Study On Natural Preservation Technology Of Fresh-cut Yam

With the improvement of people’s living standards,and the pace of life is speeding up.Fresh-cut vegetables are becoming more and more popular,because the characteristics of fresh nutrition,clean and sanitary,convenient and quick.In order to solve the problems of browning,decay and softening in the processing of fresh-cut yam.The test uses yam as raw material,The preservation effects of onion oil compound preservatives,packaging materials and garlic extract on fresh-cut yam were studied,and the changes of microorganism and the ultrastructure of cell were observed.The main conclusions are as follows:1.The formula of compound preservative for fresh-cut yam was 0.6% onion oil +1.0% citric acid + 1.0% chitosan optimized by single factor and orthogonal experiments.This formula could significantly inhibit the activities of polyphenol oxidase(PPO)and peroxidase(POD),reduce relative conductivity and the accumulation of MDA content,delay weight loss and softening,keep whiteness and total phenols content,maintain the contents of total soluble solid and reducing sugar,and has better sensory quality.This formula extended the shelf life of fresh-cut yam about 4 d compared with the control group.2.With tray covering film as control(CK),0.04 mm LDPE、0.04 mm HDPE and0.04 mm PP packaging materials could inhibit the activities of polyphenol oxidase(PPO)and peroxidase(POD)of fresh-cut yam,delay weight loss and browning,maintian texture qualities of hardness,springing and chewiness,significantly reduce relative conductivity and the accumulation of MDA content,delay senescence of fresh-cut yam.LDPE packaging material was more suitable for preservation of freh-cut yam,which could extend shelf life 6~7 d of fresh-cut yam compared with the control group.3.Compared with water treatment(CK),0.1% 、 0.3% and 0.5% allicin extract could significantly reduce weight loss rate and decay rate,maintain hardness and nutrient contents,reduce respiratory intensity,inhibit browning and the activities ofpolyphenol oxidase(PPO)and peroxidase(POD).Besides,the sensory was better,especially 0.3% allicin extract,which could prolong freshness date 9 d at least,and also had edible value storage for 15 d.4.The three methods screened by pre-experiments could significantly inhibit the growth of aerobic plate count,and coliforms were not detected during storage of fresh-cut yam.The three methods could delay cell aging and maintain cell integrity to some extent.Especially 0.3% allicin extract treatment,which had rich starch grain and not appeared obvious incipient plasmolysis and black particles after storage 12 d.