130 .^ HQi nghi KHOA HOC vA CdNG NGHg 2007
NGHIEN CUtJ CAC DAC TINH CUA M Q T SO MALT TlT THOC VA CAC DIEU KIEN TOI UtJ
DE TAO MALT THOC
Nguyin Thach Minh, Khoa Cdng nghe Thuc phdm - Sinh hoc, Trudng DHCN TPHCM Nguyen Xich Lien, Bd mdn Cdng nghe Thuc phdm, Truomg DHBK TPHCM
Hoang Kim Anh, Vien Sinh hoc Nhiet doi TPHCM
'r\
MOfDAU
Qua trinh nay mam la qua trinh sdn xuat malt cho cdng nghiep dd udng. Malt ciing cd the sir dung de ldm banh [9,10], dd udng khdng cdn [9,10] vd thiic an cho tre nhd [9,10,11]. Bdt ldm tir hat ngii cdc qua qua trinh nay mam dugc ghi nhan la cd gia tri ve dinh duong hon Id bdt lam tir ngii cdc chua qua nay mam [4,8,10]. Thuc pham cung cap tir bdt ngii cdc nay mam cd do nhdt thap, gid tri dinh dudng cao vd cd cdc dac diem phii hgp cho tre em trong thdi gian cai sura d cdc nude dang phdt trien [9]. Chat lugng cua malt ngii cdc phy thudc vao cdc dac diem tu nhien, gidng, dieu kien ngam vd uom mim, cdc chat hda hgc vd chat kich thich sinh trudng cho them vdo frong qua trinh ngam va ii mam [3,8]. Cd nhieu yeu td tdc ddng tdi qud trinh ndy mam. Trong hiu hit cdc frudng hgp, viec cung cap du oxy cho qud trinh hd hap, nhiet do vd do am phii hgp cho qua frinh frao ddi chat vd phat trien Id nhimg yeu td quan trgng nhat [3,7,14].
Gao (Oryza sativa) la loai ngii cdc quan trgng nhat tai cdc nude chau A. Hien nay, fren 60% calori frong khau phan an tai cdc nude dang phdt trien la tir gao [9]. Sir dyng tdt ngudn ngii cdc tir thoc gao, tao ra cdc sdn pham cd gia tri gia tang cao hon dl phuc vy cdng nghiep thyc pham la mdt hudng nghien ciiu cd triln vgng. Myc dich ciia nghien ciiu nay Id so sanh cdc dac tinh ciia mdt sd loai thoc d Ddng bdng sdng Cim Long va nghien ciiu ddnh gid qud trinh niy mam bang phuong phdp tdi uu hod thuc nghiem cdc yeu td toan phan de tim dieu kien thich hgp khi sdn xuat malt tir thdc.
VAT LIEU VA PHU'OfNG PHAP
Mau nghien ctru: Cac loai thdc sir dung trong nghien ciiu nay dugc lay tir Vien liia 6 Mdn, Can Tho
Qua trinh tao malt: Cdc mau thdc dugc ngam frong nude d cdc nhiet do vd thdi gian i khdc nhau. Sau 3h ngam cd sue khi, hat dugc liy ra, de rdo dl tao dilu kien tilp xiic vdi oxi. Sau khi ngam, hat dugc chuyin sang rd nhya phu giiy thim xung quanh dl duy tri do am cho qua trinh nay mim. Trong qua trinh nay mim cin thudng xuyen ddo frdn khdi hat. Hat sau khi nay mam dugc say frong thiet bi siy hdng ngoai d 5'o°C cho din • do am khdng ddi. Sau khi say, malt thdc dugc cho vao tiii nildng bit idn va bdo quan d \ trang thdi lanh.
Phin I: CdNG NGHg BigN Ddl SINH HQC
Ton that malt (%): Dugc tinh dya tren sy hao tdn khoi lugng chit khd frong malt.
Phan tich thanh phan boa hoc va enzyme: Xdc dinh ham lugng protein tdng bing phuong phdp Kjeldahl, hdm lugng lipid bdng phuong phdp Soxhlet, hdm lugng tinh bdt theo phuong phdp thiiy phan acid HCl [2]. Hoat do cua enzyme amylase dyoc phan tich dya fren nang luc dudng hda [2]. Cdc enzyme dugc chilt bdng nude d 40°C va cho thuy phan dung dich tinh bdt chuin. Lugng dudng khir tao thdnh nhd hoat ddng cua enzyme amylase dugc tinh theo phuong phdp iod. Ket qud dugc tinh bdng sd gam maltose tao thanh tir 100 gam malt d dilu kien tieu chuin. Toan bd cdc phan tich hda hgc va hda sinh dugc tiln hdnh ba lin, kit qud cd gid tri thdng ke bdi do lech tieu chuin cd y nghia.
Nghien cihi qua trinh tao malt: Qud frinh tao malt dugc nghien ciiu theo phuong dn qui hoach quay bac 2 Box-Hunter gdm 32 thi nghiem (frong dd cd 6 thi nghiem d tam) vdi 5 thdng sd ddc lap la thdi gian ngam (Xi), nhiet do ngam (X2), thdi gian uom (X3), nhiet do uom (X4), vd nong do Gibberilin (X5). Thdng sd phy thudc la sy hao tdn chit khd (YI), hdm lugng tinh bdt (Y2), hdm lugng protein (Y3), hoat lyc cua enzyme amylase (Y4) [5,6]. Cdc thi nghiem dugc lap lai 2 lin trong dilu kien ddc lap vd dugc phan tich bang phin mem Matlab-2006 vd Excel-2007. Phuong frinh hdi qui thu dugc cd dang nhu sau:
K = i)o - 1 ^^<, -^ I K ^: Xj -f E b,,Xf
Bdng 1. Cdc ylu td vd mu'c dg bidn thien cua chiing trong qui ho^ch quay bdc 2
Box-Hunter Thong s6 dpc l^p
Thdi gian ngam (gib"), Xi Nhiet dp ngdm (°C ), X2 Th6'i gian ucm (ngdy), X3 Nhiet dO u'cm (°C ), X4
Nong dp Gibberellin (mg/kg), X5
Mi>c biln thien - 2
0 5 0 5 0
-1 15 15 2 15 0.5
0 30 25 4 25
1 1 45 35 6 35 1.5
2 60 45 8 45
2
KET QUA VA THAO LUAN
Bdng 2 cho thiy cdc dac tinh tdng qudt cua hat thdc. Ham im trong hat Id tuong ddi phu hgp khi tao malt. Khdi lugng ciia mdt ngdn hat thdc la 25-28g, tuong ty nhu d hat liia miln (22-30g) nhung nhd hon so vdi hat dai mach (40-50g) [4]. Hdm lugng lipid, tinh bdt, tro d hat thdc ciing tuong ty nhu d hat dai mach nhung hdm lugng protein thi thip hon [4].
Kit qud tdn thit chit khd frong qud trinh tao malt dugc thi hien d Bdng 3. Tdn thit chit khd tir 4-7 ngdy la 4.52-16.32%. Tdn thit ngdy cdng tdng khi thdi gian ngam va uom mam tang.
182 HQi nghj KHOA HQC VA C O N G NGHg 2007
Bang 2. Thanh phdn vd ddc tinh cua cdc loai thdc khac nhau
Cac dac tinh' Dp 4m, % Kh6i iupng 1000 hat, g Protein, % Lipid, % Tinh bOt, %
Tro, % N§ng lyc nly m4m, %
OM 4088
13.2 24.86
8.65 1.20 69.7 3.53 90
VND 9520 12.4 25.99
7.19 2.31 46.53
5.09 78
AG24 8.60 24.89
6.17 2.90 49.6 4.85 80
OM 2514
9,3 26.85
8.58 3.01 63.36
3.81 92
OM 1490
10.2 25.40
6.74 3.10 64.32
4.11 82
IR 50404
10.2 24.24 7.99 2.90 60.11
2.51 87
Ndp 9.91 24.35
7.04 2.62 52.18
3.47 65
OM2517 9.29 26.26
7.26 2.30 65.54
3.74 85
L274 10.17 25.68 7.55 3.50 59.1 3.15 89
IR504 9.8 25.38
7.26 3.05 48.7 3.47 78
Bang 3. Ton thdt chdt khd trong qud trinh tao malt cua cac lea
Ngay 1 2 3 4 5 6 7
OM 4033 0.78 1.98 3.21 6.54 8.47 10.12 13.25
VND 9520 0.80 2.12 4.15 6.81 9.21 10.20 11.52
AG-24 0.75 1.85 3.25 5.61 8.75 9.87 12.29
IR2514 0.92 1.98 3.68 6.21 8.25 10.13 11.52
OM 1490 1.51 2.31 4.23 7.52 10.21 12.50 15.41
IR 50404 1.12 2.14 359 6.52 9.27 13.35 16.32
N^p 1.21 2.36 4.19 6.23 9.28 11.59 14.25
thdc khac nhau
OM2517 0.95 1.45 4.78 5.96 9.68 10.54 13.24
L274 0.87 1.98 2.35 4.52 8.24 10.21 13.12
%
IR-504 0.96 2.13 3.15 5.16 7.62 10.31 12.63
Ket qud d Bdng 4 cho thay nang lyc dudng hda (DC) cua cdc loai thdc nghien cuu.
Nang lyc dudng hda tang len theo thdi gian nay mam. Trong cdc loai malt nghien cuu, boat lyc cua hai loai malt thdc OM4088 va L274 dat gid tri cao nhit d ngay u mim thu 6 n20°WK). Hai loai thdc nip 78°WK vd AG24 cd nang lire dudng hda thip nhit la 68 WK. Nang lyc dudng hda cua cdc loai thdc cdn lai tuong duong nhau tir 96-
101°WK. Tdn thit chit khd cua OM4088 vd L274 (la 2 loai malt cd hoat luc manh nhit) la 10.12% nam trong sd cdc malt cd hao hut thap nhat. So sanh ham lugng protein frong hai loai malt OM4088 vd L274 ta thiy, ham lugng protein cua OM4088 (8.65%)) cao hon so vdi L274 (7.55%) nhung hoat tinh enzyme amylase cua chiing nhu nhau. OM 2514 cd hdm lugng protein khd cao nhung nang lire dudng hda thip hon hon hai loai malt ndi tren (95°WK).
Ngay nay milm
1 2 3 4 5 6 7
OM 4083
6 20
VND 9520 5 21
53 1 35
82 65 110 1 87 120 I 97
90 j 91
Bang
AG-24 5 12 35 45 67 63
4. Ndng
OM 2514
6 34 51 59 75 95
62 1 75
lyc dujdng hda
OM 1490
6 23 65 90 101
60 35
IR 50404
6 27 49 73 96 72 54
[DC),°WK
Ndp 4 8 16 28 34 56 73
OM2517 6 25 38 75 98 98 75
L274 6 25 36 95 112 121 100
IR504 6 25 54 \ 90 97 72 ^ 38 _ j !
Phin I: CdNG NGHg BigN Ddl SINH HgC 183 Sau khi nghien cuu cdc dac tinh cua malt thdc, chiing tdi chgn loai OM 4088 dk tiln hanh cho ndy mim vd xac .dinh cdc dilu kien tdi uu cua qud trinh tao malt Tdc ddng cua thdi gian npam, nhiet do ngam, thdi gian nay mam, nhiet do niy mim va ndng do gibberellin len tdn that chit khd, ham lugng tinh bdt, protein va hoat ddng ciia en2yme amylase duoc thi hien frong Bdng 5. Kit qua so sdnh cac he sd hdi qui theo tieu chuin Student (t) vdi cdc phuong sai tuong img va muc y nghia ciia he so hdi qui dugc thi hien frong Bang 6.
Bang 5: Cdc kit qud thyc nghi?m trong qud trinh tao malt bdng qui hoach Box-Hunter 32 thi nghiem.
S T T T N 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 - . 3 2
X, 15 45 15 45 15 45 15 45 15 45 15 45 15 45 15 45
Itt
30 30 30 30 30 30 30 30 30 30 30 30 30 30
Xz 15 15 35 35 15 15 35 35 15 15 35 35 15 15 35 35 25 25
25 25 25 25 25 25 25 25 25 25 25 25
X j
2 2 2 2 6 6 6 6 2 2 2 2 6 6 6 6 4 4 4 4
^ ^ ^
4 4 4 4 4 4 4 4 4 4
X, 15 15 15 15 15 15 15 15 35 35 35 35 35 35 - 3 5 35 25 25 25 25 25 25
^ ^ 4 5 . f e ^
25 25 25 25 25 25 25 25
x.
1.5 0.5 0.5 1.5 0.5 1.5 1.5 0.5 0.5 1.5 1.5 0.5 1.5 0.5 0.5 1.5 1 1 1 1 1 1
1 1
f^^!^P
it.--t.;-'J~ S:rf-yi5^-^-
1 1 1 1 1 1
Y, 2.65 ..:
3.45 2.15 4.65 : 4 . 2 2 :
:.6.75: ; ,5.83 •
••6.53X-
2.25 3.78
• 2.83 4.35
• 7.45
8.37 8.16 12.17 3.24.
...,.-':9.15. /^•
;••i•;6.45;:• .,
7.65 2.06
; 15.93 2.47 7.96 6.48 8.23 5.52 6.73 6.85 6.75 6.85 5.48
Y i •• : .^.
58.7 59.6 58.4' 57.9 59.7 62.7 61.1 60.3 64.8 62.1 65.2 61.4 56.8 60.1 57.1 54.2 67.4 .57.2'
60.5 59.9 63.4 49.6 61.8 • 56.7 59.4 53.8 61.2 58.5 61.8 57.5 61.1 58.2
Yj
7.85 7.65 7.84 7.72 7.55 7.65 7.76 7.42 7.86 7.54 7.86 7.97 7.85 7.84 7.55 7.98 7.37 7.51 7.65 7.51 7.65 7.75 7.55 7.66 7.44 7.55 7.15 7.43 7.45 7.64 7.53 7.22
Y4 4 8 12 42 58 79 95 102
15 10 25 36 90 95 115 130 100 ,140
120 135 12 155
21 9 120 165 145 132 136 141 130 148
184 HQi nghi KHOA HOC VA CONG NGHg 2007 Bdng 6. Cac h f s d t r o n g phu-cng t r i n h hdi q u i c d mu-c y nghTa p £ 5%
(* p<0.05; ** p<0.001; p <, 0.0001)
bo b,
b2 b3 b4
bs
bi2 b34
b„
b22 b33 b44
bss
Yi,T6n that chat kho H$s6
6.679 1.098 0.423 2.548 1.005 0.422 0.184 0.782 - 0.400 -0.187
0.299 - 0.645 -0.110
Myc y nghTa p
" *
*-**
*
" -
* • • • *
-
**
**
*
«
**
Y2, Ham lu'(j'ng tinh b$t H$s6 59.450 - 0.997 - 0.421 -1.822 - 0.288
0.580 - 0.781 -2.156
0.485 - 0.039 - 0.963 - 0.276 - 0.938
Mycy nghTa p
***
•
**
**
*
•
Yj, H^m luyng protein H$s6
7.372 - 0.003
0.001 - 0.020
0.051 0.031 0.032 0.042 -0.015
0.020 0.050 0.027 0.001
. Mycy nghTa p
«**
Y^, Hoat d9 cua amylase
H0s6 144,00 7.006 9.508 37.447
3.836 5.171 2.375 4.750 -10.620
- 8.753 -19.740 - 36.830
- 5.009
MiJcy nghTa p
***
**
• •
***
*
«
*
" •
•*
***
***
•
Cdc phuong trinh hdi qui thu dugc nhu sau: Yi =6.679+1.098*Xi + 0.423*X2 + 2.548*X3+ 1.005*X4+ 0.422*X5+0.782*X3*X4-0.400*X,^+ 0.299*X3^-0.645*X4^
¥2= 59.45-0.997*Xi -1.822*X3-2.156*X3*X4 -0.963*X3^-0.9377*X5^
¥3=7.372
Y4=144+7.006*Xi+9.508*X2+37.613*X3+4.003*X4+5.171*X5+4.75*X3*X4- 10.62*X,^-8.753*X2^-19.74*X3^-36.83*X4^
Tinh tuong thich cua phuong frmh hdi qui dugc kilm dinh theo tieu chuin Fisher, Fo,95(20,5)=4.5 vd Fi=Stt^/sthl Cdc Fi<Fo.95(20,5) cho nen phuong frmh frrong thich vdi thyc nghiem.
I
Hinh 1. Tdc dpng cua thai gian ipcm (X3) va nhif t dp u-o^ (X4) d i n t i n thdt chdt kho (Yi)
'a
94
I
Hinh 2. Tdc dgng cua thai gian u-om (X3) vd n i n g dg gibberellin (X5) d4n hdm lu-gng tinh bgt (Y2)
Phin I: CdNG NGHg BigN Ddl SINH HgC 185 Ti{ cdc phuang trinh hdi quy thu dugc cd the rut ra cdc nhdn xet sau day :
T6n that chat kho: Tdn that chat khd khi tao malt bao gdm mit mdt frong qud trinh ngam vd mit mdt bdi qud trinh hd hip tang len khi uom mim. Tdn thit chit khd cao se lam gidm gid tri dinh dudng cua malt. Quan sat cdc he sd hdi qui anh hudng din tdn that chit khd va cdc mire y nghia (Bang 6) cd thi thiy, tac ddng manh nhit din tdn thit chit khd Id thdi gian uom (b3=2.548) vd nhiet do uom (b4=l .005) d mire y nghia p<0.001.
Thdi gian uom vd nhiet do uom ciing cd tac ddng tuong ho tdi tdn thit chit khd (b34=0.782, p=0.01). Nhiet do uom tang lam cho tdn thit chit khd gidm (b44= - 0.638), nguyen nhan la do nhiet do cao se uc chl qud trinh hd hip ciia hat. YIU td thdi gian ngam ciing anh hudng khd manh din tdn thit chit khd (bi =1.098, p=0.001). Hat hiit nude cdng manh thi qua trinh ddng hda di hda sau ndy dien ra manh dan din tdn thit chit khd Idn.
Nhiet do ngam vd ndng do gibberellin tdc ddng tdi tdn thit chit khd it hon (Bdng 6).
Ham lugng tinh hot. Hdm lugng tinh bdt giam manh nhit do tdc ddng cua thdi gian uom mam (bs = -1.822, bsa = -0.963, p = 0.01). Thdi gian ngam va ndng do Gibberellin tang ciing ldm ham lugng tinh bdt gidm frong khi nhiet do ngam vd uom mam the hien dnh hudng khdng rd ret.
Ham lirgng protein. Hdm lugng ciia protein trong qud trinh nay mim the hien d bang 5. Thdi gian va nhiet do nay mam, thdi gian va nhiet do uom mam khdng tdc ddng nhieu den ham lugng protein tdng cd d trong hat. Ham lugng protein tdng trong qud trinh nay mam khdng cd sy thay ddi nhieu nhung chac chan thdnh phan ciia chimg se thay ddi nhu hdm lugng acid amin, protein hda tan... Sy thay ddi nay xay ra dudi tdc dong ciia cdc enzyme protease tuong tu nhu d cdc hat ngii cdc khdc [4,9,13].
Hinh 3. Tac dgng cua thai gian u-am (X3), nhi^t dp u-o-m (X4) va ndng dp gibberellin (X5) tai ho^t tinh cua h? enzyme amylase (Y4)
Hoat do enzyme amylase. Qua trinh niy mim Id mdt phuong phdp lam gidm do nhdt cua duiig dich tinh bdt khi hda tan [8]. Trong qua frinh niy mim, tinh bdt bi thodi hoa bdi enzyme chira frong hat. Cdc enzyme amylase se phan cit thdnh phan amylose va amylopectin ciia tinh bdt thanh dextrin mach ngin hon, maltose vd glucose.
Toan bd cdc ylu td xem xet, cd bac 1 va bac 2, diu dnh hudng rd net den boat dg ciia enzyme amylase. Anh hudng tuomg tdc giira thdi gian vd nhiet do uom cd mire y nghia Idn nhit la p = 0.05 (b34 = 4.75). Cac he sd hdi qui bac 2 diu mang dau am (-), cd
186 . ^ HQi nghi KHOA HOC VA C C N G NGHg 2007
nghia Id khi cdc thdng sd nay gidm hoat do enzyme se tang. Yeu td anh hudng manh nhit la thdi gian uom mim (b3 = 37.447; bss = -19.74, p = 0.001). Thai gian ngam ciing anh hudng rit ldm din hoat do cua enzyme amylase (bi = 7.006; bn = -10.620). Nhiet do uom cao thi hoat luc enzyme se cao nhung khi nhiet do tang den mgt miic nao dd thi boat lire se gidm manh (h^ = -36.83). Nhiet do ngam ciing gay anh hudng den hoat do cua enzyme amylase (Bang 6). Cdc tdc ddng ndy xdy ra tuong tu nhu trong qua trinh tao mahdai mach [3,14].
Cac dieu kien toi mi cua qua trinh nSy mam. Kit qua ndy mim la tdi im khi tdn thit malt nhd nhit, hdm lugng tinh bdt, protein vd hoat lire enzyme amylase dat gid tri cao nhit. Quan sdt cdc dd thi khdng gian 3 chilu (bilu thi mdi quan he giira Y va cac gia tri X) cho thiy, qud ttinh tao malt khdng thi ddng thdi thda man cdc yeu ciu fren. Chinh vi the viec lyra chgn cdc thdng sd phu hgp la dieu kien can thiet.
KET LUAN
OM 4088 vd L274 Id hai loai thdc phii hgp nhit de tao malt. Sau 6 ngdy uom mam, boat lyc he enzyme amylase dat cao nhat vd tdn that chat khd thap. Qua trinh ngam co syc khi can tien hanh frong khodng 4 ngdy de dat do am tir 40-42%. Bang phuong phap quy hoach thyc nghiem bac 2 Box-Hunter, da xay dung dugc cdc phuong trinh hdi quy md td tdn that chat khd, ham lugng tinh bdt, hdm lugng protein vd hoat lire amylase.
Ham lugng protein tdng khdng bi tdc ddng bdi cdc yeu td dugc nghien cuu. Cac dieu kien tdt nhat cua qua trinh tao malt thdc (de thu dugc boat tinh amylase cao nhat) nhu sau: thdi gian ngam 30h, nhiet do ngam 30°C, thdi gian uom mam 5 ngay, nhiet do uom la 25°C, ndng do giberrellin 1.5mg/kg
TAI LIEU THANI KHAO
1. Nguyen Thi Hien va cdng su. Nghien cuu qud trinh nay mim cua thdc P4 dl ung dung trong sdn xuat bia, Hd Ndi 2002.
2. Le Thanh Mai va cdng sy. Cdc phuong phdp phan tich nganh cdng nghe len men.
NXB KH&KT. Ha Ndi, 2005.
3. Hoang Dinh Hda. Cdng nghe san xuat malt vd bia. NXB Khoa hgc Ky thuat. Ha Ndi, 2002.
4. Pathirana, R. A., Sivayogasundaram, K and Jayatissa, P. M. Optimisation of conditions for malting of sorghum. Joumal of Food Science and Technolory 29, p.108-111, 1986
5. X.L Akhnadardva, V.V.Kaphardp (Ngudi dich Nguyen Canh va Nguyen Dinh Soa). Tdi uu hda thyc nghiem frong hda hgc va ky thuat hda hgc. Trudng Dai hgc '•
Bach Khoa TPHCM. 1994 " " i 6. Nguyen Cdnh. Qui hoach thyc nghiem. Trudng Dai hgc Bach Khoa TPHCM. 1993 I 7. Bienvenido 0 Juliano. Rice chemistry and technology. The American Association 1
of Cereal Chemists. Lis St. Paul, Minnesola, USA. 1985. j 8. Dennis E. Briggs. Malts and malting. Blackie Academic & Professional 2000
Ph^n I: CONG NGHg BigN Bdl SINH HQC
9. Laus J. Lorenz. Handbook of cereal science and technology. Marcel Dekker INC New York. 1991. ' "
10. P. C. Morris. Cereal biotechnology. Woodhead Publishing Limited and CRC Press 11. S. Mahadevamma- R. N. Tharanathan. Processed rice starch characteristics and
morphology. Springer-Verlag, 2006.
12. Nzelibe vd Nawasike CC. J hist Brew London 101, p. 345-350, 1995.
13. Trust Beta, Lloyd W. Rooney vd Ralph D. Waniska. Malting Characteristics of Sorghum Cultivars. Cereal Chem. 72(6):533-538, 1995.
14. Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevents. Brewing science and practicce. Woodhead publishing limited and CRC Press, LLC.
Cambridge England, 2004.
SUMIMARY
Malting characteristics of different varieties of rice {oryza sativa) and optimisation of malting process by second-order
experimental design
Nguyen Thach Minh, University of hidusfry HCMCity Nguyen Xich Lien, University of Technology HCMCity
Hoang Kim Anh, histitute of Tropical Biology
Ten varieties of rice were used to investigate their malting characteristics. IR50404 had the highest malting loss m the range of 16.32% (w/w) while IR2514, VND9520 had the lowest malting loss m the range of 11.52% (w/w). OM4080 and L274 had the best malting characteristics with amylolytic activity (Diastatic power 120^VK) on 6* day of germination.
The malting process of rice (OM4080 variety from Mekong Delta Rice Research histitute) was studied under pilot plan condition by means of second-order experimental design. The followang ranges of process conditions were chosen: Steeping time [0-60 hours], steeping temperature [5-45°C], germination time [0-8 days], and germination temperature [5-45°C], gibberellin concentration [0-2mg/kg]. The results showed that, all germination conditions, especially germination time, germination temperature, and gibberellin concentration have significantly affected the malting loss, amylase activity and starch content. Protein content was not clearly affected by any conditions mvestigated. The optimum conditions for malting (with highest amylase activity) were followed: steeping time 30 hours, steeping temperature 30-35°C, germination time 5-5,5 days, germination temperature 25°C, and giberrellin concentration l,5mg/kg.
Key words: Rice; Malting; Steeping; Germination; Experimental Design Diastatic power.
