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Mangoes, papayas, and litchis processed by canning, freezing, and 7 irradiation were analyzed for their ascorbic acid, carotene, and sugar content. Both experimentally and commercially canned fruits were used as well as samples frozen for up to 3 months and irradiated with doses at least 1.25 kGy higher than those recommended for commercial irradiation. Chemical changes due to irradiation were generally small, amounting to losses of between 0 and 15%. In comparison, changes due to freezing and heat processing were considerable; losses in the order of 50 to 70% were recorded.

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A new method is presented for measuring the rates of permeation of organic vapours through flexible packing films with the specific intent of studying flavour deterioration from packaged foodstuffs. The method is convenient, relatively rapid, quantitative and the results are presented as first order rate constants for the permeation of individual chemicals through a film. This allows ready calculation of such potentially useful data as the temperature effects on permeation rates, the half-life of retention of a vapour by a film barrier or the energy necessary for permeation through a particular film. As an example of the method, data for the permeation of eight organic compounds through 50 pm polyethylene film over the temperature range -25°C to +35"C are given as well as the half-lives of retention of these compounds and the permeation energies required. The permeability constants may also be readily calculated from the rate data.