The rate and exient of apple volatile produciion were several times greaier in peels than in fresh or whole apples. Volatile produciion in apples after peeling increased rapidly ai 22"c, reached a maximum in 1-2 days and then gradually declined. Harvest maturity, variety, cold storage history, room temperature ripening and storage temperature of peels greatly affected the rate and extent of volatile produciion; the op timum peel temperature appeared to be 20-30'~. The greatest increases in volatile components from peels were due to ihe production of esters, primarily eihyl buiyrate, buiyl aceiaie, eihyl 2 methylbuiyrate and 2-meihylbiriyl acetate. Controlled aimosphere storage appeared to arrest the ability of peels to produce the usual components. Under certain condiiions, the components associated wiih apple aroma increased 10-to 30-fold in peels held at room temperaiure for 1-2 days.

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Calcium alginate films were prepared by the pH-controlled release of calcium ions into alginate solution or by the cooling of hot calcium alginate gels. Thermogravimetry and calorimetry showed that the controlled Ca release films contained a greater amount of high-temperature component, and required extra energy to dissociate the tightly crosslinked calcium alginate. Structural differences were reflected by the permeability of the two films to potassium sorbate: 1.06 ϫ 10 Ϫ7 (controlled Ca release) and 1.58 ϫ 10 Ϫ7 cm 2 ⅐sec Ϫ1 (cooled). Apparent activation energy was estimated to be for the diffusion of potassium sorbate 24.1 KJ⅐mol Ϫ1 , sodium ascorbate 23.7, and ascorbic acid 36.2. Results suggested that the pH of the diffusant solution had an interactive effect on the alginate film.

No abstract