Effect of accumulated temperature on flavour and microbial diversity of japonica rice during storage

摘要

Storage temperature is closely related to rice grain quality in granaries. The purpose of this study was to determine the relationship between the microbial community and volatile components with the different accumulated temperature changes in japonica rice storage granaries NO. 37, NO. 38 and NO. 40 every two months from February to September. In the three granaries, the accumulated temperature during storage continued to increase, but the mould counts first increased and then decreased. When the accumulated temperature was 650-1000 degrees C center dot d, the quantity of mould reached its maximum. The content of volatile components such as ketones, alcohols, sulphur compounds and acids measured by the electronic nose increased significantly. Illumina high-throughput sequencing revealed that as the accumulated temperature reached 650-1000 degrees C center dot d, the fungi community richness and diversity were higher than at other accumulated temperatures in the three granaries. In addition, at the fungal genus level, unclassified_Hypocreales, Papiliotrema, Bulleromyces, Sarocladium, Dioszegia and unclassified_Ustilagina-ceae had an obvious correlation with the volatile hydrocarbons and alcohols (p < 0.05) measured by gas chromatography mass spectrometry (GC-MS). After screening the dominant strains, we found that the volatile hydrocarbons were mainly from Papiliotrema_fuscus, Pleosporales_sp, Alternaria_sp, Phaeosphaeria_microscopica, Bulleromyces_spand and Erythrobasidium_hasegawianum. Therefore, the accumulated temperature of 650-1000 degrees C.d over two months can be used as an indicator for rapid moulds growth. Furthermore, the volatile compound content reflects the extent of fungal activity and can be used as a reference for monitoring rice quality and consumption safety. (C) 2021 Elsevier Ltd. All rights reserved.