Developing radio frequency blanching process of apple slice

摘要

Compared with traditional hot water (HW) blanching, radio frequency (RF) has the advantages of faster heating rate and higher penetration depth. The aim of this study was to explore the optimum conditions of RF blanching of apple slice and compare the quality of apple subjected to RF and HW. Results showed that the optimum heating rate and uniformity can be obtained when electrode gap was of 120 mm, sample geometry of 50 x 8 x 50 mm, and not superimposed of apple slices, which were used for further RF blanching. It required 111 s and 270 s to reach the target temperature (85 degrees C) in RF and HW blanching respectively. After treated by RF and HW for 120 s, the residual enzyme activities of PPO of apples were 0% and 61.42 +/- 1.48% (P < 0.05), the hardness were 402.83 +/- 11.93 g and 469.39 +/- 10.24 g (P < 0.05), the weight loss were 10.23 +/- 1.01% and 14.39 +/- 2.58% (P > 0.05), respectively. There was no significant difference (P > 0.05) in color change.