Đề tài số 29_ qúa trình nhào bột

7/29/2019 ti s 29_ Qa trnh nho bt

1/27

B CNG THNG

TRNG I HC CNG NGHIP TP H CH MINH

VIN CNG NGH SINH HC V THC PHM

--------

GVHD : Th.S H XUN HNG

SVTH :

NGUYN MNG DUY 10050941

NGUYN T. THY HNG 10057681

Tp. H Ch Minh, thng 6 nm 2013


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DANH SCH SINH VIN THC HIN

H TN SINH VIN M S SINHVIN

PHN CNG NHIM V

NGUYN MNG DUY 10050941 Khi nim

Mc ch

Phn loi

Cc yu tnh hng n s htnc ca bt

Cc bin i trong qu trnh nhobt

NGUYN TH THYHNG

10057681 Cc yu tnh hng n qu trnhnho bt.

Xc nh cht lng bt nho

Yu cu bt nho sau khi nho

Thit b


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MC LC

1. Khi nim bt nho ................................................................................................................ 1

2. Mc ch nho bt .................................................................................................................. 13. Phn loi bt nho .................................................................................................................. 1

4. Cc yu tnh hng n sht nc ca bt: ................................................................. 2

5. Cc bin i trong qu trnh nho bt ................................................................................. 3

5.1 Cm quan .............................................................................................................................. 3

5.2 Vt l ..................................................................................................................................... 3

5.3 Ha sinh ................................................................................................................................ 3

5.4 Ha hc ................................................................................................................................. 6

5.5 Ha l .................................................................................................................................... 7

6. Nhng yu tnh hng n bt nho v qu trnh nho. ................................................... 7

6.1 Nhit nho ........................................................................................................................ 7

6.2 Cng nho ..................................................................................................................... 8

6.3 Thi gian nho ...................................................................................................................... 8

6.4 Cc cht hot ng b mt .................................................................................................. 9

6.5 Cht oxi ha: ...................................................................................................................... 10

6.6 Cht kh........................................................................................................................ 10

7. Yu cu ca khi bt sau khi nho. ....................................................................................... 11

8. Xc nh cht lng bt nho. ............................................................................................... 12

9. Thit b nho bt. ..................................................................................................................... 15

KT LUN .................................................................................................................................. 19

TI LIU THAM KHO

PH LC


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M U

Bnh l mt mn n im tm c t lu i, bnh c phn thnh nhiu loi da vo

m ca bnh, da vo cc phng php to hnh hay phng php lm n.Vi nhng loibnh nh sandwich, biscuit cng vi bnh cookie l dng bnh nng rt thng dng v tinli, chng c mi v thm ngon v hp dn. Ngoi ra cn c nhiu loi bnh nh bnh cake,waferang ngy cng c bit n nhiu hn.

Hin nay th bnh c sn xut vi s lng kh ln, mi v v hnh dng bnh phong phhn. Chng khngngng c i mi v mi mt p ng th hiu ca ngi tiu dng ,chng hn nh b sung thm thnh phn dinh dng cung cp cho c th. to ra nhngchic bnh thm ngon i hi nh sn xut phi c nhng nguyn liu cht lng cao cngvi cng thc lm bnh ring cho mi loi bnh, trong cng thc lm bnh th cng onnho trn l quan trng bi v cng on ny quyt nh n cht lng bt nho, kh nng

trng n , n hi ca khung gluten v tt c nhng yu t ny quyt nh n cht lngbnh.

Trong cng on nho trn bnh ta cn quan tm n nhng nh hng n qu trnh nhotrn, bin i ca bt nho hay yu cu ca bt nho sau khi nho ph hp vi tng loi

bnh

Chng em xin chn thnh cm n c H Xun Hng gio vin ging dy mn Cng NghSn Xut ng Bnh Ko to iu kin chng em tip xc vi ti Tm hiu v qutrnh nho bt chng em c th hiu r v s bin i hay cc yu t nh hng n qutrnh nng cao kin thc.


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Cng ngh sn xut ng bnh ko GVHD: Th.S HXun Hng

ti s 29: Qu trnh nho bt Trang 1

1. Khi nim bt nho

Bt nho l h pha phn tn ca 3 pha: rn (gluten), lng (nc t do, protide ha tan,

cc cht kh ha tan: mui, ng v cht ha tan khc), kh (nu s dng trng)

2. Mc ch nho bt

- To bt nho vi nhng tnh cht cu trc, m thch hp chun b cho qu trnhto hnh sau ny

- Kt hp thng nht cc thnh phn, phn b u nguyn liu

3. Phn loi bt nho

Da vo tnh cht, bt nho c phn chia:

- Hard dough (bt nho cng)

+ Trong cng thc lm lng ng v cht bo thp v th bt nho c tnh cht: daido do mng gel pht trin.

+ Loi bt nho ny rt thch hp cho bnh cracker (cu trc cng, gin)

- Soft dough (bt nho mm)

+ Trong cng thc lm bnh hm lng ng, cht bo cao v th bt nho c tnhcht: rt mm; khng dai do, n hi. V ng v cht bo nh hng n s to gelcho nn mng gel khng pht trin v gn nh khng pht trin

+ Loi bt ny thch hp cho cc loi bnh nh l bnh cookie, bnhbng lan

- Hard weet, semi weet dough (bt nho ng)

+ ng v cht bo chim gi tr trung bnh trong cng thc lm bnh v th btnho c tnh cht: khng mm, khng cng. Bi v mng gel pht trin mc trung

bnh

+ Thch hp cho cc loi bnh: biscuit mm, bnh cake (do s dng bt nho a dng)


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4. Cc yu tnh hng n sht nc ca bt:

Qu trnh nho bt thc s l qu trnh bt m ht nc trng n to ra mng gel, cutrc bt nho. V th chng ta cn xt n cc yu t nh hng n s ht nc ca

bt

- C ht bt: chnh l ht tinh bt, kch thc ht tinh bt nh, mn, tit din b mt tipxc vi nc cng ln dn n tc ht nc cng ln

- m bt: m bt m thp th khnng ht nc cng cao v ngc li mcng cao th khnng ht nc cng thp. m bt gim 1% th khnng ht nctng 1.6 ln

- Hm lng v cht lng gluten: Trong qu trnh nho, gluten c th ht nc gp200 ln so vi chnh bn thn chng. Tuy hm lng gluten trong bt m t nhng khnng ht nc cao hn, v th gluten cng gp phn quyt nh qu trnh ht nc ca

bt. i vi bt m c hm lng gluten cao, cht lng tt th kh nng ht nc cabt cao

- Hm lng tinh bt: Bt m c hm lng tinh bt cao. Kh nng ht nc ca tinhbt nhit nho 22 - 250C ch ht 30% so vi khi lng chnh bn thn chng.Hm lng tinh bt chim khong 80 -86% tng khi lng bt m, kh nng htnc ca tinh bt thp hn gluten, nhng do hm lng chim rt cao cho nn chngcng nh hngn s ht nc ca bt. Nu hm lng tinh bt cng cao th khnng ht nc cng cng tng. Kh nng ht nc ca tinh bt ph thuc vo nhit .Ti nhit h ha, tinh bt ht nc gp 3000 ln so vi chnh bn thn chng.

Nhng nhit thng kh nng ht nc ca tinh bt b hn ch (ch c 30% sovi bn thn chng). [1], [2]

- Nhit nho: nhit mi trng cng cao tc ht nc cng nhanh, nhng nutng qu cao ti nhit bin tnh, nh hng n kh nng ht nc ca bt.Khi kh nng, tc ht nc gim t ngt.

- Cht bo, ng, mui, sa

+ Khi c mt ca cc cht rn: ng, sa bt, mui s cnh tranh ly nc hatan, gim kh nng ht nc ca bt. i lc gia ng - nc ln hn i lc ca bt- nc, cho nn ng ht nc trc, lm gim kh nng hydrat ha ca gluten (shydrat ha b gim i, gim tc ht nc, khung gluten pht trin khng cao).Lng ng tng 1% th kh nng ht nc ca bt gim 0.6%

+ Cht bo lng lm gim kh nng v tc ht ncca bt (to mng mng ngncn s ht nc ca bt, tinh bt)

+ Cht bo rn t nh hng n s ht nc ca bt


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+ Sa, trng: tng hm m ca bt, tng tc ht nc ca bt. [3]

5. Cc bin i trong qu trnh nho bt

- Cm quan

- Vt l

- Ha sinh

- Ha hc

- Ha l

5.1 Cm quan

- Trng thi: ban u l nhng phn t ri rc, sau khi nho trn to thnh khi bt nhong nht

- Mu sc: mu khng ging nh ban u trc khi nho bt, l tp hp tt c cc muc trong khi nguyn liu. Nh l mu vng ca trng, b; mu trng ca sa;...

- Mi v: tp hp cc mi v ca cc hp phn c trong bt nho

5.2 Vt l

- Th tch gim: Khi bt dng ri rc th khng kh chui vo nhng phn t ri rc ,gia cc phn t ri rc c cc l trng. Khi nho bt l trng khng cn na, v thth tch khi bt gim. Nhng trong qu trnh nho bt, cc cht ht nc trng n,khng kh ltvo trong khi bt lm cng lm tng 1 phn th tch khi bt

- Khi lng ring: th tch khi bt gim xung ng ngha vi vic khi lng ring

tng ln (D = m/V). i vi bnh lm n bng phng php sinh hc: khi lngring khng tun theo quy lut mt d th tch khi bt tng

- S ha tan: Nu trong qu trnh nh kem cc phn t ban u: mui, ng, chaha tan ht th cng on nho ny s ha tan hon ton cc phn t

5.3 Ha sinh

Bin i- Khi cc phn t protein b bin tnh tp hp li thnh mt mng li khng gian c

trt t gi l s to gel.


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- Khi protein bin tnh th cc cu trc bc cao b ph hy, lin kt gia cc phn t bt, mch peptit b gin ra, c nhm k nc n pha trong by gi xut hin rangoi. Cc mch polypeptit b dui ra (trong iu kin gia cng nht nh) trnngn nhau, tip xc vi nhau v lin kt vi nhau m mi v tr tip xc l mt nt,

phn cn li hnh thnh mng li khng gian ba chiu v nh hnh, rn, trong ccha y pha phn tn (H2O).

- Khi c s sp xp li cu trc, trt t sp xp bo ln hnh thnh lin kt mi:protein-protein, protein-nc. Cu trc mng gel l nhng phn t proein nm ntmng nht cc phn tnc bn trong, cho nn lc tng tc gia protein - proteincn bng vi lc tng tc protein - nc.

- Cc nt mng li c thc to thnh do tng tc gia cc nhm knc. Khinhm ny gn nhau tng tc vi nhau hnh thnh ra lin kt hydrophop (knc hay

a bo), cc phn tnc bao quanh chng by ra v chng c khuynh hng tli. Tng tc a bo thng c n nh v tng cng khi tng nhit , lm chocc mch polypeptit st li gn nhau hn, khin cho khi gel trnn cng hn.

- Cc nt li c th c to thnh do cc lin kt hydro gia cc nhm peptit vinhau. Lin kt hydro l lin kt yu, to ra mt linh ng no gia cc phn t,do lm gel c c do nht nh. Cc nt li c th do cc lin kt tnh in,lin kt disulphua, ...

- Trong bt m ch c gluten to nn mng gel. Tinh bt chim hm lng cao nhngkhng ng vai tr quan trng trong sn xut bnh. Tinh bt khng c khnng togel trong iu kin nho bt, tinh bt ch to gel khi hha, ngui v c nhtthch hp. Ti cng on nho bt khng c qu trnh gia nhit cho nn khng xy raqu trnh hha v cng khng c s to gel ca tinh bt (ch h trcu trc btnho). Tuy nhin khi nho bt, tinh bt ht nc trng n, lm tng nht btnho, gp phn kt dnh, bt nho ng nht, to hnh d dng. Cc phn t c thnh ln khung gluten (mng gel do protein hnh thnh), gp phn ng to gel gluten.

- Enzyme thy phn tinh bt, protein, lipit to thnh cc phn tn gin

- {S ln men ru: t0opt = 25 350C, pH = 4 6S ln men lactic bi vi khun lactic khi bt tch tru, CO2.Khi nho bt lm n bng phng php sinh hc: Th tch khi bt tng ln, khilng ring ca bt nho khng theo quy lut

Qu trnh to gel

Cu trc mng gel (khung gluten)+ Cu trc bc cao b ph hy


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+ Mch polypeptit gin di

+ Nhm knc l ra ngoi

+ Sp xp li cu trc

Lin kt protein protein > lin kt protein nc => protein ng t (s tp hpkhng c trt t ca cc phn t protein, to thnh khi ln v th) v ngc li khi

protein-nc > protein-protein th protein ha tan. Qu trnh hnh thnh gel khi linkt gia protein protein = proteinnc. Trong mng gel lin kt S-S- lm mnhhn cho cu trc khung gluten, lin kt hydro l lin kt km bn nhng s lng linkt nhiu. Glutenin v gliadin mch di lin kt vi nhau bng lin kt disulphua.

Cc giai on to gel+ Ht nc, trng n (hydrat ha): protein hp th cc phn t nc cc phn c cc

to lp nc dy bao quanh ngoi phn ttrng n

+ Bin tnh v gin mch (lin kt bc cao b ph v): cc cu trc bc 3, 4, phn vnh hnh b phn hylin kt gia cc phn t b t cu trc bc 2 b ph v

+ Tng tc trt tgia cc protein: cc nhm bn ca acid amin trc n bn trong,by gi l ra ngoi. Cc mch polypeptit b dui ra, gn nhau, tip xc vi nhau hnh

thnh mng li khng gian 3 chiu m mi v tr tip xc ca mch l 1 nt. Cc phncn li hnh thnh mng li khng gian v nh hnh, rn, trong cha y pha phntn l nc

+ Tp hp cc phn t protein: nh hngtp hphnh thnh cc lin kt mi(lin kt S-S-, hydro, tnh in, tng tc protein protein, proteinnc, )

Shnh thnh bt nho

+ Glutein hp th nc

+ Bin tnh

+ To gel

+ By cc phn t nc vo bn trong mng gel

+ Nhng tiu phn gluten ban u hnh thnh nhng mng mng bao quanh cc httinh bt v nhng hp phn khc


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Vai tr mng gel+ Tnh d ko dn: c th thay i hnh dng thng qua qu trnh sn xut

+ Tnh khng thm kh: gi kh to ra, trng n c

+Tnh n hi: khi bt c kh nng trng n, gi khhnh thnh cu trc xp chosn phm

+ Kh nng gi nc cao: sn phm c mm sau khi nng

5.4 Ha hc

- Qu trnh nho bt to nhng lin kt ha hc mi (do qu trnh hnh thnh mnggluten)+ Lin kt knc proteinprotein

+ Lin kt a nc proteinnc gia cc nhm c cc ca protein

+ Lin kt hydro gia cc peptit vi nhau

+ Tng tc gia cc nhm a bo

+ Lin ktS- S-

+ Lin kt tnh in: lc ht cc nhm tri du, lc dy cc nhm cng du qua ion aha tr

- Khi thm nc, mui v nho trn trong 10 - 20 pht cc protein ca gluten s hpthnc, nh hng, sp xp li thnh hng v gin mch tng phn, nn s lm phtsinh cc tng tc a bo v hnh thnh cc cu ni disulphua mi (qua phn ng trao

i -SH/-S-S-). Mt mng protein ba chiu c tnh nht n hi c thit lp, dndn nhng tiu phn gluten ban u bin thnh nhng mng mng bao ly xung quanhcc ht tinh bt v nhng hp phn khc c trong bt m. Khi bt trthnh n hiv d chy.

- Thng th loi bt "mnh" cn phi c thi gian nho trn di bt nho thu cc tnh c kt cao. Vi loi bt "yu", nu cng v thi gian nho trn qu mcno , s lm ph hy nt cu disulphua (nht l khi khng c khng kh) v bt schy.


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5.5 Ha l

- nht tng, qu trnh ht nc trng nca gluten v tinh bt lm tng nhtca bt nho.

- Tnh cht lu bin thay i: to thnh khi ng nht, c tnh c kt cao, cht ch sovi ban du. Ty theo loi bt nho m tnh cht c s khc nhau: bt nho mm thcu trc rt mm v khng dai do, n hi; bt nho cng c cu trc dai do, nhi,...

- Ht tinh bt trng ndo ht nc, cht rn ha tan, hydrate ha gluten to mnggluten. [4]

6. Nhng yu tnh hng n bt nho v qu trnh nho.

6.1 Nhit nho

- Trong qu trnh nho trn th nhit tng ln do qu trnh ma st khi bt tip xc vithnh thit b,hoc nhit t s hydrat ha bt, ng thi nhit cng chu nhhng bi nhit ca cc thnh phn, kch thc v loi thit b trn, qu trnh trn(thi gian v tc ), nhit phng.

- Nhit nho nh hng n vn tc, khnng ht nc ca protein v tinh bt, nhhng n s hnh thnh cc lin kt trong mng gel ng thi cng nh hng nthnh phn ng to gel ca protein bt m.

- Di tc dng ca nhit cao, khnng ht nc v vn tc ht nc ca tinh bttng da trn tnh cht cu trc ca ht tinh bt. N bao gm 2 cu t l amiloza vamilopectin, amiloza d ha tan trong nc m to nn dung dch c nht khngcao cn amilopectin chha tan khi un nng v to nn dung dch c nht caohn, amilopectin hp th cng nhiu nc khi nhit tng.

- ng thi nhit cao protein b bin tnh tp hp li thnh mt mng li khnggian c trt t gi l s to gel. C s hnh thnh cc lin kt mi trong mng gel ny,nhit tng lm cho cc mch polypeptit st li vi nhau,cc tng tc a bo ctng cng v n nh, khin cho khi gel trnn cng hn. Cc nt lin kt trongmng gel cng c th do cc lin kt tnh in, lin kt cu ni gia cc nhm tchin ngc du hoc do lin kt gia cc nhm tch in cng du qua cc ion a hatr, lin kt disulfua gia glutelin v gliadin. Lin kt hydro l lin kt yu, to ra linh ng gia cc phn t vi nhau nn lm cho mng gel c do nht nh, nhngkhi tng nhit cc lin kt hydro bt dn n gluten trng nnhanh nhng vnnt , khnng gi kh km.

- Gluten trng ntrit nht 40oC, khi nhit tng trn 5570oC tinh bt s bh ha ht nc trng nmnh, khi nht ca huyn ph tinh bt tng mnh v


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cc ht trng phng kt dnh vo nhau, nu nhit tip tc tng c th gy ra n vht tinh bt, thy phn tng phn v ha tan phn no cc phn t cu thnh ca tinh

bt, km theo gim nht ca dung dch, khi dung dch rt m c hay nhit c gim xung s hnh thnh mng gel ng to gel gluten.

- Ngc li khi nhit thp s lm gim vn tc ht nc trng n ca tinh btnhng lin kt hidro c tng cng v cng c, khung gluten cht hn.

- V vy kim sot c nhit gim nh hng ca n ln qu trnh nho bt ta cth thm vo bt, s dng nc lnh, thit b trn h thng lm lnh (ch yu lmy trn ngang) hay s dng mt dung dch mui bo ha c th c lm lnhxung di 0oC thay v dng mui ht, h nhit cc thnh phn.

6.2 Cng nho

- Cng nho snh hng n tnh cht vt l ca bt nho v cng nho phthuc vo cht lng bt v loi bnh to ra.

- Cng nho cao to ra cc lc ct c hc lm bin tnh protein, t tng qu trnhto gluten nhng gim khnng gi kh ca gluten bi ph hy cc lin kt disulfua.Thng th loi bt mnh cn phi c cng nho cao bt nho thu c c tnhc kt cao.

- Vi loi bt yu th cn cng thp v khi cng nho cao cng vi thi giannho trn qu lu s ph hy cc cu ni disulfua (nht l khi c khng kh) , bt nhos b chy.

6.3 Thi gian nho

- y l mt yu t cn c kim sot, thi gian nho nh hng n cu trc mnggel cng nh strng nca cc ht tinh bt.

- Trong thi gian nho phi to iu kin cc nguyn liu dng tinh th ha tan honton, cc qu trnh keo xy ra hon ton to ra bt nho c cc tnh cht ha l, cutrc nh mong mun.

- Thi gian qu nhanh lm tinh bt v protein khng thi gian ht nc trng nti a, mng gel cha c hnh thnh.

- Thi gian lu lm cho nhit nho tng ln do qu trnh ma st dn n bin tnhprotein, t lm cho protein b dn mch v tp hp li theo mt trt t to mnggel, ng thi tinh bt ht nc trng n mnh. Tuy nhin nu thi gian qu lunhit tng cao s lm ph vcc lin kt hydro, lin kt disulfua lm cho khunggluten b lng lo, khi bt b chy.


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- Khi nho, bt hon ton c trn ln vi nc v bt nho trnn dnh, dnh nys gim xung khi nho n mt thi gian nht nh, l do protein v cc cht khctrong bt lin kt vi nc v lng nc t do trong bt nho gim xung.

- Tng thi gian nho trn s lm mm khi bt nho, lm gim c nht v tnh nhi, khi ta nho qu mc mt vi lin kt gia nc v cc thnh phn khc b ph v,dn ti tng hm lng nc t do.

- Thi gian nho bnh hng bi tc ca my trn, thit k my trn, kch thcbt lin quan n cng sut my trn, nhit nho (hiu qu ca h thng lm mt),cht lng ca bt m hay s hp thnc ca bt (kch thc ht), lng cht bo(cht bo slm tng thi gian nho).

- Thi gian nho ph thuc ch yu vo cc yu t sau : Loi bt nho: Bt nho dai cn thi gian nho trn lu hn bt nho xp. Hm lng gluten trong bt nho: Khi hm lng gluten tng th thi gian nho

ca bt nho gim.

Nhit ca hn hp nguyn liu: Nhit ban u ca hn hp nguyn liucng c nh hng n thi gian nho do nhit c nh hng n strngnprotein ca bt. Khi nhit ban u ca hn hp nguyn liu tng th thigian nho gim.

m bt nho: m ln th gluten trng nnhanh, do nu tng mbt nho khi cc iu kin khc ging nhau th thi gian nho c rt ngn li.

Cng khuy trn: Tng s vng ca cnh khuy trong my nho th thigian nho s rt ngn li.

6.4 Cc cht hot ng b mt

- Cc cht hot ng b mt tc dng nh nhng cht trung gian gia vng knc caprotein v mi trng ho nc do gy ph hy cc lin kt knc nn lm ginmch protein

- Nhng cht hot ng b mt c cu trc lng cc s tnh hng hai cc anc v knc ca chng ng vi hai pha ca b mt lin pha to thnh cc bt n

phn t c tc dng lm dnh cc phn t vt cht, gim sc cng b mt gii hnphn chia gia 2 pha lm bn hnh tng v ci thin tnh cht bt nho.

- Trong bt nho, nhm cht ny to thnh hp cht hp ph ca protein v tinh bt, do lm tng khnng ht nc ca gluten, lm gluten n hi hn.


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- Cc cht nh ha thng l cc ester ca cc axit bo.6.5 Cht oxi ha:

- Theo thnh phn protein, gluten c cc axit amin cha nhmSH- (cystein) to giacc nhnh v cun li thnh cu trc hnh cu, nu trong phn t cng t nhmSH-v cng nhiu nhmSS- th cht lng gluten cng tt.

- ng thi khi bt ngh cc lin kt disulfua b ph v, nng lng c hc truyncho bt trong qu trnh nho trn hoc ngh bt n nh cu trc bng cch gimcc lin kt ny. Cc lin ktSH- c hnh thnh tlu hunh ca cc lin kt b

ph vvi bt lm cho khung gluten lng lo.

- V vy cc cht oxi ha c cho vo ci thin, c thl oxi do qu trnh nh btkh chui vo hoc cc cht oxi ha nh acid ascorbic, canxi peroxide, tuy nhin acidascorbic c chuyn thnh axit dehydro- ascorbic thc hin chc nng oxi ha.Chc nng c th ca cc cht oxi ha :

Chuyn cc lin kt SH- trong phn t protein mng gluten thnh lin kt SS-lm cu trc protein cht li.

Oxy ha sc t carotenoid lm cho bnh trng hn bi c tnh cu trc cacarotenoid, chng l nhm cht mu ha tan trong cht bo, c nhiu ni i lunhp to nn nhng nhm mang mu ca chng nn rt nhy cm vi axit v chtoxy ha.

6.6Cht kh- Cc cht kh c nh hng n bn khung gluten v cu trc khi bt nho.- Khi c mt cc cht kh, chng sngn cn qu trnh to gel ca cc phn t protein

bng cch ct t cc lin ktSS- gia cc phn t protein trong mng gel, do lmgim nng lng v thi gian nho trn nhng ng thi lm gim cht v thay icu trc ca khi bt nho.

- ng thi cc cht kh c khnng tng cng hot ng ca proteinaza lm thyphn protein, gim kh nng lin kt vi nc c nh hng xu n cu trc bt

nho.


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6.7 Mui.

- Thnh phn ch yu ca mui l NaCl, NaCl c kh nng ha tan d dng trong ncdo NaCl c kh nng phn ly ra ion Na+ v Cl-, do c kh nng to lin kt hydro vi

phn t nc. Mui c tc dng lm cho khi bt nho cht li do mui lin kt vi ccphn t nc t do c trong bt nho trnh hin tng nho bt nho.

- Do mui l cht tan khi phn ly to ion mnh thay i hng s in mi xung quanh bmt ca ht keo, cc ht keo lin kt vi nhau bng lin kt ion v mt s lin kt khcnn lm tng bn ca gluten. ng thi lm mnh bt nho do n c kh nng c chhot ng ca enzym thy phn protein l proteinaza.

6.8 nh hng ca pH.

- pH ca khi bt nho c th thay i do cc acid hu c nh acid citric, acid lactic.. ctrong thnh phn nguyn liu ,pH nh hng n kh nng ion ha v s tch in ca

protein, thay i lc ht hay lc y gia cc phn t protein, nh hng n khuynhhng kt hp vi nc kh nng hydrat ha v kh nng trng n.

- Protein l nhng phn t c cu to t cc axit amin c tnh cht lng cc nnprotein cng c tnh cht lng cc va c tnh axit va c tnh bazo. Trong mi trngtrung tnh , cc axit amin trong phn t protein tn ti ch yu trng thi lng cc, ccnhm cacboxyl b phn ly, nhm amin b proton ha, trng thi ion ha ca cc nhm ny

ph thuc vo pH mi trng,. Trong mi trng axit nhm cacboxyl khng ion ha,

nhm amin dng proton ha, ngc li trong mi trng kim , nhm cacboxyl ion hav nhm amin khng ion ha.

- Khi pH mi trng bng vi im pHi ca protein ( gi tr pH m tng s in tchdng v in tch m ca phn t protein bng khng, phn t protein khng di chuyntrong in trng) th protein d dng kt t li vi nhau.

-Nu mi trng c pH pHi , protein l mt a cation, s in tch dng ln hn sin tch m, pH ln hn pHiphn t protein th hin tnh acid cho ion H+ , do sin tch m s ln hn s in tch dng, protein l a anion, tch in m. S thay i

pH ca mi trng s lm cho protein thay i in tch t c th thay i lc ht haylc y gia cc phn t protein.

- Khi ha tan, protein to thnh dung dch keo, bn ca dung dch keo ph thuc vos tch in ca phn t protein , nu cc protein tch in cng du ( pH khc pHi)dung dch keo bn.Khi pH bng pHilin kt prot prot ln hn prot nc th kh nnghydrat ha, trng n ca protein gim, protein b kt t.-

7. Yu cu ca khi bt sau khi nho.

- m ca khi bt:


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Phi gluten ht nc v trng n. Phi lm chn bnh khi nng. Phi ph hp vi phng php to hnh.

Vi phng php cn, phn tm v ct : W = 1820%.

Viphng php cn, ct : W = 2021 %

Vi phng php p quay : W = 22 -23 %.

Vi phng php p n : W = 24 25%.

Vi phng php rt : W 26 27 %

Phi ph hp vi yu cu cht lng bnh v thi gian bo qun.- Khi bt sau khi nho phi t s ng u cao.

8. Xc nh cht lng bt nho.

- Khi bt nho sau khi nho c kim tra chtlng da vo cc tnh cht lu bin sau:

Sn hi hay khnng phc hi ca bt nho : ph thuc slng cc mi lin ktc bn lin kt ln nh cu ni disulfua v lin kt ion ca protein to khunggluten.n hi cho bit khnng chu bin dng v hi phc li ca bt nho. Btnho c n hi cng cao th cng chu c cc bin dng trong qu trnh cn ct,c khnng trli hnh dng c tt.

chu ko dn ca khi bt nho. Khnng ht nc ca khi bt : Lng nc ti a m bt ht m khng gy ra hin

tng dnh, thng thng lng nc ht vo cng nhiu th mng gluten cng mnh,

bt nho scng n hi v cng c qunh. Tuy nhin nu lng nc ht vt qumt gii hn nht nh bt nho s b chy dnh. nht dnh hay khnng chy : To ra do lin kt protein to mng gluten. Slng

cc lin kt hydro v VanDar Waals nhiu nhng bn lin kt yu nn d chy,ngoi ra khi lng ca pha lng c trong khi bt nho cng s lm tng nhtdnh. nht dnh cng cao, khi bt nho cng linh ng, d chy di v d cnthnh mng mng.

chc, qunh ca khi bt nho : Do lin kt vi nhau ca cc phn t trong ckhi bt nho, trong qu trnh nho trn bt, khi t qunh t ga tr ti a l khi

bt nho t c ng u tt nht. Sau nu vn tip tc nho trn th cc tcng c hc slm t cc mi lin kt va to thnh, c qunh gim th cc tnh

cht lu bin khc cng gim.


17/27



xp : Do slng cc bong bng kh ln vo trong qu trnh nho, slng bongbng kh cng nhiu, cng mn v cng bn th bt nho cng xp v t trng cngthp. Slng, mn v bn ca cc bong bng kh ny chu nh hng rt nhiuca lng v kch ccc phn t cht bo c trong bt nho.

m, nht.Cch xc nh cc c tnh ca bt nho- Xc nh n hi ca khi bt.

Cn 4g gluten t, v vin, nhit phng 30 pht. Sau ly ngn tay nhn vo vin gluten, th ngn tay ra. Mt cch khc l dng hai tay ko di ming gluten trn thc khong 2cm ri

bung ra. nh gi mc v vn tc phc hi chiu di v hnh dng ban uca ming gluten.STT n hi Tnh cht

1Tt Gluten c khnng phchi hon ton chiu di

v hnh dng ban u saukhi ko hay nn

2

Yu Gluten hon ton khngtrli trng thi ban uv bt sau khi ko.

3

Trung bnh Gluten c t tnh gia

hai loi n hi tt vn hi km.

- Xc nh cng t.

Cn khong 4gram gluten t, v thnh hnh cu ri ngm trong chu nc c nhit 16-20oC trong khong 15 pht.

Dng hai tay ko di khi gluten trn tht chia milimet cho ti khi t. Thi gian ko l 10 giy. Khi ko khng c xon si gluten.

STT cng Chiu di (cm)

1

Ngn 10

2

Trung bnh 10 20

3

Di 20


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- Xc nh c tnh ht nc v tnh cht lu bin ca bt nho bng cch s dng gin Farinograph.

S dng thit b nho trn tc cao c tn l Brabender Farinograph

S dng gin Farino xc nh lng nc ti a bt ht m khng b chy dnh,lng nc cn b sung vo bt c khi bt nho c c qunh tiu chun500BU. Trong gin xc nh c cc im : Arrival time ( thi gian trn) l thi gian tkhi cho nc vo v bt u nho

cho n khi ng cong t gi trquy c 500BU. Thi gian ny l thi giannc c phn tn vo khi bt.

c qunh ti a (BU) : chiu cao peak, thi gian t khi bt u nho trncho n khi bt t n qunh ti a c gi l peak time, thi gian

pht trin ca bt nho hay thi gian t lng nc ht cao nht. Bt nhocng mnh th gi trc qunh ti a v peak time cng ln.

Thi gian n nh ca bt nho ( Tolerance) l thi gian t khi bt t cqunh ti a n khi c qunh ca bt nho gim n mc 500BU. Ga trny biu th khnng chu ng ca khi bt nho di tc dng ca lc chc. Bt cng mnh, cng lin kt vi nhau tt th khnng chu ng lc chc cng cao, thi gian ny cng di.[8]

- Xc nh cc tnh cht lu bin ca bt nho nh dnh, chc..da vo phngphp phn tch TPA.

S dng thit binstron model 5542 Texture with Merlin Software o cc c tnhca khi bt nho, cc thng s s hin trn mn hnh my tnh, cc thng schin ln nh sau:


19/27



chc ca bt nho l tng din tch ca A v B.( N.s). cng ca bt nho : khnng chu ng ti a i vi snn p u tin ( l chiu

cao ca peak A hay hardness 1 ) N. c kt ca bt nho : t l din tch ca 2 peak B/A, l khnng chu ng tng

i ca mu i vi s bin dng ln th 2 theo s bin dng ln th nht, c trngcho khnng lin kt bn trong khi bt nho. bm dnh ca bt nho : din tch ca peak bm dnh u tin ( Adhesiveness) N.s,

biu th cng cn thit di chuyn bt nho ra khi mt b mt tip xc ca u dovi bt nho. Ga tr c kt v bm dnh biu th cho s pht trin ca mnggluten.[9]

9. Thit b nho bt.

Cu to chung ca cc thit b nho bt l thit b c mt bn cha c cnh khuy o trn

bt. Cnh khuy c nhiu dng khc nhau v ty theo hnh dng cnh khuy m c qu oo trn khc nhau.


20/27



Thng c 2 loi c bn l my trn ngang v my trn ng vi u v nhc im sau:

My trc ng My trc ngang

uim

Ta c th quan st qu trnh o trnbt trong sut qu trnh khuy trn.

C th thm nguyn liu vo t phatrn ca thng hnh tr trong lc trckhuy ang hot ng, tc l gia qutrnh khuy trn, do vic nho trn

s linh ng hn t c chtlng sn phm mong mun.

Thit b t b rung.

y l nhng thit b rt mnh v hiuqu v cnh khuy c cc gi m haiu nn c kh nng nho bt tt vnhanh hn so vi my nho trn tng.

Ta c tht cc phu ca thit b chia

bt ngay bn di my nho trn, nh c th khng cn dng n cc thngcha bt trung gian hoc ch dng nchng khi mun vn chuyn bt nmt ni khc.

C th ddng iu khin nhit cathng trn mt cch hiu qu v chnhxc thng qua lp v o c nc tunhon.

Nhcim

Lc tc dng ca cnh quy yu hnmy trc ngang.

Cn thit b cha bt trung gian.

Tho bt kh khn hn l my trc

ngang.

Vic nhp liu chim mt khong thigian ng k trong chu k nho bt,nguyn liu phi c cho vo t phatrn thit b.

Cc trc khuy c khuynh hng thy

tung vt liu ln pha trn do bt cth b dnh trn thnh.

Np thng hon ton che kn bn trongnn ta khng th theo di qu trnh nho

bt ang xy ra.

V sinh thit b cn c ch trngnhiu hn do c vi vng kh ty ra.

Khi mun ti nho trn bt th phi


21/27



bt t thng cha vo thit b cho nn skh khn hn thit bt ng.

Hnh dng trc khuy thng c thit

k thc hin ng thi c 3 chcnng l khuy trn, phn tn v nhonn s khng c chc nng no l tiu.

Do c cc cnh khuy nm tm cathng cha bt nn khi bt ra s tnhiu gp cn tr, ngoi ra s c mt

phn bt b kt vo trc v cnh khuynn ch b quay trn ch khng c

nho trn.

Thit bthng nng v gy nhiu rungng nn phi ch thit k sn nh,nht l khi thit bkhng t tng trt.

Trong my trn ng c mt s my tiu biu nh

My trn xon c: yu cu bt phi c cht lng cao, my tng tc qu trnhtrn tng tnh thng nht, gim qu trnh oxi ha. Tc v thi gian trn clp trnh sn gip kim sot trong qu trnh trn.

My trn fork: my trn vi cng mnh, cung cp lc u n v c th nhotrn vi bt k phm vi hydrat ha no.

My trn artofex (m phng theo cnh tay con ngi). My trn loi Hobart vi cnh quy hnh li mc.- My trn ngang- Ngoi ra cn c my trn tc cao ( c hoc khng c chn khng) l loi my

trn c s dng ph bin, my trn chn khng vi thi gian trn t5 giy n10 pht,

- My trn lin tc: thch hp cho vic pha trn nhiu loi bt, vic cho cht lngvo v qu trnh iu nhit rt hiu qu, d dng lm sch v my trn lin tc


22/27



cng c u im c trng nh gip vic qun l trn hiu qu, yu cu khnggian thp v s dng ti u ha nng lng. [5], [6], [7]


23/27



KT LUN

Nho bt l mt qu trnh quan trng vi mc ch chun b v hon thin , khi bt nhoto ra phi c cht lng cao ph hp vi tng loi bt nho, bt nho c phn thnh 3 loi

l hard dough, hard weet v soft dough vi hm lng nguyn liu khc nhau. Qu trnh nhochu nh hng bi nhiu yu t trong quan trng l yu t nhit , cng nho, thigian nhong thi cng c nhng yu t nh hng n s ht nc ca bt cn cquan tm nh c ht bt, m bt, hm lng v cht lng gluten, cc thnh phn nguynliu khc nh hm lng ng, cht bo, sa, mui

Khi tm hiu v qu trnh nho th mt yu t cng cn ch l s bin i ca btnho v kha cnh cm quan, ha l, ha hc.C cc loi bt nho khc nhau nnyu cuv khi bt nho sau khi nho l khc nhau tuy nhin vn da trn ch tiu v m, s ngu ca khi bt nho..

V vy khi qu trnh nho bt tt th bnh to ra s t cht lng cao bi cht lng bnhc quyt nh bi bt nho v cht lng bt nho c quyt nh bi qu trnh nhobt.


24/27

TI LIU THAM KHO

[1] - (i hc Cng nghip Tp H Ch Minh, Gio trnh Cng ngh ch bin v sn xutlng thc, xut bn nm 2009, trang 11)

[2] - (i hc Cng nghip Tp H Ch Minh, Ging vin: H Xun Hng, Bi ging cngngh sn xut ng, bnhko)

[3] - (Duncan Manley, Biscuit, cookie and cracker manufacturing manuals 2: Biscuitdoughs, Woodhead Publishing Limited, page 34 - 40)

[4] - (L Ngc T (Ch bin) - La Vn Ch - ng Th Thu -Nguyn Th Thnh - Bi cLi - L Don Din, Ha Sinh Cng Nghip, NXB Khoa hc v K thut H Ni, trang 122)

[5] - http://www.thebiscuitdoctor.com/manufacturing-processes/biscuit-making-processes/72-resources/processes-types-of-dough/170-types-of-dough.

[6] - http://www.classofoods.com/page2_1.html.

[7] http://khotailieu.com/tim-tai-lieu#key=Quy trnh sn xut chocopie.

[8] Trng i Hc Cng Nghip TP HCM, Ging vin : L Phm Tn Quc, Bi gingCng ngh ch bin v bo qun nng sn.

[9] Trng i Hc Cng Nghip TP HCM, Ging vin :Dng Vn Trng, Bi ging Vtl thc phm.


25/27

PH LC

Hnh 1: S lin kt gia glutenin v gliadin

Hnh 2: My trn kiu xon c


26/27

Hnh 3: My trn Fork

Hnh 4: My trn Artofex

Hnh 5: My trn Hobart


27/27

Hnh 6: My trn lin tc

Đề tài số 29_ qúa trình nhào bột

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