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Cấu trúc
chapter 1: freshness/ raw milk quality
1. Purpose :
2. Procedure :
3. Results :
4. Dicussion:
B. Acidity
1 Purpose :
2 Apparatus and reagents
3 Procedure:
4 pH measurement result
5. Titration sample:
Volume of NaOH 0,1N necessary to neutralize 10 mL of milk sample:
Milk sample 1: VNaOH = 1.65 ml
We have: CM = n/ VNaOH
n = CM . VNaOH
= 0,1 x1.65x 10-3 = 1.65 x 10-4 (mol)
And we have VNaOH (2) = = 1.485x10-3 (l)
= 1.485 (ml)
So, Do = = 14.85
Sample
Volume of NaOH (ml)
Dornic degree
Sample
Standard sample
Sample
Standard sample
1
1.65
1.6
14.85
14.4
2
1.8
16.2
3
1.65
14.85
4
1.65
14.85
5
1.55
13.95
6. Dicussion :.
Dornic degree of fresh milk squeezed about 16 – 18o, after a lactation period of lactic acid bacteria in milk will increase and increase acid lactic degree in milk, so Dornic degree of milk increased. When preserving or transporting, especially in climate weather of our country, Dornic degreeoff milk will gradually increase, maybe to 20-250.
Different sample of milk will have different degrees of Dornic. The degree of Dornic is higher, fresh of milk is less, quality of milk isn’t good.
C. Alcohol test
1 Purpose:
1 Procedure :
a. Apparatus :
b. Reagents :
c. Procedure:
Single test:
Double test:
2 Results:
3. Dicussion:
D. Clot-on-boiling test:
1 Purpose :
2 Procedure:
a. Apparatus:
b. Procedure:
7. Results:
Sample
Results
1
Coagulation
2
No coagulation
3
Coagulation
4
Coagulation
5
No coagulation
8. Dicussion
E. The methylen blue reduction test
1 Purpose:
Good measure of its bacterial content and hence of its hygienic quality. This time period is governed primirily
9. Procedure :
10. Apparatus and reagents
Control tubes
Include two control tubes with each batch consisting of:
11. Results:
12. Dicussion :
The length of time milk takes to decolourise methylene blue is a good measure of its bacterial content and hence of its hygienicn quality. This time period is governed primarily by the activity of the reducing bacteria present in the milk plus the oxygen content. When the oxygen has been utilised the methylene blue is reduced, changing in colour from blue to white.
CHAPTER 2: PROCESSING TREATMENTS/ TESTS FOR HEAT TREATED MILK
A. Spray drying of milk
1. Purpose :
2. Principles of operation :
3. Dicussion :
B. Coagulation of casein:
B1. Making fresh cheese
1 Purpose:
2 Procedure:
3 Results:
4 Sensory evaluation:
B2 Salting out of milk proteins:
1 Purpose :
2 Procedure :
Put 30 ml of milk into a test tube
Put the test tube into boiling waterbath for 10 min
Add 20% CaCl2 solution slowly to the treated milk and observed the precipitation
3 Results :
Mẫu
M1
M2
M3
M4
M5
ĐC
Kết tủa
VCaCl = 0,27ml
Kết tủa
VCaCl = 0,2 ml
Kết tủa
VCaCl = 0,8 ml
Kết tủa
VCaCl = 0,3 ml
Kết tủa
VCaCl = 0,5 ml
PT
Kết tủa
Kết tủa
Kết tủa
Kết tủa
Kết tủa
4 Dicussion:
- The coagulation of proteins caused by salting out of proteins is due to the addition of ion Ca2+. At that time, the interaction between this ion and protein in milk are form and this is the cause of protein coagulation.
- Addition of CaCl2 increases the activity of calcium ad resulting in the decrement of pH. Ion Ca2+ are released and penetrate the micelle casein to create strong internal calcium bonds. pH of solution will approach the isoelectric points of the individual casein → initiate with a change in micelles, starting growth of micelles through aggregation and end with a coagulum.