Tgp chi khoa hgc TrUdng Dgi hgc Quy Nhdn Sd 2, Tgp V ndm 2011
NGHIEN Cifu SV THAY DOI CAU TRUC CUA TINH BQT DAU XANH TRlJ6C VA SAU BIEN HINH
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1. GI(5l THIEU
Trong cac loai ngu cd'c, diu xanh li mdt loai thtfc phi'm cd gii tri dinh dtfdng, nen dtfdc dung de che' bie'n nhieu loai sin phi'm: lim gii diu, cic loai bun, binh keo... Dau xanh ngoii viec cung ci'p cic axid amin, chi't khoing, him Itfdng tinh bpt trong hat diu cao nhi't. Tinh bdt diu xanh c6 cac die diem gan gid'ng cic loai tinh bdt khic dd li: tinh din hdi, tinh deo, tinh dai vi kha nang tao gel,... Cic tinh cha't tren ting hay giam phu thudc ri't ldn vao dieu kien moi trtfdng (ham am, nhiet do, che do gia cdng,...). Trong qui tiinh gia cdng che' bien dau xanh, thinh phan tinh bdt chiu nhieu tic ddng nhi't bdi le nd la thanh phan chinh lai de bi thay ddi ci'u true. Stf bie'n hinh tinh bdt bang cic chi't oxi hda chi xay ra khi cic hda chit sd dung lam bie'n ddi kich thtfdc vi ci'u true cua phan td tinh bgt. Vi qui trinh bien blnh tinh bdt dau xanh bang phtfdng phip oxi hda bdi NaClO la mdt qua trinh didn hinh lim cho ci'u true cua tinh bdt diu xanh cd stf thay ddi. Muc dich cua bii nay l i nham de khao sit cung nhtf so sinh ca'u true phan td cua tinh bdt diu xanh trtfdc vi sau bien hinh.
2. NGUYEN LIEU VA PHUdNG PHAP 2.1. Nguyen lieu va hda chat
- Diu xanh cd ten La tinh la Phaseolus aureus Rob(1832) ngiy nay li Vignaradiata thudc chi Vigna.
- Hat diu xanh gid'ng T135 thu dtfdc vio thing 12 nim 2010 d tinh Gia Lai thudc khu vtfc Tiy Nguyen.
Natrihypoclorit chda 5-10% cio boat ddng li'y td cdng ty hda cha't Viet Tri.
2.2. Tach tinh bdt td dau xanh
Diu xanh cua vung Tay Nguyen dtfdc ltfa chgn, mgi tap chi't bay nhdng hat bi htf, sau, mgt hoic bi mdc deu dtfdc loai bd, nhdng hat nguyen ven dtfdc ngim trong ntfdc (ti le the tich 1:3 v/v) d 50° C trong vdng 12h. Sau dd, mang dau xanh ra va rda sach, thtfc bien dii tich he't vd ngoii v i mang dau xanh da hoc vd nghien bang may nghien (Mykros, Trung Qud'c) vdi ntfdc. Phan cha't set dtfdc tao ra se dtfdc cho qua lgc ray N^lOO, tie'p theo de lang rdi cho qua lgc riy N''250, lai de lang rdi tiep tuc cho qua lgc ray N°300, tie'p theo thtfc hien lang can rdi cho qua lgc riy N°350, ke' tie'p de lang
94 ^ LfeTHIANHNGUYfeP va lgc qua lgc ray N"400. Tiep dd, de lang va rda sach nddc 2 lan, thdc hien si'y kho
d 40"C. Cudi cijng, mang mau tinh bgt thu dddc dem si'y khd (b^ng miy si'y dien td, CS 101-1AB, Yinhe, Trung Qud'c) d nhiet dg 40" C trong vdng 3 gid, sau dd dem cin va dem nghien vda du trong miy nghien Cyclotec ( Foss-Tecator, Hogacus, Sweden).
2.3. Bidn hinh tinh bdt b^ng phtfdng phip oxi hda bdi NaClO
Tinh bgt khd khui'y trgn trong nddc vi NaOH 0,01 N thinh huyen phd tinh bdt co ndng do 33-34% vi cd pH= 8-10. De bien hinh cho dung dich NaClO cd chda 5-10%
cio ttf do, khui'y deu d nhiet do 21 -38"C cho de'n khi dat mdc do oxi hda can thiet. Sau dd, tie'n hinh trung hda hdn hdp bang HCI 0,01 N de'n pH=6-6.5. De tach cio ttf do cdn lai dCing natu-itbiosunfat 0,1N, de kiem tra qui trtnh tich cio hoin toin tien hinh thd bang dung dich KI 0,1 N. Neu cdn cio ttf do se day I tao thinh I, lim cho hd tinh bot chuyen sang miu xanh. Tie'p tuc cho Na.S^Oj cho de'n khi khdng cdn cio ttf do. Tien hanh rda lai bang ntfdc vi li lam nhieu lan cho de'n khi thd cic chi't hda tan trong ntfdc khdng cdn nda. De thd xem cdn mud'i liTu huynh khdng diing H^SO^ vi dun nhe.
Ne'u cd ke't tua liAi huynh miu ving xui't hien, sau khi tach he't cic chi't hda tan, tie'n hinh si'y d 35" C de^n do i'm 10-12%, nghien nhd, sing va b i o quan.
2.4. Phan tich m l u bang kinh hidn vi dien td quet
Kinh hien vi dien td quet-SEM (Scanning Electron Microscope) da ke' thda phtfdng phip cua Jane, Kasemsuwan, Leas, Zobel and Robyt (1994). Nhdng bde vi anh da dtfdc thu thip bang he thd'ng kinh hien vi dien td quet JEOL JSM-35 (Jed, LTD, Tokyo, Nhit Ban). Mau tinh bdt dtfdc din tren chiee dia bac dit khdng gii chda miu thi nghiem, sau do miu tinh bdt dxXcic phu mdt ldp ving/palladium (ti le 60 : 40) trong mdt miy cd chin khdng (thiet bi bd'c hdi chin khdng), dien the' gia td'c 15 kv dtfdc sd dung trong sud't nhdng bde vi inh.
2.5. Stf nhidu xa qua tia X
Nhdng mau tinh bdt di qua nhidu xa tia X dtfdc ghi lai bang mdt nhieu xa ke (D/MAX-RA, Rigaku, Japan) (phdng xa Cu K-anpha, dien i p 40 kv, ctfdng do ddng dien li 100 mA). Mdc do dao ddng ciia gdc nhieu xa 2-teta la td 0-40" v i td'c do quet li 0,02" (4 teta/phiit). Do kdt tinh ttfdng dd'i cua tinh bdt dtfdc xic dinh dda tren phtfdng phip ciia Komiya, Nara vi Tsu (1986).
3. KET QUA VA THAO LUAN 3.1. SEM
Nhdng vi anh qua phin tich bang kinh hien vi dien td quet cua tinh bdt thudc hai nhdm dtfdc the hien qua blnh 3.1.1 va blnh 3.1.2.
Td vi anh qua phin tich bang kinh hidn vi dien td quet blnh 3.1.1 cho tha'y hat tinh bdt cua gid'ng dau xanh T135 deu cd dang hinh cau, hinh ovan hoic qui than.
NGHIEN cufu SU THAY DOI CAU TRUC CUA TINH BOT DAU XANH 95 Trong dd, nhdng hat nhd cd dang hinh cau cdn nhdng hat ldn cd dang hinh ovan hay qui thin. Ve trang thii be mat dil tinh bdt diu xanh ttfdng dd'i nhin khdng cd vet ndt, tren be mat mdt sd hat cd nep nhin.
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Hinh 3.1.1. Vi dnh hgt TBDX chua biin hinh
Hinh 3.1.2. Vi dnh hgt TBDX sau bien hinh
Sau khi bie'n blnh, quan sit vi anh cua tinh bdt diu xanh bie'n blnh ta thi'y cd stf thay ddi ve trang thii be ngoai: c i c vet nhan bie'n mat, tren be mat cua hat tinh bdt diu xanh bie'n hinh nhin hdn. Hat tinh bdt diu xanh sau bie'n blnh cd kich thtfdc nhd hdn, stf phin bd kich thtfdc hat ti-ai rdng ra, cd mdt sd hat bi vd,... Nhtf viy, qua blnh 3.1.1. v i hinh 3.1.2. ta nhin thi'y sau khi bie'n blnh bang NaClO, hinh thii hat tinh bdt dau xanh cd stf thay ddi. Nhtf viy, dieu nay cd the giai thich mdi trtfdng kiem trong phan dng lim hda tan ve't nhin dd ne'u ve't nhin l i cic mang protein bim vao. Mac du viy, ta cung cd the dtfa ra mdt ly do hoin toan thuye't phuc l i NaClO trong qui trtnh oxi hda se lim oxi hda nhdng vet nhin dd trtfdc vi lam cho chung bie'n mat.
3.2. Nhilu xa tia X
Hai mau tinh bgt da qua nhilu xa tia X dtfdc bieu hien tren 2 bieu dd 3.2.1. v i 3.2.2. Theo stf phin loai tinh bdt thtfc hien bdi Zobel (1964), miu tinh bgt diu xanh trtfdc bie'n hinh cd ca'u true thudc dang A. Tinh bdt qua bie'n blnh bang chi't oxi hda cho thi'y NaClO khdng lam thay ddi dang ke't tinh cua hat tinh bdt, tuy nhien cd stf thay ddi ding kd ve ty le ke't tinh trong hat. Ke't qua niy l i do tic ddng cua cio boat ddng t i c ddng v i o c i c nhdm-OH cua mach amilopectin-lim chung thay ddi v i khi nang lien ke't d c i c vung ke't tinh thay ddi hdn trtfdc.
Tdm lai, qui trinh bie'n blnh tinh bdt dau xanh bang bien phap oxi hda bdi NaClO lam thay ddi ltfc Uen ke't gida ldp ke't tinh v i ldp vd dinh hinh trong hat tinh bdt. Do do, lam thay ddi blnh dang, kich thtfdc va be mat ngoii cua hat tinh bdt sau bie'n blnh.
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4. KET LUAN
Ci'u true cua tinh bdt dau xanh trtfdc va sau bie'n blnh da dtfdc trtnh bay trong bai nghien cdu nay. Nhtf viy, thdng qua thtfc nghiem nghien cdu, rd rang ca'u true cua tinh bgt diu xanh sau khi bie'n hinh cd stf khic biet so vdi tinh bdt thu hdi dtfdc ban dau. Dieu do the hien qua blnh thai, miu sac, Uen ke't d cic vung ke't tinh cua hai miu tinh hot trtfdc v i sau bie'n blnh da dtfdc minh chdng nhtf tren. Ke't qui nghien cdu la nen tang cho viec xiy dtfng cdng nghe sin xui't tinh bdt oxi hda-md ra c i ky nguyen dng dung didc tien cua tinh bdt oxi hda vao ddi sd'ng v i san xua't ddng thdi gdp phan day lui viec nhip khau nhdng ngudn nguyen lieu ma tinh bgt bie'n hinh cd the thay the dtfdc.
NGHIEN CCu SU THAY DPI CAU TRUC CUA TINH BOT DAU XANH 97 TAI LIEU THAM KHAO
[1] T. T. M. Hanh, Nghiin cdu cdc dgng biin tinh tinh bgt vd hoa mdu vd dng dung trong cong nghiep thuc phdm, Luan an Tien sT Ky thuat, Dai hoc D i Nfng, (2003).
[2] T. D. Long, L. K. Ttfdng, Cdy dgu xanh. NXB N6ng nghidp. Ha Noi, (1998).
[3] L. N. Tu, Hoa hgc Thuc phdm. NXB Khoa hoc Ky thuit. Hi Noi, (1999).
[4] Y. H. Chang et al, Propeties of mung bean starch extracted l?y dijferent solutions, AACC annual meeting, Charlotte, North Carolina, 264 p, (2001).
[5] C. N. Hankins, L. M. Shannon, The physical and enzimatic properties of phytohemagglutinin from mung bean, J. of Biological Chem, 253(21), (1978), 7791-7797
[6] J. Jane et al. Effects of Amilopectin branch chain length and amiloza content on tegelatinization and pasting propeties of starch. Cereal chem, 7(5), (1999), 629-637.
SUMMARY
STUDY ON STRUCTURAL CHANGES OF MUNG BEAN STARCH AFTER TRANSFORMATION
Le Thi Anh Nguyet When physico-meehanical properties and stereochemical structure of materials change, the organoleptic properties of products also vary. This affirmation in food science is clarified and proven by theory. However, there arises an issue: why is there a change in the stereochemical structure of materials in the producing process?
Original starch has some properties that do not satisfy consumers; therefore, several methods have been applied to improve these properties, including oxidation, esterificadon, phosphatification, hydrolysis, chemical grafting, themal degradation and enzyme using etc,..., of which hypochlorite oxidation of starch is one of the most effective reactions developed for the transformation of starch. The oxidation of mung bean starch leads to structural changes of starch after transforming, which is applied to transform the properties and create new products with high organoleptic value.
"Trirdng FTTH Phu My 1-Phu My-Binh Dinh
Ngay nhan bai: 30/6/2011; Ngay nhan dang: 10/9/2011.
