Rui Wang,Yi Zeng,Jiaqian Liang,Huixin Zhang,Junjie Yi,Zhijiia Liu
Fermented vegetables are known for their unique flavors and aromas, which are influenced by the complex microbial processes that occur during fermentation. Rhodotorula mucilaginosa is a red yeast strain that is frequently isolated from fermented vegetables. However, the specific mechanisms underlying their effects on aroma production remain unclear. In this study, a simulated system of vegetables fermented using vegetable juices was used to investigate the effects of R. mucilaginosa inoculation on aroma development. The results demonstrated that this red yeast strain could utilize the nutrients present in the vegetable juices to support its growth and reproduction. Moreover, the inoculation of fermented vegetable juices with this yeast strain led to an increase in the levels of umami amino acids and sweet amino acids. Furthermore, this yeast strain was found able to significantly reduce the content of sulfur-containing compounds, which may decrease the unpleasant odor of fermented vegetables. Additionally, the yeast strain was capable of producing high concentrations of aromatic compounds such as phenylethyl alcohol, methyl 2-methylbutyrate, methyl butyrate, and nonanoic acid in a minimum medium. However, only phenylethyl alcohol has been identified as a core aromatic compound in fermented vegetable juice. The three fermented vegetable juices exhibited significantly different flavor profiles according to comparative analysis. Therefore, the core flavor compounds found in fermented vegetables are primarily derived from the release and modification of endogenous flavors naturally present in the vegetables, facilitated by the yeast during fermentation.
Liu Chen,Xue Wen-jiao,Ding Hao,An Chao,Ma Sai-jian,Liu Yao
The objective of this study was to assess in vitro probiotic potential of Lactobacillus strains derived from artisanal fermented vegetables in Shaanxi, China. In total, 74 acid-producing Gram-positive strains with rod-shaped under the microscope were isolated from 16 samples of spontaneously fermented vegetables. Out of 74 strains, 26 showed high survival rate under low pH and high bile salts conditions and were subjected to molecular identification by 16S rRNA gene sequencing analysis. The results showed that 15 isolates belonged to Lactobacillus plantarum, 9 isolates belonged to Lactobacillus brevis, and the 2 remaining strains belonged to Weissella viridescens. The 24 Lactobacillus strains were investigated for their survival rate to transit simulated gastrointestinal tract, cell surface hydrophobicity, auto-aggregation, co-aggregation with pathogen, adhesion to Caco-2, antimicrobial activity, antibiotics susceptibility, radical scavenging ability, α-glucosidase inhibition, and the cholesterol assimilation. The results showed that the probiotic characteristics were strain-dependent, and several strains exhibited great probiotic potential with specific health benefits, which indicated that they might be excellent candidates for production of functional foods. Interestingly, it was first found that L. plantarum generally had higher antibacterial activities, α-glucosidase inhibition ability, and antibiotics susceptibility compared to L. brevis in this study. The results indicated that Lactobacillus strains isolated from fermented vegetables in Shaanxi, China, could be exploited as a promising novel probiotic source.
Jie Xiong,Ya-ying Wang,Muhammad Yousaf,Dong-mei Liu
Summary The fermented vegetable is a long-history food, and the addition of probiotics in recent years has pushed it in a novel direction. This study explored the impact of a Direct-vat set starter (DVS), comprising Lactiplantibacillus plantarum MC14 and Leuconostoc mesenteroides , on pickled radish (PR). The addition of DVS triggered a rapid reduction in pH and titratable acidity, leading to lowered nitrite levels and increased viable count. Textural analysis showed that DVS increased the springiness and chewiness of PR by about 55.07% and 25.73%, respectively. Organic acid analysis unveiled eight compounds. The addition of probiotics did not significantly affect the antioxidant properties but was able to significantly enhance the XO inhibitory activity of PR. DVS decreased undesirable flavor compounds such as isothiocyanates and sulfides, while elevating esters, aldehydes, and acids. Our results suggested that DVS is a promising starter culture that can enhance the texture and flavor of fermented vegetables.
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