MASS-TRANSFER AND TEXTURAL CHANGES DURING PROCESSING OF APPLES BY COMBINED METHODS

Mass transfer and textural changes of 'Red Delicious' apple slices and cylinders during osmotic adjustment of a(w) by the combined method ap proach were studied at 30, 40 and 50-degrees-C. Mass transfer of water and sugar in the treated apple followed typical log-normal behavior w ith most changes occurring during early stages of the process. The cha nges followed Crank's equation for diffusion. A negative correlation b etween apple texture and sugar diffusion was observed. Softening, as w ell as mass transfer changes, occurred at early stages of osmotic trea tment. The texture changes were most pronounced at the edges of the ap ple tissue where the sugar had penetrated. Softening and sugar uptake were more pronounced when apples were acidified. Apples became firm wi thin 2 hr of the process, when the external layer of the apple cylinde rs penetrated by sugar was trimmed. Calcium chloride beyond 0.30% mini mized tissue softening, but the typical crispy structure of the fresh apple was not restored.