Natural variation in heat stability of concentrated milk before and after homogenization

An examination has been made of the seasonal variations in the heat stability of skimmed milk, concentrated (22.5 per cent total solids) skimmed milk, and concentrated (31 per cent total solids) whole milk. Marked seasonal differences were found to exist in the effects of homogenization on the heat stability of subsequently concentrated milk. 'Summer' milks were found to be much more stable than 'winter' milks after homogenization and to be more readily stabilized by added sodium phosphates and citrate. Milk serum rather than milk fat was shown to be the major determinant in the heat stability of concentrated homogenized milk, and all such milks were found to be very sensitive to small changes in their level of soluble calcium.     

Removal of pesticides from red and white wine by the use of fining and filter agents

Effects of the use of the fining and filtration agents, diatomaceous earth, bentonite, polyvinylpoly-pyrrolidone and activated carbon, on the removal of seven fungicides (carbendazim, chlorothalonil, fenarimol, metalaxyl, oxadixyl, procymidone and triadimenol) and three insecticides (carbaryl, chlorpyrifos and dicofol) from wines were investigated. Carbendazim was determined by high performance liquid chromatography (HPLC) after quantitative conversion into 2-aminobenzimidazole (2AB). The concentrations of all the other compounds in wine were quantified using a multi residue assay involving solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). After treatment and processing, conducted under conditions simulating those that are typical in Australian commercial winemaking, the greatest reduction in concentration in all treatments was for chlorothalonil, chlorpyrifos and dicofol. There was a significant relationship between the extent of removal of each pesticide and its solubility in wine, such that the lower the solubility, the greater the extent of removal. Activated carbon had the largest effect on the removal of most pesticides, while bentonite had a major effect on the removal of carbendazim. For all compounds and agents, the rate of removal was greater in white wine than in red wine.     

Manipulation of the heat stability of homogenized concentrated milk

An examination has been made of the means of improving the heat stability of homogenized concentrated milk. It was found that heat stability could be enhanced to the greatest extent by high temperature forewarming (145° C, 5 s), two-stage homogenization, and addition of sodium phosphates. It was shown that in the winter months homogenization per se greatly reduces the heat stability of subsequently concentrated milk. Consequently, in the production of sterilized milk products, it is essential to stabilize such milks before rather than after this destabilizing step.