Numerical and experimental study on the quick freezing process of the bayberry

Abstract

As bayberry has no peel with active respiration, it is almost impossible to store fresh bayberry in high quality for more than one day. The difficulty of freshness preservation is the biggest problem constraining the bayberry industry. Quick freezing offers a fast freezing rate to decrease the size of the ice crystals, which is an effective way to maintain the quality of bayberry. The freezing point of the bayberry flesh was firstly measured as −0.1°C by the electrical resistance method. Numerical simulation was utilized to analyze the heat transfer process of bayberry freezing. The results shows that bayberries won’t be quickly frozen in a domestic freezer (−18°C), but can be quickly frozen in a cryogenic freezer. The experiments of the bayberry frozen under different processes (−18, −60, −90 and −120°C) were conducted. After freezing and storage under −18°C for 6months, the quality of bayberries were studied for the first time, including the thawing loss, pH value, texture, color, macro and micro features. It can be concluded that a faster freezing rate led to a better quality after storage and thawing. The best freezing rate for maintaing the freshness of postharvest bayberry was 8.51cm/h at −120°C.