Freezing Point Of Milk Research Articles

309. The freezing-point of milk: III. A survey of producers' milk as delivered to creameries in England and Wales

The results of freezing-point tests on some 4000 samples of milk as delivered by individual producers to creameries in England and Wales are analysed. Prior to the war about six out of every 100 samples were found to contain added water, but, as cases of heavy adulteration were comparatively rare, the total effect on the bulked milk supplies was small. After 2½ years of war the position had remained virtually unchanged.

308. The freezing-point of milk: II. The influence of various factors and their bearing on the detection of added water

The results of a series of determinations of the freezing-point depressions of the milk of the individual cows of a Shorthorn herd over a period of 16 months are reported.The relative constancy of the freezing-point was confirmed, all but two values deviating by less than 4·5% from the mean Δ values.Significant seasonal trends were observed, especially during the spring when the supply of ample amounts of young grass may cause the production of milk with somewhat smaller freezing-point depressions.Systematic trends in the differences between the Δ of morning and evening milk were found, the evening values being generally higher, except for the winter period, during which the cows were housed at night, when the morning Δ values became the higher. The differences appear to depend on the changes in the temperature of environment to which the cows are exposed. These observations provide an explanation for the discrepancies reported in the literature.

Mastitis and the freezing-point of milk

Mastitis and the freezing-point of milk

The determination of the original freezing-point of milk preserved with formalin: determination of formaldehyde in milk

The determination of the original freezing-point of milk preserved with formalin: determination of formaldehyde in milk

287. The freezing-point of milk. I. The freezing-point and solids-not-fat content of the milk of individual cows throughout a period of lactation

The results of regular determinations of the freezing-point and solids-not-fat content of the milk of three Shorthorn cows over a period of more than six months are reported.The known constancy of the freezing-point depression was confirmed, the Δ values deviating generally by less than 2% and, in the most extreme case, by no more than 3·5% from the mean of 0·546 ± 0·002° C. No evidence was found of any influence of the state of lactation on the freezing-point depression, but a slight but definite decrease persisting for some weeks occurred at the time of year at which ample supplies of spring pasture became available to the animals.

A new apparatus for the rapid and economical determination of the freezing-point of milk

A new apparatus for the rapid and economical determination of the freezing-point of milk

A modified Hortvet apparatus and the true freezing-point of milk

A modified Hortvet apparatus and the true freezing-point of milk

A study of heat exchange in the cryoscopes of Hortvet and Monier-Williams for the determination of the freezing-point of milk

A study of heat exchange in the cryoscopes of Hortvet and Monier-Williams for the determination of the freezing-point of milk

Notes on the use of the Hortvet apparatus in determining the freezing-point of milk

The first page of this article is displayed as the abstract.

Seasonal Variations in the Freezing Point of Milk

Summary 1.There is a distinct seasonal variation in the freezing point depression of milk; the greater depression being in the spring months, the lower portion during the winter months. 2.Change in meteorological conditions offer an explanation of the wide variations of the freezing points encountered from day to day. 3.The seasonal variation of the freezing point depression is due to a change in the osmotic equilibrium maintained in the body of the animal. While meteorological changes may be a factor, the change in chemical content of the animal's food during the season is the controlling factor in the seasonal variation of the freezing point.

Societies and Academies

LONDON. Society of Public Analysts, Mar. 6.—Christine Mary Fear: On the alkaloid test for tannin. It has frequently been asserted that most alkaloids are precipitated by tannin, but the author's experiments show that the only alkaloids giving appreciable precipitates with tannin solutions alone are brucine, caffeine, cinchonine, cinchonidine, quinine, and strychnine.—A. L. Andrews: The cryoscopic method for the detection of added water in milk. The determination of the freezing-point affords a simple and trustworthy means of detecting added water in milk. Genuine milk has a freezing-point not higher than -0–550° C., when determined by the method in use in the New Zealand Dominion Laboratory. If the freezing-point rises to -0–530° C., watering may be suspected, and if to -0–520° C., the milk has certainly been adulterated with 5 per cent of added water.—A. J. Parker and L. S. Spackman: Investigations on the relations between the acidity and freezing-point of milk. The normal acidity of fresh milk is 0-14 per cent. The correction factor is 0-003° C. for each 0-01 per cent excess acidity between acidities of 0-17 and 0-60 per cent, and 0-010° C. for acidities ranging from 0-14 to 0-17 per cent lactic acid. When the cryoscopic method. is used for the determination of added water in milk, it can be applied with accuracy only when the samples are quite fresh.