Noi Dung Nien Luan-tinh

Lun vn tt nghip kha 33-2011

Bi Thanh Tnh 2071845

Chng 1. M U1.1. t vn

Bi l loi tri cy nhit i rt c a thch v c nhiu cng dng khc nhau. Khng nhng tri bi ngon, hoa bi to nn mi thm nh thng c dng nu ch hoa bi, m l, hoa, v qu bi u cha tinh du nn thng c dng xng gii cm. Ngy nay, khoa hc cn khm ph thm nhng c tnh tr liu mi ca bi nh mt lng ln cc cht chng oxy ha c sn trong nc qu h citrus, c chc nng bo v c th chng bnh lo ha (Ngun: Polydera, Stoforos, & Taoukis (2005)), lm gim cholesterol, ngn nga cao huyt p, gim tai bin tim mch, lm lnh vt lot d dy, phng chng ung th v c tc dng lm p ln da. Ngoi ra, khi nc bi hng ti c ho chung vi du olive, cn c kh nng ty tr nhng vin sn gan v mt. So vi cc loi nc ung khc, nc bi p l sn phm c gi tr dinh dng cao, c tnh cht gii nhit tt. Hin nay, vic sn xut cc sn phm t nc qu citrus c bit l nc bi ang gp phi kh khn do sn phm c v ng bi s hin din ca cc thnh phn gy ng nh neohesperidin, limonin v naringin v l nhng hp cht ng nht trong qu h citrus (Ngun: Kefford (1959); Marwaha and others (1994)). Do vy, vn nan gii nht l lm sao kh ng trong nc bi p. Nu lm theo cch truyn thng, nh la v gic bng ng, th coi nh tht bi. Cc cng trnh nghin cu c tm ra v p dng lm gim v ng trong nc bi nh: cng ngh lc cht ng, cc cng ngh nh ht bm (Ngun: Griffith, (1969), Johnson v Chandler, (1988)), phng php ha hc (Ngun: Kimball, (1987); Pritchet, (1957)), iu tr bng styrene divinyl benzen polystyrene (DVB) nha (Ngun: Kimball, (1991); Puri, (1984)), v -cyclodextrin (Ngun: Shaw v Wilson, (1983); Wagner et al, (1988)). Tuy nhin, nhng cng ngh trn khng c hiu qu v cn nhiu hn ch. Vi s tin b ca Cng ngh sinh hc, vic s dng enzyme naringinase (Ngun: Habelt v Pittner, (1983); Ting, (1958)) thy phn naringin trong nc bi lm gim v ng ca nc bi mt cch hiu qu. Do vy, c th lm gim hoc c th loi b v ng to v hi ha v nng cao cht lng cho sn phm th vic ng dng enzyme naringinase vo nc bi thanh trng l iu ht sc cn thit. 1.2. Mc tiu nghin cu V vy, mc tiu ca bi nghin cu ny l s dng enzyme naringinase thy phn naringin gim v ng trong qu trnh ch bin nc bi thanh trng.

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Chng 2. LC KHO TI LIU 2.1. GII THIU CHUNG 2.1.1. Nguyn liu bi Ngun gc, c tnh sinh hc v cc ging bi Vit Nam: Tn khoa hc ca bi l Citrus grandis (L) Osb var. Grandis,c ngun gc t ng Nam , qun o M Lai (Ngun : Alphonse de Candolle (1886)). Cy cao khong 5-15m, thng c gai ln, nhnh non c lng t. Bi chu ng tt nhit cao v c nhit thp. C nhiu ging bi c mu sc, v chua ngt khc nhau. Tri ln, hnh cu dng qu l, ng knh 10-40cm, c mu xanh vng nht khi chn, v dy, c tp ln mu vng nht hay hng, v ngt. Tri nng trung bnh 1-2kg, ht ln v n phi. min Bc c bi Phc Trch (H Tnh), bi oan Hng (Ph Th), bi M Linh (H Ni), bi Sn-T Lim (H Ni) (Ngun: ng Hng Dt, (2002)). cc tnh pha Nam c cc ging: bi Bin Ha, bi i, bi Thanh Tr, bi ng Nm, bi ng Cam, bi Nm Roi, bi Da Xanh,

Hnh 2.1. Bi Nm Roi Hnh 2.2. Bi Da Xanh Thnh phn ha hc v gi tr dinh dng ca bi Nc chim t l rt cao trong mi bi, do tnh cht ny m bi c tnh cht gii kht rt tt. Bn cnh , cn c mt t l ng nh v cht khong tp trung hu ht trong phn dch qu nn bi cn l ngun cung cp nng lng v mt s thnh phn dinh dng khc. Trong dch bi c cha nhiu vitamin C rt cn thit cho c th. V tri giu pectin c ch bin thnh nhiu dng sn phm nc gii kht, sir, mt, ru b.

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Bng 2.1. Thnh phn trong 100 gam nc bi Cc thnh phn n v Gi tr Nc g 91,38 Nng lng kCal 30 Protein g 0,55 Lipid tng s g 0,1 Tro g 0,29 Carbohydrate g 7,68 Cht khong Calcium, Ca mg 11 Iron, Fe mg 0.12 Magnesium, Mg mg 8 Phosphorus, P mg 9 Potassium, K mg 129 Sodium, Na mg 0 Zinc, Zn mg 0,07 Copper, Cu mg 0,044 Maganese, Mn mg 0,010 Vitamin Vitamin C, acid ascorbic tng s mg 38,1 Thiamin mg 0,034 Riboflavin mg 0,020 Niacin mg 0,191 Pantothenic acid mg 0,283 Vitamin B6 mg 0,042 Folate tng s mg 36 Folic acid mcg 0,00 Vitamin B12 mcg 0,00 Vitamin A, IU IU 272 Amino acid Tryptophan g 0,002 Lysine g 0,014 Methionine g 0,002 (Ngun: http://www.juicingbook.com/fruits/grapefruit/)

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Carbohydrates: Ting v Deszyck (1961) cho rng D-glucose, D-fructose v saccharose l cc loi ng ch yu trong bi. Hm lng ng bi khc nhau ty vo loi, giai on chn cng nh iu kin trng trt. Nghin cu ca Gerbinskii (1940) cho thy hm lng ng saccharose ca bi ln nht trong giai on thun thc v gim ngay giai on sau cng nh trong qu trnh tn tr do b thy phn thnh glucose v fructose. Acid hu c: Acid ch yeeuss tm thy trong bi l acid citric, bn cnh cn c mt s acid khc nh: acid tarparic, acid malonic, acid formic, Hu ht nhng acid ny hin din trong khng bo. S gim nng acid km theo s tng t l cht kh ha tan/acid xc nh mc thun thc v quyt nh v ngon ca qu (Walton, 2001). Bn cnh , acid hu c cn c vai tr quan trng trong qu trnh sinh trng v bo qun cc loi tri cy c mi. Protein v cc acid amin: Tri cy c mi khng phi l ngun cung cp protein c bn do cha hm lng rt thp. Hm lng protein tng trong qu trnh pht trin ca qu, hm lng protein v v tht qu t trng thi cn bng trong giai on thun thc (Watt v Merill, 1963). Nc bi cha b ba acid amin quan trng khng th thay th, t l amino acid trong nc qu thay i ty thuc vo mc trng thnh ca qu, y l mt ngun cung cp cht dinh dng rt cn thit. Vitamin: Gi tr dinh dng ca bi c lin quan mt thit vi hm lng cc vitamin m c bit l hm lng acid ascorbic gip tng cng sc khng ca c th. Vic b sung 5 mg vitamin C/ngy c th ngn chn bnh scurvy ngi ln (Mapson, 1967). Liu lng 30-60 mg vitamin C/ngy p ng nhu cu pht trin ton din ca con ngi. Hm lng acid ascorbic trong bi l 20-50 mg/100 g (Ting v ctv, 1971). Bn cnh , bi cn cha nhiu vitamin A, folate v vitamin B 5 rt cn thit cho hot ng sng ca c th.Bng 2.4: Hm lng vitamin ca bi so vi mt s tri cy c mi khc (mg/100g)

Tri cy Cam Chanh Qut Bi

Vitamin A 0,3 0,3 0,6 0,02

Vitamin B1 0,08 0,04 0,08 0,05

Vitamin B2 0,03 0,01 0,03 0,01

Vitamin PP 0,2 0,01 0,03 0,01

Vitamin C 48 50 55 42

(Ngun: Trn Thng Tun (1994)).

Cht khong: Cc loi tri cy c mi cha khong 0,4 % cht khong vi t l Natri/Kali hon ho v phng din dinh dng (Stevens, 1954). Kali chim t l4



cao nht trong tng hm lng cht khong ca tri cy c mi. Tri li, natri chim t l rt thp (hu nh bng 0) trong cc loi tri cy ny nn rt tt i vi nhng ngi cao huyt p, ngn nga bnh t qu. Trong tht qu n chim gn 40 % tng cht khong nhng trong v cha kali t nht. Canxi chim gn 20 % tng cht khong ca v, 8 % tng cht khong ca tht qu v 2,5 % tng cht khong ca dch p. Hm lng magie lun chim thp hn 5 % tng cht khong ca qu (Ladaniya, 2008). Phosphorus l mt phn ca nucleic acids v phospho-proteins. Phosphorus bao gm phospho v c, phospholipid, ethanol-phospho v t l ca nhng phn ny c th dng nh mt ch s v c tnh ca nc p t cc loi tri cy c mi trong thng mi (Vandercook v Guerrero, 1969). Lipid: Nc bi l mt thc phm rt t cht bo t nhin. Cht bo c tm thy thng l oleic, linoleic, palmitic v stearic acid, glycerol, 1-phytosterol trong dch v m qu. Swift v Veldhuis (1951) nhn nh lipid l ngun nng lng trong cc loi ht v tri cy. Lipid (phospholipids v glycolipids) tham gia vo thnh phn ca mng t bo thc vt. c bit, lipids v waxes gp phn quan trng to mi v cht lng ca bi (Walton, 2001). Hm lng acid bo cha bo ha tng trong sut qu trnh thun thc ca qu (Hendricson v Kerterson, 1963b). Ngoi ra, cn c s hin din ca mono, di, tri acid bo cha no, cc acid bo chim 97-99% tng s acid, acid bo cha no chim 25-31%. Cc sc t: Cc sc t c bn to mu trong tri cy c mi l chlorophylls, carotenoids, anthocyanins v lycopenes. Song song vi qu trnh phn hy chlorophylls l s tng hp carotenoid trong sut qu trnh chn ca qu. Nng anthocyanins tng nhanh khi qu gn t trng thi thun thc (Todd v ctv, 1961). Nhit ti u cho qu trnh tng hp carotenoid v lycopen ln lt l 10-150C v 16-210C. Nhit trn 300C ngn chn s tng hp lycopene (Tomes v ctv, 1956). Cc hp cht mi: Thnh phn ha hc ca cc cht mi ha tan trong nc bi rt phong ph v nh hng n mi v ca sn phm. Chng l nhng hp cht thuc cc nhm terpene, alcohols, esters, aldehydes, ketones, acid hu cCc hp cht d bay hi trong tri cy c mi gm hn 500 thnh phn. Terpene b oxi ha to thnh mi c bit (Stanley, 1962). Mc mi ca tri cy c mi tng khi tng mc thun thc v nhit bo qun. S gii phng mi tng khi v qu b tn thng v cc ti du b v (Moshonas v Shaw, 1979). Trong nc bi c mt s cht mi5



nh tangeretin (5,6,7,4-penta methoxylfavone), tetra-o-methyl-scutellarein (5,6,7,4tetra-methoxylflavone), Trong , su cht mi in hnh nht to s hp dn cho nc bi khi tch b v qu l nobitelin, sinnestin, tetra-oscutellarein, hepta methoxyl flavones, tangertin. Ngoi ra, ru cng l mt trong nhng thnh phn to mi cho tri cy c mi. Hai loi ru quan trng gp phn to mi trong tri cy c mi l 4-terpinenol v -terpinol (Attaway v ctv, 1962). Phenols, flavonoids v limonoids (i) Phenols

Phenols c vai tr quan trng i vi vic ci thin sc khe con ngi do chng c c tnh chng oxi ha, bo v tuyn thng thn, iu tr bnh thp khp v nhiu bnh khc. N l mt loi hp cht mi hu c, c cha mt hoc nhiu nhm hydroxyl (OH) gn vo vng benzene. ha tan ca cc hp cht phenol ph thuc vo s lng nhm hydroxyl. S nhm hydroxyl cng nhiu th s ha tan cng cao (Kefford v Chandler, 1970). Cc hp cht phenols c vai tr quan trng i vi s cn bng hormone, mu sc, mi v cho thc vt. Do vy, s thay i ca cc hp cht ny cng ko theo s thay i v tnh cht cm quan cng nh kh nng chu tc ng vt l, mm bnh ca qu (Neish, 1964). (ii) Flavonoids Cc flavonoid glycoside thng to v ng v lm hn ch kh nng pht trin cc sn phm t tri cy c mi. Thng thng, nng ca cc flavonoids gim khi tri t trng thi thun thc. Theo nghin cu ca Pandey (1984) chng chim khong 5 % qu thun thc v 30 % qu cha thun thc (tnh theo trng lng kh). Flavonoid glycoside cha nhiu trong tri cy c mi, ch yu l hespiridin, naringin v neohespiridin. Thnh phn v hm lng cc flavonoid trong bi c Peterson v ctv (2006) nghin cu v trnh by trong bng 2. Bng 2: Hm lng cc flavonoid trong biTn hp cht Didymin Eriocitrin Hesperidin Naringin Narirutin Neoeriocitrin Hm lng (mg%) 0,07 0,45 2,78 16,00 4,90 0,35 6

Lun vn tt nghip kha 33-2011 Neohesperidin Poncitrin

Bi Thanh Tnh 2071845 1,40 0,17(Ngun: Peterson v ctv, 2006)

Naringin Naringin (Naringenin-7-neohesperidoside) c cng thc phn t C27H32O14. Naringin l hp cht flavonoid ch yu trong bi. Naringin chim khong 0,017-0,025 % trong nc bi. Ngng pht hin ca naringin trong dch qu l 50 mg/l (Kimball, 1999). Bi cha thun thc c v rt ng do c nng naringin cao. Naringin c trong v, ci v trong dch qu bi. Naringin l glycoside bao gm aglycon naringenin v disaccharide neohespiridose (2-0--L-rhamnopyranosyl-D-glucosepyranose). Aglycones v neohespiridose s khng ng khi hin din trng thi n l. Neohesperidose cha hm lng ln trong bi non (Ladaniya, 2008). Naringin ha tan trong ru, acetone v nc nng, nhng ch tan rt t (khong 1/2000) trong nc 200C, nng chy 1710C (Maier v Metzler, 1967a). Hm lng naringin thay i trong sut qu trnh sinh trng, ch bin v tn tr. Naringin cha hm lng ln trong qu cha thun thc nhng gim trong sut qu trnh chn (Ladaniya, 2008). Trong qu trnh thanh trng, hm lng naringin trong nc bi ph thuc vo nhit v thi gian gi nhit. Nhit cao v thi gian di lm tng v ng ca nc bi (Trn Th Cm T, 2007). Kt qu nghin cu ca Nguyn Th Minh Trang (2009) v s phn b naringin trong cc phn khc nhau ca bi Nm Roi cho thy hm lng naringin gim dn theo th t: v bao (124,494 mg%); v trng (98,47 mg%); v xanh (28,4 mg%); tht qu (6,249 mg%). Bn cnh , hm lng naringin trong dch qu trch ly cn ph thuc vo phng php tc dng c hc: my xay sinh t (7,27 mg%), my p (3,66 mg%). Naringin cn c nhiu tc dng dc l nh hot ng chng oxy ha, gim lipid trong mu...Naringin c th c dng nh c ch cc hp cht gy ung th.

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Hnh 2.3. Cu to hp cht Naringin Hesperidin Hesperidin (Hesperetin-7-rutinoside) c nhiu trong ci cam, chanh, qut, bi, v ng t, c hot tnh Vitamin P. Hespiridin c th dn n s kt ta hoc lm gim ha tan ca cc sn phm t cam (Hendrickson v Kesterson, 1964b). Hesperidin nh hng rt t hoc khng nh hng n mi v ca nc bi v l hp cht khng ha tan, n thng tn ti dng kt tinh trong nc bi. Hesperidin c th b bin i thnh hesperidin chalcone nhng khng bn thng b thy phn thnh rhammose, glucose, aglucon hesperidin (Ngun: Nguyn Minh Thy, (2008)). Hesperidin c tc dng khng vim, chng oxi ha, chng d ng, chng ung th, khng vi sinh vt (vi khun, nm, virut...), gim au, h st, chng c, chng long xng v c bit khi dng phi hp vi vitamin C c tc dng cng hng v h tr hp th vitamin C rt tt (hppt://www.vinachem.com.vn). C50H60O27 + 2H2O = C10H12O5 + 2C6H12O6 + 2C16H14O6

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Hnh 2.4. Cu to hp cht Hesperidin (iii) Limonoids Limonin l mt limonoid c tm thy vi lng ln trong cc loi tri cy c mi. Hm lng limonin gim khi tri t trng thi thun thc. Limonin l cht ng, nhng cht tin thn ca n l limonin monolactone khng ng v cht tin thn ny s chuyn thnh limonin khi gp mi trng acid. nng 50 ppm limonin monolactone khng gy ng, trong khi limonin gy ng nng khong 2,7 ppm v rt ng nng 15-20 ppm. V ng xut hin khi nc p n nh trong vi gi hoc sau qu trnh gia nhit. Sau khi trch ly nc bi, trong mi trng acid (pH di 6,5), monolactone (A-lactone v D-lactone) khng ng chuyn thnh dilactone (limonin) ng (Maier v Beverly, 1968). Bi khi b tn thng c hc, gy ra s ph v t bo, to mi trng acid cho enzyme hot ng, gy ng dch qu (Cabral, 1994). Limonin cng l mt cht chng ung th. Mt s th nghim i vi t bo ung th ngi cho thy limonin c hot tnh i vi ung th vng ming, vm hng, phi, d dy, ng rut, da, gan v v.

Hnh 2.5: Limonin (ng) trong mi trng acid chuyn thnh limonoate A-ring lactone (khng ng) trong mi trng kim. (Ngun: Fayoux et al.(2007))

Dc tnh ca bi Cc nghin cu gn y pht hin mt tc dng v cng quan trng ca qu bi l chng ung th. Cc nh khoa hc chng minh cht calcium c trong cc loi thc n c ngun gc t thin nhin c th phng c ung th i trng m mt trong nhng ngun cung cp calcium tt nht chnh l t qu bi. Bi cn c chc nng bo v c th chng bnh lo ha, lm gim cholesterol, ngn nga cao huyt p, gim tai bin tim mch, lm lnh vt lot d dy, gip gim cn v phng chng bnh tiu ng, phng chng v gim bnh vim li, c tc dng lm p ln da. 2.1.2. Enzyme Naringinase Gii thiu v enzyme Naringinase9



Naringinase l mt enzyme c s dng trong sn xut thng mi ca nc tri cy c mi. Nhng hp cht ng c tm thy trong tt c cc b phn ca qu bi nh neohesperidin, limonin v naringin (Ngun: Kefford, (1959); Marwaha and others (1994)). Naringin l thnh phn chnh trong bi v n l cht ng nht. Ngng v ca n trong nc l khong 20 ppm, nhng mc 1,5 ppm c th c pht hin. Naringin c nhiu trong tri cy cha trng thnh nhng nng ca n gim khi qu chn (Ngun: Yusof et al, (1990)). Enzyme ny thy phn cc hp cht naringin, hp cht c v ng trong nc bi. Enzyme ny cha c -L-rhamnosidase (EC 3.2.1.40) v -D - glucosidase (EC 3.2.1.21). Naringin c th c thy phn bi -L-rhamnosidase to ra rhamnose v prunin (4,5,7-trihydroxyflavonone-7-glucopy ranoside), cng c th thu c prunin bi -D-glucosidase (Ngun: Park and Chang, (1979)). Lc ng ca dch qu p sau khi x l bng enzyme gim i rt nhiu do tnh ng ca prunin nh hn naringin khong 1/3. Nh vy m nc bi mang li v hi ha hn, tng gi tr cm quan ca sn phm. Ngun thu nhn enzyme naringinase Trong lch s, naringinase c phn lp t ngun thc vt nh: ht cn ty (Ngun: Hall, (1938)) v l bi (Ngun: Hall, (1938), Thomas v cng s., (1958); Ting, (1958)). Tuy nhin, ch c cc quy trnh da trn vi sinh to ra naringinases l kh thi, v loi nm mc Aspergillus Niger c ng dng rng ri. Naringinase l mt trong sn phm chnh yu ca nm loi Aspergillus v Penicillium (Ngun: Ono et al, (1978)).

(chn hnh c th)

Bng 2.2. Naringinase c sn xut bi nhiu vi sinh vt

Cc ng dng ca enzyme naringinase Enzyme ny c th c s dng to ra cc tin hp cht quan trng trong thc phm v y hc. Trong y hc Chloropolysporin C Chloropolysporin A, B, v C c th c chuyn i thnh cc dn xut enzyme deglycosylated (Ngun: Sankyo, (1988)). S kt hp ca chloropolysporin C v lactame c tc dng chng li cc vi khun gram dng nh Staphylococcus aureus. V cc khng sinh ny cng c ch cc vi khun gram dng k kh Enterobacteria.10



Rhamnose Naringinases (-L-rhamnosidases) thy phn naringin sn xut L-rhamnose. Rhamnose l mt cht trung gian trong tng hp cc hp cht hu c v n c s dng nh l mt dc phm v thuc bo v thc phm. Prunin Prunin c hot ng khng vim v c th c s dng cho bnh nhn tiu ng (Ngun: Roitner et al, (1984)). Cc glycoside flavonone t nhin ca naringenin cng c bo co ngn chn lot nim mc d dy trong cc m hnh ng vt. Trong thc phm Naringinase c s dng trong sn xut thc phm vi hai mc ch ch yu l ci thin gi tr cm qun sn phm v sn xut ph gia thc phm. Naringinase thng c s dng trong cc qu trnh kh ng nc qu t tri cy c mi. Bn cnh , n cn c s dng loi tinh th hesperidin. N cn c dng tng hp dihydrochalcone. ngt ca dihydrochalcone glucoside ca naringin, neohespiridin v hespiridin ln lt l 300, 1100 v 300 ln so vi ng saccharose (Ngun: Horowitz v Gentili. (1984)). Ngoi ra, cc hot ng rhamnosidase ca naringinase kt hp vi -glucosidase v Arabinosidase c xem l ph hp nng cao hng thm trong ru vang. Hot ng chuyn ha ca naringinase Naringinase l mt enzyme gm s kt hp ca hai thnh phn l -Lrhamnosidase (EC 3.2.1.40) v -D-glucosidase (EC 3.2.1.21). Naringinase phn ct naringin thnh naringenin qua hai cng on sau: -L-rhamnosidaseNaringin Prunin Prunin + rhamnose

-D-glucosidase

Naringenin + Glucose

Hnh 2.6. S thy phn naringin thnh prunin, rhamnose, naringenin v glucose bi naringinase gm hai enzyme l -L-rhamnosidase v -D-glucosidase11



Bc thy phn u tin l quan trng hn v n lm gim ng k v ng ca nc bi. Prunin c bn l t ng hn naringin (Ashok Pandey, (2004). Naringenin l mt thnh phn khng ng trong nc bi (Ngun: Munshi et al, (1996)). Xc nh hot ng naringinase Vic xc nh hot ng ca naringinase da trn vic xc nh quang ph ca flavonones theo phng php kim glycol diethylene ca Davis (1947). Cc phn ng naringin vi thuc th to ra mt mu vng c o bc sng 420 nm. Phng php cho hiu sut cao nh sc k lng (HPLC) c s dng cho vic xc nh hot ng naringinase (Ngun: Horuichi et al., (1985)). Phng php HPLC xc nh hot ng ca naringinase bng cch o s thay i nng -rhamnoside (Ngun: Romero et al, (1985)), bng cch s dng p-nitrophenyl-L-rhamnopyranoside o hot ng L-rhamnosidase ca naringinase bc sng 280 nm. M t c tnh ca naringinase Cc naringinase thng mi ca Aspergillus niger cng c c -rhamnosidase v cc hot ng -D-glucosidase (Ngun: Roitner v cng s, (1984)). T l ca cc hot ng ny thay i ty theo nng protein v pH. Hai enzyme ny hot ng gn nh c lp vi nhau: rhamnosidase hot ng pH trong khong 3-7, trong khi glucosidase cho thy hot ng ti u pH thay i gia 4 v 6. Hai enzyme ny c tch ra bng cng ngh lc gel. Naringinase tinh khit c c nh t Aspergillus hot ng nhit ti u c xc nh l 50C, pH ti u cho hot ng naringinase c xc nh l 4, mc d pH 3 v 5 n vn cn tng i tch cc, c b mt ch 14% hot ng ti a ca n (Ngun: Manjon et al, (1985)).

Hnh 2.7. pH v nhit ti u cho mc hot ng ca enzyme Naringinase Tsen v Tsai (1988) bo co rng pH ti u ca naringinase t Penicillium l 3,7 v enzyme ny hot ng ti a khong 75-85% trong nc tri cy t nhin (3-3,4). Naringinase t Penicillium sp. cha c -L-rhamnosidase v -D-glucosidase. pH ti u cho hai enzyme ny ln lt l 4,5 v 3,0 (Gabor v Pittner, 1984). Enzyme naringinase b c ch cnh tranh bi ru v glucose, nng ion khng nh hng n hot ng ca enzyme. Nng cn 12 % (v/v) lm gim 20 % hot tnh ca enzyme ny. Hot tnh thy phn ca naringinase gim 15 % khi c s hin din ca 21 % (w/v) glucose. Tuy nhin, tc thy phn ca enzyme ny khng b nh hng khi c SO2 nng 50 ppm (Gallego v ctv, 2001).12



Theo Thomas v cng s (1958) vic lm gim cht ng ca nc bi t c khi chuyn naringin thnh rhamnose v pruning, nhng cht ny tng i khng ng v qu trnh thy phn to naringenin l khng cn thit.Nghin cu ca Ladaniya (2008) cn cho thy cc yu t nhit , pH, nng enzyme v thi gian thu phn cng c nh hng n hiu qu thy phn naringin. Kh nng thy phn ca naringinase tng khi tng nhit . Tuy nhin, mi quan h ny khng tuyn tnh. nng enzyme thp, kh nng thy phn t l vi thi gian thu phn. Tuy nhin, nng enzyme cao hn th kh nng thy phn t ph thuc vo thi gian.

Theo Walson (2001), nhit tt nht cho qu trnh thy phn l 600C, enzyme hot ng ti a pH 4, nhng hot ng ca enzyme khng c s khc bit pH 3,5 n 4,5. Kt qu nghin cu ca Ting cho thy, nng enzyme thp th hiu qu thy phn t l thun vi thi gian, trong khi nng enzyme cao hn th t l thy phn gim theo thi gian phn ng. Nguyn nhn c th l do s c mt ca nhng enzyme khc v nhng cht c ch nh glucose v nh hng ca sn phm cui. (chn hnh) Ngoi ra, p sut cng c tc ng n hot tnh thy phn naringin ca enzyme naringinase. Vn ny c Helder v ctv nghin cu vo nm 2006. Kt qu cho thy, cng mt nhit (303 K), hot ng ca enzyme cao hn p sut 160 MPa (Vmax = 2,7 mM/pht) so vi p sut kh quyn (Vmax = 0,06 mM/pht). 2.1.3. Nc Nc l thnh phn ch yu trong dch qu v cng l thnh phn quan trng trong sn xut cc loi nc gii kht, v th cht lng nc c nh hng rt ln n cht lng sn phm. Tuy nhin, nc trong t nhin khng dng tinh khit m thng c ln nhiu tp cht, vi sinh vt Bng 2.3.Tiu chun nc dng trong cng nghip thc phmCh tiu Ch tiu vt l Mi v trong (ng Dienert) Mu sc (thang mu coban) Ch tiu ha hc pH CaO MgO Fe2O3 MnO BO43Tiu chun Khng 100ml 5 6,0 7,8 50 100 mg/l 50 mg/l 0,3 mg/l 0,2 mg/l 1,2 2,5 mg/l 13

Lun vn tt nghip kha 33-2011 SO42NH4+ NO2NO3Pb As Cu Zn F Ch tiu vi sinh Tng s vi khun hiu kh Ch s Coli (s Coli/1lits nc) Chun s Coli (s ml nc c 1 Coli) Vi sinh vt gy bnh

Bi Thanh Tnh 2071845 0,5 mg/l 0,1 0,3 mg/l khng khng 0,1 mg/l 0,05 mg/l 2,0 mg/l 5,0 mg/l 0,3 0,5 mg/l 99 % Tro

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