Effect of Heat Pasteurization and Enzymatic Maceration on Yield, Color, Sugars, Organic Acids, and Phenolic Content in the ‘Merlot Kanthus’ Grape Juice

Abstract

This study researched the combined effects of heat treatment and varying concentrations of the pectolytic enzyme on the improvement of yield, color, and extraction of sugars, acids, and bioactive compounds of the ‘Merlot Kanthus’ grape juice. Application of low (0.05 IU/mL) and high (0.09 IU/mL) enzyme treatment substantially increased the yield of unpasteurized and pasteurized juice. Color intensity significantly improved in the pasteurized juice with a high enzyme concentration (CIRG 4.4) and the pasteurized juice without enzymes (4.5). No considerable differences in the total sugar concentration between the treatments were observed; however, the concentration of organic acids was improved by 27 and 13% in unpasteurized and pasteurized juice with a high enzyme concentration, respectively. A total of 78 individual phenolic compounds were identified, and the treatment with a high enzyme concentration had the most notable effect on the total anthocyanins, improving their concentration by 33.6% and increasing the concentration of 18 individual compounds. The heat treatment increased flavonol concentration by 41%. Overall, heat and enzyme treatment, mainly the high enzyme concentration, had a very favorable effect on the parameters of the analyzed ‘Merlot Kanthus’ grape juice, with a significant increase in the yield of bioactive components.

Keywords

• heat treatment
• enzyme concentration
• juice processing
• flavonoids
• hydroxycinnamic acids