Study On The Characteristics Of PPO And Enzymatic Browning Control For Chinese Jujube

Abstract: The Chinese jujube(zizypus jujube Mill), a special fruit growning in China. The plantation area of Chinese jujube has increased more than 0.46 million ha, with an annual output of 0.8 million t, accounting for 95% of the total world output. As we know ,Jujube Mill has a high nutrition value, especially Jujube date contains polysaccharide,cyclic,which make Jujube date has all kinds of biological function.But the browning occurred in jujube storage and processing, which would effect on its merchandise appearance and edible quality. Browning of jujube includes non-enzymatic browning, Vc browning and enzymatic, In these type of browning ,enzymatic browning is the most important type of browning. It was reported that PPO is the main enzyme caused enzymatic browning. So, the research on the characteristic of PPO and inhibition of enzymatic browning will provide theory to impel the industry of jujube and promote the economical efficiency.The experiment stated that the browning of jujube mainly caused by PPO. So it is very important for research on the characteristics of PPO and control enzymatic browning caused by PPO in jujube.The relationship between browning degree and the activity of PPO of jujube; the most optimal substrate of jujube PPO and the Km and the Vm value in Michaelis-Menten parameters through the curve of Linewear-Burk;the optimal pH value and temperature; the effect of different factors such as pH value, temperature, concentration of substrates, concentration of enzyme, usage of PVP in extraction of PPO, metallic ion on the activity of jujube PPO; some physical measure such as the heat bums, microwave radiation effect on the activity of jujube PPO; several inhibitor such as organic acid, sulfite, glutathione, cysteine effect on enzymatic browning of Jujube were studied in this paper.The results are showed that:1. There were a significantly relationship between the browning degree and the activity of PPO(R~2=0.9993) or TP(R~2=0.9974) in jujube. It inferred from the obtained resulting that enzymatic browning was the main reason which lead to Jujube browning.2. The experiment of usage of PVP in extraction of Jujube PPO proved the optimal usage of PVP is 1/10.