Impact of storage time on microbial communities and flavor profiles in highland barley grains

Microbial activity and the resulting flavor changes in stored highland barley grains may reduce the product quality and pose potential risks to food safety with economic losses. This study aims to elucidate the association between microbial load and flavor compounds during the preservation of highland barley. High-throughput sequencing (HTS) was used to investigate the microbial composition in stored highland barley. The volatile flavor components of the latter were identified via the headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Moreover, the study examined the correlation between the types of microorganisms and volatile flavor molecules. The results indicated that the dominant phyla in highland barley were Ascomycota and Basidiomycota, with the dominant genera being Cladosporium, Vishniacozyma, Filobasidium, Udeniomyces, Cystofilobasidium, Aspergillus, Alternaria, Monographella, Didymella, and Neoascochyta. Inside，Cystofilobasidium, Itersonilia, Sarocladium, Ustilago, Penicillium and Pyrenophora served as effective biomarkers to distinguish highland barley grains stored at different times. Further, the highland barley samples contained 192 volatile organic compounds (VOCs), such as alcohols, ketones, esters, alkanes, aldehydes, etc. The top 20 volatile flavor compounds with differences were selected based on the variable importance of projection (VIP) > 1. Based on the correlation analysis findings, it was found that the genera Cystofilobasidium, Aspergillus, and Cladosporium hold promise in contributing volatile flavor compounds to highland barley. This study examined a pattern of changes in safety and quality across varying storage durations, providing crucial insights to enhance the flavor profile and texture of highland barley products.