KHOA HOC v A r O T K a ^
Nghldn cdu trich ly xylan trong san xudt dirdng mOdUGdSACARlT td ldi ngd
» TS. TRINH THI KIM VAN, TH.S DO JH\ THANH HUYEN,
» KS. CHU THANG, TH.S N G U Y I N THANH HA Vien Cong nghiep thiic pham
1. MO D A U :
Xylooligosacarit (XOS) la mpt loai dudng oligoza ehiie nang mdi dupc phat hien, nhvmg da va dang phat tiien rat manh, do chiing cd cac dac tinh cd lpi cho siic khde nhu thip nang lupng, khdng tiiu hda, khdng gay sau rang, thiic day su phat tiien ciia he vi sinh vat cd lpi dudng rudt (Bifidobacteria), cd hoat tinh nhu mdt chit xa thuc phim, ed kha nang giii nudc va chdng ddng dac.
Thanh p h i n chfnh ciia XOS la xylobiose, xylotriose, xylotetiaose... [1,2,3].
XOS thudng duoc san xuit tii xylan dudi xiic tac ciia enzyme xylanaza. Xylan la thanh p h i n chfnh tiong hemicellviloza ciia sinh khdi thue vat.
Ldi ngd la mdt loai sinh khdi thuc vat chiia nhilu xylan da dupc sir dung tiong san xuit XOS [4].
Do elu tnic ciia sinh khdi thuc p h i m ndi chung va ldi ngd ndi riing, viic san xuat XOS tii ldi ngd phai bat dau bang viic chiet tach xylan ra khdi cac thanh phin clu tao khac nhu celluloza va lignin. Dich chiit tach cang tinh sach thi hieu suit thu nhan dudng XOS cang eao, vi thi, viic ehilt tach xylan la cdng doan quan trpng va d n dupe nghien eiiu ky cang [5].
2. NGUYEN LIEU, HOA C H A T VA PHUOTVG PHAP NGHIEN CUU
2.1 Nguyen lieu va hoa chat
- Ldi ngd khd: Thu mua tvr cac co sd che biln ngd.
- Hda chit: Alkali peoxit, KOH, H2SO4, HCl, Axit axetic, Axit oxaUc... dupe mua d cac ciia hang hda chat trong nude.
- Enzyme xylanaza ciia Trudng Dai hpc Giang Nam Trung Qudc
2.2 Phuong phap nghien cuu
2.2.1. Trich ly xylan bang axit: Ldi ngd sau khi xay nhd dupc giii tiong dvmg dich axit loang d nhiit dp 100°C trong 2 ngay. Sau dd lpe bd ba va dilu ehinh ndng dp chit khd ciia dich d i n 5% d i thiiy phan bang enzyme xylanaza [ddT].
2.2.2. Trich ly xylan bang Idem: Ldi ngd sau khi
xay nhd dupc ngam tiong dung dich kilm d eac ndng dp khae nhau. Sau dd diing vai man lpe bd ba. Dieh trich ly thu dupc dem kit tiia bang cdn lanh, thu lai bang each ly tam va giii tiong hi lanh din khi thuc hiin phan ung thiiy phan bang enzyme xylanaza [2].
2.2.3. Trich ly xylan bangkihn sau khi khir lignin bang alkaline peroxit: Ldi ngd sau khi xay nhd dupc ngam tiong dung dich 1% (w/v) peroxit (da dupc chinh vl 11.5 bang 4 M NaOH) tiong 45 phiit dSO^C.
Sau khi ngam, ba ngd dupc thu nhan phcri khd rdi dupc ngam tilp tiong dung dich 3 M KOH. Sau khi ngam, lpe bd ba di, lly phin dich trung hda v i pH = 4,5-5 bang 50% axit acetic d l kit tiia xylan [3].
2.2.4 Trich ly xylan bang axit loang ket hop nhiet [6]: Ldi ngd da nghiin nhd dupe ngam trong dung dieh axit loang sau dd hap d nhiit dp eao tiong 1 gid rdi dupc tiich ly bang nudc saeh. Dieh tiich ly sau dd dupc diiu chinh v i ndng dp chat khd bang 5% de thuc hiin phan ving thiiy bang enzyme xylanaza.
2.3 Xac dinh ham luang duang khu (RS):
Phuang phap DNS. Don vi tfnh la % so vdi nguyin Ueu ldi ngd khd ban diu.
2.4 Xic dinh ham luong duong tdng (TS):
Phuong phap DNS. Don vi tinh la % so vdi nguyen lieu ldi ngd khd ban diu.
2.5 Xic dinh ham lugng furfural: Phuong phap so mau d budc sdng 277 nm.
2.6 Xic dinh ham lugng duong bang HPLC [6]
cac chi tiiu danh gia tiong nghien ciiu nay la dudng tdng (dai dien cho hieu suit trfeh ly xylan), ty li giiia dudng khii va dudng tdng (dai diin eho miic dp thiiy phan ciia xylan), ham lupng furfural (Bilu thi miic dp phan giai eua xyloza) va ham lupng XOS thu dupe sau thiiy phan.
3. KfeT QUA VA T H A O L U A N
3.1 Nghien cuu trich ly xylan bang tic nhin axit 3.1.1 Trich ly bang H^04.
Axit sunfvirie la loai axit hay diing trong thiiy phan da dudng tii thuc vat (cellulose va
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n KHOA HOC WA CONG NGHE
hemicellulose...) n d n g dp axit d t r u d n g h p p n a y thudng la l%-3%. Bang 1 la k i t qua thiiy p h a n ldi ngd bang axit d eac n d n g d p khae nhau. Sd Ueu tien b a n g dupe kyy h i i u n h u sau: RS/TS la ty l i giiia d u d n g khii va d u d n g tdng ed tiong d u n g dich sau thiiy p h a n , nd cd the dinh tinh b i l u thi miic dp p h a n cat ciia xylan tiong qua trinh thiiy phan. Furfural la san p h a m thu dupc tiong qua tiinh thiiy p h a n do xylose m a t nudc tao thanh, h a m lupng san p h i m nay ed the bieu thi miic dp p h a n ling p h u trong qua trinh thviy phan. D i l u k i i n thi n g h i i m la: Loi ngd: n u d c = 1:10, n h i i t dp p h a n ling la 100°C d u n tiong 2 ngay.
Bang 1: Trich Iy xylan a cac ndng do axit khac nhau.
Bang 3: Trich ly xylan bang axit oxalic a cac nong dp khac nhau.
Ndng dp (%) RS/TS TS (%) Furfiiral (mg/ml)
! 0.1 0,41 1 4,2 0,079
2 0,67 16,2 0,177
3 0,88 18,9 0,203
4 0,91 19,2 0,242 Kit qua tai Bang 1 cho thay, lupng d u d n g tdng (TS) thu dupc la tuong ddi eao, va h a m lupng nay tang eiing vdi s u tang cvia n d n g dp axit. .Ciing tuong tii n h u vay, ty le giiia d u d n g khii va d u d n g tdng (tiic miic dp thiiy ptian eiia mach xylan) ciing tang theo. Khi n d n g dp axit tang l i n den 4%
thi ty l i RS/RT dat d i n 0,91%, n h u vay, h i u n h u cac mach xylan d e u thiiy p h a n tiiet de d e n xyloza. Day la d i i u m a nghien eiiu khdng m o n g dpi. De cho qua trinh thiiy p h a n khdng bi qua dp, ta bupc phai ha thap n d n g dp axit xudng. N h u vay till h a m lupng xylan trieh ly dupe lai qua thap (thi nghiem d n d n g dp axit 0,1% cho thay tueu s u i t trich ly chi dupe 4,2%). Vi t h i , ta t h i y v i i c diing axit d o n t h u a n de tiich ly xylan la khdng phii hpp tiong san x u i t XOS.
3.1.2. Thuy phan bang axit clohydric va axit oxalic.
De khang dinh kha n a n g tiich ly xylan b a n g axit la khdng thich h p p , ta tiep tuc ttii ngtuem vdi hai axit tiep theo la axit clohydric va axit oxaUc.
Ket qua dupc trinh bay tien b a n g 2 va 3. Vdi bien luan tuong t u n h u p h i n tren ta t h i y , diing axit HCl va axit oxaUc ciing k h d n g phii h o p tiong san x u i t XOS.
Bang 2: Thuy phan loi ngo bing axit HCl a cac nong dp khac nhau.
Ndng dp (%) RS/TS TS (%) Furfiiral (mg/ml)
0.1 0,49 21,4 0,176
2 0,91 25,8 0,291
3 0,92 28,1 0,292
4 0,90 29,8 0,377
Ndngdp(%) RS/TS TS (%)
0.1 0,56 i 6,1
2 0,62
1 5 ^ 3 0,72
18 4 0,86
21 3.2 Nghien cuu trich Iy xylan bang tic nhin Idem 3.2.1 Trich ly xylan bingkiim
Thi n g h i i m dupe thuc hien n h u p h a n p h u o n g p h a p da m i i u ta. K i t qua n g h i i n eiiu dupe trinh bay tien b a n g 4.
Bang 4: Trich ly xylan bang kiem a cac nong dp khacnhau
Ndng dp (%) RS/TS TS (%)
5 0,25
5,2 10 0,46
20 15 0,61
21 20 0,76
22 25 0,80
24 Ciing n h u tac n h a n axit, dvmg tae n h a n k i i m khdng thieh h p p cho viec tiich ly xylan tiong san xuat XOS, vi vdi p h u o n g p h a p nay su thiiy phan t h u d n g bi qua dp, san p h a m thu dupc chii yeu la d u d n g d o n va d u d n g oUgoza.
3.2.2 Trich ly xylan bang kiem sau khi khii hgnin bang alkaline peroxit
c a c thi n g h i i m dupc thilt k l gidng n h u phan xu ly kiem, chi khac la trudc khi trieh ly, eae mau dupc xii ly trudc bang peroxit n h u p h i n phuong phap da ghi. Kit qua dupc ghi nhan tien bang 5. Ta thay, nhd tae dvmg ciia peoxit, h a m lupng xylan trieh ly ra tiong dieh ed cai thien dupc ddi chiit, dac biit la miic dp thiiy phan a i a chat trieh ly da giam dupc dang kl.
Bang 5: Trich ly xylan bang kiem sau khi khu lignin bang alkaline peroxit
Ndng dp (%) RS/TS TS (%)
5 0,20
5,9 10 0,32
22 15 0,41
25 20 0,56
27 25 0,70
29 3.3 Trich Iy xylan bang tic nhan nhiit De nghiin ciiu kha nang va hieu qua trich ly xylan bang phuong p h a p h i p d nhiet dp eao, chiing tdi tiin hanh h i p cae m a u thi nghiem d eac nhiit dp khac nhau tiong 30 phiit, sau khi h i p , hdn hpp dupc lpe tach ba. Dieh trieh ly thu dupc dem phan tich.
Kit qua thi nghiem dupc ghi ntian tien bang 6.
Bang 6: Anh hudng cua nhiet dp hap din qua trinh trich ly xylan.
Nhiet dp say (°C)I RS/TS
TS i Furfural (mg/ml)
130 0,30 5,2 0,2
140 0,31 6,1 0,35
150 0,31 10,9 0,41
160 0,31 12,4 0,82
170 0,32 15,2 1,1
2 2 CONG MGBliP»Ky 1, thang 8/2010 Website: www.tapchicongnghiep.vn
KHOA HOC VA CONG NGHI
Bang 6 cho thiy khi nhiit dp lin din 170°C, ham lupng dudng tdng tang lin din 15,2 %, nhung ty le RS/TS ehi dat 0,31. Tvr lupng furfural tao ra tiong dieh chiit ta thiy, lupng furfural tao ra cd Uen quan mat thiet vdi nhiit dp hip, nhiit dp cang eao, lupng furfural tao ra eang nhilu, tde dp tang eiia furfural tang theo ty li 10/2 theo su tang cua nhiit dp, nghia la a i khi nhiit dp tang lin 10°C, thi lupng furfural lai tang lin gip ddi, ngtua la lupng xyloza phan giai tang len gip ddi. Day la dilu khdng mong mudn tiong cong nghi san xuat dudng XOS.
Dl khing dinh chac ehan viic trieh ly xylan bang nhiit dp cao la khdng vm viet, d l tai tilp tuc thuc Hin eac miu thi nghiem d nhiit dp thip hon (130°C) nhung keo dai thdi gian tilp len vdi hy vpng ty le dudng hoa tan tdng va dudng khii tang ban ma ham lupng furfural khdng qua cao. Thiet kl thi nghiem va kit qua thi ngtiiim dupc trinh bay tiin bang 7.
Bang 7: Anh hudng cua thdi gian hap den hieu qua trich ly
Bang 8: Anh huong cua nhiet dp trong phuong phap xu ly axit - nhiet kit hgp
Thdi gian hap (phiit) RS/TS
30 0,29
« « ^s 1 5^2
Furfural (mg/ml) i 0,2
60 90 0,30 0,31
6,4 j 7,9 0,40 1 0,45
120 0,31 9 4 0,62 Kit qua tien bang 7 cho thiy, n i u ta giii nhiit dp hip khdng qua cao, nhvmg keo dai thdi gian hip ra thi cd thi khae phuc dupe p h i n nao su phan giai xyloza. Tuy nhiin, ham lupng dudng hoa tan tdng va ty li giiia hai loai dudng khii va dudng tdng rit thip, khdng bao dam dupe hiiu suit thu hdi. Nhu thi ta cd thi kit luan, phuang phap diing nhiet d l trieh ly ehua phai la phuang phap tdi uu tiong san xuat dudng XOS.
3.4 Trich ly xylan bang tic nhin hoa nhiet kit hap
Kit qua nghiin ciiu tiin da eho thay, niu don dde sii dung hoa chit hoac nhiit diu cho kit qua khdng tdt, khdng phii hpp vdi viic tao xylan cho san xuit dudng XOS. Mudn dat dupc ham lupng TS nhu mong mudn, ta d n kit hpp ea hai phuang phap. So sanh hieu qua trich ly eiia axit va kiim ta thiy, diing axit eho hiiu qua tdt hon, vi thi tiong nghien eiiu tiip, ta lua ehpn phuong an kit hpp xii dung axit va nhiit dp lam tae nhan trich ly xylan.
Bang 8 la k i t qua thi nghiim vdi lOOg ldi ngd xvi ly vdi 0,1% H2SO4 d nhiit dp 60°C trong 16 gid. Sau dd lpe bd nude di, riia lai bang nudc may 2 lupt, sau dd lai cho 1.000ml nudc vao, d i l u chinh pH v i 6,0 rdi dem h i p 60 phiit d cae nhiit dp khac nhau.
Nhiet dp hip ( T ) 170 160 i„150 ., I^O
" T S " ^ J ^ Y ' 16.6 ^ 10J9 '^^26 FurfUraT (mgAni) ^ y b s ' L26 [ 0.67 ; 0.34
RS/TS 0,54 0,45 0,32 0,32 Tu bang 8 ed thi nhan thiy, ldi ngd sau khi xu ly bang axit loang rdi hip d eac nhiet dp khac nhau cd the nang eao hiiu suit tiich ly len 30%. So sanh nhiet dp hip d leO^C va 170°C, tdng dudng tiich ly dupc tuong ddi cao. Nhung ty li RS/TS va ham lupng fur- fural ciing eao. Cdn niu hip d nhiet dp 150°C cho ta kit qua tdt nhit. Liic nay, dudng tdng TS dat din 10,9%, hie la miie dp bich ly eiia xylan dat din 50%, RS/TS dat 032%, Fuhiral la 0,67mg/ml. Dieu nay vl CO ban thoa man dupc viec trich ly xylan, ddng thdi eiing bao dam dupc miic dp thuy phan viia phai ciia xylan ed tiong dich eliiet.
4. KET LUAN
Qua trinh trich ly xylan tiong san xuit XOS, ngoai yiu d u thu dupc hieu xuat trich ly xylan cao, yiu d u vl chit lupng chit trieh ly ciing rit quan tipng. Kit qua nghien cihi tien cho thiy, qua trinh trich ly xylan dat hiiu qua eao nhit klii dung kit hpp phuang phap hda nhiit. Cu the la nguyen Ueu sau khi nghiin nhd, lam saeh dupc ngam tiong dung dich 0,1 % axit H2SO4 tiong 16 gid, d nhiet dp 60°C.
Tilp sau dd, san phim dupc riia v l trung tfnh bang nudc sach rdi hip d nhiit dp 150°C tiong 60 phiit.
Vdi phuong phap nay, hieu xuat thu nhan xylan dat xIp xi 10% va miic dp phan giai xylan tiong dich thu dupc dap ling yiu d u edng nghe san xuat XOS.
T A I LIEU THAM K H A O
1. Koga,K & Fuzikawa, S. (1985). Xylooligosaccharides.
In: Oligosaccharides (Vol.3, pp. 130-143). Shizuoka, Japan:
Nihon Shokuhin Kako Ltd.
2. PeUerin, P., Gosselin, M., Lepoutre, J., Samain, E., &
Debeire, P. (1991). Enzymatic production of oligosaccharides 3. Frade, RA. (1995). Xylanases: from biology to biotechnology.
Biotechnology Genetic Engineering Reviews. 13:100-131.
4. Farah Salira. H., Fazilah, A., Mohd. Azemi, M.N. and Norziah, M.H. Enzymatic Hydrolysis and izolation of oil palmp frond derived xylooligosaccharides by xylanase
Trichoderma Viiide. Internertional Coferrence on Environmental Research and Technology (ICERT2008)
5. Debora Alcida Nabarlatz . Autohydrolysis of Agricultural by- product for the production of Xylooligosaccharides (2006) Doc. Thesis.
6. Yang, R.,; Xu, S. Y; Wang, Z. Yang, W. Aqueous extraction of comcop xylan and production of xylooligosaccharides.
LWT- Food Sci. Technol 2005, 38, 677-682. •
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