| Persimmon is originated from China and its fruit is rich in nutrition and health value.,The browning is easy to take place in persimmon processing because of abundant tannin in its fruit. The browning of persimmon seriously affected the products quality and restricted the development of persimmon industrialization. This experiment will lay the foundation for persimmon processing.This paper mainly includes four parts. They are persimmon enzymatic Browning mechanism, non-enzymatic Browning mechanism, the key technologies of inhibiting Browning in dried persimmon processing and the key technologies of inhibiting Browning in persimmon juice processing.The substrate of persimmon enzymatic Browning and the characteristics of polyphenol oxidase and peroxidase participate in persimmon enzymatic Browning were researched in part one.The results show that tannin was the main substrate of persimmon enzymatic browning. The optimum temperature of persimmon polyphenol oxidase (PPO) involved in enzymatic browning is 25℃,the optimum pH value is 6.5, persimmon PPO presents certain thermal stability. The activity of PPO was basically passivated under 60℃for 5min and was completly inactivatied under boiling temperature for 90s. PPO enzymatic kinetic parameters was presented as following: Km=7.698mmol/L, Vmax=0.0458A420/min.The mixture of 0.2% citric acid and 0.2% sodium could inhibit persimmon enzymatic browning.The optimum temperature of persimmon peroxidase (POD) involved in enzymatic browning is 30℃,the optimum pH value is 5.0, persimmon PPO presents certain thermal stability. The activity of POD was basically passivated under 60℃for 5min and was completly inactivatied under boiling temperature for 120s.The relationships between persimmon juice non-enzymatic and temperature, pH, amino acids, reducing sugars and soluble solids and the affecting of some metal ions on persimmon juice non-enzymatic Browning were researched in part two.The results show that persimmon non-enzymatic browning are closely related with temperature, pH, amino acids and sugar. the higher the heating temperature, the value of pH, the soluble solids concentration of persimmon juice, more serious the persimmon juice browning. Aspartic acid could reduce and glycin could promote non-enzymatic browning of persimmon juice. Fructose and glucose could promote non-enzymatic browning of persimmon juice.The reactivities of and reducing sugars in persimmon juice were higher than in the citric acid-phosphate buffer (pH4.5). The reactivity of lysine was the highest in all amino acids.Al3+,Ca2+,Sn2+ could inhibit and Fe2+,Fe3 +,Cu2+ could promote the non-enzymatic browning of persimmon juice while Zn2+, Mn2+ presented unobvious affecting on the non-enzymatic browning of persimmon juice.The inhibiting technologies against browning in dried persimmon were researched in part three. The results show that browning degree of dried persimmons were related with deastringent methods, dried technologies, color protection processing and packaging. The higher the concentration of carbon dioxide, the shorter the persimmon deastringent time and the more light the browning of dried persimmon. The higher concentration of ethephon the longer treatment time is, the more serious the browning of dried persimmon. The browning degree of dried persimmon processed by "low-high-low"processing technology was lighter than that processed by another two processing technologies. The browning of dried persimmons could be effectively inhibited with sulfuring, sodium bisulfite solution immersion, citric acid soaking and vacuum packaging.The inhibiting technologies against browning in persimmon juice were researched in part four. The results show that sodium erythorbate, L-cysteine and sodium bisulfite presented significant inhibition effect against the non-enzymatic browning of persimmon juice. The mixture inhibitor consisted of 0.2% sodium erythorbate,0.02% L-cysteine and 0.01% sodium bisulfite presented optimum inhibitory effect against non-enzymatic browning of persimmon juice.
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