Effects of Germinated Glutinous Rice Malt Substitution on the Properties of Non-Alcoholic Beer Fermented with Saccharomyces boulardii

Information from the abstract

The rising consumer demand for functional, low-alcohol beverages necessitates innovative brewing strategies. This study evaluated germinated Thai glutinous rice (Oryza sativa var. glutinosa, cv. Kheiw Ngu 8974) as a novel malt adjunct for non-alcoholic beer fermented with the probiotic yeast Saccharomyces boulardii. Formulations with germinated glutinous rice to barley malt ratios of 0:100, 40:60, 60:40 and 80:20, designated as R0, R40, R60, and R80, respectively, were systematically analyzed for their fermentation properties, physicochemical properties, bioactive enrichment, volatile compounds, and sensory attributes. Results showed that the high substitution levels in glutinous rice restricted enzymatic saccharification, successfully limiting ethanol accumulation in R60 and R80 to below the 0.5% v/v regulatory threshold. The final ethanol values for R0, R40, R60, and R80 were 1.34 ± 0.04%, 0.65 ± 0.04%, 0.4 ± 0.04%, and 0.13 ± 0.04% v/v, respectively. Although the control formulation (R0) exhibited the highest initial total phenolic content (TPC), antioxidant capacity, and gamma-aminobutyric acid (GABA) levels, S. boulardii fermentation significantly enriched these functional compounds across all adjunct-substituted formulations. Furthermore, gas chromatography–mass spectrometry (HS-SPME-GC/MS) analysis revealed a distinct shift in the volatile profile, with increasing levels of rice substitution resulting in a reduction in fermentation-derived aliphatic esters and a greater relative abundance of hop-derived terpenes and terpenoids. Sensory evaluations indicated that while extreme substitution (R80) negatively impacted color and aroma balance, the 40% and 60% formulations maintained highly acceptable organoleptic profiles. The overall liking scores for R0, R40, R60, R80, and the commercial product were 6.71 ± 1.66, 5.42 ± 1.65, 5.68 ± 1.80, 5.03 ± 1.92, and 6.45 ± 1.65, respectively. In conclusion, integrating a 60% substitution of germinated Thai glutinous rice provides the most balanced formulation among those tested, producing compliant, sensory-acceptable non-alcoholic beer with enhanced bioactive functionality.

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Related topics: Fermentation and Sensory Analysis · GABA and Rice Research · Hops Chemistry and Applications