Optimization of Pectinase and Hemicellulase Complex Enzymatic Hydrolysis for the Preparation of Feijoa Fruit Juice

To reduce the negative effects of pectin and hemicellulose in the cell wall of feijoa fruit on fruit juice quality, and improve the juice yield, the effects of the enzyme ratio (hemicellulose and pectinase), the enzyme amount, temperature, and time on the juice yield and soluble solids of "Unique U-100" feijoa fruit juice were investigated. Based on single factor experiment, response surface methodology was further used to optimize the optimal technological parameters of enzymatic hydrolysis of feijoa fruit juice. The results showed that under the conditions of the ratio of the compound enzyme (hemicellulase/pectinase) of 2.14:1, enzyme amount of 19.6 g/L, enzymolysis temperature of 56.8 ℃, and enzymolysis time of 92 min, the juice yield of feijoa fruit was the highest, which was 79.5%, with a relative error of 5.67% compared to the predicted value of model. The soluble solid content in fruit juice was 15.7%, with a relative error of 0.83% compared to the predicted value of the model. In addition, compared to the directly squeezed fruit juice, the enzymatically hydrolyzed fruit juice showed higher clarity, total phenolic content (24.4 mg GAE/100 g), and V_C content (2.42 mg/100 g). Therefore, this study optimized the process of pectinase and hemicellulase complex enzymatic hydrolysis for the preparation of feijoa fruit, which improved the juice yield and nutritional quality and provided a theoretical basis for the further processing of feijoa fruit juice.