Steering the conversion of protein residues to volatile fatty acids by adjusting pH

This 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 only had scarce and contradictory information available. Several experiments were performed with two model proteins (casein gelatin) at three different values (5, 7 9) using chemostats batch tests. Highest was reached neutral although complete acidification never achieved. Longer chain carboxylates production favoured low pH, while acetic acid main product 9. Amino preferential consumption also varied composition. In fact, stoichiometry is mainly driven energetic yields amino molecular configuration. Overall, this identifies adjustment as way steer during fermentation proteins.