Hurood is a regional characteristic traditional dairy product made from naturally fermented milk, followed by heating, whey separation, forming and maturing. In order to understand the changes of bacterial flora and flavor compounds during the production of hurood, 12 samples from each process were collected. The changes of bacterial flora were explored by pure-culture method and Pacbio SMAT sequencing technology. 166 strains of lactic acid bacteria were isolated by pure-culture method. The sequencing results showed that the complex microflora in fresh milk, including Lactococcus raffinolactis, Lactococcus piscium and Acinetobacter johnsonii, decreased gradually with the progress of fermentation and heat treatment, while Lactococcus lactis and Streptococcus thermophilus became the highest relative abundance bacterial flora, which were consistent with the dominant strains obtained by pure cultured. The flavor compounds were determined by solid-phase microextraction-GC-MS (SPME-GC-MS), and the relationship between them and the structure of bacterial flora was explored. A total of 62 volatile flavor compounds were detected in the production process of hurood. There were significant correlations (P<0.05) between the dominant strains such as Lactococcus lactis and Streptococcus thermophilus and the main flavor compounds in the samples at different production stages, which indicated that lactic acid bacteria played an important role in the fermentation of hurood and the flavor compounds formation. The lactic acid bacteria strains and research results obtained in this study laid a theoretical foundation for the modern production of traditional hurood.
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