Polyacrylamide gel disc electrophoresis has been used to detect milk solids in a wide range of foodstuffs. The method will detect less than 1% milk solids, and may be applied to products which have not been subjected to excessive heat treatment. Detection is still possible after heating at 100-110°C for 60 minutes, but sensitivity is greatly reduced.

It was considered necessary to evaluate resuscitation procedures to existing dairying detection methods and their effect on coliforms and E. coli recovery. Results conclude that method of manufacture and type of product play an important role in the significance of stressed bacteria. Resuscitation procedures for spray dried skim milk powder produced higher recoveries than existing methods. This was not found for casein.

An electronic pulsator unit is described based on an "electron coupled" multi-vibrator circuit. The time-constants of which can be altered instantaneously by means of remote-controlled relays. The system has proved to be reliable over the period of one year of experimental operation.

The caking of skim milk and non-hygroscopic whey powders was studied and related to the moisture sorption and powder characteristics. Amorphous lactose had an effect on the moisture sorption and caking properties of the spray-dried skim milk (non-instantised) and non-hygroscopic whey powders (containing <5% amorphous lactose). The skim milk powder absorbed more moisture and formed harder cakes more rapidly than the non-hygroscopic whey powder. The thermal profiles of the dairy powders were described by TGA/SDTA (thermal gravimetric analysis integrated with single differential thermal analysis) and used to monitor the water content of the powders (i.e. free water, water of crystallisation, bound water by compounds such as protein and total water). This study suggests that storage at or below 33% relative humidity at 25°C was sufficient to prevent severe caking and the development of a 'sandy' texture in these dairy powders, but not the crystallisation of amorphous lactose and browning of the powder.

This paper highlights the problem of obtaining accurate quantitative phosphatise test results for a number of milk products when using APTW 7 Lovibond phosphatise discs in the Aschaffenburg and Mullen phosphatise test. It introduces an extraction / spectrophotometric step to the test so that it can be applied successfully to the analysis of coloured milk products. The method can also be used for other milk products such as cream and skim milks for which the original method does not give a linear relationship between phosphatase activity and measured colour.

An improved version of a curd-fusing machine was tested as a mock-up model. The model comprises of four stages: screening and drying, compression and flow, guillotining, holding. It can successfully cheddar curd made by either the short or the traditional method of manufacture. Cheese of very good quality with all the characteristics of Cheddar cheese was made with the mock-up model. The design of the first commercial model will be based on this experimental machine.

A mechanical milking system is described which employs a large diameter milk pipe beneath the cows. The line is of such volume that it replaces the releaser tank, and a milk pump is used to withdraw the milk from the pipe. Peak flow is absorbed by the pipe capacity. Air admission is eliminated from the claws and what air passes into the system is removed at the distal end of the milk pipe. The machine eliminates lipolysis caused by air admission and dropper agitation, produces a highly stable vacuum and is readily cleaned using a third line circulation system.

This original article discusses an improved test for the detection of leaks in the seals of the wraps of rindless cheese.

A short article describing an improved test for the detection of marker dyes in milk.

An improved laboratory method for determining the rate and extent of whey expulsion (syneresis) from stirred rennet curd involves measuring the progressive dilution of Blue Dextran 2000 in the whey. Rennet is added to 354 mL of milk at the required temperature and pH. When the coagulum reaches a predetermined firmness it is cut into cubes and Blue Dextran 2000 is added. The curd is stirred and samples of whey are taken at intervals. The whey samples are clarified and the absorbance is measured at 620 nm. The total whey volume for each sample time is calculated. Blue Dextran 2000 was found to be a suitable tracer as its adsorption to the curd is slight, it can be added to the curd in a relatively small volume and it is commercially available. The average coefficient of variation of the calculated whey volumes was 1.4% for five replicates. The method appears to be more precise than other laboratory methods for measuring syneresis and gives a reasonable estimate of the volume of whey drained from the curd on the completion of sampling.

An investigation was made into the cause of shattering of curd during cottage cheese manufacature. Cottage cheese was made from Jersey, Friesian, Australian Illawarra Shorthorn (A.I.S.) and bulk factory milk. Shattering was estimated by measurement of the 'fines' lost in whey and wash water and of 'grit', particles of 1 - <5 mm diameter, present in the cottage cheese curd. Of several milk components analysed, citrate, total protein and casein showed the highest (negative) correlations with fines formation. Of the casein component, the proportion of α _S1-casein was significantly positively correlated and that of β-casein significantly negatively correlated with both fines and grit formation. No other significant correlations between levels of milk components and grit formation were observed. Addition of sodium citrate, alone or in combination with sodium caseinate, reduced the formation of fines and grit during laboratory manufacture of cottage cheese. A possible mechanism by which added citrate and casein can reduce shattering in cottage cheese is presented.

An objective method for determination of heat stability of non-fat and full-cream milk powders for use in the manufacture of recombined or reconstituted evaporated milk is described. Factors influencing variations in results between laboratory assessment of the functional characteristics of powders and commercial applications are outlined.

A quick and simple objective technique has been devised for measuring the curd tensions in laboratory scale batches of cheese coagulum. The technique involves only standard laboratory equipment, and can be used to measure the tensions in up to forty tests per hour. Good agreement has been found between and tension measurements and subjective assessments of curd firmness.

Several observations have been made on the inhibition of starter streptococci in pasteurized and raw milk b a factor (other than bacteriophage) destroyed on boiling or autoclaving the milk (1, 2, 3, 4,). Cultures commonly used in cheese manufacture in Australia vary in their susceptibility to this inhibitory effect. Jago (4) using milk from the same source s in the experiments reported below found that strain C7 was amongst those not affected by the inhibitory milk. He also reported that in cheesemaking the inhibition is most pronounced at the cheddaring stage. Both Czulak and Meanwell (3) and Jago (4) found that the inhibitory effect was at a maximum during the winter months. We have over the last season observed with culture C7 (a strain of Streptococcus cremoris) an inhibition of acid production during the cheesemaking process which differs in several of these respects from the inhibitory effects previously reported.

Discussion on the inhibitory effect of cheese milk on starter growth at some seasons of the year has been widely observed in Australia as well as in England and other countries. The "C" series of starters was selected in England for their resistance to this inhibitory effect and they have shown similar resistance (NOTE: this paper is incomplete in the original document).