果胶酶处理对5个品种橙汁主要理化指标的影响

Effect of Pectinase on the Main Physicochemical Parameters of Orange Juices from Different Orange Varieties

将5个主要汁用品种的橙(哈姆林、特罗维他、锦橙、橘橙、凤梨甜橙),去皮打浆后加入相同质量分数的(0.1%)果胶酶(PectinexBeXXL,NovoEnzyme),经45℃水浴、酶解1h后,与未酶解样品相比较,分析果胶酶对不同品种橙汁主要理化指标的影响。结果表明,经果胶酶处理的各品种橙汁的Brix、果汁澄清度、钙含量及可溶性果胶的含量增加,而pH值、可滴定酸和黏度均降低。但此酶处理对各橙汁的色泽及游离氨基酸含量的影响,不同品种间存在一定的差异。其中凤梨甜橙与特罗维他橙汁的酶解样品与未酶解样品的色泽差异显著(△E>2),凤梨甜橙主要体现在a*(红值)增加,而特罗维他则主要体现在b*(黄值)的降低,其余样品则差异不显著;哈姆林、锦橙和橘橙的酶解样品的游离氨基酸总量较低,主要体现在天冬氨酸、丝氨酸、谷氨酸和组氨酸含量较低,特罗维他的酶解样品与非酶解样品差异不显著,而凤梨甜橙的酶解样品除苏氨酸外,其余均显著增加。这些数据将为橙汁加工中酶的选择以及橙汁的鉴伪提供参考,

The juices from five commercially harvested orange varieties （Pineapple orange, Hamlin, Trovita, Jincheng and Jucheng） were treated with a commercial pectinase （pectinex Be XXL, novo enzyme） independently. Some physicochemical parameters of them were analyzed and compared with the juice without pectinase treatment. Results showed that all the juices treated with pectinase got higher value on Brix, clarity, calcium and water soluble pectin content, and they got lower value on pH, titratable acidity and viscosity. But the difference between the treated samples and untreated samples of color parameters and free amino content of juices differed with cuhivars. The treated sample of pineapple orange were found with higher a^＊, which showed deeper reddish color. But Trovita were found with higher b^＊ （yellow value） and the difference between the treated and untreated samples were not significant （△E〈2） of the other three varieties. The treated samples of Hamlin, Jincheng and Jucheng with lower amino acid content due to the lower content of Asp, Ser, Glu, His. The treated samples of Pineapple orange were found with higher amino acid than untreated samples due to the higher content of all amino acids detected except Thr. All these data would offer valuable information for the application of pectinase in orange processing and authentic juice identification.