Enzyme activity and constituent extractability of kilned and non-kilned oats at pH values relevant for acidic food fermentations.

Oat fermentation is often hampered by reduced enzymatic activity caused by kilning. We here investigate whether different enzymatic activities of oats at acidic-fermentation-relevant pH can enhance their nutritional and functional properties. Enzymatic activity (protease, xylanase, β-glucanase, amylase, phytase, and lipase) was assessed in kilned and non-kilned oat suspensions at pH 3.5-7.0. Then, changes in dietary fibre and protein extractability and starch and phytate hydrolysis were evaluated after a 24-h incubation (with added antimicrobials to ensure no fermentation occurred) at pH 6.4, pH 4.0, and under gradual acidification. Non-kilned oats exhibited higher enzymatic activities overall. Arabinoxylan and β-glucan extractability of non-kilned oats (23-26 % and up to 73 %, respectively) were higher than of kilned oats (11-12 % and 40-46 %, respectively). Incubated non-kilned oat demonstrated higher starch (4-5 %) and phytate hydrolysis (43-49 %). These findings highlight the potential of fermenting non-kilned oats to improve oat-based foods like sourdough bread and fermented dairy or meat alternatives.