As it was proposed to set up a routine testing procedure to estimate the incidence of penicillin in milk received by a milk factory a preliminary survey was carried out to compare these two factory tests. Initially a series of laboratory trials using high grade penicillin were added, was first made to check the relative sensitivity of these two tests. Certain modifications were made to the Heinemann (1960) test, and these are described in this report.

A rapid test for the determination of penicillin in milk based on a method previously reported is described in detail. The test is sensitive to concentrations of penicillin of about .03 units/ml or greater. Because of its simplicity the test lends itself readily for use in dairy factories and milk plants as a tool in the elimination of penicillin from milk supplies.

During the interesterification process the free sterols present in a fat are esterified. A simple thin-layer chromatrographic procedure is presented whereby the presence or absence of free sterols and sterol esters may be detected in their respective zones.

The microstructure of mozzarella cheeses was studied using a simplified method of specimen preparation for imaging. Mozzarella cheeses were prepared each with and without exopolysaccharide-producing Streptococcus thermophilus and Lactobacillus delbruckeii ssp. bulgaricus. Samples were obtained from the cheeses to study their microstructure. Specimens were cut from the cheese samples, fixed in 2% glutaraldehyde, dehydrated and impregnated using 1.5% osmium tetroxide. The specimens were dried in a critical point drying apparatus, fractured at room temperature (~20°C), sputter coated with gold, and images of the cheese specimens taken using a scanning electron microscope. The images showed clear internal structures of the specimens. The compact protein structure of cheeses interspersed with small and large voids representing locations of the fat and serum phases, respectively, was seen. The exopolysaccharide produced by the streptococci appeared to be delicate and filamentous. The lactobacilli seemed to produce the exopolysaccharide in meagre amounts. The micro-organisms were found in serum channels.

In much of the work of the Dairy Research Section on the better utilization of skim milk solids, especially in the development of special milk powders for the pastry-cooking trade, it has been necessary to have a supply of concentrated skim milk made under know and carefully controlled conditions, To this end a small stainless steel circulating concentrator suitable for laboratory use was designed and constructed. It has proved a most effective piece of equipment.

Apparatus is described for the measurement of the corrosiveness of detergent solutions or alternatively the resistance of materials to the corroding action of a standard detergent. Test pieces are submitted to a two-minute cycle involving the flow through a vertical column of detergent at 60°C for one minute followed by a rapid draining of the detergent back through the test column, and a 44-second exposure to air while still moist. The test simulates field conditions, is highly standardised, and has provided valuable in the testing of both detergent solutions and the resistance of materials to corrosion.

A modified domestic microwave oven was used for rapid determination of the moisture contents of 19 cheese and cheese products, from moisture levels in the range 16-78%. For 16 of the samples, the results did not differ significantly from those obtained by a reference method. Minimum heating conditions varied with the type of cheese. Cheddar, for example, required microwave heating for 6 min in an oven previously heated to 45°C. A final 2 min period of restive heating was used for all products. Results using the new method exhibited greater variation than those from the reference method. The method is suitable for simultaneous assay of multiple samples.

A sample of butterfat was transesterified to butyl esters by three different procedures (a) acid catalyzed butanolysis (b) di-n-butyl carbonate induced transesterification (c) a boron trifluoride-butanol transesterification . The three methods gave excellent agreement for recoveries of short and medium chain length fatty acids, and were in this respect superior to methyl esters prepared by (a) boron trifluoride-methanol transesterification, or (b) sealed tube methanolysis. The latter method gave the highest recoveries for methyl esters.

A method for the preparation of butyl esters by a boron trifluoride-butanol transesterification is discussed.

Pasteurizing and concentrating cream in an evaporator was shown to prepare cream which consistently churned to low butter moistures. The experiment compared evaporated cream with vacreated cream and showed that, even if the level of solids-not-fat (SNF) of evaporated cream were reduced to normal, the evaporated cream maintained the low butter moistures. Part of the reduction was due to higher SNF, but most was considered to be due to differences in properties of evaporated and vacreated creams. The following differences in properties were observed – evaporated creams showed higher free-fat content, a greater proportion of fat present as large globules with smaller proportions present as small globules and lower viscosity. It was concluded that these characteristics are important in the control of butter moisture in continuous buttermakers.

Flow properties of thickened creams have been examined. The creams exhibited non-Newtonian flow behaviour and shear degradation. A second order kinetic model is proposed to describe this behaviour. An empirical procedure for the use of a simple rotational viscometer for quality control purpose is proposed.

A research paper detailing a study of three instruments for milk composition payment testing.

A study on some of the functional properties of three types of calcium co-precipitate, important in the manufacture of comminuted meat products, was carried out in a model system. It was found that the three types, High Calcium co-precipitate No. 2 (High Cal 2), High Calcium co-precipitate No. 6 (High Cal 6) and Low Calcium co-precipitate (Low Cal) improved the emulsifying and water binding capacity of the meat at the 20 per cent replacement level. It was also found that the performance of the three types of co-precipitates studies was equal to that of the conventional non-meat proteins e.g. isolated soya protein and sodium caseinate, used in sausage manufacture.

A telephone survey was conducted in Melbourne and Brisbane to obtain a profile of milk consumption in Australia and determine consumers' attitudes regarding UHT milk. It was anticipated that this survey would reveal the reasons for the low level of UHT milk consumption in Australia. Pasteurised milk was the main milk type used by more than 80% of respondents. For UHT milk this figure was much lower (approximately 10%), even though two thirds of respondents had tried UHT milk. Factors that were found to influence UHT milk consumption included existing milk consumption habits, consumer perception, flavour and price. The majority of non-users of UHT milk stated " habit of using other milk type" as their main reason for not using UHT milk. Other reasons included " poor nutritional value", " poor flavour" and " not real/pure milk" , indicating a negative consumer perception of the product. The flavour of UHT milk was identified as a problem, with nearly half of UHT milk users considering it to be worse than the flavour of pasteurised milk. However, a small proportion of UHT milk users preferred the flavour of UHT milk, with the majority of them stating that it was creamier, richer and/or stronger than the flavour of pasteurised milk. Prior to post-farmgate deregulation, price was shown to discourage consumers from using UHT milk. At the time of the survey, post-farmgate prices in Victoria were deregulated resulting in UHT milk being priced below that of pasteurised milk in some instances. This was believed to contribute to a significantly higher market share of the product in Melbourne than in Brisbane.

The copper content of butters made in the seven factories in Western Australia was determined two or three times a month for a year. Of a total of 230 samples, 20% had a copper content below 0.08 ppm. There was a seasonal variation in the copper content, the maximum levels corresponding to minimum production (February-April). The mean copper level from all factories ranged from 0.27 ppm in March to 0.10 ppm in October. It was shown that exposed copper surfaces on fittings in wooden churns as well as in pumps, cocks and pipelines played a significant part in increasing the level of copper in butter during manufacture.

The general bacteriological quality of goat milk produced in Queensland was assessed. Quality was based on advisory standards used for cow milk (i.e. 50,000 cfu/mL for farm raw and pasteurized milks and 150,000 cfu/mL for factory raw milk). Using these standards, 19.86 (22%) farm raw milks, 31/33 (94%) factory raw milks and 4/23 (17%) pasteurized milks failed. Large increases in some populations with refrigerated storage suggested significant initial contamination of those milks with psychrotrophs. High levels of coliforms in some samples suggested that very poor hygiene was exercised during production of those milks. The general bacteriological quality was concluded to be poor.