The enzyme addition favored a marked decrease of the latency phases of growth and acidification, the time needed to reach pH 4.2 was 8 h. It may be hypothesized that this acceleration was related to the higher availability of fermentable carbohydrates, which were released from polysaccharides through the different hydrolytic activities. Similarly, the decrease of the ratio between lactic and acetic acids may be related to the higher availability of pentoses (deriving from
xylanase activity), which were fermented by L. plantarum through the acetate kinase route of the phosphogluconate pathway Compared to the beverage started with L. plantarum LP09 alone, the combination with enzymes also caused significant changes in the physical characteristics of the matrix. It was less viscous and had a lower water holding capacity, probably as the consequence of the intense cell-wall-degrading activities (β-glucanase and xylanase). The viscosity due to oat β-glucanswas lowered by splitting these molecules into smaller sub-units.