Chat khang khuan thuc vat

8/7/2019 Chat khang khuan thuc vat

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I. Gii thiu v cht khng khunII. Phyto-phenol

II.1 Gii thiuII.2 Tnh khng khun

II.2.1 Cc hp cht trong du oliuII.2.2 Thymol v carvacrolII.2.3 BorneolII.2.4 Eugenol v cinnamic aldehyde

II.2.5 Linalool v chavicolIII. Saponin

III.1 Gii thiu, phn loiIII.2 Tnh khng khunIII.3 ng dng trong thc phm

IV. FlavanoidV. a

I. Gii thiu v cht khng khunN lc ch bin v tch tr lng thc t lu l mt nhu cu bc thit cho s

pht trin ca con ngi. Khng th no tm hiu chnh xc s pht trin ca cng nghch bin thc phm. Nhng nghin cu nhn chng hc lin tc khm ph ra s tn tica vic nu n bng la trong nhng thi k u ca loi ngi. S gn b vi t nhinv s quan st mi trng dn n vic xc nh nhng loi thc phm n c; chtgii c hoc bi thuc bo v v cha bnh; cng nh mt mng rng ln cht muv mi phc v cho s ngon ming. S tch ly mt lng kin thc khng l bin mthc thnh mt mn khoa hc.

S khm ph ra nhng vi sinh vt na cui th k 18 em thc n n trcng knh hin vi. Sc truyn bnh ca vi khun sa Coxiella burnetti hay hoc kh nngln men sa ca cc loi lactobacillus c khm ph. Phng php Pasteur (thanhtrng) tr thnh bin php st khun u tin da trn khoa hc ca vic sn xut sa.

Ngnh vi sinh thc phm nghin cu v vic nhim khun v nhim c thc phm rai ti c cu hon ton h thng x l thc phm truyn thng. Li ch dinh dngcng nh sc mnh cha bnh ca mt s nguyn liu thc phm c pht hin tnhiu th k v ang ngy cng c nghin cu tng tn.

Cng ngh khng khun thc phmYu cu v s lo lng ton cu l mt ng lc cho s tng tc trong nghin cu

v pht trin k ngh bo v thc n. Yu cu v thc n t qua ch bin v cha cht chot tnh sinh hc t nhin ang ngy mt tng. Yu cu ny tng ln do s lo ngi vcht bo qun tng hp vi rt t bo co v an ton; s lin quan gia vic s dng chtkhng khun qu mc v s khng thuc ca vi khun; v s ph bin ca nhng thngtin v thc phm v sc khe trn bo ch. Hn na, vic lin tc xut hin nhng dch

bnh v v ng c thc phm trong khong thi gian vi chc nm tr li do nhng vikhun nh E.coli, Salmonella typhi, Listeria, Vibrio cholera, Staphylococcus aureus bin khi nim an ton thc phm thnh mt u tin hng u cho mi quc gia.

Bo v thc n khi h hng v nhng tc nhn gy bnh c th c thc hinbng nhiu bin php nh bin php tit trng dit hu ht vi khun; tiu dit bngphng php vt l nh ra, ly tm hay lc, tiu dit bng un nng, kh hay chiu x; vkm hm s ph trin bng phng php lnh, lnh ng, bao gi kh, hay thm ph gia.Mi bin php c mt li ch ring trong h thng bo qun thc phm.

Nhiu tc nhn khng khun hin din trong c th ng v thc vt nh c chphng th ca c th . Nhng cht ny xut hin rt phong ph trong t nhin. Nhng


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hp cht ny ngoi vic bo v bn thn nguyn liu t nhin khi vi sinh vt cn c thdng lm ph gia cho thc phm. Cc cht nh vy c th chia lm 6 nhm:

- Cht khng khun sa (Lacto-antimicrobials): Gm cc cht nhLactoferrin (LF), Lactoperoxidase(LP), Lactoglobulins, Lactolipids,

- Cht khng khun trng (Ovo-antimicrobials): Gm Lysozyme,Ovotransferrin.

- Cht khng khun thc vt (Phyto-antimicrobials): Gm cc nhmchnh nh Phyto-phenol, Saponin, Flavanoid, Thiosulfate, Catechin,

Glucosinolate, Agar (thch)- Cht khng khun vi sinh: Probiotic, Nisin, Pedioxin, Reuterin, Sakacin- Acid khng khun: Acid lactic, acid sorbic, acid citric- Cht khng khun v c: NaCl, Polyphosphate, Chloro-cide (CD),

Ozone (O3).Trong bi tiu lun ny, chng ti xin gii thiu v cc hp cht c hot tnh sinh

hc c ngun gc thc vt, hay cht khng khun thc vt.Cc hp cht ny l nhng cht thuc c ch phng th ca thc vt. Chng c

th chia lm 7 nhm: Phyto-phenols, Saponin, Flavanoid, Catechin, Thiosulfinate,Glucosinolate, Agar (Thch)

II. Phyto-phenolII..1 Gii thiuPhyto-phenol c th c nh ngha l mt hp cht c trong tinh du ca gia v,

tho mc hay ht, l dn xut ca phenol v c tnh khng khunVic bo qun thc phm bt u t thi tin s v mt s ni trn th gii

n dn pht trin thnh mn m thc. Li ch tim tng ca nhng thc vt n c,cng nh kh nng gia tng tnh cht cm quan ca chng c thc hnh qua nhiuth k. 5000 nm trc, ngi Trung quc bit dng cy lm thuc. Nhng bi nghincu gn y cho thy ngi Ai cp c dng qu (cinnamon), cy th l (cumin) vhng ty (thyme) c trong bo qun thc phm v p xc. Ngi hi gio xa bo qunsa chua bng du oliu v cho rng du oliu c kh nng bo qun.

Nghin cu khoa hc v kh nng bo qun thc phm ca gia v dy ln voth k 19. Chamberland (1887) lu u kt lun rng tinh du qu c tnh khng khuni vi bo t ca anthrax bacilli. Grove (1918) quan st kh nng bo qun s c chuaca dung dch v ru chit xut t qu. Prasad v Joshi (1929) pht trin mt phngphp bo qun tri cy ti bng cy inh hng v mui. Fabian v cng s (1939) phthin ra rng qu km hm s pht trin ca vi khun nng th tch 1:50; inh hngc ch vi khun Bacillus subtilis 1:100 v S.aureus 1:800.

Gia v v tho mc thc vt c dng thm mi c trng cho thc phm.Theo Lindsay (1996) th tho mc l thc vt chuyn ly l, cn gia v l thc vt chuynly r, tri, ht, cnh hoa, v (Bng 1). Tho mc thng mc vng cn nhit i v ni trong khi gia v moc vng nhit i. Gia v c bn dng ti hoc kh. Gia v

kh c th c tch ly tinh du bng dung mi, v d nh ehtanol.D ngi c i bit v tnh khng khun v st trng ca chit xut t cy,nhng hp cht khng khun ca chng ch mi c nh danh v nh tnh gn y.Nhng bc tin trong k thut tch chit phn t h tr cho vic phn lp nhiu hpcht phyto-phenol. Nhu cu ngy mt tng v thc n t qua ch bin, hn s dng luhn lm sng li cng cuc khai thc nhng hp cht khng khun ny.

Bng 1: Gia v v tho mc vi tnh khng khun v hp chtchnh


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Nhng hp cht c tnh khng khun ca gia v thng l dn xut ca phenol.Nhng hp cht nh trn thng c trng cho mt hoc vi loi cy (Bng 2).

Bng 2. Cc dn xut phenol gn vi ngun gc thc vtDn xut ca phenol Ngun gc thc vtApigenin-7-gucoside H Oleaceae (cy oliu)Acid benzoic Cc loi gia vBerbamine BarberryCaffeine TrAcid Caffeic Oliu/tri b/cy a-ti-so/toAcid O-caffeylquinic A-ti-so/mn/C rt

Caryophelene Cy hp b (hop)Catechin V v ht cy nho/TrAcid cinnamic Du ht cy Brassica (M tt)Acid chlorogenic A-ti-so/toAcid Chelldonic BerberryChicorin Rau dip xon (chicory)Columbamine BerberryCoumarin Cc loi gia vAcid p-coumaric Tri b/toCyanarine A-ti-soAcid dihydrocafeic Oliu

Dimethyloleuropein OliuEsculin Rau dip xonAcid ferulic Oliu/b/m ttAcid Gallic Oliu/nho/b/m ttGingerol Cc loi gia vHimulin Cy hp bHydroxytyrosol M ttAcid 4-hydroxybenzoic B/m tt/vani/c rtAcid 4-hydroxycinnamic M tt/c rt


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Isovamillin BLinalool Rau ngLupulon Hp bLuteoline-5-glucoside M ttLigustroside M ttMyricetin TrAcid 3-methoxybenzoic M ttOleoside M ttOleuropein M ttParadols Cc loi gia vO-pyrocatechuic BQuercetin-3-rutinoside TrQuercetin M tt/trAcid resocrylic BSesamol VngShogoals Gia vAcid syringic OliuAcid sinapic B/oliu

TanninN

ho/gia v/oliu/vng/tho mc/trAcid tannic Tr/nhoThymol Hng tyTrimethoxybenzoate M ttVanillin Gia vi/VaniAcid vanillic Vani

Tnh khng khun ca qu, t v inh hng gn lin vi cht eugenol (2-methoxy-4-allyl phenol) v cinnamic aldehyde, trong tinh du ca chng c hm lng 2cht ny rt cao. Tinh du qu chim 0,5-1% khi lng cy, trong eugenol 65-75%khi lng tinh du. Tng t hm lng eugenol trong tinh du ca t v inh hng l

80% v 93-95%.Rau oregano, rau savory v hng ty c tnh khng nm. Cc hp cht terpenenh carvacrol, p-cymene v thymol l thnh phn chnh ca tinh du cc loi rau ny.Tinh du ca rau oregano cha 50% thymol; hng ty cha 43& thymol v 36% p-cymene; v rau savory cha 30-45% carvacrol v 30% p-cymene

Tnh khng khun ca cy ngi ng v cy m it cng do nhng terpene trongtinh du. Cy m it cha borneol, camphor, 1,8-cineole, -pinene, camphene,verbenone v bornyl acetate trong khi cy ngi ng cha thujone [4-methyl-1-(1-mehtylethyl)bicyclo-3-1-O-hexan-3-one]

Gn y, nhiu hp cht phyto-phenol c tch chit t cy oliu. Chng ctc dng trn vi khun lactic. Hp cht ny c xc nh l tyrosol, acid p-

hydroxyphenylacetic, p-coumaric v acid ferulic.


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II.2 Tnh khng khunTnh khng khun ca cc phyto-phenol ph thuc vo nhiu yu t. Chng hn

nh thnh phn ha hc, iu ny ph thuc vo ngun gc a l ca loi thc vt. Cchchit xut cng ng vai tr nht nh. Nhng thnh phn ha hc ca thc n, hmlng cht khong, pH, nhit cng nh hng n tnh khng khun ca phyto-phenol.Nhng quan trng hn c l tnh cht ca vi sinh vt hin hu trong thc phm: loi (vikhun, nm mc, nm men), dng (t bo, bo t), dng, chng, thi k pht trin (phalag, pha log) Bng tm tt cc phyto-phenol cng loi vi sinh vt chng tc dng c

cho bng 3Bng 3: Hp cht phyto-phenol v ph khng khun ca chng

Phyto-phenol Loi vi sinh vt thch hp-pinene / limonene Vi khun Gram dng / nm men pulegone Vi khun / nm mcTerpinen-4-ol Vi khun/ Candida albicansIntermediol / borneol B.subtilis / S.aureus / E.coli / T.mentagrophytes / C.albicansLinalool / terpinene C.albican/ E.coli/ S.aureusChavicol S.cerevisiae

II.2.1 Oleuropeiny l mt polyphenol c nhiu trong du oliu. N c ph khng khun kh rng.Oleuropein tinh khit c tnh cht khng khun rt mnh. nng thp C=0,1%

oleuropein lm chm s sinh si ca Staphylococcus aureus, nng cao hn 0,4-0,6%c ch hon ton. Tuy nhin, oleuropein ch c tc dng khi vi khun pha lag v phalog, pha m th khng c tc dng.

Oleuropein, nng cao hn 0,2% km hm s sn sinh cht enterotoxin B. Tuynhin nng nh hn 0,1% khng c tc dng ny nhng gim c lng vi khun.

Oleuropein cn tc dng lm chm sinh trng ca nhiu vi khun khc nhEscherichia coli, Klebsiella pneumoniae, Bacillus cereus, nmAspergillus flavus vAspergillus parasiticus, Bacillus cereus.

Ngoi oleuropein, trong du oliu cn nhiu hp cht khc cng c kh nng khng khunnh p-hydroxy benzoic, vanillic, caffeic, protocatechuic, syringic, acid coumaric v quercetin.

ng dng trong thc phm:Kh nng c ch ca oleuropein vi vi khun Salmonella enteridis trong sa cng c

nghin cu. S c ch tt nht trong iu kin pH thp. Oleuropein thng phm ang c snxut ng dng lm cht khng khun trong sa.

Du oliu tng c xem l qu nh vng trong cng ngh thc phm. Du oliu c gi trdinh dng cao, khng cn bo qun lnh, thi gian bo qun lu, c th ch bin trong thc n lnhhay un nng. Du oliu c dng nhiu trong nu nng: chin xo, trn salad, lm m . Ngoira, du oliu cn dng bo qun nhng gia v khc nh gng, tiu. Tuy nhin, nh nhiu li dukhc, du oliu cha cc cht bo d b oxi ha, v vy cn c bo qun trong ti.

II.2.1 Thymol v carvacrol


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Tnh khng khun ca 2 loi rau: oregano v hng ty(thyme) gn vi cc hp cht terpenec trong tinh du ca chung: carvacrol [2-methyl-5-(1-methylethyl)phenol] va thymol [5-methyl-2-(1-mehtylethyl)phenol]

Thymol v carvacrol nng thp (1:2000 v th tch) c ch cc vi khun Bacillussubtilis, Salmonella enteridis, S.aureus, Pseudomonas aeruginosa, Proteus v E.coli.

Nng c ch ti thiu (MIC) ca oregano i vi vi khunListeria monocytogenes 24oCkhong 0,5-0,7%. S sn sinh acid lactic ca vi khunLactobacillus plantanum vPediococcuscerevisiaeb c ch nng oregano 4mg/ml. Tuy nhin, nng rt thp, chng li kch thch vi

khun sinh ra acid.Di y l bng tm tt v hot tnh khng khun ca thymol v carvacrol.

Bng 4: MLC (Minimal lethalconcentration: nng gy cht; g/ml; lng vi sinh vtgim >=99.9%) ca thymol va carvacrol

Vi sinh vt Hot cht chnh MLC (g/ml)Vi khun Gram mEscherichia coli Thymol / Carvacrol 225Salmonella Typhymirium Thymol 56,25Yersinia enterocolotica Thymol / Carvacrol 225Vi khun Gram dngBacillus cereus Thymol 450Listeria mococytogenes Thymol / Carvacrol 450Staphylococcus aureus Thymol 225Nm mcCandida albicans Thymol / Carvacrol 112,5Saccharomyces cerevisae Thymol / Carvacrol 112,5

Qua bng ta thy, thymol c bit c tc dng vi Salmonella typhi,Staphylococcus aureus v nm mc.

Carvacrol c tc dng mnh hn thymol i vi E.coli vPennicilum.Thymol v carvacrol lm thay i cu trc mng t bo ca vi khun, lm ri lontrao i cht v git cht vi khun.

Bng 5: Nng cch ti thiu (%th tch/th tch) (Minimum Inhibitoryconcentration) ca mt s tinh du tho mc v gia v xc nhh bng phng php agardilution:

Thc vt Enterococcusfaecalis

E.coli Pseudomonasaeruginosa

Salmonellatyphimurium

S.aureus Candidaalbicans

Basil (Hng qu >2,0 0,5 >2,0 2,0 2,0 0,5Bay (nguyt qu) 0,5 0,12 1,0 0,25 0,25 0,12Black pepper 1,0 >2,0 >2,0 >2,0 >2,0 >2,0

Clove (inh hng 0,5 0,25 >2,0 >2,0 0,25 0,12Coriander (ng ta) 0,25 0,25 >2,0 1,0 0,25 0,25Fennel (th l) >2,0 0,5 >2,0 1,0 0,25 0,5Ginger (gng) >2,0 >2,0 >2,0 >2,0 >2,0 >2,0Lemongrass (s) 0,12 0,06 1,0 0,25 0,06 0,06Marjoram (kinh gii) 2,0 0,25 >2,0 0,5 0,5 0,25Oregano 0,25 0,12 2,0 0,12 0,12 0,12Peppermint (bc h cay) 2,0 0,5 >2,0 1,0 1,0 0,5Rosemary (m it) >2,0 1,0 >2,0 >2,0 1,0 1,0Sage (ngi ng) 2,0 0,5 >2,0 2,0 1,0 0,5


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Spearmint (bc h lc) 2,0 0,25 >2,0 0,5 0,25 0,12Tea tree 2,0 0,25 >2,0 0,5 0,5 0,5Thyme (hng ty) 0,5 0,12 >2,0 >2,0 0,25 0,12Wintergreen >2,0 0,5 >2,0 0,5 2,0 0,25

Thymol v carvacrol cn c tnh khng nm. S sinh trng v sinh aflatoxin caA.parasiticus b c ch 500g/ml trong 10 ngy 28oC.

Ngoi tnh khng khun, thymol, carvacrol cn c tnh chng oxi ha. Tnh chng oxi ha l

tnh cht ngn cn s oxi ha lipid thc phm. Nhng hp cht k trn ngn cn qu trnh peroxiha pohspholipid lyposome nu c mt ion Fe3+ v ascorbate.

ng dng trong thc phm:Thymol v carvacrol b mt hot tnh khng khun trong mi trng: hiu kh, pH thp, cha

cht Polysorbate 80, bovine serum albumin.Thymol c dng dit mt loi k sinh trng tn Varroa trong mt ong. Thymol dit

c hon ton loi k sinh trng ny nhng khng c cho ngi hay ong do lng thymol tnng trong mt ong b ph hy rt nhanh. Tuy nhin, mt bt li l cht ny lm thay i mi v camt ong.

Trong ch bin, hng ty v ht ajowan (mt loi cy khc cng cha nhiu thymol) cdng lm gia v. Chng to mi hng c trng. Tuy nhin, chng li to v cay, cht thymol trong

chng gy kch thch vi mt v da, gy c vi mng nhy. V th, hng ty thng c ch binvi thc n nng ch khng n sng.

II.2.3 Borneol

Borneol c nhiu trong cy ngi ng (sage) v rosemary(m it). N c tnh khng khunmnh hn khng nm, khng c c vi khun Gram dng v Gram m.

Tinh du ca 2 loi cy u c ch sinh trng vi vi khun nng 0,3%, v tiu dit vikhun 0,5%.

Tinh du ngi ng tc dng tt vi Bacilluscereus, S.aureus, Pseudomonas trong mitrng vi sinh nhng hot tnh gim trong go, tht g v m gi. Nguyn nhn l v nhng hot chtkhng khun t tan trong lipid ca thc phm.

Borneol tc dng mnh nht viL.monocytogens.ng dng torng thc phm:Borneol c ch bin thnh ch phm, dng trong cng ngh ch bin thc phm nh

mt loi ph gia to mi.C mt nghin cu v ng dng borneol trong bo qun u sau thu hoch.Borneol cng gy kch thch vi da v mt, v vy khng c n sng ngi ng hay m

it. Nut ch phm borneol gy cht.

II.2.4 Eugenol v cinnamic aldehydeHai loi gia v cinnamon (qu) v clove (inh hng) u c tnh khng khun rt tt. Trong

thnh phn tinh du ca chng cha a phn cht eugenol [2-methoxy-4-(2-propenyl)-phenol] inhhng v cinnamic aldehyde (3-phenyl-2-propenal) qu.


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Tinh du qu chim 0,5-1% cht kh trong 75% l cinnamic aldehyde, 8% l eugenol.Trong khi , tinh du inh hng chim 14-21% cht kh, 95% tinh du l eugenol.

37oC, tinh du qu 0,5% c ch mnh vi khunL.monocytogenes. MIC ca tinh du qui vi Campylobacter jejuni, E.coli, Salmonella enteridis, L.monocytogens v S.aureus ln lt l0.05, 0.05, 0.05, 0.05 v 0.04%, bng phng php agar dilution. Tinh du qu 1,0% trong qu trnhln men ru c tc dng c ch sn sinh c cht aflatoxin ca Aspergillus flavus.

Tinh du inh hng 2% (klg/ttich) c ch sn sinh cht c ca cc loi nmAspergillus v

Penic

illum trong vng 21 ngy 25

o

C. Du inh hng 0,1-1% km hm vic sinh bo t caBacillus subtilis. MIC ca tinh du inh hng i vi Campylobacter jejuni, E.coli, Salmonellaenteridis, L.monocytogens v S.aureus ln lt l 0.05, 0.04, 0.04, 0.04 v 0.04%. Dung dch 0,5%tinh du inh hng b 2% NaCl c ch hon ton sinh trng v sinh tng hp amine caEnterobacter aerogenes.

ng dng:Eugenol c dng nhiu trong cng nghip nh mt cht to mi v cht khng khun. c

bit c dng trong kem nh rng, nc hoa.Eugenol t c dng trong thc phm do tnh c ca n. Eugenol gy hi gan nng

cao. Eugenol cn gy di ng vi mt s ngi, triu chng l: hen suyn, au bng, au u. Nngc th c nhng triu chng nng ging nh b ong chch, b rn cn.

Cinnamic aldehyde c dng to mi qu c trng trong cc thc phm nh singum, kem,ko, nc ung vi nng thp (t 9 ti 4900 ppm, tc khong 0,5%). N cng c dng nhcht thm, cht ngt, to mi tri cy v mi. Nhng loi bt mi thng dng nh bt vani, btcacao, bt hnh nhn thng c thm cinnamic aldehyde to thm mi d chu v tng thigian bo qun.

Cinnamic aldehyde c t c c tnh. N ch hi gy kch thch da.

II.2.5 Linalool v chavicol

Tinh du hng qu (Ocimum bacilicum) c tnh khng khun nh hp cht linalool vmethyl chavicol trong tinh du.


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Thm 0,1% tinh du hng qu trong nc p c chua tiu dit c 104CFU/ml vi khunLactobacillus curvatus trong 7 ngy, thm 1% tiu dit mt lng tng t nm Saccharomycescerevisiae 30oC.

Nhn chung, linalool v chavicol c tc dng khng nm mnh hn khng khun, nht ltrong mi trng mui. V d, trong mi trng NaCl 5%, tinh du hng qu c ch mnh cc loinm mc nhng khng tc dng ng k ln vi khun.

ng dng:Linalool v chavicol c tnh khng khun khng cao. Trong cng nghip, chng thng dng

to mi thm cho x phng, chai xt phng.Trong thc phm, linalool c nghin cu to mi thm cho bt cacao v tng thi

gian bo qun. Khc vi nhng phyto-phenol khc, linalool t gy kch thch hn, ngc li chngcn tc dng gim stress cho h thn kinh.

II.2.6 VanillinHt vani cha mt hp cht khng khun tn vanillin (4-hydroxy-3methoxybenzaldehyde).

Vanillin tc dng ch yu vi nm mc v vi khun Gram(+) khng ln men lactic.Vanillin nng 1500 g/ml c bit c ch tt c cc loi nmAspergillus trong mi

trng cc loi tri cy nh u , da, to, chui v xoi. Cc loi nmDebaryomyces hansenii,Saccharomyces cerevisiae, Zygosaccharomyces bailii vZygosaccharomyces rouxii b c ch sinh

trng hon ton khi c mt vanillin 2000 g/ml, aw 0,95-0,99, 27oC trong 40 ngy. Tuy nhin,trong chui v xoi, vanillin t hot ng hn. iu ny c gii thch bi vic to lin kt giavanillin vi protein hay lipid trong chui v xoi.

Vanillin l cht to mi c trng cho ht vani. Ch phm vanillin quen thuc vi ng` sdng qua nhng sn phm nh kem, sa, bnh, chocolate. Tuy nhin, tnh khng khun ca n vnang c nghin cu nhiu hn.

II.2.7 C ch khng khun.C ch khng khun ca cc phyto-phenol vn cha c bit tng tn.Tuy nhin, gi thit c nhiu nh khoa hc chp nhn l do hot ng ca nhm phenol

trong cu to ca cc hp cht ny. Nhm phenol c kh nng lm thay i tnh cht mng t bo

ca vi khun: nh lm thay i tnh thm thu, lm ri lon qu trnh trao i cht. Thc t, ngi ta chng minh c rng thymol lin kt vi mt loi protein trn mng t bo ca Salmonellatyphimurium t dn n git cht vi khun.

Ngoi ra cn mt s gi thuyt khc t thuyt phc hn nh cc phyto-phenol c th thmnhp vo t bo v v hot enzyme ca vi khun (Conner v Beuchaut 1984); hay phyto-phenol lmvi khun b mt nng lng t ngt (Conner 1984).

III. SaponinIII.1 Gii thiu v phn loi


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Saponin l tn gi chung cho mt nhm cc hp cht glycoside trong t nhin. Chng cmt a s cc loi thc vt (76% thc vt c cha cht ny). Tnh cht chung ca saponin l chngto mng bt dai khi lc vi dung dch.

Cu to chung ca saponin thng l mt nhm aglycone (khng c tnh ng) gn vi mtnhm c tnh cht ca ng. (V d di l cu to ca solanine)

Solanine

Ty vo bn cht nhm aglycone m ngi ta phn loi saponin thnh loi steroidal hay

triterpene.

III.2 Tnh khng khunDo cu to phc tp vi 2 u ho nc v ho steroid ring r, saponin tc ng ln t bo

vi khun qua 2 giai onC ch chnh ca s tc ng ln t bo vi khun ca saponin l tnh ho sterol ca n. Vic

lin kt gia u aglycone vi cc lipid trn mng t bo lm xo trn mt phn cu trc thnh tbo. Sau , u c tnh ng (vi nhiu nhm OH v COOH) l lm tht thot protein venzyme khi t bo vi khun.

Hot tnh ca saponin ph thuc vo cu trc phn t v vi khun mc tiu. Nhn chung,saponin thng c tc dng khng khun nng 1,25-5 mg/ml, cao hn phyto-phenol; tc tnh

khng khun yu hn. Tuy nhin, ngi ta vn nghin cu c tnh khng khun ca mt s loisaponin (nht l saponin ca nhn sm) i vi Bacillus subtilis, Staphylococcus aureus.Ngoi tnh khng vi khun, saponin cng c tnh khng nm v khng virut.

III.3 S dng saponinTrong thc phm, ngi ta nhc nhiu ti saponin nh mt ph gia va c tnh khng khun

va c kh nng gim cholesterol. Nguyn nhn l do saponin c kh nng lin kt vi cholesterol(do nhm aglucone).

Nh tnh khng khun, saponin c dng nh cht bo qun khi nhng tc nhn vi sinhvt nh vi khun (E.coli, Staphylococcus aureus, Salmonella, Pseudomonas aeruginas) v nm mc(Aspergillus nifer, Penicilium chrysogenum). Thm saponin vo sa, kem, b c th gim ng k

lng cholesterol trong nhng sn phm ny.Saponin ch phm thng ly t 2 loi cy Quillaya v Yucca (2 loi u chu M).Tuy nhin, tr 2 loi saponin chit t 2 cy k trn, cc loi saponin cn li u b khuyn

co hn ch s dng. Nguyn nhn l ngi ta vn cn nghi ng v c tnh ca saponin.Ngi ta thy rng saponin lm gim trng lng ca ng vt nh b, heo khi b sung

saponin vo thc n cho chng. Ngi ta vn cha hiu c ch ca vic gim trng ny. Li c mts nghin cu khc cho thy saponin c tnh cytotoxic (toxic for the cell-c cho t bo), lm phhy thnh t bo. Mt s nghin cu khc trn vi khun cho thy saponin cn c th gy t bin.

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