Analysis of the fungal community structure and sensory quality of high-temperature Daqu via high-throughput sequencing and the PAM algorithm

The present study analysed the sensory quality and fungal community structure of three color types of high-temperature Daqu (HTD) produced in Qingzhou using electronic nose, electronic tongue, and high-throughput sequencing technology. The data were compared to the fungal data obtained from HTD produced in Xiangyang via the "partitioning around medoids" (PAM) clustering algorithm. PAM analysis indicated that all HTD samples from the two regions could be divided into two clusters. Cluster I samples were mainly characterized by Thermomyces, and cluster II samples were mainly characterized by Aspergillus and Thermoascus. Cooccurrence network analysis revealed that the correlations between fungal communities were stronger in the HTD dominated by Aspergillus and Thermoascus. The identification of key species and core operational taxonomic units demonstrated that the differences in the fungal community structure between the two HTD clusters were related to the abundance of certain fungal groups. Correlation analysis between fungal genera and sensory quality parameters showed that Thermomyces-dominated HTD had lower aftertaste-A, aftertaste-B, and organic sulfide and terpene content but a higher richness of flavor. Meanwhile, HTD dominated by Aspergillus and Thermoascus exhibited the opposite traits, and its sourness was relatively higher.