NGHIEN CU KHOA HOC KY THUAT

ai hoc Nong Lam Tp. HCM Tap ch KHKT Nong Lam nghiep, so 3/2007

95

KHAO SAT S BO VA NGHIEN CU NANG CAO CHAT LNGKHO CA TRA PHONG CHAU OC - AN GIANG

PRELIMINARILY STUDY ON PROCESSING OF BLOATING FRIED DRIED TRA-BASAAT CHAU DOC AN GIANG AND TESTING TO IMPROVE ITS QUALITY

Nguyen Thuy Linh, Nguyen Duy Tan, Nguyen Huynh TanKhoa Thuy san, ai hoc Nong Lam Tp. Ho Ch Minh

ABSTRACT

Bloating fried dried Tra-Basa was one of specialcommodities at Chau Doc An Giang, the provincewhich had over 45 big and small bloating frieddried Tra-Basa shops. Their processes were notbeen ensured in terms of hygiene standardbecause they soaked fish meat in the river waterand dried them on the outdoor drying ground.

The aim of this study were: (i) preliminarilyinvestigate the processing of bloating fried driedTra-Basa at Chau Doc An Giang; (ii) suggest sometechnical parameters in processing to improve thequality of this product.

There were three (3) experiments to guaranteethe hygiene standard and to improve flavor andtaste of bloating fried dried Tra-Basa safe: soakingfish meat in tap water, soaking fish meat in saltsolution and drying. The result showed that theconcentration of NH3 was in safe range (24.04 mg/100g) if soaked in 20 hours and the sense valuewas best (3.46 mark). The salt content was reducefrom 10.11% to 7.66% when soaked in 13% saltsolution for 5 hours. The peroxide got 3.65 mg/100g at 45oC when dried for 32 hours and the sensevalue were improved.GII THIEU

Hien nay, thc trang au ra cho san pham canuoi nc ngot khong on nh, gap nhieu kho khan.Ca Tra cung khong ngoai le. ay la loai ca co giatr kinh te cao, c ngi dan ac biet la cactnh ong bang song Cu Long au t nuoi ratnhieu. V vay, viec th trng tieu thu cac san phamche bien t ca Tra khong on nh anh hng ratln en kinh te gia nh cua nhng ngi dan nay.Mat khac, cung vi s phat trien kinh te th nhucau ve thc pham cua con ngi ngay cang cchu trong hn ac biet la ve gia tr dinh dng,cam quan cung nh tnh tien dung cua san pham.

Van e at ra cho nganh che bien thuy san lanang cao gia tr gia tang, a dang hoa san phamcung nh am bao ve sinh an toan thc pham oivi san pham che bien t nguon li ca nc ngotnoi chung va oi vi ca Tra noi rieng.

San pham kho ca tra phong la mot trong nhngac san Chau oc An Giang c nhieu ngibiet en. Hien nay tai Chau oc An Giang co nhieu

c s san xuat, tuy nhien san pham kha man,ieu kien ve sinh cha c quan tam. e tai Khaosat mot so c s san xuat va nghien cu nangcao chat lng kho ca Tra phong Chau ocAn Giang nham cai thien o man cho phu hpvi th hieu ngi tieu dung cung nh nang caochat lng ve sinh, rut ngan thi gian san xuat sovi san pham kho ca tra phong tren th trng.

VAT LIEU VA PHNG PHAP

Khao sat tnh hnh san xuat kinh doanh khoca tra phong chau oc an giang

- So lieu c ghi nhan tai c s san xuat vaPhong thong ke Chau oc An Giang

- Ghi nhan quy trnh che bien tai c s sanxuat nham cai thien chat lng san pham da trenquy trnh ghi nhan

Th nghiem 1: Ngam trong moi trng ncmay

- Ca sau khi c cat au, moi ruot, lam sach vaphile lay hai mieng tht ca hai ben con nguyen da.Tien hanh em ngam trong moi trng nc may.- T le ca: nc c khao sat la 1:8.- Thi gian ngam c khao sat 18h, 20h,

22h, 24h.Cac ch tieu theo doi:

+ Phan tch NH3 (TCVN 3706-1990)+ anh gia cam quan (Ha Duyen T).

Th nghiem 2: Khao sat qua trnh p muoiCa sau khi ngam c em i p muoi theo

phng thc p muoi t tc la p ca trong dungdch nc muoi. Thay oi thi gian va nong omuoi.- Nong o muoi c khao sat la 10%, 13%,

16%, 19%.- Thi gian ngam c khao sat 3h, 4h,

5h, 6h.- Cac ch tieu theo doi:

+ Nong o muoi trong san pham (TCVN3701-1990)

+ anh gia cam quan. (Ha Duyen T)

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Tap ch KHKT Nong Lam nghiep, so 3/2007 ai hoc Nong Lam Tp. HCM

96

Th nghiem 3: Khao sat nhiet o va thi giansay- Ca sau khi ngam, p muoi, tien hanh say

vi cac nhiet o va thi gian say khac nhau.- Nhiet o say c khao sat la 40oC, 45oC,

50oC, 55oC.- Thi gian say c khao sat 20h, 24h, 28h,

32h.- Cac ch tieu :

+ o am cua san pham bang phng phapsay kho 1050C

+ Phan tch ch so peroxyt (TCVN 5777-1994)+ anh gia cam quan san pham (Ha Duyen

T)X ly so lieu

S dung phan mem Stagraphic 7.0 e so sanhs khac biet ve mat thong ke gia cac nghiem thcKET QUA VA THAO LUANKhao sat s bo tnh hnh san xuat kinh doanhkho ca Tra phong Chau oc

Hien nay, Chau oc An Giang co khoang 5c s chuyen san xuat ac san kho ca Tra phong,qui mo san xuat va va nho. Trong o, co the noic s san xuat kho ca Tra phong Trng Hai la coqui mo ln nhat vi vai chuc en hang tram congnhan vi hp ong lam viec theo mua vu, ke enla c s Nam Tan, Anh Quoc, Hai Ton, Hong aochu yeu tap trung phng Vnh My, th xa Chauoc.

Cac c s hang nam a cung cap ra th trngkhoang 880 tan san pham (so lieu phong van).Trong o, san lng cua cac c s c tnh nhsau:

- C s Trng Hai: 10 tan/lan x 4 lan/thang x10 thang = 400 tan/nam

- C s Nam Tan: 05 tan/lan x 4 lan/thang x 10thang = 200 tan/nam

- C s Anh Quoc: 03 tan/lan x 4 lan/thang x 10thang = 120 tan/nam

- C s Hai Ton: 02 tan/lan x 4 lan/thang x 10thang = 80 tan/nam

- C s Hong ao: 02 tan/lan x 4 lan/thang x 10thang = 80 tan/nam

Trong khi o, so lieu chung toi thu thap t phongthong ke th xa Chau oc la 614,5 tan/nam 2005tang khoang 16% so vi nam 2004 (531,7 tan/nam).

Theo thong tin t chu c s san xuat kho ca Traphong Trng Hai, th hien nay Ong ang bat tayvao viec lap d an xay dng nha may che bienthuy san, vi cong xuat 11.000 tan kho thanh pham/nam ngay tai Chau oc. Ong cung a c cac nha

khoa hoc gii thieu day chuyen san xuat cong ngheHan Quoc tr gia 600.000 USD, co the cho thanhpham 50 tan kho/ngay.

Qua ay, chung ta cung thay c mot xu hngphat trien tng lai cho san pham kho ca Traphong, mot ac san truyen thong cua ngi danChau oc tnh An Giang. Ha hen cho mot sanpham kho ca Tra phong chat lng tot, am baoan toan ve sinh thc pham cao, co the m rong thtrng tieu thu va xuat khau, ap ng nhu caungay cang cao cua th hieu ngi tieu dung.Khao sat quy trnh san xuat kho ca Traphong cua mot c s a phng

C s: Nam Tan (Thanh Truc)a ch: ap Chau Long I, phng Vnh My, th

xa Chau ocien thoai: 076.863041 076.867261Quy trnh san xuat kho ca Tra phong cua c s

Nam TanTheo chu c s th quy trnh san xuat cua cac c

s eu tng t nhau, nhng se cho san pham khacnhau tuy theo kinh nghiem san xuat cua moi c strong cac khau chon nguyen lieu, ngam noi, pmuoi va phi kho

Xat muoi

Ra muoi

Phi kho

Ngam nc

Cat au, moc ruot

Nguyen lieu (ca Tra)

Phi le

Vt ca

Thanh pham

Ca 0,9-9Kg/con

Ngam noi 28-32h

10 kg ca/2-4kg muoi 6-8 gi

NGHIEN CU KHOA HOC KY THUAT

ai hoc Nong Lam Tp. HCM Tap ch KHKT Nong Lam nghiep, so 3/2007

97

Theo quy trnh san xuat cua c s kho ca Traphong Nam Tan tren, chung toi nhan thay comot so van e can ban luan nh sau:- Ca c cat au xe bung ngay khi mua ve e

tranh hien tng ca chet ong mau trong cac ctht anh hng en mau sac cua san pham.- Ngam ca trong khoang 4-6 h trc khi phi le,

e ca dien ra qua trnh te cng va de dang trong viecphi le. (Kch hoat cho vi sinh vat, enzyme trong noitang ca hoat ong va xam nhap vao c tht chuan bcho qua trnh phan giai dien ra sau o).- Trong san xuat ch nhn ca noi mc o nao

la vt ra c, no anh hng trc tiep en mui vcua san pham; cung nh trong kinh nhgiem gainen ca khi muoi va nhn biet c mieng ca naoan muoi hay khong an muoi ma co phng phapkhac phuc tot hn.Tuy nhien khau ngam ca trong cac be nc trensong Hau, chung toi nhan thay cha am bao vesinh nc mat tren cac song Tien va song Hau khu vc ong bang song Cu Long ngay cang b onhiem ve nong o chat hu c, thuoc bao ve thcvat, rac thai, o nhiem t cac long nuoi ca nhat lavao mua ma (Khoa hoc va phat trien, so 7, tr.4,13-19/2/2003).

T o, chung toi e xuat cai oi khau ngam noica trong moi trng nc may thay cho moi trngnc song ang ngay cang b o nhiem.

Trong khau lam kho, tuy khong ton nang lnge say kho do s dung anh nang mat tri nhng phuthuoc rat ln vao thi tiet nhat la vao mua ma, anhhng rat ln en chat lng san pham khi gap phainhng ngay tri ma lien tuc. Mat khac co the nhiemban trong qua trnh phi do phi tren nen xi mang,khong kiem soat c ruoi nhang

T o, chung toi thay neu cac c s co ieu kiennen lam kho san pham bang phng phap say thaycho phi nang.

Tren ay la 2 khau ma chung toi thay can phaicai tien, e am bao an toan hn ve mat ve sinhcung nh cac ch tieu hoa hoc cua san pham. Bencanh o, theo y kien cua nhieu ngi tieu dung lasan pham rat man, nen can nghien cu xem cothe giam lng muoi xuong en mc co the chapnhan ma khong anh hng en viec bao quan vahnh thai cau truc cua san pham.Ket qua khao sat qua trnh ngamCh tieu NH3 (mg/100g)

Qua x ly thong ke chung toi nhan thay s khacbiet gia cac nghiem thc la co y ngha ve matthong ke vi P < 0,05. Nh vay, ngam ca trongnc may cac thi gian khac nhau th ham lngNH3 tao ra trong tht ca cung khac nhau.

Trong thi gian au (t 18h en 22h) lng NH3tao ra khong nhieu bang vao thi gian sau (t 22hen 24h) va ham lng NH3 tang dan theo thigian ngam t 21,27 mg/100g tht ca 18h en 31,41mg/100g 24h. Tuy nhien tat ca ham lng NH3nay eu nam trong gii han cho phep ( 40 mg/100g-TCVN).

Ben canh o chung toi cung tien hanh anhgia cam quan

Qua hai ch tieu ham lng NH3 va anh giacam quan chung toi chon thi gian ngam tht catrong nc may la 20h. Thi gian ngam ngan hnso vi cac quy trnh tham khao cac c s (28 32h) va ngam nc may th at chat lng ve sinhhn, tranh c s nhiem ban cua cac chat o nhiemkhac co trong nc songKet qua khao sat qua trnh p muoiCh tieu ham lng muoi trong tht ca

Qua x ly thong ke, chung toi nhan thay, skhac biet gia cac nghiem thc la co y ngha vemat thong ke vi P < 0,05. Ham lng muoi trongtht ca tang ty le thuan vi thi gian va nong o

0

10

20

30

40

18 20 22 24

Thi gian (gi)

NH

3 (m

g/10

0g)

o th 1. Anh hng cua thi gian ngam en ham lng NH3 (mg/100g)

NGHIEN CU KHOA HOC KY THUAT

Tap ch KHKT Nong Lam nghiep, so 3/2007 ai hoc Nong Lam Tp. HCM

98

dung dch muoi ngam theo phng trnh tng quanz = - 1,85 + 0,87x + 0,37yanh gia cam quan

Qua hai ch tieu ham lng muoi trong tht cava ch tieu cam quan chung toi chon ngam tht catrong dung dch muoi co nong o 13%, thi gianngam la 5h. So vi san pham cua cac c s Chauoc th san pham cua th nghiem co v t man hn(7,66% con cac c s Chau oc la e 10%) vathi gian ngam ngan hn.Ket qua khao sat qua trnh sayAnh hng cua che o say len ham lng peroxideva am o cua san pham

o am cua tht ca giam dan theo nhiet o vathi gian say theo phng trnh tng quan z =106,01 -1,08x 0,67y vi R2= 95,95% Co s khacbiet co y ngha gia cac nghiem thc ve mat thongke vi P < 0,05; va s khac biet gia cac nghiemthc la co y ngha ve mat thong ke.

Chung toi cung nhan thay ca tra la nguyen lieucha nhieu chat beo, di tac ong cua nhiet ode dang tao thanh cac peroxide; khi thi gian keo

dai, nhiet o tang cao, ham lng peroxide sansinh ngay cang nhieu va ham lng peroxide cuatht ca tang theo phng trnh tng quan z = -7,06 + 0,13x + 0,15y (R2 = 96,7%).

Che o nhiet cung anh hng kha ro len gia trcam quan cua san pham qua o chung toi anh giachat lng cam quan san pham qua 4 che o nhiettot nhat

Theo ket qua anh gia cua cac cam quan vienth iem cam quan mau 2 c anh gia cao nhat:mau sac (2,730,05), mui v (2,730,05) va cau truc(2,73b0,04).

Qua ba ch tieu am o, ham lng peroxyde vach tieu cam quan toi chon say tht ca nhiet o45oC, thi gian say la 32h.

Say kho tht ca bang may say rut ngan cthi gian lam kho ca, ong thi co the chu ongc qua trnh lam kho, khong phu thuoc vao thitiet nh phng phap phi nang ma cac c ssan xuat thc hien. Mat khac no tranh c snhiem ban bui cat trong qua trnh phi gop phancai thien ve sinh cho san pham.Ket qua phan tch mau san pham:

4

5

6

7

8

9

10

11

10% 12% 14% 16% 18% 20%

Nong o NaCl dch ngam

Ham

ln

g N

aCl t

rong

ca

sau

khi n

gam

(g

/100

g)

3h 4h 5h 6h

o th 2. Anh hng cua thi gian va nong o muoi trong qua trnh ngam ca

Bang 1. Ket qua anh gia cam quan cua qua trnh ngam

Ch tieu Mui Cau truc

18h 20h 22h 24h 18h 20h 22h 24h 0,30a0,03 4,79b0,04 -1,33a0,02 -2,63a0,03 -1,63x0,04 3,64xy0,05 2,30yz0,03 -3,46z0,04

Ghi chu: a, b, c cho biet s khac biet co y ngha ve mui vi xac xuat p < 0,05. x, y, z cho biet s khac biet co y ngha ve cau truc vi xac xuat p < 0,05.

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99

Bang 2. Ket qua anh gia cam quan cua qua trnh ngam muoi

Ch tieu V Cau truc

3h 4h 5h 6h 3h 4h 5h 6h 0,73a 0,03 -2,36c0,02 2,73b0,05 -1,10c0,02 1,03x0,03 -1,03y0,01 2,73x0,04 -2,73y0,03

Ghi chu: a, b, c cho biet s khac biet co y ngha ve v vi xac xuat p < 0,05. x, y, z cho biet s khac biet co y ngha ve cau truc vi xac xuat p < 0,05.

o th 3. Anh hng cua nhiet o va thi gian say len am o va ham lng peroxide cua san pham

30

35

40

45

50

55

23 25 27 29 31 33 35 37 Thi gian (h)

2

3

4

5

6

aw40oC aw45oC aw50oC aw55oCp40oC p45oC p50oC p55oC

Am o/aw (%) peroxyde (mg/100g)

Bang 3. Anh hng cua che o say len gia tr cam quan cua kho ca tra phong

Nghiem thc Ch tieu 40oC/36h 45oC/32h 50oC/28h 55oC/24h

Mau sac 0,73a0,02 2,73b0,05 -2,36c0,04 -1,10c0,02 Mui v 1,03a0,06 2,73b0,05 -1,03c0,03 -2,73c0,03 Cau truc -2,36a0,04 2,73b0,04 0,73c0,02 -1,10a0,02

Ghi chu: a, b, c cho biet s khac biet co y ngha vi xac xuat p < 0,05.

Bang 4. Thanh phan hoa hoc cua san pham kho ca tra phong

Ch tieu n v tnh Ket qua Protid N amin Lipid Tro Am o Vitamin A Vitamin D

% % % % %

mg/kg

mg/kg

22,44 1,88 25,00 9,0

39,05 Khong phat hien

LOD = 0,3 Khong phat hien

LOD = 0,1

NGHIEN CU KHOA HOC KY THUAT

Tap ch KHKT Nong Lam nghiep, so 3/2007 ai hoc Nong Lam Tp. HCM

100

Cac ch tieu ve vi sinh vat nay ieu at tieuchuan do bo Thuy san qui nh cho san pham khos che (Bang 5).KET LUAN

Sau qua trnh thc hien e tai chung toi nhanthay e cai thien chat lng san pham kho ca traphong tai Chau oc-An Giang chung ta can thaynguon nc ngam noi bang nc sach; rut ngan thigian ngam (20h); giam ham lng muoi ngam sanpham xuong 13%; s dung may say e rut ngan thigian lam kho, chu ong hn trong san xuat cung nhcho chat lng san pham tot hn va ve sinh hn.TAI LIEU THAM KHAONguyen Trong Can va o Minh Phung, 1990. Congnghe che bien thc pham thuy san. Tap 1, Nguyenlieu che bien thuy san. ai hoc Thuy SanNguyen Thanh Hien, 2003. Thanh phan dinhdng cua ca Basa, ca Tra. Thong tin khoa hoccong nghe Kinh te Thuy san. NXB Nong nghiep,2/2003: 22 23.Huss H.H., 1995. Ca ti chat lng va cac bienoi ve chat lng. Bo thuy san an Mach. D ancai thien chat lng va xuat khau thuy san(Seaquip), Bo thuy san, 2004. NXB Nong nghiepHa Noi.

Bui Th Nh Thuan, 1991. Kiem tra chat lng vathanh tra ve sinh an toan thc pham. NXB Y hoc.Ha Duyen T, 2000. Ky thuat phan tch cam quanthc pham. ai hoc Bach Khoa Ha Noi.Finnbogadottir E., Magnusson H., Reykdal O.,Arason S., 2007. Dried fish as health food. Matsohf/matis Food research, inovation & safetySmith G., Hole M., Hanson S. W., 2006.Assessement of lipid oxidation in Indonesiansalted-dried marine catfish (Arius thalassinus).Food Chemistry, Volume 97. Issue 3, August 2006,Paages 490-497.James G. B., 2006. Food processing handbook.WILEY-VCH Verlag GmbH & Co.KGaA,Weinheim.Jon S. W., 2005. Sensor technology handbook.Elseviers Science & Technology RightsDepartment in Oxford, UK.Fellow P. , 2000. Food procession technology.Woodhead published limited and CRC press LLC,Ellits Horwood Ltd.

Bang 5. Ket qua kiem nghiem ch tieu vi sinh vat cua san pham kho ca tra phong

Ch tieu n v tnh Ket qua Salmonella E.Coli Tong men moc Staphylococcus aureus Vibrio parahaemolyticus Coliforms Clostridium perfringen TPC

/25g MPN/g CFU/g CFU/g /25g

CFU/g CFU/g CFU/g

Khong phat hien 0

< 10 20

Khong phat hien 50

< 10 1600