Effects Of DPCD On The Quality Of The Pickled Carrot

DPCD(dense phase carbon dioxide)is a kind of new-type non-thermal sterilization technology which can ensure the food safety andreducethe microbial effectively.The pickled carrot is a kind of traditional fermented food of China.To prolong its shelf life and maintain its brittleness and color,this paper has studied the sterilization of the pickled carrot using DPCD.Firstly,the DPCD treatment conditions were optimized,and to research the mechanism of the pectin structure of DPCD-treated pickled carrot on the texture.Then DPCD was compared with the thermal treatment during storage to detect the quality changes of the pickled carrot.This aims to provide a theoretical basis for the application of DPCD in the sterilization of pickled vegetables.Major achievements of the study are given below:The DPCD treatment could significantly realize the sterilization of the pickled carrot.The sterilization effect enhanced along with the increase of the treatment strength.Based on the results of experiments,4 optimized groups of treatment conditions with good sterilization effects have been obtained:20MPa 20min;25MPa 20min;20MPa 30min;25MPa 30min.It was determined that the 20MPa 30min treatment can promote the sterilization,texture,cell integrity and nutrient retention,to obtain the best DPCD conditions for maintaining the quality of the pickled carrot.The hardness of fruits and vegetables are in close relation with the pectin.DPCD could improve the PME enzyme activity and decreased the esterification of the pickled carrot.The pectin was degraded and dissoved after pasteurization treatment,while DPCD treaatment remained well.After DPCD treatment,the high molecular weight substance of the pectin molecule was preserved.After pasteurization lowmolecularweight moleculewastransformed.The FT-IR scan suggested that the pectin group composition was changed insignificantly after DPCD treatment.The test results of both total plate count and lactic acid bacteriademonstrated that the sterilization effect of the DPCD was better than the pasteurization.DPCD can maintain the stability of the microorganism within 40 days to obtain a good preservability of the pickled carrot.The hardness of the pickled carrot during the storage was in a declining tendency.The control group and the pasteurized group losed their test value on the 24th day,while DCPD could maintain a good hardness within 40 days.DPCD can maintain the color,texture and smell of the pickled carrot during the storage.DPCD can preserve both the pectin content and the P-carrotin content in a way much better than the pasteurization.Through comprehensive analysis,it was determined that DPCD treatment can promote the sterilization,texture,cell integrity and nutrient retention in a way much better than the pasteurization,during the storage.