Effect of Enzymatic Peeling under Cold Conditions on Fruit Quality and Functional Component Contents of Citrus, and the Effect of the Temperature for Boiling Sterilization and the Concentration of Sugar Syrup on the Avoidance of Flesh Disintegration by Enzymatic Peeling during the Bottling Process

Abstract

Enzymatic peeling is an effective method of producing processed foods that preserves the original flavor and taste of fruit. However, there is limited information available about the effects of enzymatic peeling on the hardness of flesh and functional components of processed citrus food. Accordingly, we evaluated the flesh hardness and content of reduced ascorbic acid and β-cryptoxanthin under low-temperature conditions in some citrus species. We also estimated the effects of persisting enzymatic activity in flesh syrup after enzymatic peeling on flesh crumbling in satsuma mandarin. Our results show that hand peeling versus enzymatic peeling led to no differences in flesh hardness. There were also no differences in the reduction of ascorbic acid and β-cryptoxanthin in fresh fruit between enzymatic peeling, acid and alkali peeling, and the control (without enzymatic/acid and alkali peeling). Thus, the flesh hardness and content of functional components with enzymatic peeling under low-temperature conditions are comparable to those of acid and alkali peeling and the control. Furthermore, temperatures for boiling sterilization and concentrations of sugar syrup were significantly correlated with the avoidance of flesh crumbling during the bottling process. Consequently, to suppress flesh crumbling, more intense boiling for sterilization and a higher sugar syrup concentration may be required.