Influence of fruit juice addition on quality of fermented whey-based beverage

Abstract

The aim of this study was to evaluate the influence of fruit juice addition on the quality of fermented whey-based beverages that contain commercial ABY-6 starter culture. Milk (30%) and Cornelian cherry fruit juice (30%) were used for beverages formulation. Cornelian cherry fruit was used based on high antioxidant activity and specific texture that can improve overall quality of beverages. After 4h of whey fermentation followed by fruit juice addition, overall quality of beverages was evaluated by determining the viable cell count, pH value, titratable acidity, antioxidant activity and syneresis of produced beverages. Stability of beverages was monitored during 28 days of storage. Based on the results fruit juice does not have statistically significant influence on viable cell count of probiotic bacteria. On the other hand, fruit significantly improves antioxidant activity and syneresis of beverages. Antioxidant activity reaches level of 88.6-94.5% in beverages formulated with fruit juice addition in contrast to the level of 36-36.7% without added fruit juice. Addition of fruit juice decreases syneresis of beverages for 9.5-11.9% after fermentation and for 9.5-25% after 28 days of storage. Titratable acidity and pH value of beverages were significantly affected by fruit juice addition but remain within recommended levels and stable during the whole storage period. To formulate healthy beverage, supplementation of whey with 30% milk and 30% of Cornelian cherry fruit juice is advisable. Obtained fruity whey-based beverage has desirable quality attributes such as antioxidant activity of 97.0% and syneresis of 54.1%. Beverage contains 6.89 log (CFU mL-1 ) probiotic bacteria, has a shelf life of at least 14 days and expresses quality that meets consumers’ demands.