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Effect of rehydration temperature on functional properties, antioxidant capacity and structural characteristics of apple (Granny Smith) slices in relation to mass transfer kinetics

Abstract:

Apple slices dried at 60C were rehydrated at 20, 40 and 60C to analyze the influence of processing temperature on quality attributes and rehydration kinetics. Diffusion coefficient increased with process temperature from 1.36 to 2.37 × 10-9 m2/s. The Weibull model obtained the best fit quality for the experimental data based on statistical test, chi square. Color was not recovered during rehydration and the results indicated that the use of low temperatures is more adequate. Water-holding capacity decreased, while rehydration ratio increased with increasing rehydration temperature, indicating structural modifications. Increasing rehydration temperatures led to a reduction in the glass transition temperature and hardness values of samples. The radical-scavenging activity showed higher antioxidant activity at higher rehydration temperatures rather than at lower temperatures. It was found that rehydration temperature modifies the cell structure and antioxidant capacity of final product. © 2013 Wiley Periodicals, Inc.