Effect of a Multifunctional Biosurfactant Extract Obtained from Corn Steep Liquor on Orange and Apple Juices

Biosurfactant extracts are multifunctional ingredients composed of natural polymers that can be used in the food industry as stabilizing and antimicrobial agents, although their inclusion in food matrices has been scarcely explored. In this work, a biosurfactant extract, with antimicrobial properties, obtained from a fermented stream of the corn wet-milling industry was introduced into an apple and orange juice matrix to evaluate the changes produced in the sugar consumption, pH, and biomass formation at different temperatures (4-36 °C) and storage time (1-7 days). It was observed that the addition of biosurfactant extract reduced the hydrolysis rate of polymeric sugars, decreasing the concentration of soluble sugars from 85.4 g/L to 49.0 g/L in apple juice after 7 days at 20 °C in the absence and presence of biosurfactant extract, respectively. In general, soluble sugars increased in juices for 5-6 days and after those sugars decreased at different rates depending on the temperature of storage. Differences in sugar solubilization and degradation were more significant in apple juice than in orange juice at 20 °C and 7 days of storage, achieving for orange juice values of 101 and 102 g/L in the absence and presence of biosurfactant extract, respectively. Biomass growth was almost unaffected by the biosurfactant extract concentration and the optimal conditions for biomass production were detected at intermediated temperatures after 6-7 days of storage for both apple and orange juices, obtaining maximum concentrations of 1.68 g/L and 1.54 g/L for apple juice and orange juice, respectively, in the absence of biosurfactant extract. The pH during storage was kept in the range of 3.35-3.48 for apple juice and of 3.40-3.77 for orange juice.