Physicochemical, nutritional, sensory and microbial characteristics of fresh and pasteurized pineapplecarrot-ginger beverage

Abstract

A beverage was prepared from pineapple, carrot and ginger juices using Response Surface Methodology to form a refreshing nutritional drink. Three independent variables were used to prepare the beverage: pineapple-tocarrot juice ratio (75/25-90/10), fibre size distribution (0.6-1.2 mm) and ginger concentration (2-5%). The effects of the variables were investigated and represented using quadratic models on pH, total soluble solids, beta-carotene and sensory attributes as responses. Responses for independent variables and responses were optimized by setting goals to optimize the beverage. The optimized beverage was obtained at pineapple-to-carrot juice ratio, fibre size distribution and ginger concentration of 80/20, 0.6 mm and 3% respectively. Optimized unpasteurized beverage was prepared and stored at -24, -10 and 4 oC and quality changes studied every five (5) days for 40 days. Significant decrease in ascorbic acid, beta-carotene, total antioxidant activity, total soluble solids was observed at the end of storage while total phenolic content remained almost unchanged. Minimal quality changes occurred in frozen samples. In another experiment, pasteurized (80 oC, 15 mins) optimized beverage was treated with 0.1% sodium benzoate and 0.1% citric acid and stored at 4, 28 and 38 oC and quality changes studied every 15-days for 90 days. Significant decrease in total phenolic, ascorbic acid, beta-carotene and total antioxidant activity were observed at the end of storage at rates depending on storage temperature. Frozen storage, therefore, can help slow the degradation in the quality of fresh unpasteurized beverage, while storage at low temperature can slow quality degradation in pasteurized beverage.