Physicochemical characterization and OECD-guided toxicological evaluation of a beer extract supplemented with Monascus ruber-fermented Rice

Abstract

This study investigated the physicochemical characteristics and performed an initial toxicological evaluation of a freeze-dried beer extract supplemented with Monascus ruber-fermented rice (BEMR). Two Pilsner-style beers were produced and characterized according to European Brewery Convention (EBC) analytical methods, including pH, density, bitterness, and color measurements (SRM and CIELAB). The freeze-dried extract was subsequently evaluated in Wistar rats using acute (OECD Test Guideline 423) and repeated-dose 28-day oral toxicity (OECD Test Guideline 407) protocols. No mortality, treatment-related clinical signs, or gross organ abnormalities were observed following acute administration up to 2000 mg/kg or repeated oral administration up to 1000 mg/kg/ day. Hepatic, renal, and hematological parameters remained largely within physiological ranges throughout the study. Treated animals exhibited reduced body-weight gain without significant changes in feed or water intake. Modest increases in serum creatinine and reductions in creatine kinase activity were observed in the absence of corresponding clinical or pathological findings. Physicochemical analyses confirmed that incorporation of Monascus-fermented rice markedly modified beer color while maintaining the principal brewing parameters within acceptable ranges for the beer style. Under the experimental conditions evaluated, BEMR was well tolerated in both acute and repeated-dose toxicity screening assays. The biological significance of the observed physiological responses remains to be clarified through additional studies incorporating targeted chemical characterization (e.g., citrinin and monacolin contents), histopathological evaluation, and longer-term repeateddose investigations.