Study On Control Technology Of Fresh-cut Purple Sweet Potato Browning

Fresh-cut products have the advantages of convenient,cleanliness and safety,increasingly valued by the market and consumers.Purple sweet potato has been widely recognized by people for its nutrient composition and efficacy.Therefore,the development of fresh-cut purple sweet potato products has certain practical significance.However,the purple sweet potato is subjected to a series of adverse reactions such as browning caused by cutting,which restricts the market of fresh-cut purple sweet potato.In this paper,fresh purple sweet potato was used as raw material to determine the browning mechanism of fresh-cut purple sweet potato through the determination of the weight loss rate,hardness,color difference,browning degree,enzyme activity,total phenol and nutrients(soluble protein,anthocyanin),and to establish a set of economical,safe and effective browning control technology.The main findings are as follows:(1)After the fresh-cut purple sweet potato was cut,the activity of polyphenol oxidase(PPO)and peroxidase(POD)was determined by colorimetry.PPO showed a rising trend after segmentation,and POD activity increased rapidly and then decreased.The total phenolic content was determined by the Folin phenol method,and the total phenolic content increased first and then decreased.Correlation analysis showed that the browning of fresh-cut purple sweet potato was mainly caused by PPO and POD catalyzed phenolic substances.The determination of phenolic substances in fresh-cut purple sweet potato by HPLC method mainly includes chlorogenic acid,caffeic acid and ferulic acid,and the content of chlorogenic acid is the main.4℃ can effectively inhibit the activity of PPO and POD in fresh-cut purple sweet potato,thereby inhibiting browning.(2)Vacuum packaging can effectively reduce the weight loss rate of fresh-cut purple sweet potato,only 0.450%when stored on the 12th day.There were also maintain the original hardness and color of purple sweet potato,the color difference growth rate only 22.02%on the 12th day,inhibit the increase of browning degree and the activity of PPO and POD,and retain the nutrition of purple sweet potato.(3)The optimal treatment time of heat treatment was determined to be 5 min,and the optimum treatment temperature was 60℃.Heat treatment can maintain the quality and hardness of purple sweet potato,inhibit the activity of PPO and POD,but it was not conducive to the preservation of soluble protein and anthocyanin content.(4)The optimum treatment time of the color protection agent was determined to be 15 min,L-cysteine(L-cys)The optimum treatment concentration is 0.2%;the best optimal treatment concentration of citric acid(CA)is 0.3%,and the optimal treatment concentration of ascorbic acid(AA)is 0.35%.By orthogonal test,the best color-protecting agent ratio of fresh-cut purple sweet potato is 0.25%citric acid+0.05%L-cysteine+0.35%anti-septic acid,which can inhibit the browning degree up to 75%.The color treatment can maintain the original color of fresh-cut purple sweet potato,and delay the decline of nutrient content;it can also inhibit the content of malondialdehyde(MDA)and the activity of PPO and POD to some extent,delaying fresh The degree of browning of cut purple sweet potato has a good preservation effect.