20 BULLETIN 661, U. S. DEPARTMENT OF AGRICULTURE. 
Table 2. — The effect of washing curd on the strength of the casein. 
Buttermilk. 
Butter- 
milk fat 
Times 
curd 
Acidity 
of drain 
Drying 
temper- 
Casein 
required. 
Ash. 
Fat. 
H 2 0. 
Lot No. 
Portion 
No. 
Acidity. 
content. 
washed. 
water. 
ature. 
Per cent. 
Per cent. 
Per cent. 
°F. 
Grams. 
Per cent. 
Per cent. 
Per cent. 
56.9 
9A 
0.82 
0.20 

0.60 
125 
12 
1.65 
23.32 
5.84 
56.9 
9B 
.82 
.20 
4 
.04 
125 
10 
0.26 
22.55 
5.33 
56.10 
10A 
.72 
.16 
2 
.19 
125 
9 
1.18 
5.86 
7.14 
56.10 
10B 
.72 
.16 
4 
.05 
125 
9 
0.88 
6.04 
7.65 
56.20 
20A 
.81 
.01 

.54 
125 
9 
2.18 
4.29 
5.91 
56.20 
20B 
.81 
.01 
4 
.14 
125 
9 
1.26 
4.07 
5.68 
56.31 
56.31 
56.35 
31A 
31B 
35A 
.81 
. .81 
.65 
.12 
.12 
.19 

4 

.58 
.05 
.44 
125 
125 
125 
9 
8 
9 
2.38 
4.18 
5.90 
56.35 
35B 
.65 
.19 
5 
.07 
125 
9 
0.86 
4.66 
6.14 
56.50 
56.50 
56.52 
56.52 
56.52 
56.52 
56.54 
56.54 
56.56 
56.56 
50A 
SOB 
52A 
52B 
52C 
52B 
54AC 
54BD 
56A 
56B 
.67 
.67 
.74 
.76 
.97 
.96 
.63 
.63 
.93 
.93 
.06 
.06 
.32 
.32 
.32 
.32 
.07 
.07 
.14 
.14 

2 

4 

4 
4 


4 
.42 
.14 
.42 
.04 
.57 
.02 
•04 
.37 
.56 
.02 
125 
125 
125 
125 
125 
125 
125 
125 
125 
125 
8 
8 
9 
8 + 
10 
9 
9 
9 + 
10 
8 + 

:::::::"! 
Table 2 gives data on the effect of washing the curd upon the 
strength of the casein. The increased strength consistently shown 
in the washed curd from high-acid buttermilk emphasizes the im- 
portance of washing the curd from that kind of material. Xo notice- 
able increase in strength could be found, however, in the washed curd 
of low-acid buttermilk. Any difference in strength appears more 
marked in the samples made from buttermilk of higher acidity or 
fat content, substantiating the assumption that it was caused by a 
combination of factors which by themselves may not have any direct 
effect. The samples from the unwashed curd, taken as a whole, 
required more time to effect a complete solution, which may have 
been caused by the free acid remaining in the whey rather than by 
any injury to the quality of the casein. A portion of the alkali is 
used up in neutralizing the free acid found in the unwashed-curd 
casein, thus leaving a weaker solution for dissolving the sample. 
The reaction accounts for the decreased quantity of alkali found 
necessary to dissolve the casein from a well-washed curd. 
DRYING TEMPERATURE OF THE CURD. 
A high drying temperature in combination with one of the other 
factors has an injurious effect upon the quality of the casein which 
is most pronounced with a high-fat or unwashed curd. A well- 
washed curd from buttermilk of a low-fat content can be dried at a 
relatively high temperature with no. apparent injury to the quality, 
but it is not to be recommended. The lower the temperature the less 
probability of injuring the quality, and for that reason the lowest 
temperature possible should be used. A temperature of 130° F. 
