Effects of mixed starters of plant- and wine-derived L. plantarum on hawthorn juice fermentation: Physicochemical properties, phenolic and volatile profiles

Lactic acid bacteria (LAB) fermentation is an effective way to improve the nutrition and sensory qualities of hawthorn juice, however the scarcity of LAB strains adapting to the high acidity of hawthorn juice limits its industrial application. In this study, a total of thirty-seven LAB strains belonging to different genera and species were isolated from spontaneously fermented plant and spine grape wine products, and four acid-resistant L. plantarum strains (Lpl.58, Lpl.55, Lpl.69 and Lpl.HY-1) were finally screened according to their viability and fermentation activity in hawthorn juice. The influences of their single and dual-mixed inoculation on the physicochemical properties, antioxidant activity, phenolic compounds and volatile flavor compounds of hawthorn probiotic beverages were subsequently investigated. Compared to single fermentation, mixed fermentation achieved higher fermentation activity, cell viability, and acid production, especially Lpl.69 + Lpl.HY-1, which also exhibited the greatest antioxidant activity. A significant increase of phenolic compounds (e.g. chlorogenic acid, proanthocyanidin B1, proanthocyanidin B2) was observed in Lpl.58 + Lpl.HY-1. Notably, co-inoculating Lpl.69 + Lpl.HY-1 and Lpl.55 + Lpl.HY-1 largely reduced volatile compounds with unpleasant odor (hexanol and hexanal), and increased the levels of desired aroma compounds (alcohols, esters, aldehydes and ketones) compared to single fermentation. The obtained results of this study indicated that screening L. plantarum strains from different acidic matrices and conducting mixed fermentation was a promising approach to produce hawthorn probiotic beverages with high nutrition and aroma complexity.