摘要:
苹果果汁为国人喜爱饮品之一，但经传统热加工处理后，会破坏其营养成分及影响外观质量，进而降低消费者购买意愿。多酚氧化酶、过氧化酶及果胶甲酯酶会造成果汁褐变及混浊，为影响苹果果汁外观质量之关键酵素。本研究藉由高压技术达到破坏酵素及维持营养成分的目的，首先将苹果果汁分为三大组，控制组、传统热处理及高压处理。不同加工处理对苹果果汁pH、可溶性固形物及可滴定酸并无显着影响，而总生菌数以100 MPa处理10分钟可达安全卫生标准。影响苹果果汁外观质量的关键酵素多酚氧化酶及过氧化酶并无显着降低的效果，但高压处理对苹果果汁果胶甲酯活性具有抑制效果于300 MPa处理10及20分钟后活性下降至0.17 ± 0.012~0.19 ± 0.026 [ΔOD min−1 (g of fw)]。而营养成分苹果果汁经200 MPa处理10分钟条件下可维持和控制组相当的维生素C含量(145.9 mg L−1)，影响果汁浊度的可溶性蛋白经200、400 Mpa高压处理下也随之降低。热敏性苹果果汁利用高压处理可达到和传统热处理相同的杀菌效果，且在维持其营养价值及外观质量上效果皆比传统热加工良好。综合以上结果，高压处理不影响果汁物理成分，相较于加热处理也可得到较好保留果汁中营养成分的效果。
Abstract:
Apple juice is one of the popular beverages in Taiwan, but after conventional heat processing, it will destroy its nutrients and affect the appearance and quality that reduce consumer willingness to buy. Polyphenol oxidase (PPO), peroxidase (POD) and Pectin methyl esterase (PME) can cause browning of fruit juices as the key enzymes of affecting the appearance quality. In this study, we utilize the high-pressure processing technique to destroy the enzymes activity and maintain the nutrients. First, the apple juice is divided into three groups: untreated (Control), traditional heat treatment (Thermal Processing, TP) and High Pressure Processing (HPP). The results show apple juice has no significant change on pH, soluble solids, titratable acidity. However, apple juice can reach the safety standard with 100 MPa for 10 minutes processing. PPO and POD, the key enzymes affecting appearance quality of apple juices, do not significantly decrease. PME activity in apple juice reduces at 300 MPa, 10 and 20 minutes treatment, 0.17 ± 0.012 - 0.19 ± 0.026 [ΔOD min−1 (g of fw)]. For nutrients, the apple juice can reach the considerable vitamin C 145.9 mg L−1 content, the same to the control group 200 MPa for 10 minutes treatment. Soluble proteins affecting turbidity in apple juice reduce when treated with 200, 400 MPa pressure treatment. The heat-sensi- tive apple juice with high-pressure treatment can achieve the same sterilization effect to conventional heat treatment, and is better than the traditional thermal processing in maintaining the nutritional value and appearance quality. Based on the above results, the high-pressure treatment not only does not affect the physical ingredient juice, but also reserves better nutrients compared to the heat treatment.