Development of novel wheat biorefining: Effect of gluten extraction from wheat on bioethanol production

Wheat has been used in a novel biorefinery as the sole raw material for the production of bioethanol and some co-products (bran-rich pearlings, gluten and pure yeast cells). Minimisation in waste production has been achieved either by generating co-products from major wheat components that are not required for bioethanol fermentation or by re-generating nutrients contained initially in wheat via microbial autolysis. On-site production of enzymes required to hydrolyse wheat macromolecules has been achieved by Aspergillus awamori fermentation of pearled wheat flour. Complete gluten extraction was made feasible by providing the required amount of free amino nitrogen (FAN) for bioethanol fermentations via on-site fungal autolysis. A wheat to ethanol conversion yield of 0.296 g g−1, which constitutes 77% of the maximum theoretical conversion (0.385 g ethanol (g wheat)−1) calculated from the starch content in the wheat used, has been achieved including the starch requirements for enzyme production. A modified unstructured model has been proposed to describe fermentations of Saccharomyces cerevisiae on wheat-derived media for bioethanol production.