bài 1 phương pháp kiểm nghiệm thóc

8/11/2019 Bi 1 Phng Php Kim Nghim Thc

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BO CO PHN TCH THC PHM

CHUYN : LNG THC THC PHM

NHM 3 | GING VIN: VNH LONG 1

I. Phng php ly mu

Ly mu l mt giai on quan trng trong vic nh gi cht lng ca htthc.

Mu phi phn nh chnh xc mi c im cht lng ca ht v phi ctrng cho thnh phm trung bnh ca ton thl ht.

ly mu phn tch, trc ht phi ly mu u tin. Mu u tin bao gm cc nhm ht ly cc vtr khc nhau ca khi ht ri

tp trung li.Nu khi ht cng ln, snhm ht phi ly cng nhiu skhng thun li cho

vic phn tch. V vy tmu u tin sly ra mu trung bnh.

Nu mu u tin c khi lng khng qu 4kg th n ng thi l mu trungbnh.

xc nh cc chscht lng ca ht thc, tmu trung bnh li chia thnhnhiu mu nhgi l mu phn tch.

Thtly mu nh sau:

Khi htmu u tinmu trung bnhmu phn tch

II. Cc chtiu cht lng ca thc

1. Chtiu cm quan

Mu sc c mu tnhin ca thc Mi c mi c trng ca thc Vkhng c vlNm mc khng c nm mc

2. Cc chtiu ha l

Chtiu Hng cht lng

1 2 3 41. m (%) nhhn2. Tp cht (%) nhhn3. Ht bc bng4. Ht bin vng5. Ht khng hon thin

14270,53

1421214

1422026

1424048


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6. Ht h hng7. Ht rn nt8. Ht ln loi9. Ht

10. Su mt (con /kg)

0,51051

5

115103

5

325158

5

5402015

5

III. o m

Hin nay c 2 phng php xcnh m ca thc:

a) Phng php sy nhanh

1. Nguyn tc

Dng sc nng lm bay hi ht lng hi nc tdo c trong mu thc (n khilng khng i). Cn trng lng thc trc v sau khi ly sy kh, t tnh ralng hi nc (%) c trong thc.

2. Dng cv ha cht

Tsy Chn sy Cn phn tch Bnh ht m

Kp gp My nghin ht hoc ci xay c ph Ry kim loi kch thc l0,5-0,8 mm

3. Cch tin hnh

Cn mi nhm 50 g mu thcNghin thc bng my nghin Phn nghin c cho qua ry kim loi kch thc l0,5-0,8 mm Cn 3 g phn lt ry cho vo chn sy c lm kh v bit trc khi lng

Cho vo tsy, sy nhit 130 trong 40 pht (n khi lng khng i) Ly mu ra v lm ngui trong bnh ht m. Sau em cn khi lng chn sy v mu sau khi sy. Ghi nhn li kt quv tin hnh tnh ton.


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Hnh 1.1. Chn sy trc khi sy Hnh 1.2.Chn sy v mu thc sau khi sy

4. Tnh kt qu

m ca thc c tnh theo cng thc sau:

W =

. 100 (%)

Vi:

W: m ca thc

: Khi lng mu v chn sy trc khi sy

Khi lng mu v chn sy sau khi sy

m: Khi lng chn sy

Kt qut c:

m = 50,7568 g

= 53,772 g

= 52, 3718 g

Vy W =

. 100 =

. 100 = 46,43 %


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b) o m bng my o m

1. Nguyn tc

Dng my o m trong thc, o 3 ln sau ly gi trtrung bnh.2. Dng c

My o m (Model: Kett F511)

THNG S K THUT RICETER-F SERIESPhng php o Tr khng in

ng dng v khong o

La ht di (9-30%), go xay ht di(9-20%), la m (10-30%), u phng(10-24%), tiu en (7-20%), tiu trng(9-20%)

chnh xc 0,5% o trong khong 10 ~ 20% m

Hin th Mn hnh LCD backlight

Ngun in 4 pin 1,5V (loi AA Alkaline)

Kch thc (rng x di x cao) 164 x 94 x 65mm

Trng lng 445g (Net)

3. Cch tin hnh

Nhp v gint Average xa bnhtrc. La chn cho cho thc , la (paddy) trn mn hnh hin th. Cho lng thc va vo chn o, sau lp chn vo my. Gi cnh chn

v vn trc quay n vch quy nh.Nhp nt Measure xc nh chsm


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Thc hin 3 ln lin tc, sau nhp nt Average ly gi trtrung bnh

4. Kt quo c

o ln 1: 18,3 %

o ln 2: 18,4 %

o ln 1: 18,7 %

Gi trm trung bnh: Wtb = 18,46 %

Bn lun

Gia 2 phng php o m trong phng th nghim th:

Phng php sdng my o c u im: n gin, dthc hin, kt qutngi chnh xc nu thao tc ng. Tuy nhin, nhc im phng php ny: phthuc vo my, chquan, dsai kt qunu khng bit cch iu chnh my.

Phng php sy nhanh c nhc im: mt nhiu thi gian, i hi phi kholo trong tng bc, dcho kt qusai lm (phthuc vo cc yu t: conngi, my mc, mi trng xung quanh). Tuy vy, phng php ny cho ktqukh chnh xc, chp nhn c v thng c gi l Phng php trngti.

Vkt quo c:

Phng php sdng my o: Wtb = 18,46 % Phng php sy nhanh: W = 46,43 %


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C mt schnh lch kh ln gia 2 phng php, iu ny chng ttrong lc thnghim nhm cn nhiu sai st. Cth:

phng php sy, c thqu trnh sy chn cha t yu cu ( n khi khi

lng khng i), lc cn chu nhiu nh hng cc yu tmi trng dn nsai s

Cn i vi phng php my o, y l ln u tin nhm sdng my o mnn khng trnh khi nhng thiu st ( vn trc quay cha ng ti vch).

Kt lun:

Nhn chung, in kin phng th nghim th phng php o m bng sy nhanh sc nhiu bt li hn(iu kin phng th nghim cha tht sph hp, sai st cangi thc hin)v cho kt qusai khc qu xa so vi dng my o m. Nn ta chp

nhn kt quo c tphng php my o: W = 18,46 %

So snh vi chtiu cht lng ca thc th m (%) thc nhhn m yu cu hay18,46 % > 14%. Do , mu la ang th nghim khng t yu cu cht lng.

IV. Xc nh khi lng tuyt i ca thc

nh ngha

Khi lng tuyt i ca thc l khi lng ca 1000 ht nguyn vn

ngha

c trng cho ln ca ht thc. Nu khi lng tuyt i ca ht cng ln th chngtht cng to ngha l phn ni nh cng nhiu, khi chbin tlht go thu ccng cao.

1. Nguyn tc

Cn 1000 ht nguyn m c tmu trung bnh v biu din theo n v(g/ 1000ht)

2. Dng cv ha cht

Cn in t Khay nha vung 20 x 30 cm Cc 100 ml


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Cc 250 ml Que gt

3. Cch tin hnh

Sau khi ly mu trung bnh, trn u khi ht thc nhiu ln, dn u trnkhay

Dng que gt gch 2 ng cho

m chnh xc tam gic thnht 250 ht ri gp vi 250 ht tam gic idin, em cn c khi lng ca 500 ht l m1(g)

Lm tng tvi 2 tam gic i din cn li, cn c m2(g)Nu chnh lch gia 2 kt quca 2 mu 500 ht khng vt qu 5% th chp

nhn, cn vt qu 5% th phi tin hnh lm li.

4. Tnh kt qu

Kt quo c:

m1 = 11,4352 gm2= 11,626 g

Chnh lch (%) gia 2 mu 500 ht c tnh theo cng thc

%CL =

. 100 =

. 100 = 1,64 %


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Do 1,64% < 5% nn ta chp nhn kt quo c ca 2 mu 500g

Vy khi lng tuyt i (KLTD) ca mu thc theo cht kh c tnh theo cngthc:

KLTD = (m1 + m2) .

= (11,4352 + 11, 626).

= 18,8 (g / 1000 ht)

5. Bn lun

Vy khi lng ca 1000 ht thc ang kho st t 18,8 g.

V. Xc nh chiu di ca ht thc

1. Nguyn tc

Dng thc cp xc nh chiu di ca ht go lt.

o chiu di ca mt slng ht thc i din cho ton bl mu, sau ly gi trtrung bnh. Tra bng tiu chun xp loi c tnh ca thc.

ngha

Ht thc cng di th ht go sau khi xay ra cng di. Ngi ta ng dng sn xut raht go ng kch thc yu cu ca n hng.

2. Dng c

Thc cp Cc thy tinh 100 ml Kp gp My bc vthc Khay nha

3. Cch tin hnh

Chn ngu nhin 50 ht thc nguyn vn sau bc vtng ht bng tay (hocbng my bc v).


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Dng thc cp o phn ni nh bn trong (n v: mm). Ly mt sl. Ghi li kt quo c v tnh ra gi trtrung bnh.

4. Tnh kt qu

Kt quo chiu di 50 ht go nh sau:

Ht Chiudi(mm)

Ht Chiudi(mm)

Ht Chiudi(mm)

Ht Chiudi(mm)

Ht Chiudi(mm)

1

2345678910

6,7

5,255,45,75,25,45,95,25,5

11

121314151617181920

5

5,65,45,155,75,35,65,55,9

21

222324252627282930

5,5

5,35,15,75,65,65,35,55,56

31

323334353637383940

5,6

5,25,15,355,55,46,55,35,4

41

424344454647484950

5,1

5,95,45,45,75,25,55,65,45,3

Chiu di ht trung bnh c tnh ra kt qunh sau: Ltb = 5,464 mm.

5. Bn lun

Tra bng tiu chun go, mu go ang kho st thuc loi go ht trung bnh (chiudi t5mm n 6mm).


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VI. Xc nh tp cht

1. Nguyn tc

Loi nhng ht khng phi l thc nguyn vn ttrong mu thc. T tnh ra % tpcht trong mu.

2. Dng c

Bsng gm 3 loi c kch thc l: 2,5; 1,7; 1,0. Cn phn tch

3. Tin hnh

Cn 400g mu thc, dng sn phn ly v tay nht tch cc tp cht. Cn v biu din

tng tp cht theo %.

Hnh 1.3.Mu thc c chn. Hnh 1.4.Tp cht trong mu thc.

4. Tnh kt qu

% Tp cht trong mu c tnh theo cng thc

X =

Vi m: khi lng tp cht (ht lp, bi vn) (g)

M: khi lng mu (g).


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Kt quth nghim thu c: m = 4,174 g ; M = 400 g

Vy X=

=

= 1,0435 %

5. Bn lun

Vy mu thc ang kho st t yu cu vchtiu tp cht (1,0435 % < 2 %).

VII. Xc nh ht rn nt

1. Nguyn tc

Dng my hoc tay bc vtru ca mu thc. Quan st ht go lt pht hin ccht rn nt, t tnh ra % ht rn nt.

2. Dng c

Cn phn tch Khay nha My bc v Knh lp

3. Tin hnh

Cn 20g thc tmu trung bnh, a vo my bc vthu c ht go lt. Dng knh

lp pht hin nhng ht rn nt trn ht go.

4. Tnh kt qu

% Ht rn nt c tnh theo cng thc

R =

(%)

Vi m: khi lng ht rn nt (g)

M: khi lng mu phn tch (g)

Kt quthc nghim: m= 0,4g

Tuy nhin trong qu trnh bc v, vn cn nhng ht thc cha c tch vhonton. Do vy khi lng mu sbng khi lng thc tri khi lng ht thc bc vcn st (M1= 1,688g).


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M = 20M1= 20 -1,688 = 18,312 g

Vy: R=

=

= 2,18 %

5. Kt qu

Mu thc ang kho st t hng 1 cht lng vchtiu ht rn nt.

VIII. Xc nh % cc loi ht

1. Nguyn tc

Chn cc loi ht: bc bng, ht bin vng, ht xanh non, ht h hng, ht , ht lnloi c trong mu phn tch. T tnh ra % cc loi ht.

2. Dng c

Cn phn tch Khay nha My bc v Cc 50ml

3. Tin hnh

Cn 20g mu thc tmu trung bnh, dng my xay tch vtru, dng tay nht tng

loi ht ri biu din theo %.

4. Tnh kt qu

Trong qu trnh bc v, vn cn nhng ht thc chac tch vhon ton. Do vykhi lng mu sbng khi lng thc tri khi lng ht thc bc vcn st(M1= 2,765g).

M = 20M1= 202,765 = 17,235 g

Kt quthc nghim, khi lng cc ht:

Ht xanh non: 0,45 g Ht : 0,116 g Ht bc bng: 0,602 g Ht h hng: 0,095 g


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Biu din theo thnh phn % cc loi ht, ta c:

% Ht xanh non

.100 = 2,61 %

% Ht

.100 = 0,67 %

% Ht bc bng

.100 = 3,49 %

% Ht h hng

.100 = 0,55 %

5. Bn lun

Mu thc ang kho st t hng 1 cht lng vchtiu ht khng hon thin

(2,61 % < 3 %).

Mu thc ang kho st t hng 1 cht lng vchtiu ht (0,67 % < 1 %).

Mu thc ang kho st t hng 1 cht lng vchtiu ht bc bng (3,49 % < 7 %).

Mu thc ang kho st t hng 2 cht lng vchtiu ht h hng

(0,5 % < 0,55 % < 1%).


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I. o m:

1/ Nguyn tc:

Dng my o m trong thc, o 3 ln sau ly gi trtrung bnh.

2/ Dng c:

My o m dng cm bin

3/ Cch tin hnh:

Nhn nt Power khi ng my.

Nhn nt Select chn loi ht cn o. y chn chRice 12.

Nhn nt Measure chun bo m ca ht. i mn hnh hin thch

pour ri bt u go vo my o, ch tc ht phi u trnh sai

s.

i mt vi giy mn hnh hin thkt qu, ghi nhn kt qu. Tip tc tin hnh

nh vy tbc go thm 2 ln na, sau bm nt Average tnh kt

qutrung bnh sau 3 ln o. Ghi nhn kt qutrung bnh.

Hnh 2.1.My o m


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4/ Kt quo c:

Ln 1: W1= 13%

Ln 2: W2= 13,1%Ln 3: W3= 13,3%

1 2 3W W W 13 13,1 13,3

W 13,1%3 3

Gi trm trung bnh l: 13,1%.

5/ Bn lun:

Kt qusau 3 ln o khng chnh lch nhau nhiu. Ngoi ra kt quthu c so vicc nhm khc cng khng chnh lch nhiu nn kt qung tin cy.

II. Xc nh chiu di ca go

1/ Nguyn tc:

Dng thc cp xc nh chiu di ca ht go. T tra bng tiu chun xp

loi c tnh ca go.

2/ Dng c:

- Cn phn tch

- Khay nha

- Thc cp

3/ Tin hnh:

Cn 20 g mu go, chn ngu nhin 50 ht thc nguyn vn. Dng thc cp o

chiu di 50 ht go ri tnh chiu di trung bnh ca mt ht go


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4/ Tnh kt qu:

Kt quo chiu di 50 ht go nh sau:

Bng 1:Kt quchiu di ca 50 htHt Chiu

di ht

(mm)

Ht Chiu

di ht

(mm)

Ht Chiu

di ht

(mm)

Ht Chiu

di ht

(mm)

Ht Chiu

di ht

(mm)

1 6,3 11 6,1 21 6,6 31 6,2 41 5,6

2 6,6 12 6,0 22 6,4 32 6,9 42 5,5

3 6,7 13 7,0 23 7,1 33 6,4 43 5,3

4 6,6 14 6,5 24 6,6 34 6,7 44 6,5

5 6,9 15 6,7 25 6,5 35 6,2 45 7,0

6 6,2 16 6,7 26 7,1 36 5,9 46 6,3

7 7,0 17 6,3 27 6,4 37 6,3 47 6,6

8 6,7 18 6,4 28 6,7 38 6,0 48 6,6

9 6,4 19 6,6 29 6,7 39 6,1 49 6,8

10 6,8 20 6,5 30 6,5 40 5,7 50 6,1

Ta c:6, 3 6, 6 6, 7 ... 6, 6 6, 8 6,1

6, 47( )50

l mm

5/ Bn lun:Go ca nhm o c c chiu di trung bnh nm trong khong t6mm n 7mm

nn c xp trong loi ht go di.


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III. Xc nh tltm:

1/ Nguyn tc:

Sdng my chn ht tch ring phn go nguyn vn v tm. tnh ra phn %tm so vi khi ht.

2/ Dng c:

- My chn ht.

3/ Tin hnh:

Ly 100g go vo my chn ht, cho my hot ng tch ring tm v go

nguyn. T tnh ra % ht tm so vi khi ht.

Hnh 2.2 My tch tm

4/ Tnh kt qu

Kt quthu c l: 27,95g tm.


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Suy ra:

Tltm trong 100g l 27,95%

Tlgo nguyn trong 100g l 72,05%5/ Bn lun:

T l tm so vi khi ht khng ln vo khong 27,95%. Kt lun l cht lng go

kh tt.

IV. Xc nh % cc loi ht:

1/ Nguyn tc:

Chn cc loi ht: bc bng, ht bin vng, ht xanh non, ht h hng, ht , ht lnloi c trong mu phn tch. T tnh ra % cc loi ht.

2/ Dng c:

- Cn phn tch

- Khay nhm

3/ Cch tin hnh:

Cn 20g go tmu trung bnh dn u trn mt khay hoc mt knh. Nht cc ht ni

trn thnh tng phn ring bit vo cc ng mu. Cn ring tng loi v t suy ra

kt qu% khi lng cho tng chtiu cn xc nh.

4/ Tnh kt qu:

Khi lng ht bc phn l 0,67g.

% ht bc phn =0,67.100

3,35%20

5/ Bn lun:phn trm(%) theo khi lng ca ht bc phn l 3,35%. Tlny

khng ln lm nn kt lun go t cht lng. Do go kim nghim c ty trng

ttrc nn cc loi ht bh hng, , xanh non, bin vng hu nh khng cn.


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V. Xc nh hm lng tinh bt:

1/ Nguyn tc:

Thy phn tinh bt bng HCl sau xc nh hm lng ng tng bng phngphp Bectrand.

Glucid khCu(OH)2mi trng kim mnh, to kt ta di dng Cu2O mu

gch. Slng Cu2O tng ng vi slng glucid.

RCHO + 2Cu(OH)2 RCOOH + Cu2O + 2H2O

Cu2O c tnh cht kh, tc dng vi Fe(III) lm cho mui ny chuyn sang dng

Fe(II) mi trng acid.Cu2O + Fe2(SO4)3+ H2SO4 2CuSO4+ H2O + 2FeSO4

FeSO4c tnh kh, tc dng vi KMnO4. Do , c thdng KMnO4chun

FeSO4mi trng acid.

FeSO4+ 8H2SO4+ 2 KMnO4 K2SO4+ 2MnSO4+ 5Fe2(SO4)3+ 8H2O

Tsml KMnO40,1N dng chun FeSO4hnh thnh, tra bng c smg

ng glucoza, maltoza, lactoza hoc saccaroza nhn vi hthng pha long ta chm lng ng trong 1g bt go.

2/ Dng c:

- Cn phn tch

- Bnh tam gic 250ml

- Bnh nh mc 250ml

- Cc thy tinh 250ml

- Phu lc

- Bp in

- Ni inox

- Burret

- Pipet 0,5ml


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- Bnh tia

- ChthPP 1%

- Dd HCl

- Dd NaOH 20%

- Dd Fe2(SO4)3

- Felling A, B

- KMnO40,1N

3/ Cch tin hnh:

1g Bt go Thy phn 4ml HCl +100ml nc Lm ngui Trung ha

nh mc Vm= 15ml + FA 20ml + FB 20ml un si (3 pht) Lng

Ha tan Chun = KMnO4 V tiu tn.

Hnh 2.3.un cch thy thy phn mu.


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Hnh 2.4. Cho dung dch NaOH 20% to MT kim.

Hnh 2.5. Cho dung dch vo bnh nh mc 250ml.

Hnh 2.6.un dung dch sau khi cho Fel A, B.


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Hnh 2.7. Xut hin kt ta gch.

Hnh 2.8. Lc qua giy lc tch kt ta.

4/ Tnh kt qu:Thtch tiu tn KMnO4 l 3,2 ml.

ng nghch o (mg) KMnO4 0,1N (ml)10 3,2411 3,55

Ta c : TB =.

.100.0,9.1000.

dm

m

a V

m V

Trong : a khi lng ng nghch o


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Vdm: thtch nh mc

m: khi lng mu

Vm: thtch mu.

0,9 l hschuyn i tglucose sang tinh bt

11 10

10 . 3,3 3, 24 10,193,55 3, 24

a mg

TB =. 10,91.250

.100.0, 9 .100.0, 9 16, 365%.1000. 1.1000.15

dm

m

a V

m V

5/ Bn lun:

Hm lng tinh bt trong go tng i ch so vi tiu chun. C thtrong qu

trnh tin hnh th nghim cha c chun xc. Ngoi ra sau qu trnh lc tch kt

ta th tht thot nhiu kt ta, kt ta cn bm trn bmt dng cth nghim vv


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I.

Xc nh m ca bt m- Sdng my o in t, o 3 ln, sau ly kt qutrung bnh.

- m t yu cu ca bt m phi nhhn 13.5%.

Kt qu:

Kt lun: m ca bt m l 13.07% < 13.5%=>bt m t tiu chun vm.

II. Xc nh chua ca bt m (hm lng axit)

- nh ngha:

chua ca bt m l sml NaOH 1N dung trung ha lng acid c trong 100gbt m.

1. Nguyn tc:

Trung ha lng acid c trong mu dung dch NaOH 0.1N vi chthPP 1%.

2. Dng cv ha cht:

Cn phn tch

Bnh 150 ml

ng ong 50 ml

Bnh xt tia

Sln Kt qu(%)

Ln 1 12.9

Ln 2 13.1

Ln 3 13.2

Trung bnh 13.07

Hnh 3.1. Xc nh m ca bt m


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Burete 10 ml

DD NaOH 0.1N

DD PP 1%

Nc ct.

3. Tin hnh:

Cn khong 5g bt cho vo 2 bnh tam

gic 150ml, thm vo 100ml nc ct

trung tnh, lc u tan ht bt. Dng

bnh tia ra nhng ht bt dnh trn thnhbnh.

Bnh 1: thm vo 2-3 git PP 1% v em

chun bng dd NaOH 0.02N cho n khi

xut hin mu hng, bn sau 30 giy th dng

li v ghi thtch tiu tn ca dung dch

NaOH 0.02N.

Bnh 2: lc trn phu thy tinh, thu ly dch

lc. Sau thm vo dch lc 2-3 git PP 1%

v em chun bng dd NaOH 0.02N chon khi xut hin mu hng, bn sau 30 giy

th dng li v ghi thtch tiu tn ca dung

dch NaOH 0.02N.

Hnh 3.2. Ha tan bt m

Hnh 3.3. Chun bng dd NaOH 0.02N


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4. Kt qu:

chua ca bt tnh bng (0) theo cng thc sau:

Trong :

V: sml dung dch NaOH 0.1N dng trung ha lng axit c trong 50 gam mu,(ml).

m: sgam mu cn phn tch, (g).

Bnh 1:

Bnh 2:

5. Bn lun:

Kt qucabnh 1 (bnh cha lc) c chua cao hn bnh 2 (bnh lc). iuny chng tbt m cha tan trong bnh 1 scn trim dng ca phng phpchun bng NaOH 0.02N (khi xut hin mu hng, bn trong 30 giy), do ktqusbsai lch.

Nhn chung, vic lc cn bt b cha tan (bnh 2) scho kt quchnh xc v ngtin cy hn.

III. Xc nh mn ca bt m

1.

Nguyn tc:sdng ry c l= 125 m.

Yu cu: phn lt ry 95% lt trng = 125 m.

2. Tin hnh:

Cn 100g btry tt(Lu :trong qu trnhry khng sdng tay ch p bt xung) cn

phn khng lt ry => biu din theo phn trm

khi lng. Hnh 3.4. Ry bt m


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Yu cu: phn khng lt ry < 5%.

3. Kt qu:

Khi lng phn bt khng lt ry: 0.75g ~ 0.75% => t yu cu.

IV. Xc nh hm lng v cht lng ca gluten1. Nguyn tc:

To khi bt nho tbt m, ra khi bt nho loi bht tinh bt, p kit nc.T xc nh hm lng v cht lng gluten.

2. Dng cv ha cht

Cn phn tch

Cc thy tinh 100ml

a thy tinh

Ry c k l= 125m

Thc k

Khn kh

Chu nha

Dung dch I2

3. Cch tin hnh

a. To khi bt nho

- Cn 25g bt m cho vo cc thy tinh 100ml

cha sn 15ml nc.

-

Dng a thy tinh trn u sao cho tt c

bt u thm nc v khi bt t m l

4045%.

- Ly bt ra, dng tay nho nn cho tht u,

vo thnh hnh trn v li trong cc vi

thi gian 20.

Ra khi bt nho

Hnh 3.5. Khi bt m sau khi nho nn


28/28



Cch 1: ra trc tip di vi nc

t khi bt vo lng bn tay tri, nm cc ngn tay li v a vo di vi nc,pha di t mt ry kim loi v dng tay phi iu chnh tc dng nc (1l

trong 5 pht). Dng tay phi nho nn khi bt nhnhng tinh bt btch ra theodng nc. Tip tc ra cho n khi gluten trthnh mt khi n hi th tng tcnc ra cho n khi gluten sch ht tinh bt.

Cch 2: ra trong chu nc

t khi bt trong lng bn tay tri vo chunc c sn 2-3l nc. t mt ry kim loi

pha di tay nm khi bt. Dng tay phi nho

nn khi bt nhnhng tch tinh bt ra khigluten. Khi nc c th thay nc mi v tinhnh cho n khi ht tinh bt.

b.

p nc:

Sau khi ra khi bt nho xong, dng tay vt kitnc trong khi gluten, lau tay kh v p htnc ra khi khi gluten.

c. Nhn xt mu sc khi gluten:

Bt tt c gluten t mu trng ng nht

Bt xu c gluten t mu sm

Bt hng c gluten t mu ti hn

Kt qu:

Lng gluten thu c: 6.85g.

Gluten t c mu sm chng tbt xu.

Hnh 3.6. Khi gluten thu c

bài 1 phương pháp kiểm nghiệm thóc

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