Benzoic and propionic acids in fishery products on the Korean market.

A new pretreatment technique for the sensitive and accurate determination of benzoic and propionic acids in fishery products by HPLC-DAD and GC-MS was established to address the regulatory problem posed by the natural metabolic production of preservatives during food processing. A total of 786 samples (332 raw fish and 454 processed fish products) were investigated. Benzoic acid was detected in 2.4% of raw fish samples, 9.7% of processed product samples, while the corresponding numbers for propionic acid equalled 88.3% and 94.7% respectively. As are result of monitoring the samples obtained from the Korean market, propionic acid was detected in most samples, but benzoic acid was detected in some fish. These results provide fundamental data regarding naturally occurring preservatives in fishery. As a result of these databases in fishery could be used as important data for the judgement that they are naturally originated preservatives.

Effects of different storage conditions on the metabolite and microbial profiles of white rice (Oryza sativa L.).

Microbial populations in white rice (Oryza sativa L.) samples stored for 6 months in open or closed conditions were studied and their metabolite profiles analyzed using GC/MS to elucidate the relationship between storage and rice quality. Rice samples stored in open conditions at 25 °C were contaminated by Aspergillus tritici, Cladosporium cladosporioides, and Penicillium sp., whereas the control stored in closed conditions at 5 °C was mainly contaminated by Hyphopichia burtonii and A. tritici. These differences resulted in significantly different metabolite profiles. Increased mold population decreased the levels of fresh rice flavor-associated volatile metabolites and primary energy sources, but increased the levels of metabolites associated with lipid oxidation, polyols, and energy production. Thus, rice quality, especially flavor, could be significantly influenced by the increased mold population caused by open storage at 25 °C; volatile metabolites and polyols are potential indicators of rice quality.

Metabolomics Analysis of the Lipid-Regulating Effect of Allium hookeri in a Hamster Model of High-Fat Diet-Induced Hyperlipidemia by UPLC/ESI-Q-TOF Mass Spectrometry.

Hyperlipidemia is a risk factor for atherosclerotic cardiovascular disease and is a major public health concern. Allium hookeri (AH) is an Allium species containing high levels of bioactive organosulfur compounds such as methiin and cycloalliin. AH exerts hypolipidemic effects in animals fed a high-fat diet. However, there exists little information on the mechanisms underlying these effects. To address this issue, we used a metabolomic approach based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry to identify factors mediating the lipid-lowering effects of AH. Principal component and partial least-squares discriminant analyses of serum metabolome profiles revealed 25 metabolites as potential biomarkers for the effects of AH on lipid levels. These compounds were predominantly phospholipids, including phosphatidylcholines (PCs), lysoPCs, and lysophosphatidylethanolamines. Glycerophospholipid metabolism was identified as a significantly enriched pathway. These results provide mechanistic insight into the antihyperlipidemic effects of AH and evidence for its efficacy as a therapeutic agent.

Sorbic, benzoic and propionic acids in fishery products: a survey of the South Korean market.

This study was conducted to provide basic data as part of a project to distinguish naturally occurring organic acids from added preservatives. Accordingly, we investigated naturally occurring levels of sorbic, benzoic and propionic acids in fish and their processed commodities. The levels of sorbic, benzoic and propionic acids in 265 fish and their processed commodities were determined by high-performance liquid chromatography-photodiode detection array (HPLC-PDA) of sorbic and benzoic acids and gas chromatography-mass spectrometry (GC/MS) of propionic acid. For propionic acid, GC-MS was used because of its high sensitivity and selectivity in complicated matrix samples. Propionic acid was detected in 36.6% of fish samples and 50.4% of processed fish commodities. In contrast, benzoic acid was detected in 5.6% of fish samples, and sorbic acid was not detected in any sample. According to the Korean Food and Drug Administration (KFDA), fishery products and salted fish may only contain sorbic acid in amounts up to 2.0 g kg-1 and 1.0 g kg-1, respectively. The results of the monitoring in this study can be considered violations of KFDA regulations (total 124; benzoic acid 8, propionic acid 116). However, it is difficult to distinguish naturally generated organic acids and artificially added preservatives in fishery products. Therefore, further studies are needed to extend the database for distinction of naturally generated organic acids and added preservatives.

Effects of Different Salt Treatments on the Fermentation Metabolites and Bacterial Profiles of Kimchi.

The effects of purified salt (PS) and mineral-rich sea salt (MRS), both with different mineral profiles, on kimchi fermentation were studied using a culture-dependent 16S rRNA sequencing technique and mass-based metabolomic analysis. The different mineral profiles in the fermentation medium caused changes in the bacterial profiles of the 2 kimchi products. An increase of Leuconostoc species in MRS-kimchi decreased the Lactobacillus/Leuconostoc ratio, which led to changes in metabolites (including sugars, amino acids, organic acids, lipids, sulfur compounds, and terpenoids) associated with kimchi quality. Although further studies on the relationship between these salt types and kimchi fermentation are needed, these results suggested that the MRS treatment had positively affected the changes of the kimchi mineral contents, bacterial growth, and metabolite profiles, which are linked to kimchi quality.

Mass-Based Metabolomic Analysis of Lactobacillus sakei and Its Growth Media at Different Growth Phases.

Changes in the metabolite profiles of Lactobacillus sakei and its growth media, based on different culture times (0, 6, 12, and 24 h), were investigated using gas chromatography-mass spectrometry (MS) and liquid chromatography-MS with partial least squares discriminant analysis, in order to understand the growth characteristics of this organism. Cell and media samples of L. sakei were significantly separated on PLS-DA score plots. Cell and media metabolites, including sugars, amino acids, and organic acids, were identified as major metabolites contributing to the difference among samples. The alteration of cell and media metabolites during cell growth was strongly associated with energy production. Glucose, fructose, carnitine, tryptophan, and malic acid in the growth media were used as primary energy sources during the initial growth stage, but after the exhaustion of these energy sources, L. sakei could utilize other sources such as trehalose, citric acid, and lysine in the cell. The change in the levels of these energy sources was inversely similar to the energy production, especially ATP. Based on these identified metabolites, the metabolomic pathway associated with energy production through lactic acid fermentation was proposed. Although further studies are required, these results suggest that MS-based metabolomic analysis might be a useful tool for understanding the growth characteristics of L. sakei, the most important bacterium associated with meat and vegetable fermentation, during growth.

Mass-based metabolomic analysis of soybean sprouts during germination.

We investigated the metabolite profile of soybean sprouts at 0, 1, 2, 3, and 4days after germination using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-MS (LC-MS) to understand the relationship between germination and nutritional quality. Data were analyzed by partial least squares-discriminant analysis (PLS-DA), and sprout samples were separated successfully using their PLS-DA scores. Fifty-eight metabolites, including macromolecular derivatives related to energy production, amino acids, myo-inositol metabolites, phytosterols, antioxidants, isoflavones, and soyasaponins, contributed to the separation. Amino acids, myo-inositol metabolites, isoflavone aglycones, B soyasaponins, antioxidants, and phytosterols, associated with health benefits and/or taste quality, increased with germination time while isoflavone glycosides and DDMP soyasaponins decreased. Based on these metabolites, the metabolomic pathway associated with energy production in soybean sprouts is suggested. Our data suggest that sprouting is a useful processing step to improve soybean nutritional quality, and metabolomic analysis is useful in understanding nutritional change during sprouting.