Quality-maintained Study Of Frozen Sweet Potato Pieces And Kiwifruit Slices During Storage

Frozen prepared food was one of the five kinds of frozen food, the quality of frozen preparedfood especially frozen fruit and vegetable could decline during the processing and storage due tokinds of reasons. The object of the paper was to discuss the quality-maintained methods of twomaterials—sweet potato and kiwifruit occurred in freezing and cold storage.The browning caused by polyphenoloxidase (PPO) and nutrition loss would occur during theprocessing and storage of frozen sweet potato. The attempts to prevent in the paper includedusing chemical inhibitors and Maillard Reaction Products (MRPs) inhibitors. The range of pHstability of PPO in sweet potato was determined by studing pH stability of PPO;the stability ofPPO in sweet potato at different temperature were determined by studing heat stability of PPO;the best inhibitor was determined by studing the effect of different inhibitors on the PPO andfrozen sweet potato;the best reation condition of MRPs were determined by studing the effect ofdifferent MRPs on the PPO and frozen sweet potato.Color loss, chlorophyll degradation and nutrition loss would occur during the processing andstorage of frozen kiwifruit slices. The attempt to prevent in the paper was to use sugar treatment.The best ZnCl2 concentration was determined by studing the effect of ZnCl2 on frozen kiwifruitslices;the effect of vacuum osmotic dehydration was better than that of ZnCl2 treatment bycomparing the two treatments;the best sugar and best concentration were determined bycomparing the effect of different sugars and different concentrations on the frozen kiwifruitslices;the effect of sugar concentration on the glass transition temperature of frozen kiwifruitslices was studied, and the relation betweet the glass transition temperature and water activity,water content were analysed.Water loss during the processing and storage and juice loss during thawing of frozen sweetpotato pieces and kiwifruit slices were occurred too. In the paper, partial glass storage was usedto avoid them. The qualities of frozen sweet potato pieces and frozen kiwifruit slices storedunder their glass transition temperature were better than that of samples stored above the glasstransition temperature. The effects of different factors (freezing rate, storage temperate andpre-treatment) on the indices of frozen sweet potato pieces and frozen kiwifruit slices wereanalyzed in detail by range analyse of thogonal experiment.