Abstract:

The aim of this study was to achieve optimal simultaneous color protection and hardening in the production of lowsugar preserved apples by using a solution of compound reagents to soak fresh-cut apples. The individual color protection and hardening effects of different reagents on fresh-cut apples were investigated in single factor experiments. Based on this investigation, the optimal amounts of citric acid, VC, CaCl2 and NaCl and soaking time were examined using orthogonal array design for minimizing the degree of browning (DB) of apples. Results showed that a minimum DB was obtained when 0.30% citric acid or 0.06% VC was used for soaking fresh-cut apples. The hardening treatment with a mixed solution of 1.5% CaCl2 and 1.0% NaCl gave appropriate hardness, regular appearance and good mouth feeling to preserved apples. The optimal treatment time for a minimum DB ranged from 2.0 to 3.0 h. SPSS analysis demonstrated that VC had an extremely significant color protection effect, CaCl2 had a significant effect, while no significant effects of citric acid, NaCl and treatment time were observed. The optimum conditions for simultaneous color protection and hardening were determined as follows: citric acid 0.30%, VC 0.08%, CaCl2 1.5%, NaCl 1.2%, and soaking time 3.0 h. Under such conditions, DB reached minimum, and an appropriate hardness of preserved apples was obtained.

Key words: low-sugar preserved fruit, color protection and hardening, browning