Bioethanol production from waste bread samples made from mixtures of wheat and buckwheat flours

Abstract

In this paper yields of bioethanol from seven samples of bread were compared. Samples of bread were produced and prepared in a laboratory by mixing wheat and buckwheat flour in amounts of 0, 20, 40, 50, 60, 80 and 100%. At first, the analysis of all seven samples of bread was done (dry matter, starch content and pH value of bread sample suspensions). Then the waste bread suspensions were hydrolyzed by applying commercial hydrolytic enzymes, Termamyl® SC and SAN Extra® L. The fermentation process was carried out with dry instant yeast, Saccharomyces cerevisiae, after which distillation of all fermented suspensions was performed. The ethanol contents in the distillates of all seven samples were determined. The highest yield of bioethanol was detected in the bread sample made of pure wheat flour. The ethanol yield gradually decreased with increasing content of buckwheat flour in bread. These results could be useful when considering the possibility of utilization of waste bread from different sources as a feedstock for bioe­thanol production.

Keywords

• waste bread
• saccharomyces cerevisiae
• bioethanol
• yield
• kitchen garbage