K H O A HOC C 6 N G NGHE
IXIGHIEIV C U U HAIVI LUQIXIG A X I T CYAIXIHYDRIC Q CU V A L A M O T S O GldlXIG sAlXI V A S U DIEIXI D O I HAIVI LUQIVG
C Y A I V H Y D R I C DAIVG P H U O I V G P H A P U C H U A
Nguyin Thi Ldc', U Ykn An'
T6MTAT
Nghien ciru ham lugng axit cyanhydric (HCN) cua cu va la sSn dugc trien khai tai cac phong thi nghiem thugc Dai hgc Hue. Miu cac gidng san thu thap a tinh Thira Thien-Hue, Quang Tri va Quang Binh. Ket qua cho thay ham lugng HCN trong cu sSn bien dpng rat lon tir 175,3 - 489,6 mg/kg VCK. Ham lugng HCN trong cu tang dan theo thtr tu giong Canh Nong, Gon, Ba Trang, H34 va sdn Xanh. Sin Xanh co ham lugng HCN trong cii cao nhat la 489,63 mg/kg VCK. Ham lugng HCN a vo thit cao nhat, sau do den loi sin, vo gb va thit sin co ham lugng HCN thaip. Ty le HCN giira vo thit va thit sin gidng Canh Nong 4,84/1, Gon 4,50/1, Ba Trang 3,50/1, H34 la 4,05/1 va sin Xanh 4,70/1. Ham lugng HCN frong la cac giong sin cao hon cu 3-5 lan va bie'n dong tfr thaip den cao la sin Gon, Canh Nong, Ba Trang, H34 va sin Xanh (689 den 1575 mg/kg VCK). Cu sin dugc nghien, trgn voi 0,5% NaCl roi u chua, ket qua pH khdi u dat 3,9 tai 14, 21, 30 ngay u, sau do pH dn dinh 3,8 den 180 ngay u. Ham lugng HCN trong cu giam con 63% sau 21 ngay va 32% sau 180 ngay u so voi HCN ban dau. La sin ii chua voi mpt trong cac chat phu gia la ri mat, hot sin hoac cam ty le 5% va 0,5% NaCl (khoi lugng tuoi) co ham lugng HCN giam con 3441% sau 56 ngay u so vai HCN ban dau.
Tirkh6a: Gidng sdn, cii vd Id sdn, hdm Iwgng cyanhydric, it chua, chdt phu gia.
I. DAT VAN DE
Cay san, ten khoa hgc Manihot esculenta Crantz cd ngudn gdc vung chau My nhiet ddi. Q Viet Nam, sin la mgt trong nhfmg cay luong thttc quan trgng cho ngudi va thirc an chinh frong chan nu6i. San lugng sin hang nam khoang 2 trieu tan, trong dd cac tinh ven bien mien Trung chiem khoang 23%. Cu san giau tinh bgt (76,2 - 77,2%), nhung ngheg protein (2,2-2,7%) (Vu Duy Giang va ctv, 1995). La sin rat giau protein (Hoang Van Tien, 1987). Mgt trong nhfing han che chii yeu khi sir dung san lam thiic an cho gia sue la ham lugng axit cyanhydric (HCN) frong san. Kajarern, 1977 cho biet sin chita cyanogenic glucoside la linamarin va lotausfralin dd hda tan trong nudc va bi phan buy dudi tac ddng ciia nhiet do fren 150"C. Nhd xuc tac cua enzym linamase hoac boat dgng cua axit htru ca, glucoside bi thuy phan thanh HCN (Coursey, 1973) dd bay hoi va hda tan trong nudc.
Ham lugng HCN frgng san bien dgng tir 75-400 ppm, frong dd sin dang chira 200-400 ppm va sin nggt chira dudi 100 ppm (Oke, 1978). Coursey, 1973 nghien ctiu gidng san nggt cho thay ham lugng cyanogenic glucoside frong vd s i n so vdi thit sin la 5:1 den 10:1.
TS. Truong Dai hoc Nong lam - Dai hoc Hu8,
• TS. Ban hgp tac quoc te - Dai hoc Hue.
Him lugng HCN gay chet bien ddng tiiy theo ddi tugng ddng vat va sd lugng ddc td dugc tieu thu
(Nartey, 1968 va Limon, 1995). Hien nay, cac nudc frong Cgng ddng chau Au (EC) de ra tieu chuan: 1 kg chat kh6 thiic an, ham lugng HCN phai thap hon 60 mg thi mdi dam bao su sinh trudng va phat frien binh thudng ciia gia siic {frich (Biii Van Chinh, 1995)).
O mien Trung nudc ta sin dugc frdng phd bien de lim luong thuc cho con ngudi va thiic an chan nuoi, tuy nhien lugng dgc td HCN cd the gay hai cho gia sue frong cic gidng sin van la an sd lim ngudi chan nu6i nghi ngai khi sir dung. Do dd, lam sang td van de niy va xay dung phuang phap khit ddc nhim sit dung an toin sin frong chan nuoi la muc tieu ciia de tai nly.
II. NOI DUNG VA PHUONG PHAP NGHIEN CUU
1. Xic dinh h i m lugng HCN ciia cti v l 11 mdt sd gidng sin b mi^n Trung
Thi nghiem dugc tien hanh nam 1999, miu dugc lay fren cic dia diem thugc cic tinh Tliira Thien - Hue, Quang Tri vi Quang Binh tiieo phuong phap dudng cheo gdm 5 6 cho 1 sao Trung bg voi dien tich 20 ml Lay miu tiatng binh theo TCVN-4325-86. Thdi diem chgn miu: Sin khi tiiu hgach cd thdi gian frdng 11 thing ke hi khi dat hom (Canh N6ng, sin Gdn, H34 va sin Xanh) va 7 thing (Ba Trang). Thdi gian lay miu via liic 8 gid sang, lay ngiu nhien 30 cu va 10 kg l i cho mdt gidng sin de phan tich theo phuang phap ciia Easley, 1970.
42 NONG NGHIEP VA PHAT TRIEN NONG THON - SO 6 - THANG 6/2009
KHOA HOC CONG NGHE
2. Nghifin cthi su bi^n ddi him lugng HCN ctia cti sin Ba TrSng frgng qnk trinh ti chua
Cu sin sau khi thu hoach, kh6ng bde vd, rira sach, nghien min rdi frgn deu vdi mudi NaCl ty le 0,5%
(% khdi lugng tuoi). Hdn hgp fren dugc nen chat vao tiii nilon vdi khdi lugng 10 kg/tiii va bugc kin. Xic dinh pH va ham lugng HCN tai cic thdi diem: 0, 7,14, 21, 30, 60, 90,120,150,180 ngiy, ii vdi 3 lan lap lai.
3. Nghidn ctm knh hudng ciia eke chkt phii gia d^n him lugng HCN cua khdi ii chua l i sin
La sin Ba Trang dugc bam nhd 2-3 cm vi trgn theo 7 phuang thirc: (1) LS Qi sin -i- 0,5% NaCl); (2) LS5R Ga sin + 0,5% NaCl + 5% ri mat); (3) LSIOR Oi sin + 0,5% NaCl + 10% ri mat); (4) LS5B (}a sin + 0,5%
NaCl -H 5% bgt sin); (5) LSIOB Ga sin + 0,5% NaCl + Bang 1. Him lugng HCN frgng cic b6 phin
10% bgt sin); (6) LS5C Gi sin + 0,5% NaCl -H 5% cam);
(7) LSIOC Ga sin + 0,5% NaCl + 10% cam). Hdn hgp tren dugc chg vao bao nylon voi khdi lugng 10 kg/tui, nen va bugc chat de q u i frinh len men tu nhien xay ra. Phan tich hda hgc: Him lugng HCN va pH khdi u tai cic thdi diem 0, 7, 14, 21, 28 va 56 ngiy sau khi ii vdi 3 Iin lap lai.
Sd lieu dugc xir ly bang thdng ke sinh vat hgc theo phuang phap phan tich phuang sai (ANOVA) qua mO hinh tuyen tinh (GLM) fren phan mem Minitab version 14, chuang trinh Excel 9.0. So sanh su sai khic bing phuang phip Turkey voi khoang tin cay 95%.
III. KET QUA VA THAO LUAni
1. Him lugng HCN ctia cii v i Ii mdt sd gidng sin b midn Trung
cii ctia mdt sd gidng sin (mg/kg VCK) (M. ± SE) Cac bo
phan Canh Nong Sin Gon
Gidng sin
Ba Trang Sin H34 Sin Xanh Toan cu
Vo go Vo thit Thit sin Loi sin
12 12 12 12 12
175,29 ± 8,10 132,24 ± 4,21 615,60 + 4,50 127,21 ± 6,02 230,87 + 5,92
223,50 ±6,13 216,65 ±2,18 754,98 ± 8,59 167,64 ± 5,33 237,59 ± 10,01
306,10 ±9,00 265,17 ±2,26 876,63 ± 13,62 250,14 ±10,13 316,92 ± 8,48
418,07 ±11,06 321,36 ±2,77 1306,68 ± 19,95
322,53 ± 9,92 380,14 ± 10,92
489,63 ± 14,15 444,90 ± 4,56 1874,10 ±22,31
398,50 ± 10,98 636,61 ± 15,33 Ket qua bang 1 cho thay, hira lugng HCN frgng
cu sin bien dgng rat ldn tir 175,3 - 489,6 mg/kg VCK.
Ham lugng HCN tang dan theo thti ttr gidng Canh N6ng, Gdn, Ba Trang, H34 vi sin Xanh. Sin Xanh cd him lugng HCN cag nhat l i 489,63mg/kg VCK.
Ham lugng HCN d vd thit caa nhat tiep sau li lgi sin, vd gd vi thit sin cd ham lugng HCN thip nhat.
Ty le HCN gitia vd thit vi thit sin gidng Canh N6ng 4,84/1, Gdn 4,50/1, Ba Trang 3,50/1, H34 l i 4,05/1 va sin Xanh 4,70/1.
Theo Bolhuis, 1954 h i m lugng HCN frgng sin tuoi < 50 mg/kg kh6ng gay ddc cha gia sue, nhtmg HCN tir 50-100 m g / k g gay dgc nhe v i HCN > 100 mg/kg gay dgc manh. Nhu vay gidng sin Ba Trang, H34 vi sin Xanh deu cd h i m lugng HCN cag vi vay khong nen diing de cho gia sue an tuoi ma phai qua che bien de giam ddc td. Bing 2 phan anh h i m lugng HCN frgng li cic gidng sin nghien cuu.
Qua bang 2 chg thay, h i m lugng HCN frong l i cic gidng sin bien ddng r i t lgn. Him lugng HCN frgng l i cic gidng sin bien dgng tir thap den cag li sin Gdn, Canh N6ng, Ba Trang, H34 v i sin Xanh (689 den 1575 m g / k g VCK).
Bing 2. Him lugng HCN ciia Ii mOt sd gidng sin (M±SE)
Gidng sin Canh nong Sin Gon Ba trang Sin H34 Sin Xanh
Sd miu
4 4 4 4 4
VCK 27,52 ± 3,25 28,67 ± 2,16 28,58 ± 2,75 26,82 ± 1,98 28,37 ± 4,05
HCN (mg/kg VCK) 717,59 ± 8,24 689,00 ± 12,35 1056.68 ±23,41 1292,09 ± 13,11 1575,14 ± 21,57 2. Su bi6i ddi pH v i him higng HCN ciia khdi u chuacii sin theothdigian
Gii tri pH v i h i m lugng HCN frgng khdi u tai cac thdi diem dugc frinh biy d bieu dd 1.
HCN (mfl/lfg(^'
0 7 14 21 30 60 90 120150180 Thai gian u, (ngay) Bilu dd 1. Str biln ddi pH vi h i m lugng HCN
ciia khdi ii theg thdi gian
NONG NGHIEP VA PHAT TRIEN NONG THON - SO 6 - THANG 6/2009 43
KHOA HOC CONG N G H l
Khdi u cii sin cd pH dat den dd bao quin la 4,2 sau 7 ngiy li vi tiep tuc giim nhe cdn 3,9 tai 14, 21, 30 ngiy li. pH tiep tuc dn dinh 3,8 den 180 ngiy u.
pH duy fri 3,8 frong thdi gian 60 -180 ngiy u. Him lugng HCN giam manh tir 0-21 ngiy, sau dd giim dan den 180 ngiy li. Him lugng HCN giam cdn 63%
tai 21 ngiy vi 32% sau 180 ngiy li sg vdi HCN ban diu. Ket qui niy phii hgp vdi cic ket qui ciia CIAT, 1978; Gomez vi ctv, 1988. Bing 3 phin anh str bien ddi ham lugng cac axit htru ca frong khdi sin u chua.
Bang 3. Su bi^n ddi him lugng cic axit htiu eg frgng khdi sin ti chua theg thdi gian
nhung den 56 ngiy u, pH tang len 4,3. Cic khdi u chua cd chit phu gia, gii tri pH cd xu hudng giam nhanh tir 0 den 7 ngiy ii, sau dd giam dan den ngiy u 21. Tai 21 ngiy il, pH dat 3,6-3,8 vi dn dinh den 56 ngiy u.
Bing4. Subi^nddipH ciia cic khdi u chua theg thdi gian u
Ngay u 0 30 60 90
Axit huu ca (% VCK) Axit axetic
0,11 0,96 0,78 0,55
Axit lactic 0,28 4,35 4,67 5,32
Axit butyric 0,03 0,19 0,11 0,02
Phuang thitc LS LS5R LSIOR LS5B LSIOB LS5C LSIOC
Thai gian u (ngay) 0
6,7 6,6 6,6 6,7 6,7 6,7 6,7
7 4,3 3,7 3,7 4,1 4,0 4,1 4,2
14 4,1 3,7 3,7 3,9 3,9 4,0 3,9
21 4,1 3,6 3,6 3,8 3,8 3,8 3,8
28 4,2 3,6 3,6 3,8 3,8 3,8 3,8
56 4,3 3,6 3,6 3,8 3,8 3,8 3,8
Ket qui bing 3 cha thay, ham lugng axit lactic frong khdi u tang dan ttr 0,28% tai 0 ngiy ii den 5,32%
tai 90 ngiy ti. Axit lactic da tic che cac loai vl khuan CO hai nhu vi khuan gay thdi (spoilage bacteria), vi khuan gay benh dudng rudt (E.coli) vi giti cha khdi il khong bi hdng.
3. Anh hudng cic chit phu gia d^n pH vi him lugng HCN frong khdi u li sin theo thdi gian
Ket qua bang 4 cho thay, khdi u chua la sin khang cd chat phu gia tai thdi diem 21 ngay cd pH li 4,1
Sir bien ddi him lugng HCN ciia cic khdi u li sin, dugc the hien bang 5. Ket qua bang 5 chg thay, him lugng HCN d cic khdi li vdi laai vi ty le chat phti gia khic nhau deu giam din theg thdi gian. Tai 28 ngiy u, him lugng HCN khdi u LS giam cham cdn 63% HCN so vdi ban diu. Trgng khi dd, khdi li LS5R vi LSIOR giam nhanh cdn 43% vi 38% so vdi HCN ban diu. Cic khdi ii LS5B, LSIOB, LS5C va LSIOC giam tugng tmg 50%, 46%, 49% va 48% so vdi HCN ban dau. Sau 56 ngiy ii, khdi ti LS cdn 54%, cac khdi il LS5R, LSIOR, LS5B, LSIOB cdn 37- 41% va khdi il LS5C, LSIOC cdn 34-36% sg vdi HCN ban dau.
Trgng qua frinh ii, him lugng HCN khdi ii LS deu cag hgn cac khdi u khic tir 20-35% (P<0,05).
Bing 5. Sir bi^n ddi him lugng HCN
Phuong thiic LS
LS5R LSIOR LS5B LSIOB LS5C LSIOC
0 302 ±2,5 291 ± 1,8 276 ± 2,0 287 ±2,2 274 ± 2,8 283 ± 1,8 269 ±2,1
7 284 ± 5,1 250 ± 3,5 220 ± 4,5 258 ± 0,9 235 ± 2,3 231 ±2,2 240 ± 6,1
cua cic khdi
Thoi gian 14 226 ± 5,3 233 ± 8,7 212 ±1,6 237 ±4,3 221 ± 7,0 215 ±1,2 217 ±6,0
u Ii sin theo ihdi gian (mg/kg tuoi)
u (ngay) 21 192 ± 4,9 164 ± 2,1 177 ±1,0 171 ±4,6 192 ± 6,4 172 ±0,9 134 ± 0,8
28 189 ± 3,0 126 ± 1,4 106 ± 2,2 143 ± 0,9 125 ± 6,6 137 ± 0,4 130 ± 5,3
56 141 ±3,1 120 ± 0,4 102 ± 1,6 110 ±4,4 112 ±3,6 103± 2,0
91 ± 1,4 IV. KET LUAN
1. Him lugng HCN frgng cu cic gidng sin d mien Trung bien dgng rit ldn 175,3-489,6 mg/kg VCK. Ham lugng HCN frong cu tang dan theo thir ttr gidng Canh Nong, Gdn, Ba Trang, H34 va sin Xanh.
San Xanh cd him lugng HCN trong cu cag nhat la 489,63 mg/kg VCK. Ham lugng HCN d vd thit cao nhat sau dd den loi sin, vd gd vi thit sin cd him lugng HCN thap nhat. Ty le HCN gitra vd thit vi thit
sin gidng Canh Nong 4,84/1, Gdn 4,50/1, Ba Trang 3,50/1, H34 li 4,05/1 vi sin Xanh 4,70/1.
Him lugng HCN frgng li cic gidng sin cag hgn cu 3-5 Iin vi bien ddng tir thap den cag li sin Gdn, Canh Nong, Ba Trang, H34 va sin Xanh (689 den 1575 mg/kg VCK).
2. Khdi il cu sin cd pH dat den dg big quan la 4,2 sau 7 ngiy li, giam nhe den 3,9 tai 14 ngiy u vi hep tuc dn dinh 3,8 den 180 ngiy u. Ham lugng HCN giam manh tir 0 - 21 ngiy, sau dg giam dan den 180
44 NONG NGHIEP VA PHAT TRIEN NONG THON - SO 6 - THANG 6/2009
KHOA HOC CONG NGHE
ngay li. Ham lugng HCN giam cdn 63% tai 21 ngay va 32% sau 180 ngiy u sg vol HCN ban diu.
3. Khdi li li san vai chat phu gia cd pH dat 3,6-3,8 tai 21 ngay u v i dn dinh den 56 ngay ii. La sin ii chua vdi mgt frong cac chat phu gia la ri mat, bot sin hoac cam ty le 5% v i 0,5% NaCl (khdi lugng tuoi) cd ham lugng HCN giam con 34-41% sau 56 ngiy u so vdi HCN ban dau.
TAI UEU THAIVI KHAO
(1) Bui Van Chinh (1995), Nghien citu che bien va sir dttng phu pham nong nghiep va ngudn thirc an sin cd d nong thon. Tuyen tap nghien cm khoa hoc Vien Chdn nudi. Nxb Khoa hgc Ky thuat Ndng nghiep. Ha Ndi, fr.36-42.
(2) Vu Duy Giang, Biii Dtic LQng, Hoing Van Tien vi Biii Chinh (1995). Thuc dn vd dinh duang gia sue. Nxb Nong nghiep, H i Ndi, fr. 5.
(3) Hgang Van Tien (1987). Cdch tinh thiic dn cho lgn. Nxb Khoa hgc va ky thuat. H i Ngi, tr. 54-58 va fr. 100.
(4) Bglhuis, G. G. (1954). The tgxicity gf cassava root. Netherlands J. Agricutural Science, pp. 176-185.
(5) CIAT (1978). Swine nufrition unit annual report. CIAT, Call, Colombia.
(6) Coursey, D. G. (1973), Cassava as a food:
Toxicity and technology. Chronic cassava Toxicity, Proceeding of the Interdisciplinary workshop, London, England, 29-30 Jan., 1973. IDRC-OlOe, pp. 27-36.
(7) Easley, J. F., McCall, J. T , Davis G. K. and Shirley, R. L. (1970). Nutrition laboratory of Department of Animal Science University of Florida, University of Florida, FL.
(8) Gomez, G. and Valdiviesa, M. (1988). The effects of ensiling cassava whole-raat chips on cyanide elimination. Nutrition Reports International 37, pp. 1081-1092 and 1161-1166.
(9) Kajarern, S. (1977). Cassava in nutrition of swine. Cassava as Animal Feed. Proceeding of a Workshop at University ofGuelph, 18-20 April, 1977.
IDRC-095e, Ottawa, Canada, pp. 56-64.
(10) Limon (1995). Ensilage of casava products and their use as animal feed. Roots, tubers, plantains and bananas in animal feeding. FAO Animal Production and Health Paper, pp. 100-109.
(11) Nartey, F. (1978). Cyanogenesis, Ulfrastructure and seed gemination. Abstract on cassava. Vol 4, Series 183C^. CLYPPublicatian, Calambia.
(12) Oke, 0 . L. (1978). Problems in the use of cassava as animal feed. Animal Feed Science Technology 3, pp. 345-380.
RESEARCH ON CYANHYDRIC CONTENT IN ROOT AND LEAF OF SOME CASSAVA VARIETIES AND CHANGE OF CYANHYDRIC CONTENT BY CASSAVA SILAGE
Nguyen TTii Loc, Le Van An Summary
The research on cyanhydric (HCN) content in cassava root and leaf has been implemented in laboratories of Hue University. Samples of cassava varieties were collected from provinces such as Thua Thien - Hue, Quang Tri and Quang Binh. As the result showed that the content of HCN in cassava root varied significantiy, from 175.3 to 489.6 mg/kg of dry matter. The content of HCN in cassava root was increased as to varieties, such as Canh Nong, Gon, Ba Trang, H34 and Xanh respectively. Xanh cassava had the highest content of HCN in root which was 489.63 mg/kg of dry matter. The content of HCN was highest in fresh thick peel and reduced from fresh pith to fresh thin peel and fresh pulp respectively. The rate of HCN between the fresh thick peel and fresh pulp of Canh Nong variety was 4.84/1, Gon was 4.50/1, Ba Trang was 3.50/1, H34 was 4.05/1 and Xanh was 4.70/1. The content of HCN in cassava leaf was higher than cassava root from 3 to 5 times and varied increasingly from -Gon, Canh Nong, Ba Trang, H34 and Xanh respectively (from 689 to 1575 mg/kg of dry matter). Ground cassava root mixing with 0.5% of NaCl and ensiling would create a pH of 3.9 at the days of 14, 21 and 30 after ensiling. Then, pH was stable at 3.8 until 180 days of silage. The content of HCN in root was reduced to 63% at the day 21 and 32% after 180 days ensiling compared with the content of HCN at the beginning. Cassava leaf ensiling with 5% of one of additives such as molasses, cassava meal or rice bran and 0.5% of NaCl (fresh amount) made the content of HCN reduced to 34-41% after 56 ensiling compared to the content at the beginning.
Keywords: Cassava variety, cassava root and leaf cyanhydric content, silage, additive.
Ngudi phin hifn: TS. Trin Qudc Vi$t
NONG NGHIEP VA PHAT TRIEN NONG THON - SO 6 - THANG 6/2009 45
