Formulation of sustainable gluten-free beer from rice malt and potato processing residue with a view to a circular economy

Abstract This study explores the development of a sustainable, gluten-free beer using regionally sourced ingredients, including rice, potato peels, and native forest botanicals (St. John's Wort, Juniper, and Helichrysum). The research aimed to optimize the fermentation of rice-based wort at a lab-scale by incorporating potato peels and various amylolytic enzymes to improve brewing efficiency and sugar profile complexity. Rice malt was produced at the experimental facilities of KU Leuven (Belgium), and fermentation trials were conducted using both malted and unmalted rice. The study employed different mashing techniques, including traditional decoction mashing, an innovative proprietary enzyme, and a combination of commercial enzyme preparations. Results demonstrated that the novel enzyme significantly enhanced starch hydrolysis, reducing mash times by approximately 30 minutes while improving overall fermentation efficiency. Additionally, the integration of potato peels contributed to a more balanced sugar composition, mitigating glucose dominance and increasing the diversity of fermentable sugars, which could influence yeast metabolism and flavor profile. These findings suggest that enzymatic innovations and agro-industrial byproducts, such as potato peels, could play a key role in advancing sustainable brewing practices while maintaining desirable fermentation characteristics in gluten-free beer production.