Microbiome Analysis of Traditional Grain Vinegar Produced under Different Fermentation Conditions in Various Regions in Korea

The fermentation of traditional vinegar is a spontaneous and complex process that involves interactions among various microorganisms. Here, we used a microbiome approach to determine the effects of networks, such as fermentation temperature, location, physicochemical and sensory characteristics, and bacterial profile, within traditional grain vinegar samples collected from various regions of Korea. Acetic acid and lactic acid were identified as the major metabolites of grain vinegar, and sourness and umami were determined as taste fingerprints that could distinguish between vinegar samples. Acetobacter ghanensis and Lactobacillus acetotolerans were the predominant bacterial species, and the functional composition of the microbiota revealed that the nucleotide biosynthesis pathway was the most enriched. These results reveal that vinegar samples fermented outdoors are more similar to each other than vinegar samples fermented at 30 °C, when comparing the distance matrix for comprehending bacterial networks among samples. This study may help obtain high-quality vinegar through optimized fermentation conditions by suggesting differences in sensory characteristics according to the fermentation environment.

Determination of the geographical origin of Tetrastigma hemsleyanum Diels & Gilg using an electronic nose technique with multiple algorithms

Tetrastigma hemsleyanum Diels & Gilg, an herbal medicinal plant, is planted widely in bamboo forests in southern China to promote economic benefits. Volatile compounds (VOCs) of T. hemsleyanum from different geographical regions are difficult to identify in field forests. In this study, VOCs from leaf samples of different geographical origins were analyzed using an electronic nose with 10 different sensors. Principal component analysis (PCA), partial least-squares regression (PLS), hierarchical cluster analysis (HCA), and radial basis function (RBF) neural networks were used to determine differences among different local samples. The results demonstrated that PCA achieved an accurate discrimination percentage of 91.31% for different samples and HCA separated the samples into different groups. The RBF neural network was successfully applied to predict samples with no specified localities. T. hemsleyanum samples from geographically close regions tended to group together, whereas those from distant geographical regions showed obvious differences. These results indicate that an electronic nose is an effective tool for detecting VOCs and discriminating the geographical origins of T. hemsleyanum. This study provides insights for further studies on the fast detection of VOCs from plants and effect of forests and plant herbal medicines on improving air quality.

Geoherbalism evaluation of Radix Angelica sinensis based on electronic nose

Radix Angelica sinensis (Danggui, DG), derived from the dry root of Angelicae sinensis, is popularly used for its antioxidant, hematinic and immuno-enhancement. However, DG from different origins possess different quality, and difficult to identity. In this study, we used electronic nose technique to investigate DG from different producing areas for monitoring the correlation of origin and quality. The electronic nose was employed to establish classification model of DG originated from four main producing areas of Gansu, Yunnan, Sichuan and Hubei in China. Principal component analysis (PCA) and discriminant function analysis (DFA) were performed to differentiate DG samples from four main producing areas. The content of phthalides of DG were determined to confirm the quality changes and investigate its correlation with the odor response values by Gas Chromatography-Mass Spectrometer (GC-MS). The results of PCA and DFA analysis showed that the electronic nose could accurately distinguish DG from four main producing areas. The method of electronic nose for identification could be verified by GC-MS technology, and the main ingredient content was consistent with its odor of DG. In conclusion, electronic nose could effectively identify different origins of DG, and could be applied for rapid identification and quality control of genuine Angelica herbs.