The effect of γ-irradiation on cassava biomass in bioethanol production as an alternative method to hydrolysis

Cassava is a widely cultivated, economically accessible tropical crop that has gained attention not only as a food staple but also as a promising feedstock for bioethanol production. This study explored the application of γ-irradiation as a nuclear-based alternative or complement to conventional enzymatic hydrolysis in cassava bioethanol conversion. Two processing pathways were compared across irradiation doses of 0, 50, and 100 kGy: a direct fermentation–distillation pathway without hydrolysis (FD), and a sequential hydrolysis–fermentation–distillation pathway (HFD). Results showed that γ-irradiation alone could not adequately replace hydrolysis, as the FD treatments yielded only 0.10–0.11 g sugar/g sample with negligible ethanol output. In contrast, combining irradiation with hydrolysis substantially improved process performance; the HFD treatments achieved ethanol yields of 0.20–0.25 g/g sugar and concentrations of 62% (v/v). Moreover, the combined treatments (50HFD and 100HFD) reduced fermentation time from 72 hr to approximately 12–24 hr. These findings indicate that γ-irradiation functions most effectively as a synergistic pretreatment rather than a standalone process. To our knowledge, this is the first study to directly compare γ-irradiation-only and γ-irradiation-plus-hydrolysis pathways in cassava bioethanol production, identifying 50 kGy as an optimal irradiation dose.