QUALITY OF APPLE SLICES PROCESSED BY COMBINED TECHNIQUES

The effectiveness of single pretreatments and combinations of pretreat ments on the prevention of enzymatic browning during freezing and thaw ing of apple slices was investigated. The combinations of blanching an d dipping, either of which alone could not control enzyme activity, we re studied. Blanching of apple slices caused a significant decrease of firmness even before the freezing-thawing phase. The use of a ''light '' dip after a short blanch allowed the product to be cooled and helpe d the antioxidant agents (ascorbic and citric acids) to enter apple ti ssue. The anti-browning action of sodium chloride, even at very low le vels in dipping solutions, was confirmed. Partial drying avoided the l oss of firmness but negatively affected the color. ''Mild pretreatment s'', including partial drying, gave satisfactory results in terms of f irmness and color.