It has been shown that the acidity developed in a vat of milk at the “running” stage has a very important influence on the quality of the resultant cheese. A high acidity causes increased mineral losses in the whey and a corresponding lowering of the mineral content of the cheese, while it also has a detrimental effect on the body of the cheese. The acidity at “running” also controls to a great extent the acidity of the cheese produced. Even where the acidities at the late stages of the process are kept the same, vats of cheese made at a high “running” acidity show more acid characteristics than cheese made at low “running” acidity.The quantity of lactose incorporated in the cheese is also of importance in determining the acidity of the cheese. An increase in the lactose content, either by raising the lactose concentration of the cheese milk or by the addition of lactose to the curd, produces a more acid type of cheese at maturity, although some unfermented lactose is still present in the cheese at 4 months after manufacture.

Results of a survey of the carotene and vitamin A contents, and of the vitamin A potency, of New Zealand butterfat and butter, are presented. The butter samples were drawn from twenty representative commercial factories at fortnightly intervals over three successive years (1946–8). The survey covers the analysis of 1517 samples of fresh butter and 670 samples of stored butter.There were uniform and regularly recurring seasonal variations in both carotene and vitamin A contents of butterfats from all North Island districts. Maximum values were found in the late-autumn/winter/early-spring, and minimum values in the late-summer/early-autumn butterfats. The seasonal trends were thus distinctly different from those which have been reported for northern hemisphere butterfats, for which the maximum values are commonly found during the summer grazing period.The seasonal variations in carotene and vitamin A contents of South Island butterfat were less marked and less consistent than those in the corresponding values for North Island butterfat.

SummaryA single injection of 100 i.u. ACTH given to milking cows had no statistically significant effect on the yield or composition of the milk. A long-acting preparation of ACTH, when given to cows in single doses of 200 and 400 i.u., depressed milk yield and raised the butterfat content of the milk. There was no significant change in the SNF content of the milk but the SNF content of the milk serum was increased. Three injections of 300 i.u. of long-acting ACTH given at 24-h intervals reduced yields of milk, fat and SNF and increased the fat and SNF contents of the milk.Small but generally consistent changes occurred in the butterfat characteristics of the milk of all groups treated with ACTH. There was a decrease in the iodine number and refractive index and a rise in the softening point of the fat in all the experiments. The Reichert value of the butterfat was lowered by single or multiple injections of the long-acting preparation. The carotene content of the butterfat was lowered by injections of the long-acting ACTH preparation but the vitamin A content was unaffected.

With 6 Figures)The variations in the chemical and physical properties of butterfat have already been extensively studied. In many European countries, e.g. Holland, Denmark, Ireland, where examination is made of random samples of butterfats from butters from every factory at intervals throughout the year as part of the regular ' Butter Control Service' to ensure the absence of adulteration with other fats, the information available on the variations in the properties is very complete. Detailed studies of the butterfats from some New Zealand butters have been made by English workers (i, 2, 3), but information has not hitherto been published on variations throughout the year. The present paper presents the results of analyses of butterfats from butters collected monthly from nine commercial factories selected as representative of the main butter-producing districts, which are located throughout the two main islands, from lat. 35° S. to lat. 46° S. The factories chosen were as follows

The white specks appearing in mature Cheddar cheese have been shown by analysis to be calcium lactate.