The term stickiness, as used in the butter industry, refers to that property of butter which permits it to remain attached to solid surfaces. It is a phenomenon in which the components of force caused by adhesion and cohesion are inseparably involved and have been described by the term ‘hesion’. Hesion measurements of commercial samples of conventionally-made butter were much higher than those of continuously-made butter. The results of experiments on conventional and laboratory continuously-made butter from the same butterfat source indicated that the characteristic crystal structure influenced the hesion values. Homogenization of Gold'n Flow and conventional commercial butters markedly increased hesion readings. When nitrogen gas was added to pre-crystallized continuously-made butter the hesion values decreased with increasing gas content. However, there was an increase in the amount of butter which remained on the adherend when it became detached from the butter surface. Limited experiments on the effect of gas content in conventional butter also indicated that an increase in gas content resulted in a decrease in hesion values with more butter remaining on the adherend. The results of this investigation indicated that the crystal structure was responsible for the adhesive property of butter and the gas content influenced the cohesive property. It would appear, then, that both the crystal structure and the gas content play an important part in causing stickiness of butter.

Proteinase systems of 3 strains of Staphylococcus lactis from Cheddar cheese have been studied. Proteinase of one organism was found in the culture supernatant, those of the other two were obtained in significant amounts only by disruption of the cells of the organisms. All 3 proteinases possessed maximum activity at alkaline pH (about 9·0–10·0). They were most active at relatively high temperatures (45–55 °C) and possessed temperature characteristics (μ) of 7000–8000 cals. Casein, ²-lactoglobulin and haemoglobin were hydrolysed by the proteinases; casein most readily and β-lactoglobulin more readily than haemoglobin. Because of their characteristics, such proteinases are considered potentially capable of contributing to the ripening of Cheddar cheese.

A relatively simple method is described for the manufacture of Cheddar cheese under controlled bacteriological conditions. This method is shown to give the required degree of asepsis and to permit the manufacture of cheeses of uniform and normal composition.

The composition, bacteriology and flavour of 28 ‘aseptic’ cheeses and of 18 ‘nonaseptic’ control cheeses made by this method are discussed. Thirty-nine of these cheeses were made using singly 3 strains of Streptococcus cremoris and 2 strains of Str. lactis as starter and 7 were made using gluconic acid lactone in place of starter. The effect of inoculating the milk with a strain (25·2) of ‘Lactobacillus plantarumcasei’ and a strain (L1) of micrococcus was also investigated.

A portable apparatus is described for indicating continuously as a measure of pulsation ratio the proportion of the cycle during which a liner is more than half open. With the machine set for milking, a probe with an electric switch which opens as the liner collapses is inserted in one liner, the others being closed with rubber bungs. The pulses of current from the switch are fed to a damping circuit so that the proportion of the cycle time during which current flows can be read on a meter. The problem of interpreting the various measures of pulsation ratio are discussed.

It is proposed that —N—P—N— bonds exist in casein and that these bonds can be hydrolysed probably at different rates by the action of rennin. It is proposed that the phosphorus is linked with the guanido group of arginine.

The vapour/liquid equilibrium coefficients for the steam distillation of indole and skatole from water solution over the range of concentrations 0·1 to 20–30 ppm. were found to be 2·4 and 4·7, respectively. The coefficient for indole in a cream containing 30% fat was found to be 0·31, and for skatole, in a cream containing 40% fat, 0·14. It is concluded that complete removal of indole and skatole contaminations from cream by use of steam distillation equipment is not commercially practicable.

Casein derived from cow's colostrum contains 0·85% N-acetyl neuraminic acid and liberates 2·95% nitrogen soluble in 12% trichloroacetic acid (NPN) under the action of rennin. It therefore appears to contain a large proportion of κ-casein (calculated to be approximately 35%).

The smaller the micelles of casein in colostrum the larger is the amount of N-acetyl neuraminic acid they contain. Soluble casein, i.e. 25% of the casein in colostrum, contains 1·52% of this acid and gives 6·24% NPN under the action of rennin.

Casein and particularly the soluble casein of colostrum appear to be important sources of κ-casein and caseino-glycopeptide.

The homogenization of milk and cream with a piston-type homogenizer has been studied. An examination has been made of the influences upon the mean fat globule diameters of changes in milk fat content, flow rate and homogenization temperature. The results are discussed in terms of the variations in the parameters q and P0 of the empirical equation d = (P0/P)q relating the globule diameter d to applied pressure P.