Improvement of Enzymatic Assisted Extraction Conditions on Anthocyanin Recovery from Different Varieties of V. vinifera and V. labrusca Grape Pomaces

The incomplete anthocyanin extraction during the industrial processes turns grape pomace into an inexpensive source of phenolic compounds. The effects of temperature and enzyme preparation percentage (% E/S) on the anthocyanin recovery from grape pomaces of eight grape varieties were evaluated by their physicochemical characteristics and phenolic composition. A factorial 2(2) design with center point was used to select the preferred conditions for extraction, and the variables of temperature, enzyme preparation, and their interaction were assessed. The grape skin characteristics affected the anthocyanins' content and their recovery yield, and different improvement conditions were found for each variety of grape. Anthocyanin extraction from Cabernet Sauvignon-the variety which showed the highest percentage of anthocyanin recovery (over 50%)-was improved. The lowest tested temperature (40 degrees C) and percentage of preparation enzymatic (0.25% E/S) promoted higher anthocyanin extraction, resulting in a natural food colorant with 2.67 g anthocyanins/100 g grape skin dry basis (db). The extraction improvement allowed for a non-toxic natural extract rich in anthocyanins to be obtained; a natural additive which can be considered for potential food industry use in place of synthetic dyes, especially into acidic matrices.