Three-ways changed in headspace air on anaerobic fermentation.

Different headspace condition has a great influence on fermentation process. In this study, whey protein was used as substrate, and the headspace air was changed in three different ways (H2 mixed N2, H2 mixed CO2, N2 with different sparging rates) to explore the effects of these three methods on products. The result showed that H2 mixed with CO2 is more conducive to acid production. Homoacetogenesis played a central role in fermentation process. There is a turning point in the role of hydrogen and Homoacetogenesis, which is when the partial pressure of hydrogen is 0.268 atm. In the first two conditions, the acid concentration increased with the increase of hydrogen percentage. Nitrogen sparging way is adverse to acid production, but conducive to gas production.