热水萃取法生产澄清香蕉汁的研究

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12.9 mg。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 the study, effects of hot water temperature on clarification, total soluble solids, polyphenol oxidase （PPO） and color of juice during hot water extraction were discussed on the basis of the theory in which heat treatment might induce the pectin and protein in banana pulp to form insoluble products. Results showed that the hot water temperature, which showed the strongest ability to form insoluble products at 75℃, had a significant effect on the ability of forming insoluble products for pectin and protein in banana pulp. The clarification of banana juice extracted by hot water of 75℃ was highest, and its light transmittance at 660 nm was close to 90%. The contents of pectin and protein in banana juice extracted by hot water of 75℃ were the least, which were lower than 7.3 and 12.9 mg/100mL respectively. Hot water extraction of 75℃ could not completely inactivated the PPO of banana pulp because of its resistance to heat, so 0.05% L-cysteine or ascorbic acid needed to be added to banana pulp to inhibit the browning of juice induced by residual PPO.