ACHNOWLEDGEMENT
Our thanks are due to Mr Zal R. Kothavalla for his keen interest in the work and helpful
suggestions.
REFERENCES
Groh (1937). Proceedings of the 11th World Dairy Congress, Berlin 2, 127-9
Haglund et al (1930). Bull. 387, Centralaustalten
Kilde and Winther (1930). Milchwir and Schaft Forach, Bd. 10 Heft. 3, 288
Mpolomovsky and Thomas (1933). Lait 13, 249, 499-583
Moghul, H.K. et al (1945). Unpublished
Plymen and Iy 1921). Memoirs of the Dept. of Agriculture, India, 6, 4 and 5
Singh, I.P. et
945). Unpublished
NATURE OF CALCIUM IN BUFFALO MILK
By I. P. SINGH VERMA and C. P. ANANTHAKRISHNAN, Imperial Dairy Research Institute, Ban-
galore
(Received for publication on 24 December 1945)
O NE of the main reasons for the heat coagulation of evaporated milk during sterilization is the
salt balance. Rogers et al [1921] have explained that thickening in condensed milk as due to
high calcium and magnesium contents. These workers have also shown that the use of citrates and
phosphates has a stabilizing effect by counteracting the effect of high calcium and magnesium
contents.
The difficulty in overcoming thickening has been found to e more pronounced in the manufac-
ture of evaporated buffalo milk than in the case of evaporated cow milk. It is likely that this is cor-
related with the state of the calcium present. Calcium in milk is found in both soluble and colloidal
forms and also in organic and inorganic combinations and their proportions exercise considerable
effect on heat coagulation of evaporated milk. Apart from the data reported by Acharya and
Devadatta [1939] no further attention has been paid to this aspect of the problem.
For the present studies ten Murrah buffaloes at about the same stage of lactation were selected.
Individual samples from each animal were collected once a week and analysed. Also one composite
sample was prepared and analysed once a week by mixing equal quantities of milk from each animal.
Similarly a composite sample from ten cows was prepared and analysed. Whey was prepared from
all these samples by the use of rennet and the amount of calcium was calculated by subtracting
the whey calcium from the total calcium of the milk. With whey a correction was made to bring
the results from whey percentage to milk percentage by using the correction factor as 9.48. In
all 120 samples of milk were analysed including 100 individual samples from ten animals and 20
composite samples from cows and buffaloes.
The total calcium was estimated by precipitating with calcium oxalate and then titrating with
potassium permanganate in sulphuric acid solution. Whey calcium was estimated by coagulating
100 ml. of milk at 30°C. with 0.7 ml. of liquid rennet. The curd was cut with stainless steel knife
and the whey allowed to drain off. The whey was filtered through Whatman No. 40 filter paper.
To 25 ml. of this whey were added 100 ml. of 10 per cent trichloroacetic acid solution with constant
stirring. 100 ml. of the filtrate were neutralized with ammonia and acidified with dilute acetic
acid. Ammonium chloride was added and the calcium precipitated from the hot solution with solid
ammonium oxalate and estimated by titrating with permanganate as for total calcium.
For converting whey percentage figures to milk percentage figures the value was multiplied
by the factor 100 [fat percentage + (protein percentage— 0.4)], as explained by Ling [1936].
The detailed results of calcium in milk of buffaloes and cows are given in Table I.
177