Ability of lactic acid bacteria strains to improve the safety and functionality of fermented fruits juices

Abstract

Fruits are an essential part of human nutrition, therefore, the development of fruit- based foods promoting health is a key research priority of the food industry. On the other hand, the growth and metabolism of lactic acid bacteria (LAB) affect the fermented foods quality. Thus, lactic acid or malolactic fermentations may be a natural technology for improving safety, nutritional, and/or sensorial properties of by-product fruits. In this context the behavior of Oenococcus oeni and Lactobacillus plantarum strains in terms of growth, substrates utilization, antimicrobial and antioxidant activities, and/or probiotic potential of fermented juices were investigated. Two O. oeni strains (MS46 and MS9) isolated from a cellar from Cafayate, Argentina, were selected by exhibiting malolactic activity, low diacetyl production and detectable glycosidase cell surface activities in laboratory media. When inoculated (~106 CFU/mL) in grape juice (GJ), prepared from Malbec grapes, both strains grew without lag period by 1.34±0.02 and 1.46±0.03 log CFU/mL at 12 days with maximum growth rates of ~ 0.019 h-1 respectively, and adequate changes in the sugars and organic acids profiles from the sensorial viewpoint. At this time, initial pH decreased ~0.45 units, however, it increased by ~ 0.12 units during the first three days. In addition, both strains showed antibacterial properties against human pathogens, and ability to increase the antioxidant properties of fermented GJ. These results demonstrated the potential of O. oeni to ferment GJ with health benefits, which represents a novel alternative to its use in winemaking. In addition, the MS46 strain when inoculated in a commercial wine also increased its antioxidant activity at the end of MLF. On the other hand, L. plantarum strains isolated from oranges from our region also exhibited capacity to inhibit pathogenic bacteria, ability to grow in orange juice without pH-adjustment and probiotic potential. Thus, these studies show new insights on the O. oeni and L. plantarum strains behaviour to ferment new, safe and functional fruit juices.