Combination of different preservation techniques as low-cost strategies inhibiting sugar degradation in liquid feedstock used for bioethanol fermentation

Abstract

Just like for the food supply chain, sugar-based feedstock used in the bioethanol industry might be affected by biological contamination, resulting in important economic losses. Therefore, it is necessary to develop cost-effective storage techniques capable of preserving feedstock over several months. In this study, three different techniques (ozonation, acidification, and addition of a corn oil layer) were investigated individually as well as combined for the long-term storage of sugars dedicated to fermentation. After 300 days of storage, up to 100% of the initial fermentable sugars were preserved with acidification (pH 2.0), independently or in conjunction with other conservation techniques. However, in terms of fermentation potential, the groups treated with acid had a lower ethanol yield than the groups maintained at pH 6.0. When the solution was treated with ozone combined with acidification, it yielded 55.71% of bioethanol efficiency, whereas when treated only with ozonation at pH 6.0, fermentation reached a 67.20% yield. Ozonation was found to be efficient to preserve fermentable sugars, either with the use of an oil layer (80% conservation) or at lower pH (100% ethanol efficiency). Finally, the combination of ozonation and an oil layer presented the highest total ethanol production, reaching 101g L−1 after 96h of incubation using Saccharomyces cerevisiae. Thus, the combined use of ozonation and an oil layer has the potential to be used in the bioethanol sector as a system to preserve liquid feedstock without the use of evaporation to increase sugar concentration.