinh lam khd d^ thu dgng bdt vk hda tan trcr lai <\o thu dich chidt.
0 ngay 3 ngiy
Hinh 2. S\/ thay ddi ch^t lupng cam quan cua tdm trong quk trinh bio quin l^h b 5°C. C<ic ky hl$u trdn cdt khic nhau chi ra sir khic nhau ding ki(p<
0,05). GTE chuin bj theo TN3 5 ngiy 7 ngiy 9 ngay
„ mK i:^44:/immW^-¥^
• c^^l;^ ( g f ^ H ^
Hinh 3. S\f thay ddi muc dd bidn den ctia tdm trong qui trinh bio quin l^nh b S^C. GT^ chu^ b| theo TSZ 3. Oxi hda ch^t bdo cua thit tdm trong qui trinh
bao quan
Su thay ddi gia tr; TEARS trong qui trinh bio quan tdm d 5"C dupe trinh bay trong hinh 4. Nhin chung, gii tri cua TEARS ting dang k^ (p < 0,05) trong 5 ngay bio quan dau tidn trude khi giim tdi 7 ngay va sau dd tidp tuc tang trd lai tdi 9 ngay. Mau xiJr ly bang dich chi^t la tri xanh ludn cd gii tri TEARS thap hon ding kd (p < 0,05) so vdi miu ddi chung trong sudt qui trinh bao quin. Cu th^, trong 5 ngiy bao quan dau tien gii trj TEARS cua miu ddi chung ting tir 1 ddn 3,54 mg MAD/kg thjt tdm, trong khi dd ddi vdi miu xu ly bing GTE li 0,94 ddn 2,89 mg MAD/kg thit tdm. Tai thdi didm 9 ngiy bao quin, gii tri TEARS ciia mau ddi chung Ii 2,72. Trong khi dd, mau GTE chi la 2,19 mg MAD/kg.
Gia tri TEARS tang li do qui trinh oxi hda chit beo didn ra manh md trong giai doan diu, cic sin pham cua qui trinh oxi hda ch^t beo nhu hydroperoxit dupe hinh thinh vi nhanh chdng bj oxi hda thanh cic sin pham bac hai nhu aldehyt (Eenjakul vi cpng sir, 2005b). Cic san pham oxi hda bic hai tidp ttic bj bidn ddi thinh cic sin pham khac dudi tic ddng cua enzym vi vi sinh vat, dan d^n lam
giam gii tri ciia TEARS (Nirmal vi Benjakul, 2009a).
Mau tdm dupe xir ly bang GTE cd gia tri TEARS thap hon mau ddi chung li do trong djch chidt GTE cd chua cic chat chdng oxi hda nhu catechin vi cic din xuat cua no, day la nhimg chit chdng oxi hda manh (Nirmal vi Benjakul, 2011), Nirmal vi Benjakul (2009b) cung da bio cio ring catechin (1 g/l) cd kha nang chdng oxi hoa mgnh me trong thit tdm trong qui trinh bao quin trong da Ignh.
Hinh 4. Svr thay ddi gii tri TBARS cOa thit tdm tiong qui trinh bio quin 1 ^ dr S^C. Cic k;^ hi^u tr&n cOt khic nhau chi ra si; khic nhau ding k^ 0> < 0,05).
GTE chufc bi theo TN3
68 NONG NGHllP VA PHAT TRIEN NONG THON - K^ 1 - THANG 6/2012
KHOA HOC CdNG NGHfi
4. Oxi hda chit b ^ cOia thit c i trong q u i trinh bao quan
Thit ca thu dupe xu ly bang dich chi^t l i tra xanh c6 tac dung han che sir oxi hda chat beo ding U(p< 0.05) so vdi miu ddi chung Oiinh 5). Trong 5 ngay bao quin dau tidn, gia tri TEARS ciia mau ddi chmig tang tir 0,88 den 1,44 mg MAD/kg thit ci, Irong khi dd ddi vdi mau dupe xii ly bdi GTE thi giam tir 0,94 xudng 0,66 mg MAD/kg thjt ci. Tai thdi di^m 9 ngay bao quan, trong khi gii tri TEARS cua miu d6i chiing la 1.74 mg MAD/kg thi miu xii ly GTE chi la 1,07 mg MAD/kg thit ci. K^t qua nghidn ciiu nay cho thfiy sir dung dich chiet GTE cd tic dyng h^n ch^ su oxi hda chat bdo mdt each rd rdt. Kdt qua nghien cihi nay cung phii hpp vdi cdng bd ciia Tang VEl cong su (2001) khi thdm dich chidt tra xanh cd tic dung han chd su oxi hda chat beo cho sin pham ca thu vien trong thdi gian bio quin lanh d 4"C. Djch chiet la tra xanh cd tic dung chdng oxi hda da dupe bio cao bdi nhidu tie gii (Nirmal vi Eenjakul, 2010, 2011; Tang va cdng sir, 2001). Vi vay, sir dung dich chi^t nay nhu la mdt each an toin va hieu qui trong viec han str oxi hda chat beo.
Hinh 5. Su thay ddi gii tri TBARS ciia thit c i trong qui trinh bio quan lanh 6 5°C. Cic ky hi^u trdn cdt Wi^ nhau chi ra su khic nhau ding k^ (p < 0,05).
GTE c h u i n b i theo TN3 nr. XET LUAN
Dich chiet tir l i tri xanh thu dirpc tir cic didu ki&n chiet tdi uu da dupe xac dinh bao gdm; nhidt dd 70°C, thdi gian 1-1,5 gid, ty le nguydn liduinude (1:15, w/v) hoac nhiet dd 90"C, thdi gian 0,5 gid, ty !§
nguyen lidu:nude (1:15, w/v). Djch chiet thu dupe cd ho^t tinh chdng oxi hda vi k h i nang ire chd hieu q u i sir hinh thanh ddm den b tdm v i han che su oxi hda
^at beo cho thit c i trong q u i trinh b i o quan lanh b 5X. Ket qua nay cho thiy tiem n i n g cd th^ sir dung
dich chidt tir la tra xanh trong bio nguydn lieu thuy sin sau thu hoach.
LOICAMON
Tic gii gui ldi cim on chin thanh den Phong Thi nghiim Cdng nghi Sinh hpc, Vien Cdng nghi Sinh hpc va Mdi trudng, D^ hpc Nha Trang da hd tro ve ca sd vit chit cho nghidn cuu. Bdn canh dd, cic tac gii cung niudn gui ldi cam on siu sic den NguySn Hoang Duy Quang vi Lirj TdDio dagiup da chung toi trong qui trinh chuan bi mau vi phin tich miu.
TAI UfU THAM KHAO
1. Amara P. U., Mojica S., Zeljko K.. Bernd W., Frank 0., Sabine G. (2006). Extraction of active ingredients from green tea (Camellia sinensis/.
Extracttion efficiency of major catechin and caffeine.
Food Chemistry, 96,597-605.
2. Benjakul, S., Visessanguan,W., Phongkanpai, v., & Tanaka, M. (2005b). Antioxidative activity of caramelisation products and their preventive effect on lipid oxidation in fish mince. Food Chemistry, 90,231-239.
3. Dinh Van Dien, Nguydn Thi Eich Hanh, Tran Trpng Loan. Nghidn ciiu qui trinh trich ly polyphenol tir li che xanh vun va ling dung U-ong thuc pham chiic nang (2009).
4. Fu H. Y. and Shieh D. E. (2002). Antioxidant and free radical scavenging activities of edible mushrooms. Journal of Food Lipid, 9,3546.
5. Khan N., and Mukhtar H. (2007). Tea polyphenols for health promotion. Life Sciences, 81, 519-533.
6. Ladikos D. and Lougovois V. (1990). Lipid oxidation in muscle foods: A review. Food Chemistry, 35, 295-314.
7. Lemon D. W. (1957). An improved TBA test for rancidity. New Series Circular, 51,52-55.
8. ht Tu Hii, Pham Thi Thiiy Trang, Duong Ngpc Cim va Tran Van Thim (2010). Nghidn ciiu chiet tich, xac dinh thanh phan hda hpc ciia hpp chat tanin tir la tra xanh vi khao sat tinh chat lie che an mdn kim loai ciia nd. Tap chi Khoa hpc va Cdng nghd. Dai hpc D i Ning. sd 1 (36), trang 71-76.
9. Montero, P., Lopez-Caballero, M. E., Perez- Mateos, M. (2001). The effect of inhibitors and high pressure treatment to prevent melanosis and
N 6 N G NGHIEP V A PHAT TRIEN N O N G T H 6 N - KY 1 • THANG 6/2012 69
KHOA HOC C d N G NGHC
microbial growth on chilled prawns (Penaeus Japonicus). Journal of Food Science, 66.1201-1206.
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EFFECT OF GREEN TEA LEAF EXTRACT CONDITIONS AND APFUCATION IN RETARDATION OF SHRIMP MELANOSIS FORMATION AND FISH MEAT LIPID OXIDATION
Cao Thi Kim Nguyen, Nguyen Xuan Duy, Nguyen Anh Tuan Summary
Effect of green tea leaf (GTE) extraction conditions, including temperature, time and ratio of solvent/matenal and use of the GTC extract to inhibit melanosis fomiation of shrimp and prevention of bpid oxidation of fish meat was caned out. Results showed that optimal extraction condition to obtain cmde extract with the higliest antioxidative activity (based on DPPH radical scavenging capacity) as follow:
Temperature 70"C, time 1 - 1.5 hours, ratio of matenal/solvent was 1/15 (w/v) or temperature 90"C, time 0.5 hours, ratio of material;solvent was 1:15 (w/v). Solvent used for both was water. Shrimp samples were treated v^th GTE retarted significantly melanosis fomiation compared to control sample during refngerated storage at 5"C (p < 0.05). Similarly, fish meat samples were treated with GTE suppressed slgnificantiy lipid oxidation compared to control sample during refrigerated storage at SX (p < 0.05). Results obtained in this research indicated that potential of use green tea leaf extract in preservation of fisheries post-harvest Keywords: Shnnip melanosis fonnation. mackerel, green tea leaf extraction, lipid oxidation, white shrimp.
Ngudi phin bi$n: PGS.TS. NguySn Duy Lim Ngiy nhin bii: 10/11/2011
Ngay thdng qua phan bien: 12/12/2011 Ngiy duy^t ding: 20/12/2011
70 NONG NGHlf P VA PHAT TRIEN N 6 N G T H 6 N - KY 1 - THANG 6/2012
