热水萃取法生产澄清香蕉汁的研究（英文）

Study on Processing of Clear Banana Juice Using Hot Water Extraction Method

基于热处理可能诱导香蕉果肉中果胶和蛋白质形成水不溶物的理论,研究了热水萃取温度对香蕉汁澄清度、可溶性固形物含量、多酚氧化酶(PPO)和色泽的影响。结果发现,热水温度对香蕉果肉中果胶和蛋白质形成水不溶性聚合物的能力有显著的影响,其中75℃的热水萃取诱导香蕉果肉中果胶和蛋白质形成水不溶物的能力最强,获得香蕉汁的澄清度最高,其透光率(660 nm)接近90%;75℃热水萃取获得的香蕉汁的果胶和蛋白含量最低,分别低于每100 ml香蕉汁7.3和12.9mg。由于香蕉果肉中PPO耐热性强,75℃的热水萃取难以将其完全失活,为防止在香蕉果肉中的PPO在香蕉汁打浆期间引起酶促褐变,需添加0.05%的L-半胱氨酸或抗坏血酸进行护色。

In this study, the effects of hot water temperature on clarity, total soluble solids, polyphenol oxidase （PPO） and color of banana juice during hot water ex-traction were discussed based on the theory in which heat treatment might induce the pectin and protein in banana pulp to form insoluble products. The results showed the hot water temperature had a significant effect on the formation of insol-uble polymers in banana pulp from pectin and protein. In 75 ℃ water, the pectin and protein in banana pulp were most inclined to form insoluble products. Under this condition, the clarity of banana juice was also highest. The light transmittance at 660 nm was close to 90%. In the banana juice, extracted by 75 ℃ water, the pectin and protein contents were lowest, and they were lower than 7.3 mg/100 ml and 12.9 mg/100 ml respectively. The 75 ℃ water could not inactivate completely the pectin in banana pulp due to its high heat resistance, Therefore, 0.05% L-cys-teine or ascorbic acid needed to be added into banana pulp to inhibit the browning of juice induced by residual PPO.