Effects of heat treatment on production cycle and quality of pidan

The aim of this research was to shorten production cycle and keep quality of pidan. The effect of different heat treatments on quality of pidan which were pickled by a zinc-copper salt was investigated. The L9(34) orthogonal tests were conducted in this study and three factors of heat treatment as follows: heat time (15, 20, 25 d), heat duration (14, 22, 30 h) and heat temperature (35, 42, 49℃) were investigated . The moisture content, hardening rate, free alkalinity and color of pidan were used for the evaluating indicator.The results showed that heat treatments make pidan have lower moisture content, faster solidification, more hardening rate, lower free alkalinity, great color, and improved taste and favor. Analysis of variance from combination score of hardening rate and free alkalinity of pidan obtained by fuzzy weighted transformation, showed that the degree of the influence factors decrease in the following order: heat time, heat temperature, heat duration, and the optimal processing condition was that samples were treated at the temperature of 42℃ for 22 h after being preserved for 20 days. This method can shorten production cycle of pidan to 21 days, which is 40%-50% less than the traditional method.