The effects of pineapple juice multistage evaporation on the freezing rate of frozen pineapple brownie cake

Pineapple has been used in a wide range of food industries. However, there are still many losses because of the short shelf life of fresh pineapple. The over ripe pineapple juice was evaporated using multistage falling film evaporator to increase their value. Frozen brownie cake is introduced as an innovative frozen food. The application of pineapple concentrate in frozen pineapple brownie cake was evaluated during freezing process. The changes of brownie surface and core temperature were recorded for 8 h. Representation of freezing rate was shown by Plank model. During freezing process, the center temperature of pineapple brownie cake was gradually changed. Formulation with double stage evaporated pineapple concentrate had the highest temperature decrease or fastest freezing with the linearized gradient of 3.9794 °C.h-1 and freezing rate of 166.67 °C.m-1.h-1. The freezing time of 7 h had the lowest center temperature. The surface temperature of pineapple brownie cake was also reduced with the lowest value at 5 h of freezing. This formulation of pineapple brownie cake could decrease the fat content from 18.42%(w/w) to 0.13%(w/w).