Optimization of Pre-fermentative Skin Treatment Parameters for Production of Quality Wines from Punjab Purple (syn-516) and H-144, Grape Cultivars of Punjab

A study was conducted to determine the effect of skin contact pretreatment on the visual, aromatic and phenolic properties of the grape juice from two cultivass viz., Punjab purple and H-144 cultivars. Response Surface Methodology (RSM) was used to optimize the three parameters i.e. skin weight (30–80%), temperature (10–20°C) and KMS concentration (100–250 mg/L). Among the RSM combinations, 80% skin weight and 100 mg/L KMS concentration at 10°C for 16h resulted in the maximum extraction of anthocyanins and phenolics from skin into the juice in both the cultivars. Overall, the pre-treatment process resulted in increasing the anthocyanins content from 20.5 to 43.5 mg/100 ml and total phenolics from 152.0 to 205.1 mg/100ml in Punjab Purple cultivar. However, in H-144 cultivar anthocyanin and phenolic contents increased from 0.70 to 1.9 mg/100ml, and 121.4 to 147.3 mg/100ml respectively.