Cong Nghe Len Men San Xuat Sinh Khoi Vi

7/24/2019 Cong Nghe Len Men San Xuat Sinh Khoi Vi

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I. NGUYN LIU LM MI TRNG VI SINH VT: 1.Vi khun lactic

1.1.c im chung ca vi khun lactic

Vi khun lactic thuc hLactobacilliaceae.Vi khun lactic c dng hnh cu hoc hnh gy, ng ring l hoc to chui,

thuc vi khun gram dng (+). Vi khunlactic khng di ng. Vi khun lactic khng to bo t (tuy nhin hin nay ngi ta tm thy mt s

ging trong h vi khun lactic c kh nng to bo t). Vi khun lactic thuc vi khun k kh chu dng.Vi khun lactic khng cha cytochrom v enzyme catalase.Vi khun lactic c kh nng sinh tng hp enzyme peroxydase rt mnh.

Chng phn gii H2O2 to ra nc v O2 pht trin.

1.2.

S phn b:t gp trong t v nc,thng pht trin trong nhng mi trng c chanhiu cht hu c phc tp nh:

- Trong sa v cc sn phm t sa thng gp Lactobacillus lactic,Lactobacillus bulgarius, Lactobacillus helviticus, Lactobacillus casei, Lactobacillus

ferment,Lactobacillus brevis, Streptococcus diacetyllactis. tn ti trong mi trngsa vi khun lactic tng hp ATP t c cht lactose.

- Trn b mt thc vt v xc thc vt ang b phn gii hay c Lactobcillusplantanium, Lactobcillus delnikii, Lactobcillus ferment, Lactobacillus brevis,

Streptococcus lactis...Chng cn ctm thy trn cc loi rau qu, tri cy.

- Trong rut v cc nim dch ngi v ng vt cLactobacillus acidophilus,Streptococcus faecalis, Streptococcus bovis, Streptococcus salivanius, Streptococcuspyogenes, Bifidobacterrium, Pneumococcus.

1.3.Phn loi vi khun lactic

Da vo qu trnh ln men ng: c 2 loi- Vi khun lactic ng hnh: Streptococus lactic, Streptococcus cremoris, Vi

khun ln men lactic ng hnh sn sinh 85-95% acid lactic. Do thiu porphyrin vcytochrom, khng c chui vn chuyn electron nn chng thu nng lng bng conng ln men bt buc. Trong t bo vi khun c cha enzymealdolase vtriosophotphatizomerase.

- Vi khun lactic d hnh: Vi khun ln men lactic d hnh sn sinh 50% ac idlactic, 25% cn v 25% acid acetic. Nhm vi khun ny gm c cc vi khun sinh hngStreptococcus votrovorus,Streptococcus paracotrovorus, Streptococcus diactylactis,...v

Lactobacillus brevis,Lactobacillus fermenti,...


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Bng 1: Cc chi vi khun lactic, kiu ln men v sn phm chnh

Chi v di chi Ki u ln men Sn ph m chnh(T l phn t)

C u hnh caacid lactic

Streptococcus ng hnh lactat L (+)Pediococcus ng hnh lactat DL v L (+)Lactobacillus ng hnh lactat

Thermobacterium nghnh lactat D (-),L (+), DLStreptobacterium D hnh

(ty tin)Lactat : axetat

1 : 1

D (-),L (+), DL

Betabacterium D hnh Lactat : axetat : CO21 : 1 : 1

DL

Leuconostoc D hnh Lactat : axetat : CO21 : 1 : 1

D (-)

bifidobacterium D hnh Lactat : axetat2 : 3

L (+)

Da vo hnh thi: c 2 loi

- Cu khun lactic: Streptococcus

- Trc khun lactic:Lactobacillus

Da vo tnh mn cm vi oxi: c 3 nhm

- Vi khun lactic k kh nghim ngt

- Vi khun lactic ym kh ty tin: Pediococcus cerevisiae

- Vi khun lactic vi hiu kh (hiu kh ty tin):Da vo nhit pht trin ti u: c 2nhm

- Vi khun lactic a m: 25-35 C

V d: Streptococus lactic,Lactobacillus casei,L. plantarum,

- Vi khun lactic a nhit: 37-45 C

V d: Streptococus thermophilus, Lactobacillus bulgaricus,L. helvetcus,

2. SINH KHI VI KHUN LACTIC

2.1.

Mc ch thu nhn sinh khi vi khun lactic

Trong thi gian trc y mi c s sn xut c phng php v qui trnh ring nhn ging v bo qun ging dng cho sn xut. Khi cn s dng ngi ta s tinhnh nhn ging qua nhiu giai on theo nguyn tc thu nhn mt canh trng vi sinhvt thun khit. Hin nay mt s nh my ch bin thc phm v nhng nh my sn xutcc sn phm trao i cht t vi sinh vt vn ang s dng phng php ny nn ging visinh vt c xem l c quyn s hu ca mi nh my.


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T nhng nm 1980, trn th gii pht trin mnh mt ngnh cng nghip mi,cng nghip sn xut v cung cp ging vi sinh vt. Cc ch phm ging thng mi baogm loi: vi khun, nm men, nm si Vi khun lactic cng khng ngoi l, sinhkhi vi khun lactic c thu nhn, bo qun v cung ng cho ngnh cng nghip snxut cc sn phm t sa.

Ch phm ging thng mi c th cy trc tip vo mi trng ln men hochot ho chng trn mt mi trng dinh dng trong mt khong thi gian nht nhtrc khi cy.

2.2.Cc loi vi khun lactic dng trong cng nghip sn xut sinh khi vi khunlactic

Quan trng l sinh khi ca vi khun lactic ln men ng hnh. Streptococcus thermophilus

Lactobacillus bulgaricus

Streptococus lactic

Streptococcus cremorisLactobacillus acidophilus

Nhm vi khun sinh hng

a/ Lactobacil l us acidophil us

Hnh 1:Lactobacillus acidophilus

Thuc trc khun, c kch thc : rng 0.6-0.9 m, di 1.5-6 m. Trong thin nhin chng tn ti ring l, i khi chng to thnh nhng chui

ngn, thuc nhm vi khun gram dng (+) v c kh nng chuyn ng. Chng c kh nng ln men mt lot ng nh : glucose, fructose, galactose,

mannose, maltose, lactose, saccharose to acid lactic. Chng hon ton khng c kh nng ln men xylose, arabinose, rhamnose,

glycerol, mannitol, sorbitol, dulcitol, inocitol.

Trong qu trnh ln men chng to ra c hai dng ng phn quang hc ca acidlactic. Nhit pht trin ti u l 45 C, pH 4-5.

b/ Lactobacill us bulgaricus


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Hnh 2:Lactobacillus bulgaricus

Thuc trc khun c kch thc rt di, lin kt vi nhau to thnh chui, gram(+).

Chng khng c kh nng di chuyn. C kh nng ln men c cc loi ng glucose, lactose, galactose. Khng ln men c xylose, arabinose, sorbose, dulcitol, ma nnitol, dextrin,

inulin.

Chng khng c kh nng to initrit t nitrate. Nhit pht trin 40-50 C, pH thch hp 5.5-6.0.

c/ Streptococcus thermophi l us

Hnh 3: Streptococcus thermophilus

T bo hnh cu hoc hnh trng, ng knh 0.7 -0.9 m, khng chuyn ng,

thng kt thnh chui ngn, gram (+). Pht trin tt 40-45 C, pH 5.8-6.0. Khng pht trin c 53 C v di 20 C,

sng c 65 C trong 30 pht. Khng pht trin c trong mi trng sa cha 0.01% methylen blue, mi

trng mu cha 10% mt. C kh nng ln men glucose, fructose,lactose, saccharose. Nhy cm vi cc cht khng sinh 0.01g/ml tetracycline hay 0.1g/ml

chloremphen.

d/ Str eptococcus cremori s

Hnh 4:Streptococcus cremoris


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Cu khun, trong thin nhin chng to thnh tng chui rt di, gram (+). Nhit thch hp cho chng pht trin l 30 C. Chng khng pht trin c nng NaCl 4%. Khi ln men ng to ra acid acetic, CO2, diacetyl. Chng c kh nng to ra nhng cht khng khun

e/ Streptococcus lacti c

Hnh 5:Streptococcus lactic Thuc chui cu khun, gram (+).

Nhit pht trin 10-45 C, ti thich 30-35 C. C kh nng chu c nng NaCl 4%. Khi ln men ng glucose, maltose, lactose, xylose, arabinose, saccharose,

trehalose, mannitol, salicin to ra acid lactic, CO2, acid acetic, diacetyl.Chng khng c kh nng ln men c raffinose, insulin, glycerol, sorbitol

2.3.Ging vi sinh vt dng cho sn xutGing vi sinh vt l mt trong bn yu t quyt nh nng sut sn xut sn xut

cng nghip vi sinh vt. Cng vi cht lng mi trng, iu kin ln men, ccphng php thu nhn v tinh ch sn phm,ging vi sinh vt l khu u tin canphi quan tm c bit.

Ging vi khun lactic dng cho sn xut phi p ng cc yu cu sau: Ging c kh nng thch ng nhanh, pht trin mnh Ging c kh nng sinh sn cao. Ging c kh nng chng li c i vi cc iu kin bt li. Gingd dng tch khi mi trng nui cy Kh nng d bo qun v bo tn c c tnh di truyn trong sut thi

gian bo qun v s dng. Thi gian ln men ngn, hiu sut cao

3. MT R:Mt r l th liu trong cng ngh sn xut ng t cy ma hay c ci ng.

Trc y mt r t c s dng trong cng ngh vi sinh. Sau ny ngi ta thy my r

c rt nhiu u im to mi trng nui cy vi sinh vt. Nhng c tnh quan trngph hp vi qua trnh ln men ca mt r bao gm :

- Cha hm lng ng cao.- Ngoi ng saccharose cn cha rt nhiu cht hu c, v c, cc chtthuc vitamin v cc cht kch thch sinh trng- Tuy nhin r ng cng c nhng c im khng ph hp vi qu trnhln men. Mun s dng chng cho qu trnh ln men i hi phi c cc qutrnh s l thch hp. Cc c dim cn lu mt r bao gm:


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R ng c mu nu sm. Mu ny kh b ph hy trong qu trnh ln men. Sauln men chng bm vo sinh khi vi sinh vt v bm vo sn phm. Vic tch mu rakhi sinh khi v sn phm thng rt tn km v rt kh khn.

Hm lng ng kh cao (thng nm trong khong 40-50%). Lng ny chyu l saccharose nn khi tin hnh ln men phi pha long vi nng thch hp.

c im gy kh khn ln nht cho qu trnh ln men l h keo trong mt r. Keocng nhiu, kh nng ha tan oxy cng km v kh nng trao i cht ca vi sinh vtcng km. Do cng vic quan trng ca nht khi s dng mt r l phi ph h keony.

V r ng l cht dinh dng kh l tng nn chng rt d b vi sinh vt xmnhp v pht trin. Nh vy cht lng mt r cng d thay i theo thi gian boqun

Thnh phn ha hc:Thnh phn r ng dao ng nh sau:

- Nc chim 15-20%, cht kh chim 80-85%.- Trong , c 60% l ng ( 40% l ng saccharose, 20% l fructose v

glucose v 40% cht cn li l cht phi ng ) - Trong thnh phn phi ngc khong 30-32% hp cht hu c v 6-105hp cht v c. Trong hp cht v c c :

K2O: 3,5% Fe2O3: 0,2% MgO: 0,1% Sulfat: 1,6%

CaO: 1,5% SiO2 : 0,5% P2O5: 0,2% Clor it: 0,4%- Trong nhng hp cht hu c gm c cc hp cht ch nit v khng chnit dng amin nh: acid aspactic, acid glutamic, leuin, izoleuxin. Nito tngs chim khong 0,3-0,5% ( t hn so vi so vi lng nit c trong r ngc ci)


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Cng ngh sn xut sinh khi vi khun lactic

CBGD: PGS.TS L Vn Vit Mn Trang 7

Bng 2:Thnh phn cc cht trong r ng

Cc cht thnh phn Hm lng % trong rng

Saccharose 32

Cht hu c phi ng 10

Cht tro 8

Trong : K2O 3.5

CaO 1.5

MgO 0.1

SiO2 0.5

SO3 1.6

Cl2 0.4

Na2O + Fe2O3+Al2O3 0.2

P2O5 0.2

N tng 5-2.2

N-amin 0.2-0.5


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Bng 3:Thnh phn vitamin trong r ng ma

Cc cht mu ca rng ma bao gm:

- Caramel: xut hin nhqu trnh nhit phn saccharose km theo loi tr

nc v khng cha mt cht nitno. Khi pH khng i, tc to cht caramen tl

thun vi nhit phn ng.- Phc cht polyphenol-Fe2+: c mu vng xanh, khng b loi ht trong giai

on lm sch v tn ti trong mt r

- Melanodin: y l sn phm ngng tca ng khv acid amin m ch

yu l acid aspartic. Sn phm ngngtquen bit nht l acid fuscazinic ng vai tr

quan trng lm tng mu ca rng.

- Melanin: c hnh thnh nhphn ng oxy ha khcc acidamin thm

nhxc tc ca enzym polyphenol oxydaza khi c mt ca oxy v Cu+2.

- Cc acid amin thm thng boxy ha l tiroxin v brenzcatechin. Cc

melanin thng bloi ht giai on lm sch nc ng nn chtm thy mt lng

rt nhtrong rng.

- Cht keo: c hnh thnh bi potein v pectin. Cc cht ny nh hng rt

nhiu n spht trin ca vi sinh vt to thnh mng bao bc quanh tbo, ngn cn

Vitamin Hm lng (mg%)

Thiamin 0.5

Riboflavin 0.12

Pyridoxin 0.9

Nicotinamit 1.5

Acid pantotenic 7.0

Acid foleic 0.02

Biotin 0.15

Inozit 500.0


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qu trnh hp thcc cht dinh dng v thi cc sn phm trao i cht ca tbo ra

ngoi. Ngoi ra keo l nguyn nhn chnh to ra mt lng bt ln trong mi trng nui

cy vi sinh vt, gim hiu sut sdng thit b.

Vi sinh vt trong r ng ma.C rt nhiu vi sinh vt trong r ng ma . a s chng c t nguyn liu, mt

s nh t khng kh, nc, t vo dch ng. Loi no chu c tc dng nhit haytc dng ca ho cht th tn ti. Ngi ta chia r ng thnh 3 loi tu theo s lng visinh vt tp nhim.

Bng 4:Phn loi r ng theo s lng vi sinh vt tp nhim.

Loi r ng S lng VSV trong 1g ng nh gi v x lI 100000 R t t t, khng c n x l II 100000- 1000000 Trung binh, c n thanh

trngIII 1000000- 5000000 Nhim nng c n x l

nghim ngt


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II. QUI TRNH THU NHN SINH KHI VI KHUN LACTIC

Mt r

X l

Chun bMi trng

Thanh trng

Nui cy Sy thng hoa

Ly tm ng gi

Nhn ging

Gi ngVSV

Sn phm


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III. GII THCH QUY TRNH CNG NGH:1. X l mt r:

1.1 Pha long s b:

a.Mc ch: chun b cho qu trnh acid ha.

b.Bin i:Ha hc: gim nng cht kh.

Vt l: gim nht.

Ho l: tng ho tan cc cht.

c.Thc hin:Pha long vi nc theo t l Vmt r: Vnc= 1 : 3

1.2 X l dch pha long:Truc tin, ta phi ty mu v tch cc keo c trong mt r

1.2.1. Acid ho:

a. Mc ch: chun b cho qu trnh ln men v tiu dit vi sinh vt b. Bin i:

Ha hc: ng saccharose chuyn thnh glucose v fructose di s xc tcca acid; pH gim v 2.8-3.0Ha l: h keo b ph vVi sinh: vi sinh vt b tiu dit do nhit cao v pH thp.

c. Thc hin:Lng acid sunfuric m c thm vo l 5% khi lng dung dch. Trong giai on

ny, ta un dung dch n 90-95oC trong 6 gi. Sau ta tin hnh ly tm thu dch trong. d.Thit b v thng s cng ngh:

- Ni phn ng

.


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1- ng ni np cht ti nhit;2- ng chy trn sn phm;

3- ng qu p;4-u ni ng np nguyn liu;5- Ca quan st;6- Ca thot cht ti nhit;7- Ca vo ca cht ti nhit;8- Ca ra ca sn phm;

9- Ca thot cht ti nhitHnh 6:Ni phn ng dng ng

Ni phn ng bng thp hay bng gang trng men dng tin hnh cc qu trnh

ho - l khc nhau.

Ni phn ng - my trn l mt thit b dng xilanh ng c th tch t 0,1 100m

3

hoc hn, c o hi.Bn trong thit b c c cu o trn dng tuabin h.

Khi s dng cc thit b c o hi dng bn ng th p sut lm vic cho php n

1,6 MPa, cn trong o hn phng khng nh hn 0,4 MPa. Nc my hay nc tun

hon, nc mui, hi nc bo ho hay cht ti nhit hu c c nhit cao c th cho

vo o hay vo rut xon.


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Ni phn ng - my trn c th thori hay hn c nh vi cc b phn y elip

v np. Trn thit b c cc khp ni np cc cht ti nhit, chy trn sn phm, ni

ng qu p, ni khp u ng nguyn liu, kho st cht liu, cc khp ni np v thi

cht ti nhit v sn phm, van an ton, nhit k. Sau khi np vo thit b mt lng nc

nht nh.Tin hnh un nng mi trng n mt nhit cho bng phng tin iu

chnh t ng.

Tn s trn ca my khuy 0,2 0,33 vng/s, ph thuc vo dng c cu trn

v cc tnh cht ca cc cu t em trn.

Khi thit k my trn dng tuabin, s vng quay 3 3,3 vng/s, dng khung 0,33

1 vng /s.

Dn ng my trn c thc hin nh ng c in qua hp gim tc.

1.2.2. Ly tm thu dch trong:

a.Mc ch: chun b cho qu trnh ln menb.Bin i:

Ha hc: tp cht b loi b, gi li cht ha tan Ha l: tch pha rn khi pha lngVt l:tng trong, gim khi lng ring dung dch

c.Thit b v thng s cng ngh:

Hnh 7:Thit b ly tm lc


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Thit b ly tm lc hot ng theo nguyn tc: khi h thng quay vi tc cao

to ra lc ly tm mnh v y cc thnh phn pha lng v rn ra st thnh thit b nh

hnh v, thnh thit b c gn vi lc cc cu t cht ho tan i qua v gi li c c thnh

phn pha rn.

2. Chun b mi trung:Khi chun b mi trng nui cy , ta phi ch nhng c im sau y:

Cc nguyn vt liu lm mi trng nht thit phi cung cp y cc thnhphn dinh dng cho cc qu trnh trao i cht ca tbo vi sinh vt, ngthi duy tr c th oxy hakh, p sut thm thu v to c s n nhca pH thch hp ca mi trng. Thnh phn nguyn vt liu phi c cn o chnh xc v pha ch theo ng

trnh t hng dn.

2.1.Nhu cu dinh dng ca mi trng nui cyVi khun lactic c nhu cu dinh dng rt phc tp, khng mt i din no thuc

nhm ny c th pht trin trn mi trng n gin ch cha glucose v NH 4+m chng

i hi hng lot cc vitamin nh lactoflamin, thiamin, acid pantothenic, a cid nicotinic,acid folic, biotin... v cc acid amin. V th ngi ta thng nui cy chng trn mt mitrng phc tp cha mt lng tng i cao nm men, cao tht v nc chit c chua.

2.1.1.

Nhu cu dinh dng cacbon:Vi khun lactic c th s dng c rt nhiu cc loi carbonhydrate khc nhau t

glucose, fructose, maltose n saccharose... Cc ngun cacbon ny dng cung cpnng lng tham gia vo hu ht cc cu trc ca t bo. V vy y l ngun thc ncacbon c ngha quan trng nht i vi s sng ca t bo vi sinh vt. Trong qu trnhln men cc c cht cha cacbon, vi khun lactic c th s dng c cc acid amin nhacid glutamic, arginine hay tyrozyne lm ngun cung cp nng lng. Khi din ra qutrnh decacboxyl v to CO2.

Ngun cacbon tt nht l cc loi ng c tnh kh liu lng nh. Nu khinhn ging ngi ta dng mt loi ng thng thng him khi c dng lm nguncacbon th khi a vo sn xut vi khun c th pht trin hiu qu trn cha loi ngny m khng lm nh hng n kh nng ln men i vi cc ngun cacbon thng

thng.

2.1.2. Nhu cu dinh dng nit:

Ngun nitt d hp th i vi vi sinh vt l NH3,NH4+.Sau khi ng ha gc

NH4+trong mi trng s tch ly cc anion v c (SO4

2-,HPO42-,Cl-) lm h

thprt nhiu tr s pH ca mi trng,ta phi iu chnh pH ca mi trng nuicy.


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a s vi khun khng c kh nng sinh tng hp cht hu c phc tp c chanit t ngun dinh dng v c. V vy, m bo cho s pht trin ca mnh, vi khunlactic phi dng ngun nit c sn trong mi trng di dng cc acid amin. Tuy nhin vi khun pht trin bnh thng th ngoi ngun nit ca acid amin th vi khun lacticcn cn nhng cht hu c phc tp c cha nit nh cao tht, cao nm men, peptone,

cazein...

2.1.3. Nhu cu v vitamin:

Vi khun lactic rt cn vitamin cho s pht trin ca mnh v cc vitamin nyng vai tr l coenzyme trong qu trnh trao i cht ca chng. Rt t vi khun lactic ckh nng tng hp vitamin, phn ln chng cn nhiu loi vitamin nh riboflavin,thiamin, acid pantothenic, nicotinic, biotin.. Nhu cu vitamin chu nh hng ca nhiuyu t nh nhit nui cy, pH, nng CO2ban u, th oxy ho kh v thnh phnca mi trng.

Bng 5:Vitamin v cc cht sinh trung cn thit cho s sinh trungca cc vi khun lactic

Ch t Vi sinh vt i nhnh

Acidp-aminobenzoicLactobacillus plantarum

Acid folicLactobacillus arabinosus

Lactobacillus caseiStreptococcus faecalis

Acid 5-focmyl-5,6,7,8-tetrahidrofolicLeuconostos citrovorum

Streptococcus faecalis

Locovorin Lactobacillus casei

Acid nicotinic

Lactobacillus arabinosus

Leuconostoc menssenteroidesStreptococcus faecalis

Riboflavin

Lactobacillus casei

Streptococcus lactic

Acid pantothenicLactobacillus casei

Leuconostoc menssenteroidesStreptococcus faecalis

Panteterin.pantetin

Lactobacillus acidophyllus

Lactobacillus bulgaricusLactobacillus casei

Acid lipoicStreptococcus lactic

Streptococcus faecalisLactobacillus fermenti

Thiamin Streptococcus lacticLactobacillus plantarum


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BiotinLeuconostoc menssenteroides

Streptococcus faecalisLactobacillus arabinosus

Bioxitin Lactobacillus casei

2.1.4.

Nhu cu v cc mui khong: m bo cho s sinh trng pht trin, vi khun lactic cn rt nhiu hp cht

v c nh P, S, Mg, Ca, Zn, Mn, Fe, Na, Cl. i vi lactobacillusth Mn2+, Mg2+, Fe2+c tc ng tch cc ln s pht trin v sinh ra acid lact ic.

- Cc nguyn t a lng: l nhng nguyn t khong m vi sinh vt i hipha cungcp vi liu lng ln

- Cc nguyn t vi lng: l nhng nguyn t khong m vi sinh vt i hiphi c cung cp vi liu lng rt nh.

- Cc nguyn t khong:

+ P : chim t l cao nht trong cc nguyn t khong ca t bo vi sinh vt, cmt trong cu to ca nhiu thnh phn quan trng ca t bo ( acid nucleic,phophoprotein, photpholipid)

+ S : l khong quan trng trong t bo vi sinh vt trong mt s acid amin(xixtrin,xixtein, metioin), mt s vitamin (biotin, tiamin)

+ Mg : nguyn t vi sinh vt i hi vi lng kh cao, tham gia vo nhiu phnng enzyme c lin quan n qu trnh photphoryl ha.

+ Ca : c vai tr quan trng ng k trong vic xy doing cu trc tinh vi ca tbo,vai tr cu ni trung gian gia cc thnh phn quan trng ca t bo sng.

+ Zn : tham gia vo nhiu qu trnh enzyme, c tc dng ng k trong vichot ha cc enzyme.

+ Mn : cha trong mt s enzyme h hp, c vai tr trong vic hot ha mt senzyme.


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m: nc l mi trng cho cc phn ng trong t bo do m l mtyu t quan trng cho s pht trin ca vi khun lactic. p sut thm thu: mng t bo cht ca vi khun l mng bn thm. Khinng mui trong mi trng nui cy cao (trn 2%) s c ch s pht trinca vi khun lactic.

3. Thanh trng mi trngMi trng sau khi c pha ch s qua thanh trng nhit tiu dit, c ch vi

sinh vt v hot tnh enzyme trong mi trng, to iu kin cho ging pht trin. Theo l thuyt, nu nhit thanh trng cng cao vi thi gian cng di th mc

tiu dit v v hot enzyme cng cao, tuy nhin gi tr dinh dng ca mi trng sb gim:

o Vitamin b phn hu. o Mt phn ng kh v acid amin tham gia phn ng Maillard lm

gim hm lng ccht cacbon v ngun nit ca mi trngTrong thc t, tu thuc vo ging VSV, thnh phn ho hc ca mi trng v

mc nhim VSV trong cc nguyn liu pha ch mi trng m cc nh sn xut s xut ch thanh trng vi gi tr nhit v thi gian thch hp, thng p dng ch thanh trng dao ng trong khong 80 - 90 C trong 30 - 60 pht.

Phng php thc hin: thit b ng lng ng Thng s cng ngh

nhit 85-900C

a. Cu hnh nhiu knh ; b. Cu hnh nhiu ngHnh 8 :Thit b trao i nhit dng ng


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4) Nhn ging

a. Yu cu

S lng t bo trong mi trng nui ln gi tr cao nht, trong khong thi

gian ngn nht, vi nhng chi ph thp nht v nguyn liu v nng lng. Sinh khi thuc phi c hot tnh ln men cao, t l t bo cht cng thp

cng tt.

Trong qu trnh nhn ging cn m bo cho ging c thun khit, iu ny rtquan trng v nu ging c ln cc vi sinh vt l th trong qu trnh ln men s gy hhng v lm sn phm khng t yu cu v i khi cn c hi cho ngi tiu th.

b. C s khoa hc ca qu trnh nhn ging

Chn mi trng vi thnh phn c cht thch hp nui vi sinh vt.

Chn phng php v cc iu kin nui ti u (pH, nhit , s cung

cp oxi,...) cho qu trnh tng sinh khi ca ging.

Mc ch: tng s lng VSV

c.

Tin hnh nhn ging

cy ging, mt lng canh trng vi khun xc nh c cho vo mi trngdinh dng c x l nhit sau khi iu chnh n nhit thch hp. ngn chnnhng bt thng trong canh trng, iu quan trng nht l lng ging cy, nhit nui cy v thi gian nui cy phi c gi khng i trong sut tt c cc giai on.

Trong PTN:

Ging c nhn trong cc bnh cu. khi nhit khang 37 40 oC, cho

canh trng lng vo, t l 5% th tch. Gi 40 45oC, sau 8 -10h, gingt yu cu. c th dng nhn ging tip tc cc th tch ln hn.


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S TNG QUT QU TRNH NHN GING VI SINH VT CHO SN XUT


21/36



Trong phn xngVi khun lactic c nui cy ring phn xng nhn ging. Khi lng

ging m bo v s lng t bo( khong x*10 6t bo/1ml), tin hnh ln men.5. Nui cy:

Ngi ta chuyn ging vo thng ln men vi t l ging l 2.5- 3%. Trong sn

xut lactic, ngi ta thng s dng cc loi vi khun lactic ng hnh , trong vikhun lactic lactobacillusc s dng nhiu hn c. - i vi vi khun ny ,ngi ta thng duy tr nhit trong sut qu trnh ln menl 400C , pH duy tr 5-6, thi gian ln men 1-8 ngy, tuy nhin,nhng iu kin ln mentrn c th thay i tu theo ging vi khun lactic m ta s dng sn xut. - Trong qu trnh ln men ngi ta tin hnh khuy trn lin tc mi trng. Nhiutrng hp, ngi ta tin hnh thi kh, khi thi kh lng acid lactic to ra cao hn nhiuso vi khng thi kh.

a.

Phng php thc hin:

Dng thit b ln men b su, gin on :

Thit b ln men c th tch 63 m3

: Dng thit b ln men ny l mt xilanhng c ch to bng thp X18H10T hay kim loi kp cnp v y hnh nn.

T l chiu cao v ng knh bng 2,6: 1. Trn np c b dn ng cho c cu

chuyn o v cho kh bt bng c hc; ng ni np mi trng dinh dng,

vt liu cy, cht kh bt, np v thi khng kh; cc ca quan st; ca a vi

ra; van bo him v cc khp ni cm cc dng c kim tra.

Khp x 16 y ca thit b dng tho canh trng. Bn trong c trc

6 xuyn sut. Cc c cu chuyn o c gn cht trn trc. C cu chuyn o

gm c cc tuabin 8 c ng knh 600 1000 mm vi cc cnh rng 150 200mm c nh v 2 tng, cn tuabin h th ba c gn cht trn b si bt 13

phn tn cc bt khng kh. B si bt c dng hnh thoi c lm bng nhng

ng t l. phn trn ca b si bt c khong 2000 3000 l theo kiu bn c.


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1-ng c; 2-Hp gim tc; 3-Khp ni; 4- bi; 5- Vng bt kn;

6- Trc;7- Thnh thit b ; 8-My khuy trn tuabin; 9-B trao i nhit

kiu ng xon; 10-Khp ni; 11- ng np khng kh; 12-My trn kiu cnh

qut; 13-B si bt; 14-My khuy dng vt; 15- ; 16-Khp tho; 17-

Ao; 18-Khp np liu; 19-Khp np khng kh

Hnh 9 :Thit b ln men vi b o trn c hc dng si bt c sc cha 63 m3

ng c -b truyn ng lm quay trc 6 v cc c cu o trn 8, 12, 14. S

dng b gim tc v b dn ng c dng in khng i iu chnh v cp s

vng quay trong gii hn 110 200 vng/ pht.

Thit b ln men c trang b o 17, gm t 6 8 . Mi c 8 rnh cch to bng thp gc c kch thc 12060 mm. Din tch lm vic ca o 60 m2.

B mtlm vic bn trong 45 m2gm ng xon 9 c ng knh 600 mm vi s

vt 23 khi tng chiu cao ca rut xon 2,4 m.

Thit b ln men c tnh ton hot ng di p sut d 0,25 MPa v

thanh trng nhit 90-950C, cng nh hot ng di chn khng. Trong


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qu trnh nui cy vi sinh vt, p sut bn trong thit b 50 kPa; tiu hao khng kh

tit trng n 1 (m3/pht). Chiu cao ct cht lng trong thit b 5 6 m khi chiu

cao ca thit b hn 8 m.

tin li cho vic thao tc v trnh nhng sai lm cn dn vo thit b s

ch dn thao tc .

m bo tit trng trong sut qu trnh (gi c hi), cc trc ca c

cu chuyn o phi c vng bt kn. Cc vng bt kn c tnh ton hot ng

p sut 0,28 MPa v p sut d khng nh hn 2,7 kPa, nhit 30 250 0C v

s vng quay ca trc n 500 vng/ pht. Nh cc vng m ny m ngn nga

c s r r mi trng hay s xm nhp khng kh vokhoang thit b v tr

nh ra ca trc.

Vng bt kn khi tip xc vi mi trng lm vic c ch to bng thpX18H10T v X17H13M2T, cng nh bng titan BT-10. Thi gian hot ng n

nh ca cc vng ny khng nh hn 2000 h khi tui th 8000 h. o hng

knh cho php ca trc trong vng m kn khng ln hn 0,25 mm, o chiu

trc ca trc khng ln hn 0,250.


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1- Hivo;2- Khng kh tittrng vo;3- Khng kh tittrng hay hivo vng bt kn;4- Thot hihay khng kh tit trng tibsibt;5- Hihay khng kh tit trng vo thit b phn trn;6- Thi hi hay khng kh tit trng ti b ly mu th nghim;7- Thihihay khng kh tittrng;8- Ccungnhnh c van iuchnh bngkh nghc;9- Nphihay khng kh tit trng vo thit bphndi;10- Tho nc ngng;

11- Ap k; 12- Van; 13- ngtho; 14- Van kho; 15- Van lymu;16-Nphi haykhng kh tit trng khi lymu;17-onng nip kkimtra;18, 25- Cc p k;19- Van npvtliucy;20- Npcanh trng;21, 23- Npdung dch chun;22- Thihihay khng kh tvng bt kn; 24- ng nhnh npdung dchchun;26- Cung cpkh thitthitb;27- Cung cpnc; 28- Van rt;29- Van rt nc t o;30- Van npnc lnh;31- ng nhnh npnc lnh;32- Lc; 33- Ap k;34- Van an ton; 35- Cmbinnhit;36, 37- Cc dngcthcponhitv pH;

38- Cm bin pH met; 39- Thit b ln men; 40- C cu lm sch khng kh

Hnh10 . S chdn thao tc ca thit bln men Thng s cng ngh

- pH 4.5

- nhit 30-32oC


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b. Cac bien oi xay ra trong quatrnh nuoi cay

Cac bien oi sinh hoc

Giai oan thch nghi (pha lag):

Vi khuan cha co s phan chia nhng co s tang ro ret ve the tch va

khoi lng te bao do qua trnh tong hp cac chat, trc het la cac chatcao phan t (protein, enzyme, acid nucleic) dien ra manh me.

Hnh thanh cac enzyme can thiet cho qua trnh tong hp c chat va cacenzyme nam trong qua trnh chuyen hoa glucide.

Giai oan tang trng (pha log):

Vi khuan sinh trng va phat trien theo cap luy tha, ngha la sinh khoiva so lng te bao tang rat nhanh.

giai oan nay xay ra hang loat cac bien oi quan trong e tao sinhkhoi te bao: s tong hp enzyme tiep tuc c xuc tien, s chuyen hoa

cac hp chat cacbonhydate, s chuyen hoa cac hp chat cha NitGiai oan on nh:

Quan the vi khuan trang thai can bang ong hoc, so te bao mi sinh rabang so te bao cu chet i, do o so lng te bao khong thay oi.

Toc o sinh trng phu thuoc vao nong o c chat.Cho nen khi giamnong o c chat th toc o sinh trng cua vi sinh vat giam.Do o viecchuyen t pha log sang pha on nh dien ra dan dan.

Nguyen nhan ton tai cua pha on nh la do s tch luy cac san pham ochai cua trao oi chat va viec can cac chat dinh dng.

Hnh 11 : S bien oi cua sinh khoi theo thi gian trong phng phap

nuoi cay tnh


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Hnh 12 : S bien oi cua hang so toc o sinh trng vsv theo thi gian trong

phng phap nuoi cay tnh

Cac bien oi vat ly

Do s trao oi chat dien ra lien tuc nen co s tang nhiet o cua canh trngnuoi cay.

pH cua canh trng cung thay oi do co s xuat hien cua cac san pham trao oichat.

Cac bien oi hoasinh

Cac bien oi hoa sinh chu yeu la xay ra ben trong cung vi s trao oi chat cuate bao vi khuan lactic.

Cac vi khuan lactic ong hnh phan giai glucose theo con ng EMP dochung cha cac enzyme can thiet cho qua trnh nay, ke ca enzyme aldolaza.

Cac vi khuan lactic d hnh do thieu cac enzyme aldolaza vatrioxophotphatizomeraza nen giai oan au cua s phan giai glucose xay ratheo con ng PP. Muc ch cua cac qua trnh nay la tong hp vat chat tebao va nang lng cho vi khuan lactic sinh trng.

6. Ly tmSinh khi vi sinh vt nn thu nhn vo u giai on pha n nh. Canh trng sau khi nhn ging c lc v a vo thit b ly tm tch thu sinh

khi. Thit b ly tm c hai dng thot: hn hp canh trng c np vo theo ng

dn bn di thit b. Thng qua h thng knh dn c to thnh t cc l trn da lytm, dng giu VSV (c khi lng ring ln hn) s chuyn ng v pha bn ngoi


27/36



thng quay v theo ca bn hng thng thot ra ngoi. Dng cha t t bo vi sinh vtdo khi lng ring thp hn s chuyn ng v pha trc quay ri thot ra khi thit btheo ca trn nh thng

Hnh 13 : Thit b ly tm tch vi sinh vt

7. Sy

- Mc ch: thu ch phm VSV dng ht

- Phng php thc hin: sy thng hoaSy thng hoa l qu trnh tch m t cc sn phm bng phng php lnh ngv tip theo l chuyn lm lnh ng c to thnh trong sn phm thnh hi, quapha long ngn ngi khi un nng sn phm trong chn khng. Khi sy thng hoa, mchuyn di trong sn phm dng hi khng ko theo n nhng cht trch ly v nhng visinh vt. Trong sn xut vi sinh, sy thng hoa c ng dng cho cc vi sinh vt, nmmen, vitamin, khng sinh, cc enzim khng bn nhit cao.

Thng qu trnh sy thng hoa c bt u t lc lm lnh ng b mt sn

phm n nhit 20o

C,

30o

C. Tc lm lnh ng cc vt liu khng bn nhitnh hng ti vic bo qun hot ng sng ca vi sinh vt v hot ho ca cc chphm sinh hc, v khi lm lnh nhanh cc sn phm to nn bn trong t bo, xy ra

bin i nhanh chng thnh phn cc dung dch sinh l bn trong v bn ngoi t bo vdn ti s ph hu v lm cht t bo.

Tt c cc vt liu sinh hc em sy thng hoa c m khc nhau, cho nnchng c nhng im ba tecti khc nhau, khi c th c s cn bng , pha lng vpha hi. Cho nn i vi cc vt liu vi sinh , tc lnh ng ca chng c xc nhbng thc nghim. Qu trnh thng hoa xy ra nhng gi tr p sut hi trn b mt vtliu v gi tr nhit trong cc im nm di im ba cn bng pha ca dung mi(nc).


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Thng khi sy thng hoa cc vt liu vi sinh, p sut d = 133,3 13,3 Pa, v

nhit ca vt liu bt u sy bng 20o

C, 30o

C. Khi m ca sn phm b gim

xung ti thiu, nhit ca vt liu tng n 30o

C, 40o

C. iu kin sy nh th bom qu trnh oxy ho ti thiu ca sn phm do hm lng oxy khng ng k trongmi trng kh ca phng sy. Trong cc my sy thng hoa dng cng nghip, vic npnhit ti sn phm hoc bng dn nhit hoc nh cc tia hng ngoi.

Hnh 14:Thit b sy thng hoa tc ng tun hon

Cc my sy thng hoa c s tc ng tun hon hay lin tc. trnch s nguyn tc sy thng hoa tc ng tun hon.Thit b ny gm phng sy hnh tr kn(ni thng hoa) 1, trong c gin ng rng 2, vt liu sy cho vo y. Ni thng hoalm vic mt cch tun hon nh mt phng lnh. ch lm lnh, bm 5 y tc nhnlnh bn trong ng rng 2.


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S lm lnh ca cht ti nhit c tin hnh trong b trao i nhit 3 c nhrut xon, cht lm ngui i qua v vo thit b lm lnh 4. Khi ni thng hoa lm vic ch ca my sy, cht ti nhit c un nng trong b trao i nhit 7 v y vocc ng rng nh bm 6.

S ngng t hi c to ra khi sy trong ni thng hoa c tin hnh trong

ni ngng t chng thng hoa 10. N l mt b trao i nhit, hn hp hi - khng kh tni thng hoa vo khng gian gia cc ng ca b trao i nhit. Cht lm ngui(amoniac, freon) qua cc ng 11 ca ni chng thng hoa vo thit b lm lnh 9. Thng lm lnh b mt thng hoa v ngng t, ngi ta s dng my nn 2 hoc 3 cp c kh

nng m bo lnh b mt n nhit 60o

C, 40o

C.Cc kh cha ngng t c tch ra khi ni chng thng hoa bng bm chn

khng 8. Hi ngng t c lm lnh dng lp trn b mt cc ng lnh ca nichng thng hoa. V trong qu trnh lm vic ca ni chng thng hoa, cc ng 11 b phbi mt lp ng k, nn cn lm tan bng mt cch chu k. thc hin iu , ync nng t b un 7 vo cc ng 11.

Hin nay ngi ta bt u s dng ph bin cc thit b thng hoa tc ng lin

tc. Sy thng hoa lin tc gm hai ni thng hoa v hai b chng thng hoa, chng lmvic lun phin nhau.

Nng sut ca thit b thng hoa tc ng lin tc tnh theo m bc hi lnhn 200 kg/h. Thi gian c mt ca sn phm trong my sy t 40 n 110 pht, nhit

cao nht ca sn phm cui qu trnh sy nh hn 27o

C.

Thng s cng ngh

- m 5-12%

- nhit cht ti nhit 130oC

- nhit sn phm sy 50oC

8. ng giSau qu trnh nhn ging, ta nn s dng ngay sinh khi VSV cy ging

cho cc qu trnh ln men cng nghip. Nhng nh sn xut c th bo qun ging nhn trong mt thi gian ngn nhit 4 6 oC, trong iu kin v trng. Ty thucchng vsv s dng v hot tnh sinh l ca chng m thi gian bo qun theo phngphp ny c th ko di t vi gi n vi ngy. Nu thi gian bo qun ko di, ging sgim dn hot tnh v s t bo cht s gia tng.

Nu mun ko di thi gian bo qun ging sn xut n hng thng hoc luhn, ta nn tin hnh x l ngay canh trng thu c sau qu trnh nhn ging. Phngphp thng dng cho cc canh trng lng l ly tm lnh tch sinh khi, k tip sdng phng php sy thng hoa tch m ri em nghin v ry thu ch phm vsvdng ht. Ging vsv ng kh nu c bo qu n 4 0C c th bo tn c hot tnhban u trong thi gian 1 nm.

Qua sy lnh, sau mi ng gi, bo qun ta c sn phm dng ht

Mc ch:bo qun sn phm

Phng php thc hin


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Hnh 15 : Phng php ng gi Thng s cng ngh

- Rt iu kin v trng

- Nhit 4oC bo qun c 1 nm

IV. SN PHM SINH KHI VI KHUN LACTIC

Ch phm dng htCc cng ngh mi p dng trong sy thng hoa lm cho canh trng ny c th

b sung trc tip vo sa nh phng php trn. Sau khi lm lnh, canh trng c c

c t di mt p sut chn khng cao tch nc bng s thng hoa. Lun lun ckhong 60 70% t bo sng st. T bo sau khi sy dc ng gi di iu kin vtrng, tt nht l khng c mt oxi. S c mt ca oxi s nhanh chng lm hng snphm.

Ch tiu cht lng:

- T l t bo sng st : 60 70%

- m : 5 12%

- Kch thc ht : ty thuc nh sn xut, nhng nh th tt, khong 1 2 mm.

- mu sc ht: vng nht. - Khng c Oxy, v s c mt ca Oxy s nhanh chng lm hng snphm.


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Hnh 16 : sinh khi sy thng hoa

V.NG DNG CA SINH KHI VI KHUN LACTIC

Sinh khi vi khun lactic c dng cung cp cho cc nh sn xut cc sn phmc lin quan n qu trnh ln men lactic. Khi mua ch phm sinh khi v, cc nh snxut ch cn hot ho, nhn ging v a vo sn xut . Sinh khi vi khun lactic ch yuc dng nhiu trong cng ngh thc phm v y hc.

1. ng dng trong cng ngh thc phm :Vi khun lactic l nhm vi khun c rt nhiu trong thin nhin, v th chng tham

gia vo tt c hot ng sng ca con ngi, trong c bit quan trong la ch binthc phm.

a. ng dng sn xut da chua:Qa trnh mui chua rau qu chnh l qu trnh hot ng sng ca vi khun

latic v vi khun axetic. Trong qu trnh pht trin ca chng , trong rau qu khi ln mens to ra acid lactic v acid axetic cng mt s loi acid hu c khc. Cc acid hu cny lm gim pH ca dung dch, chng li hn tng gy thi rau qu. Mt khc nh clng acid hu c dc to ra s lm tng hng v ca khi chua rau qu.

Cc sn phm mui chua rau qu: Bacillus brassicae fermentati, Lactobacilluscucummeris, Lactobacillus plantarum, Lactobacillus brevis,

b. ng dng lm chua qu:Ngi ta thng s dng acid lactic ngm chua qu.phng php ny hiu qu

v chng t lm bin i mu t nhin ca qu v vn m bo cht lng qu ngm chua.

c. ng dng trong sn xut tng:Sn xut tng theo phng php ngi min Bc( Vit Nam) c giai on ng

nc u sau khi rang. Qu trnh ng nc u xy ra nhiu phn ng sinh ha khcnhau, trong c qu trnh ln men lactic to pH thch hp cho sn phm v lm tnghng v cho sn phm.


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d.

ng dng trong sn xt u phTrong sn xut u ph c giai on kt ta protein ca u. Phng php

truyn thng thng lm l dng nc chua (cha vi khun lactic) to kt ta (nh pHgim n im ng in ca protein u nnh.

e.

ng dng sn xut cc sn phm ln men t saTrong sn xut cc loi sa chua u c s dng qu trnh ln men lactic. Nhc qu trnh chuyn ho ng thnh acid lactic m casein kt ta v to cho sn phmhng v c trng.

Bng7 : Mt s vi khun c trng cho cng nghip ch bin sa

Chng vi sinhvt

Nhit ln men

0C

Ln men lactose n Ln menacid xitric

n

S dngtrong sn

xutAcid lactic Cht khc

S.thermophilus 40-45 0,7 Sa ln menS.lactic 25-30 0,7 PhomatS.cremoric 25-30 0,7 Sa ln men

S.diaxetylactic 25-30 0,7CO2

Diaxetyl

Salnmen,

phomat, b

Leuc.cremoric 25-30 0,4 CO2CO2

DiaxetylSa ln men

L.casei 30 1,5 Phomat

L.lactic 40-45 1,5 Phomat

L.helveticus 40-45 2,0Sa ln

men,phomatL.bulgaricus 40-45 1,5 Sa ln men

Bifidobacterium 37 0,9 Acid acetic Sa lnmen

f. Cng nghip ch bin thtCc sn phm tht ln men, xc xch ln men: P. acidilactici, Lb. plantarum,

Staphylococcus carnosus

g. ng dng thc n gia scV nguyn tc, cc loi c v l cy lm thc phm gia sc cng ging nh

cng ngh sn xut da chua. Qu trnh ln men lactic xy ra lm tng gi tr dinh dng

v kh nng bo qun c, l cy cho gia sc.

2. ng dng trong y hc

ng dng vi khun lactic cha bnh ng rutDa vo hiu qu s dng vi khun lactic trong vic cha tr tiu chy, Php

sn xut v ara th trng t hng chc nmnay sn phm mang tn Biolactyl. Snphm ny chuyn tr tiu chy bng nhiu vi khun lact ic.


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VI. THNH TUHin nay, vi s pht trin vt bc ca khoa hc k thut, v p ng yu cu

ca canh trng nui cy, cc chuyn gia tp trung pht trin rng hai hng sau:

1. Nghin cu mi quan h cng sinh v c ch ln nhau gia cc loi tin

hnh nui cy canh trng hn hp gm nhiu loi.Trc y, ngi ta ch yu tp trung sn xut canh trng ging thun khit,nhng hin nay p ng yu cu sn xut, c bit trong ngnh cng nghip sa,ging thng c s dng di dng t hp nhiu loi vi sinh vt khc nhau. Do tin hnh nui cy t hp ging ny th cc nh sn xut phi nghin cu, xem xt k miquan h ln nhau trong t hp ging chn ra iu kin nui thch hp nht t hpging cng nhau pht trin. Trong trng hp nhn ging l t hp nhiu loi vikhunlactic, do mi loi VSV c nhit sinh trng ti u ring, vic chn nhit cho qutrnh nhn ging l rt quan trng.Bng cch thay i gi tr nhit trong khong vi0C, ta s c c cc kt qu khc nhau v t l s t bo ca tng loi vi khun trong

canh trng thu c trong q trnh nhn ging.V d nh theo Beal v Corrieu (1991),nu nhn ging t hp Lactobacillus bugaricus v Streptococcus thermophilus 44 0C ,laiLactobacillus bugaricus s sinh trung t hn v chim t l cao hn trong sinh khithu c. Ngc li, nu qa trnh nhn ging l 42 0C ,loi Streptococcus thermophiluschim t l co h trong inh khi. V d trong sn xut kefir, ngi ta dng t hp nhiuloi vi khun lactic v nm men ln men to sn phm, hay trong cng ngh sn xutyaout, ging l t hp nhiu loi lactic khc nhau.

2.Nghin cu chuyn ho gen

Nhng ging truyn thng pht trin da trn s tuyn chn t nhng ging tnhin v s t bin. Tuy nhin, k thut mi trong thao tc gen, tch gen v chuyn ho

gen ha hn nhiu ci tin cho nhng ging ng dng trong ngnh cng nghip sa. Kthut gen cho php thay i trc tip nhng c im ang tn ti, trao i nhng ctnh (protease, bacteriocins, chuyn ho cacbonhydrat) gia nhng ging hoc loi cmi quan h gn nhau v a vo nhng gen ngoi t nhng ging khc nhau. Phngphp chuyn gen vo ging mi gm: tip hp, chuyn np v bin np.

Mc d vic s dng vi khun lactic bin i gen khng nh hng n kh nngri ro trong vic tiu th nhng snphm ln men t sa nhng an ton, ngi ta vnch s lng vi khun a vo. iu ny cng bao gm nhng tng tc c kh nngxy ra vi vi sinh vt gy bnh cng nh l nhng rc ri c th xy ra vi k thut x l,gi tr dinh dng v kh nng gy d ng ca sn phm.

Trong tt c nhng loi lactic lm ging, vi khun lactic a m c nghin cunhiu nht. Bng di cung cp nhng nghin cu v bin i gen quan trng ca vikhun dng trong cng nghip sn xut sa.

Nhim th thc khun l nguyn nhn quan trng lm chm qu trnh hnh thnhacid trong khi ln men. V vy c rt nhiu nghin cu tp trung vo vic thay i cctnh trng ci tin canh trng ging dng trong cng nghip.


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Bng 8:Mt s v d v bin i gen ca canh trng ging trong ngnh sa

Loi S bi n iLc.lacticssubsp To ra ging c kh nng sinh nicin A km

Lc.lactissubsp.lactis Ci ti n hot tnh phn hu protein ca n b ng cchnhn plasmid m ho gen proteinase t Lc.lactis

subsp. cremoris

Lc.lactis subsp. lactis v Lc. Lactis

subsp. cremoris

Sc khng thc khu n

Lc.lactis Chuyn plasmid c sc khng thc khun

Lc.lactis subsp. lactis subsp. lactisvar. diacetylactis

Kiu hnh Lac+ c sn xut bng cch chuynplasmid lactose tLc.lactissubsp. lactis

Lc.lactissubsp. lactis Gi ng Prt-

c bi n i t Prt+

b ng s bi n iphc hp gen proteinase tLc. Lactissubsp. cremoris

Lc.lactis Gia tng sn lng diacetyl

Pediococcus Ci tin tnh hp th lactose v galactose v gia tnghot tnh phosphor-beta galactosidase bng cchchuyn mt plasmid lactose tLc.lactis


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VII. TI LIU THAM KHO1. L Vn Vit Mn, Cng ngh sn xut cc sn phm t sa v thc ung, tp 1

Nh xut bn i hc Quc Gia Thnh ph H Ch Minh - 2004

2. Nguyn c Lng,Cng ngh sinh hc,Nh xut bn i Hc Quc GiaTpHCM, nm 2001, 342 trang.

3.Nguyn c Lng,Cng ngh vi sinh vt (tp 1: C s vi sinh vt cngnghip),Nh xut bn i Hc Quc Gia TpHCM, nm 2004, 236 trang.

4.Nguyn c Lng,Cng ngh vi sinh vt (tp 2: Vi sinh vt hc cng nghip),Nh xut bn i Hc Quc Gia TpHCM, nm 2002, 370 trang.

5.Kiu Hu nh, Gio Trnh Vi Sinh Vt Hc Cng Nghip,Nh Xut Bn Khoa

Hc V K Thut H Ni, nm 1999, 291 trang

6. L Ngc T, Ha sinh cng nghip - Nh xut bn Khoa hc v K thut,2002, 443 trang.

7.http://.www.ebook.com8.

MC LC
http://.www.ebook.com/http://.www.ebook.com/http://.www.ebook.com/http://.www.ebook.com/


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I. Nguyn liu lm mi trng vi sinh vt ---------------------------------------------- 1

1. Vi khun lactic ------------------------------------------------------------------------------- 1

1.1. c im chung ca vi khun lactic --------------------------------------------------- 11.2. S phn b --------------------------------------------------------------------------------- 1

1.3.Phn loi vi khun lactic ------------------------------------------------------------------ 12. Sinh khi vi khun lactic ------------------------------------------------------------------ 11

3. Nguyn liu sn xut v ging dng cho nui cy ---------------------------------- 11II. Qui trnh thu nhn sinh khi vi khun lactic ----------------------------------------- 17III. Gii thch quy trnh cng ngh -------------------------------------------------------- 181. X l nguyn liu ------------------------------------------------------------------------ 182. Chun b mi trng ---------------------------------------------------------------------- 183.Thanh trng mi trng ------------------------------------------------------------------- 18

4.Nui cy (nhn ging) --------------------------------------------------------------------- 195, Thu sinh kh i -------------------------------------------------------------------------------- 246. Lm lnh ------------------------------------------------------------------------------------- 257. ng gi v bo qun -------------------------------------------------------------------- 27IV.Sn phm sinh khi vi khun lactic ----------------------------------------------------- 28V. ng dng ca sinh khi vi khun lactic ------------------------------------------------- 28VI. Ti liu tham kho ------------------------------------------------------------------------ 34

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