College of Food Science and Engineering, Qingdao Agricultural University, Qingdao 266109, Shandong, China.
Institute of Feed Research, Xinjiang Academy of Animal Science, Urumqi 830000, Xinjiang, China.
Food Res Int. 2024 Dec;197(Pt 1):115233. doi: 10.1016/j.foodres.2024.115233. Epub 2024 Oct 21.
The dynamic changes in physicochemical properties, microbial communities, and volatile compounds in kombucha made from Flos sophorae (FLSK) and Elm fruit (EFK) were compared to those of black tea (BTK) and green tea (GTK) over a 12-day fermentation period. The results revealed that overall flavonoid and polyphenol content, as well as antioxidant activity, increased initially and then decreased, accompanied by a steady reduction in pH within the fermentation broths investigated. Notably, the GTK exhibited stronger antioxidant activity than the other fermentation broths. Furthermore, 16S rRNA gene sequencing revealed that Komagataeibacter rhaeticus, Komagataeibacter saccharivorans, and Acidovorax wautersii were the dominating microbial species in the fermentation broths under this study. Komagataeibacter rhaeticus initially reduced and then increased throughout the FLSK fermentation, whereas Komagataeibacter saccharivorans increased from day 0 to day 6, and remain stable by day 12 during the EFK fermentation. Comparative analysis revealed that Komagataeibacter rhaeticus was more abundant in the FLSK and GTK than in the EFK and BTK, whereas Komagataeibacter saccharivorans showed a higher abundance in the EFK relative to the other fermentation broths. Gas chromatography-mass spectrometry identified acetic acid, linalool, ethanol, and ethyl acetate as the major volatile chemicals that rose significantly in fermentation mixtures of the examined substrates. The FLSK had a much higher linalool concentration than the other fermentation broths, although the EFK and GTK had higher ethanol content. Correlation study found that Komagataeibacter rhaeticus was negatively related with alcohol compounds, but Komagataeibacter saccharivorans was positively associated with a diverse spectrum of acids, alcohols, and esters. The study found changes in bioactive chemicals as well as interactions between bacterial populations and volatile compounds throughout fermentation in the substrates investigated.
比较了槐米（FLSK）和榆钱（EFK）与红茶（BTK）和绿茶（GTK）在 12 天发酵过程中理化性质、微生物群落和挥发性化合物的动态变化。结果表明，总黄酮和多酚含量以及抗氧化活性先增加后减少，发酵液的 pH 值也随之稳定下降。值得注意的是，GTK 表现出比其他发酵液更强的抗氧化活性。此外，16S rRNA 基因测序显示，发酵液中主要的微生物种类为 Rhodococcus komagatae、 Saccharibacter saccharivorans 和 Acidovorax wautersii。在 FLSK 发酵过程中， Rhodococcus komagatae 先减少后增加，而在 EFK 发酵过程中， Komagataeibacter saccharivorans 从第 0 天增加到第 6 天，到第 12 天保持稳定。比较分析表明， Rhodococcus komagatae 在 FLSK 和 GTK 中的丰度高于 EFK 和 BTK，而 Komagataeibacter saccharivorans 在 EFK 中的丰度高于其他发酵液。气相色谱-质谱法鉴定出乙酸、芳樟醇、乙醇和乙酸乙酯是主要的挥发性化合物，在被检测底物的发酵混合物中含量显著增加。FLSK 的芳樟醇浓度远高于其他发酵液，尽管 EFK 和 GTK 的乙醇含量较高。相关性研究发现， Rhodococcus komagatae 与醇类化合物呈负相关，而 Komagataeibacter saccharivorans 与各种酸、醇和酯呈正相关。该研究发现，在所研究的底物中，生物活性化学物质以及细菌种群和挥发性化合物之间的相互作用在发酵过程中发生了变化。
