Bài 1 Phương Pháp Kiểm Nghiệm Thóc
Transcript of Bài 1 Phương Pháp Kiểm Nghiệm Thóc
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
1/28
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
2/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 2
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.
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
3/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 3
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 %
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
4/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 4
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
5/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 5
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 %
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
6/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 6
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
7/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 7
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 %
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
8/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 8
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).
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
9/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 9
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).
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
10/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 10
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).
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
11/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 11
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).
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
12/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 12
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
13/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 13
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%).
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
14/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 14
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
15/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 15
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
16/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 16
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.
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
17/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 17
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.
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
18/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 18
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.
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
19/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 19
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
20/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 20
- 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.
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
21/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 21
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.
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
22/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 22
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
23/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 23
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
24/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 24
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
25/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 25
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
26/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 26
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
27/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
NHM 3 | GING VIN: VNH LONG 27
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
-
8/11/2019 Bi 1 Phng Php Kim Nghim Thc
28/28
BO CO PHN TCH THC PHM
CHUYN : LNG THC THC PHM
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