Freezing protocol effect on quality properties of fruit tissue according to the fruit, the variety and the stage of maturity

Among the changes induced by freezing of fruits, it is still difficult to determine the major properties which are the most representative of quality variation. A range of characteristics (texture, color, soluble solids, water activity, water content, pH, titrable acidity) were determined before and after three different freezing protocols (at -20 degrees C in a cold chamber, at -80 degrees C in gas nitrogen convection chamber and after immersion in liquid nitrogen at -196 degrees C) for two fruit types (apple-Malus domestica Borkh- and mango - Mangifera indica L. cv. 'KENT-), two varieties of apples (Golden Delicious and Granny Smith) and two maturities of one variety (ripe and unripe Granny Smith). Freezing induced significant changes mostly in texture, color and soluble solids. Property variations due to freezing depended mainly on the type of fruit, to a lesser extent on the variety of apples studied and slightly on the maturity of Granny Smith apples. Among the freezing conditions tested, gas nitrogen convection at -80 degrees C appeared to be the best choice for limiting fruit quality degradation. (C) 2010 Elsevier Ltd. All rights reserved.