Bevilacqua, RiccardoRegueira López, AlberteMauricio Iglesias, MiguelLema Rodicio, Juan ManuelCarballa Arcos, Marta2021-03-102022-10-282021Bioresource Technology, 320 (2021), 1243150960-8524http://hdl.handle.net/10347/24683This study investigates the influence of pH on protein conversion into volatile fatty acids by anaerobic mixed-culture fermentation, a topic that, in contrast to glucose fermentation, only had scarce and contradictory information available. Several experiments were performed with two model proteins (casein and gelatin) at three different pH values (5, 7 and 9) using chemostats and batch tests. Highest conversion was reached at neutral pH although complete acidification was never achieved. Longer chain carboxylates production was favoured at low pH, while acetic acid was the main product at pH 7 and 9. Amino acids preferential consumption also varied with pH and protein composition. In fact, protein conversion stoichiometry is mainly driven by energetic yields and amino acid molecular configuration. Overall, this study identifies pH adjustment as a way to steer volatile fatty acid production during mixed-culture fermentation of proteinseng© 2020 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license (http://creativecommons.org/licenses/by-nc-nd/4.0/)Attribution-NonCommercial-NoDerivatives 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Amino acid fermentationMixed cultureBiorefinerySelectivityVolatile fatty acidsjournal article10.1016/j.biortech.2020.124315open access