The effect of heat treatment of milk on low molecular weight, volatile compounds was studied in order to relate changes in the flavour of milks to changes in chemical composition. Milks were heat treated in a UHT plant for 3 or 90 s at 140 °C and stored at ambient temperature for periods up to 112 d. Volatile compounds in raw milk and in heated milks were isolated by a low temperature spray distillation technique and identified using gas chromatography and mass spectrometry. Cabbagey defects in heated milks are correlated with total volatile sulphur and it is concluded that the compounds H 2 S, COS, CH 3 SH, CS 2 and (CH 3 ) 2 S could be responsible for this defect.Many methods have been developed for isolating and collecting flavour volatiles from foods. Methods involving direct headspace analysis (Manning, Chapman & Hosking, 1976) are inapplicable to milk because milk is very bland compared with other foods due to a lower concentration of flavour producing compounds. Methods involving the heating of milk were also avoided since the effect of heat on milk was the subject of this study.A method was required for extracting the volatiles, that would minimize the pickup of water, give a true representation of the composition, of the headspace over milk, and yet avoid the production or introduction of spurious substances.The purpose of this work was to develop a method of isolating and identifying the volatiles of milk at various stages of processing, including the original raw milk, and to observe chemical changes which occur during processing and storage. Efforts were made to relate these chemical changes to changes in the flavour quality of the product, using a taste panel to follow the flavour changes organoleptically. EXPERIMENTAL Procedure for preparation of milkMilk was taken from the NIRD herd, bulked and stored at 4 °C for 24 h before processing. The milk was sterilized by an indirect ultra-high temperature (UHT) laboratory scale plant and aseptically filled in a single head machine. A schematic diagram of the UHT plant is shown in Fig. 1. Raw milk in the tank (1) was removed by the centrifugal pump (2) and pre-heated to 80 °C in the section of the plate heat exchanger, R, by steam at approximately atmospheric pressure. From there, it passed to the single-stage homogenizer (3) operated at 17250 kPa and then to the

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The effect of gamma-radiation, in the range 5-30 KGy on free, total and pure gossypol was investigated in an attempt to reduce or eliminate gossypol from cottonseed meal using different solvent systems. Maximum reduction in gossypol concentration was attained at a dose of 25 KGy of gamma-radiation with chloroform as a solvent, a spectrometric method was used for analysis. The reductions attained for pure, free and total gossypol were found to be 96%, 60% and 80%, respectively.

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