Triticale and sorghum as feedstock for bioethanol production via consolidated bioprocessing

Abstract

Corn starch is currently the primary feedstock for bioethanol production, but concerns about food security have prompted the evaluation of alternative cereals as feedstock. Two potential candidates, triticale and sorghum, can be grown on marginal farming land and mainly serve as animal feed. This study assessed flour and bran-like fractions of triticale and sorghum grains as feedstocks for bioethanol production using a consolidated bioprocessing approach. A Saccharomyces cerevisiae Ethanol Red™-derived amylolytic strain (ERT12) achieved ethanol conversion efficiencies of 100 and 96% from sorghum (after 96 h) and triticale flour (after 168 h), respectively. Supplementation with 10% of the recommended STARGEN™ 002 enzyme loading halved the fermentation time for sorghum and triticale flour. The raw starch in sorghum flour was more digestible than in triticale flour under consolidated bioprocessing conditions, whereas simultaneous saccharification and fermentation proved more effective for triticale flour. The two substrates also showed different hydrolysis patterns, which may be linked to their amylopectin content. This study demonstrated that both substrates could be converted to ethanol using only an efficient amylolytic strain without nitrogen supplementation. However, process development for biofuel production may require different fermentation configurations to be optimised for each substrate.