June 15,1914 
209 
Ripening of Cheddar Cheese 
Table XIX .—Analysis of curd, showing lactic acid as zinc lactate 
Fraction 
No. 
Curd at hoop¬ 
ing time. 
Curd kept 46 hours in 
pressing room. 
Curd kept 46 
hours at 35® C. 
Curd kept 17 
days with chlo¬ 
roform. 
Curd kept 3 
months with 
chloroform. 
Zinc 
lactate. 
Water 
of crys¬ 
talliza¬ 
tion. 
Zinc 
lactate. 
Water 
of crys¬ 
talliza¬ 
tion. 
Zinc 
oxid in 
lactate. 
Zinc 
lactate. 
Water 
of crys¬ 
talliza¬ 
tion. 
Zinc 
lactate. 
Water 
of crys¬ 
talliza¬ 
tion. 
Zinc 
lactate. 
Water 
of crys¬ 
talliza¬ 
tion. 
1. 
Grams. 
0.1902 
.0000 
P.ct. 
12.92 
Grams. 
0. 5601 
• 5854 
*2314 
.0000 
P.ct. 
15-97 
14-14 
13. 48 
P.ct. 
33 - 8 
33*9 
Grams. 
0.6515 
. 6040 
.3901 
. 0000 
P.ct. 
18.00 
18.11 
17. 86 
Grams. 
0.2637 
.0000 
P.ct. 
12.96 
Grams. 
0.1490 
.2183 
. 2119 
1.0895 
.7685 
.2074 
. 1546 
P.ct. 
17.92 
14 * 13 
12. 79 
12. 78 
9 ... 
3. 
4. 
5. 
6. 
13 * 21 
13-06 
7. 
In order to verify the results secured on the increase of racemic acid 
and the decrease of active acid in fresh cheese curd, as shown above, 
another sample of fresh curd was divided into three portions. One 
portion was examined immediately for lactic acid, another after 24 
hours, and the third portion after keeping at 6o° for 48 hours. See 
Table XX. 
Table XX .—Analysis of curd and fresh cheese , showing lactic acid as zinc lactate 
Fraction 
No. 
Fresh curd. 
One-day-old cheese. 
Two-day-old cheese. 
Zinc 
lactate. 
Water of 
crystalli¬ 
zation. 
Zinc 
oxide. 
Zinc 
lactate. 
Water of 
crystalli¬ 
zation. 
Zinc 
oxid. 
Zinc 
lactate. 
Water of 
crystalli¬ 
zation. 
Zinc 
oxid. 
Grams. 
Per cent. 
Per cent. 
Grams. 
Per cent. 
Per cent. 
Grams. 
Per cent. 
Per cent. 
1. 
0. 2 704 
12. 52 
33-6 
0.1786 
17.19 
32. 7 
0.1670 
17- 25 
33 -o 
2. 
. 0617 
11.80 
33-4 
• 0975 
12. 20 
33-3 
*0457 
17.07 
33- a 
3 . 
. 0000 
.0778 
12.90 
33-9 
.1946 
12.90 
33-8 
4 . 
. 1514 
12.30 
33- 8 
.2472 
13 - 50 
33-9 
5 . 
• 2133 
12.00 
33-6 
• 0551 
12.00 
34 -o 
Total. 
•3321 
. 7186 
. 7096 
The theoretical percentage for water of crystallization in racemic zinc lactate is 18.18; in active zinc 
lactate it is 12.89 per cent. The theoretical percentage of ZnO in anhydrous zinc lactate is 33.3. 
From Table XX it is clear that in fresh curd, which contains active 
lactic acid, the production of racemic acid begins after about 24 hours at 
room temperature and that this production is accelerated by a tem¬ 
perature of 35 0 C. In the curd kept with chloroform for 17 days the 
production of racemic acid appeared to have been checked, while curds 
kept with chloroform for 3 months gave a small amount of the racemic 
variety. A parallel case was found by Saiki (1909) in the autolysis of a 
normal dog's liver, even in a strictly sterile solution. In his experiments 
racemic lactic acid gradually formed. This enzymic action may be 
considered a partial cause of the appearance of the racemic acid. The 
question whether enzymic action decomposes the lactose of the curd 
