Combinations of potassium sorbate and polyphosphate, in conjunction with vacuum or modified atmosphere packaging, were assessed for their preservative effects on morwong fillets (pH 6.75) stored at 4°C. Vacuum packaged and/or frozen fillets were used as comparisons for microbiological and taste panel analysis. A combination of potassium sorbate, polyphosphate and 100% CO2 was the most effective packaging regime. Potassium sorbate on vacuum packaged fish was more effective than a 100% CO2 atmosphere alone. Polyphosphate had no apparent additional effect on fillets stored under vacuum with or without potassium sorbate.

A BS T R A C TFree-choice odour and flavour profiling of fish spoiling under diflerent regimes leads to a wide range of descriptors which are difjicult to collate and quantify. An attempt was made to gain an insight into the spoilage process by applying a variety of analytical techniques to the profile data including cluster analysis, principal coordinates analysis and especially generalised Procrustes analysis. However, it was concluded that manipulation of 9 e echoice profiles does not provide any additional information about the spoilage of fish that cannot be obtained from analytical taste panels, simple chemical tests and a cursory examination of the profiles themselves.

A computer program is available which allows the experimentor to examine the radial distribution of specific gravity within individual potato tubers by processing data obtained by peeling tubers concentrically and weighing in air and water between consecutive peelings. The program enables one to calculate optimum estimates of eight parameters of a mathematical model which describes the mean change in specific gravity from the geometric center of a tuber to its periderm. Significant differences in intratuber specific gravity distributions between cultivars and between treatments within the same cultivar have been found. Mathematical modelling may be a method of describing the distribution of other tuber constituents of interest.

Summary Evidence is presented to support the observation that within potato tubers, the mean solids concentration gradient in the perimedullary zone within the xylem ‘ring’ is linearly related to its mean spatial distance from the xylem ‘ring’. Within any tuber the point most remote from the xylem ‘ring’, irrespective of tuber shape, is its geometric centre. If, for any tuber, this point is taken as the zero mean radius, then data obtained by a concentric peeling technique (vide Appendix I) may be used to construct a mathematical model of the mean solids concentration from the geometric centre to the periderm. A sampling technique is proposed whereby the mathematical parameters describing the tuber may be used to transform quantitative data from discrete tissue samples to values representative of whole tubers.