Impact of low aging temperature on the microbial and metabolic dynamics of rice wine during long-term storage

This study investigated the effects of aging temperature and microbial inoculation on the physicochemical, microbiological, and metabolic properties of Korean rice wine (makgeolli) during long-term storage. Samples were aged at three different temperatures (4 °C, -1 °C, and -5 °C) for 180 days and were inoculated with Lactiplantibacillus plantarum or Saccharomyces cerevisiae to examine their respective influences on metabolite shifts during cold storage. Microbial communities were analyzed using amplicon (16S rRNA) and shotgun metagenomic sequencing, and metabolite profiles were determined by GC-MS to provide an integrative understanding of microbial and metabolic stability during long-term cold storage. Lower aging temperatures reduced fluctuations in metabolic and microbial activities, particularly among LAB, thereby contributing to a more stable physicochemical profile and extended shelf life. During rice wine aging, LAB exerted a more pronounced effect on metabolite dynamics than yeast, particularly for pyruvate, γ-aminobutyric acid, and lactic acid, underscoring their role in the aging process. Additionally, sub-zero aging temperatures preserved the initial microbial composition, limited enzymatic degradation, and stabilized organic acid profiles, reflecting enhanced chemical stability of the product during aging. While such chemical stability may have implications for sensory outcomes, this remains a hypothesis that requires direct sensory evaluation in future studies. Overall, the findings suggest that controlled storage temperatures and targeted microbial inoculation can improve the chemical and microbiological stability of rice wine during long-term storage.