Lactic acid bacteria play important roles in various fermented foods in Asia. Besides being the main component in kimchi and other fermented foods, they are used to preserve edible food materials through fermentation of other raw-materials such as rice wine/beer, rice cakes, and fish by producing organic acids to control putrefactive microorganisms and pathogens. These bacteria also provide a selective environment favoring fermentative microorganisms and produce desirable flavors in various fermented foods. This paper discusses the role of lactic acid bacteria in various non-dairy fermented food products in Asia and their nutritional and physiological functions in the Asian diet.

The effects of climatic conditions on green tea metabolites in three different growing areas of Jeju Island, South Korea, were investigated through global metabolite profiling by (1)H nuclear magnetic resonance (NMR) spectroscopy. Pattern recognition methods, such as principal component analysis (PCA) and orthogonal projection on latent structure-discriminant analysis (OPLS-DA), revealed clear discriminations of green teas from the three different growing areas. Variations of theanine, isoleucine, leucine, valine, alanine, threonine, glutamine, quinic acid, glucose, epicatechin (EC), epigallocatechin (EGC), epigallocatechin-3-gallate (EGCG), and caffeine levels were responsible for the discriminations. Green teas grown in an area with high temperature, long sun exposure time, and high rainfall had higher levels of theanine but lower levels of isoleucine, leucine, valine, alanine, EC, EGC, EGCG, and caffeine than those grown in areas with relatively low temperature, short sun exposure time, and low rainfall. These results indicate that high temperature, long sun exposure, and high preciptation stimulate theanine synthesis in green tea during the spring season. This study highlights how metabolomics coupled with multivariate statistical analysis can illuminate the metabolic characteristics of green tea associated with climatic variables, thereby allowing for the assessment of quality strategy in green tea production.

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The dependence of global green tea metabolome on plucking positions was investigated through (1)H nuclear magnetic resonance (NMR) analysis coupled with multivariate statistical data set. Pattern recognition methods, such as principal component analysis (PCA) and orthogonal projection on latent structure-discriminant analysis (OPLS-DA), were employed for a finding metabolic discrimination among fresh green tea leaves plucked at different positions from young to old leaves. In addition to clear metabolic discrimination among green tea leaves, elevations in theanine, caffeine, and gallic acid levels but reductions in catechins, such as epicatechin (EC), epigallocatechin (EGC), epicatechin-3-gallate (ECG), and epigallocatechin-3-gallate (EGCG), glucose, and sucrose levels were observed, as the green tea plant grows up. On the other hand, the younger the green tea leaf is, the more theanine, caffeine, and gallic acid but the lesser catechins accumlated in the green tea leaf, revealing a reverse assocation between theanine and catechins levels due to incorporaton of theanine into catechins with growing up green tea plant. Moreover, as compared to the tea leaf, the observation of marked high levels of theanine and low levels of catechins in green tea stems exhibited a distinct tea plant metabolism between the tea leaf and the stem. This metabolomic approach highlights taking insight to global metabolic dependence of green tea leaf on plucking position, thereby providing distinct information on green tea production with specific tea quality.

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Lactic acid bacteria (LAB) were isolated from Korean Meoru (Vitis coigneties) wine and identified as Lactobacillus plantarum meoru0711 (KACC 91436C). The fermentative behavior and metabolic effects of L. plantarum during malolactic fermentation (MLF) were compared with those of the commercial Oenococcus oeni strain through 1H NMR- and GC-based metabolic profiling. Twenty-two primary metabolites of amino acids, carbohydrates, and organic acids, and 55 secondary metabolites of volatile compounds were identified in wines by 1H nuclear magnetic resonance (NMR) spectroscopy and gas chromatography (GC), respectively. Principal component analysis (PCA) revealed that malolactic (ML)-fermented and non-ML-fermented wines, and wines ML-fermented with O. oeni and L. plantarum were clearly differentiated. Both the primary and secondary metabolites were responsible for these differentiations. Compared to non-MLF wines, MLF wines were characterized by increased levels of primary metabolites such as lactic acid, phenylalanine, uracil, ornithine, alanine, threonine, leucine, isoleucine, and valine with decreased levels of monosaccharides, glycerol, malic, and citric acids. In addition, higher levels of secondary metabolites such as butanal, ethyl isobutylate, isobutanol, isoamyl acetate, 2-butanoate ethyl ester, isoamyl alcohol, ethyl hexanoate, glycine, acetic acid, and benzaldehyde characterized the MLF wine. Higher levels of primary metabolites such as tyrosine, monosaccharides, glycerol, alanine, 2,3-butanediol, valine, and leucine, and of secondary metabolites such as propyl acetate, isobutanol, isoamyl acetate, 1-butanol, ethyl hexanoate, prenyl alcohol, glycine, 2-hexen-1-ol, ethyl octanoate, acetic acid, benzaldehyde, and butyric, together with lower levels of lactic acid, were observed in the wines fermented by L. plantarum compared with those by O. oeni. This present study demonstrates that different genera of LAB affect both the primary and second metabolites in wine. Moreover, metabolomics with multivariate statistical analysis provide insight into wine fermentation.

The effects of five commercial Oenococcus oeni strains (MCW, Enoferm alpha, Wyeast, Vinibacti111, and Vinibacti222) on fermentative behaviors, and variations of metabolites in Meoru ( Vitis coigneties ) wines during malolactic fermentation (MLF) were investigated by metabolomic analysis of (1)H NMR and GC data sets. In the development of MLF with various O. oeni strains, the fastest conversions of malic acid to lactic acid occurred in wines fermented with Enoferm alpha and Vinibacti111 strains. Seventeen primary metabolites and 65 secondary metabolites of volatile compounds in the wines were identified by (1)H NMR spectroscopy and GC-MS, respectively. In pattern recognition models of principal component analysis (PCA) and orthogonal projection to latent structures discriminant analysis (OPLS-DA), significant differentiations between wines with O. oeni strains were identified by the secondary metabolites rather than by the primary metabolites, showing the effects of O. oeni strains only on the secondary metabolites. Twelve volatile compounds, 2-phenylethanol, isoamyl alcohol, 2-butanol, ethyl octanoate, ethyl hexanoate, hexadecanoic acid, diethyl succinate, butyl butyrate, octanoic acid, 9-hexadecanoic acid, isobutyric acid, and 2-ethyl-1-hexanol, contributed to the differentiation of wines according to O. oeni strain, including spontaneous MLF. This study demonstrates that O. oeni strains affect the secondary metabolites, which are easily identified through multivariate statistical analysis of GC-MS data set.