Changes in the Quality and Microflora of Yellowtail Seriola quinqueradiata Muscles during Cold Storage.

We evaluated the changes in the quality and microflora of yellowtail flesh cold-stored until spoilage. Based on the sensory evaluation, odor palatability was deemed unacceptable for dark muscle (DM) and the dorsal part of the ordinary muscle (OD) after >10 days and 14 of storage, respectively. Log 7 CFU/g in DM as well as OD was obtained on days 10 (Aeromonas spp.) and 14 (Enterobacteriaceae and Pseudomonas spp.) of storage, whereas log 5 (Brocothrix thermosphacta) and 6 (H2S-producing bacteria) CFU/g in them were obtained on day 14 of storage. In these bacteria, the viable bacterial counts of Pseudomonas spp. and Aeromonas spp. in DM were significantly higher than those in OD only at some storage times. Amplicon sequencing revealed that in both muscles, Pseudomonas became predominant after storage, with greater than 90% recorded after more than 10 days of storage. The relative abundances of Acinetobacter, Unclassified Gammaproteobacter, and Shewanella were relatively high in both muscles after more than 10 days of storage; however, these values were less than 5%. Ethyl butyrate in the OD and DM and 2,3-butanedione in the OD were first detected on days 14 and 10 of storage, respectively. Acetoin in the OD increased by 81-fold after 14 days of storage and was significantly increased in the DM after more than 10 days compared with the amount detected pre-storage. Volatiles, such as (E)-2-pentenal in the OD and 1-pentanol in the DM, decreased and increased linearly, respectively, throughout the 14-day storage period. Altogether, these volatile components may cause quality deterioration due to spoilage and/or lipid oxidation during cold storage of the OD and DM.

Association of eating habits and Firmicutes/Bacteroidetes ratio among Japanese female university students: A cross-sectional study.

Background & Aims: University students are prone to changes in their health status and lifestyle due to changes in their living environment and associated stress and anxiety. These changes may affect them in later life. This study utilized a cross-sectional study among Japanese female university students to examine dietary factors affecting their fecal microbiota. Methods: Sixty-eight healthy female university students were evaluated using an eating behavior assessment and diet history questionnaire. The 12-component Japanese diet index (JDI-12) was then calculated. A quantitative real-time PCR method was used to analyze the predominant bacterial species in the gut, and the Firmicutes/Bacteroidetes ratio (F/B ratio) at the phylum level was calculated. The partial correlation between the fecal microbiota and eating behavior abnormality score was assessed, and dietary habits associated with the F/B ratio were analyzed. Results: A significant correlation was identified between F/B ratios and the eating behavior abnormality score (r = 0.26, FDR = 0.064). Additionally, multiple regression analysis identified a negative correlation trend between the F/B ratio and JDI-12 score (ß = -0.22; p = 0.091), and exploratory analysis found a negative association between the F/B ratio and consumption of beef and pork, one of the less beneficial JDI-12 components (ß = -0.33, FDR = 0.120). Conclusion: In healthy female university students, there was a positive correlation between eating behavior abnormality and the F/B ratio, indicating that adherence to the Japanese diet pattern may be associated with a lower F/B ratio.

Effect of storage after heating on odor of muscles of yellowtail (Seriola quinqueradiata).

Effects of storage after heating on the odor of yellowtail Seriola quinqueradiata muscle were investigated. Sensory evaluation demonstrated odor degradation during storage of ordinary muscle as well as dark muscle (DM). First, different volatile profiles between OM (dorsal and ventral) and DM were found; their profiles were also different between non-stored samples (raw samples and just-heated samples) and stored samples except for a part of stored OM. Although the dorsal and ventral OMs differed in lipid content, their volatile profiles were similar to each other. The aforementioned differences were due to increased levels of lipid oxidation compounds (eg, aldehydes and alcohols) during storage after heating. However, none of the muscle parts showed significant changes in the intensity of each odor perceived by gas chromatography-olfactometry and trimethyl amine during storage. These findings suggested multiple volatile components may contribute to the odor deterioration of heated yellowtail muscle during cold storage.

Effect of different heating conditions on odor of yellowtail Seriola quinqueradiata muscles.

The effects of different heating conditions set to prevent food poisoning on the volatile components, lipid oxidation, and odor of yellowtail, Seriola quinqueradiata, were investigated. The heating conditions did not affect the lipid oxidation, fatty acid composition, and volatile compounds of each part of the flesh. High-temperature/short-time (90 °C for 6 min) heating led to significantly higher trimethylamine (TMA) contents in all muscle parts and higher odor intensity of TMA in dark muscle (DM) compared to those of lower temperature heating. Sensory evaluation showed that the odor intensities of all muscle parts heated at high-temperature/short-time were stronger than those at low-temperature/long-time (63 °C for 30 min). All DM samples had less odor palatability than the other flesh parts. Therefore, DM may have contributed to the unfavorable odor of steamed yellowtail meat and high-temperature/short-time heating may have enhanced the odor of all flesh parts compared with those subjected to low-temperature/long-time.

Analysis of Primary Metabolites in Cabbage (Brassica oleracea var. capitata) Varieties Correlated with Antioxidant Activity and Taste Attributes by Metabolic Profiling.

Brassica vegetables, such as cabbage, have many health benefits arising from their antioxidant and anticancer properties. These properties are endowed by the metabolite composition of the plant, and it is therefore important to elucidate the metabolic profile and associated activities in this genus. This study objectively evaluated the characteristics of cabbage varieties using metabolic profiling to identify the primary metabolic components that correlate with antioxidant activity and taste attributes. GC-MS analysis was used to identify the primary metabolites. Antioxidant activity was measured by oxygen radical absorbance capacity (ORAC) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging assays, and an electronic tongue was used to quantitate nine taste attributes. Orthogonal projections to latent structures (OPLS) using SIMCA 14 correlated the metabolite components with the taste and antioxidant characteristics. We identified 4-aminobutyric acid, fructose 1-phosphate, adipic acid, 5-oxoproline, N-acetylglycine, O-phosphoethanolamine, and homovanillic acid as important determinants of DPPH scavenging activity and umami, sourness, acidic bitterness, irritant and saltiness, bitterness, astringency, and richness, respectively. These metabolites represent markers indicating breed differences and contribute to differential cabbage functionality. These studies could be extended to measure additional metabolites, as well as to understand the role of growth conditions on the metabolic profile and health benefits of plants.

Changes in Metabolic Profiles of Yellowtail (Seriola quinqueradiata) Muscle during Cold Storage as a Freshness Evaluation Tool Based on GC-MS Metabolomics.

We applied metabolomics to the evaluation of yellowtail muscle as a new freshness evaluation method for fish meat. Metabolites from yellowtail ordinary and dark muscle (DM) stored at 0 °C and 5 °C were subjected to metabolomics for primary metabolites based on gas chromatography-mass spectrometry (GC-MS). For the annotated metabolites, we created statistically significant models for storage time prediction for all storage conditions by orthogonal partial least squares analysis, using storage time as the y-variable. DM is difficult to evaluate using the K value method, the predominant existing freshness evaluation method. However, in the proposed method, the metabolic component profiles of DM changed depending on storage time. Important metabolites determined from variables important for prediction (VIP) values included various metabolites, such as amino acids and sugars, in addition to nucleic-acid-related substances, especially inosine and hypoxanthine. Therefore, metabolomics, which comprehensively analyses different molecular species, has potential as a new freshness evaluation method that can objectively evaluate conditions of stored fish meat.

Taste Evaluation of Yellowtail (Seriola Quinqueradiata) Ordinary and Dark Muscle by Metabolic Profiling.

We performed metabolic profiling on yellowtail (Seriola quinqueradiata) muscle to develop an objective taste evaluation method for fish meat. Dark (DM) and ordinary (OM) muscle samples before and after storage were subjected to gas chromatography-mass spectrometry (GC-MS) analysis and taste measurements using an electronic tongue. The metabolites identified by the GC-MS analysis were treated as x variables, and the taste values obtained by the electronic tongue were treated as y variables. The relationships between the metabolites and taste attributes were evaluated by two-way orthogonal projections to latent structures (O2PLS) analysis. The O2PLS analyses were normalized in two ways, unit variance (UV) and pareto (Par) scaling. The O2PLS (UV) analysis produced 3+1+0 models in Autofit and this model was statistically significant with R2Y (0.73) and Q2 (0.52) metrics. In particular, significant correlations were found between DM or OM and metabolite intensity and taste attributes, and strong associations were found between "sourness" and lysine, "irritant" and alanine and phenylalanine, "saltiness" and pantothenic acid, and "umami" and creatinine and histidine. The O2PLS (Par) analysis of DM generated significant predictive models for "acidic bitterness," "irritant," "saltiness," "bitterness," "astringency," and "richness." Among these, only "irritant" was affected by storage. This method was thus effective in evaluating the taste of yellowtail muscle.

Metabolic Profiling of Fish Meat by GC-MS Analysis, and Correlations with Taste Attributes Obtained Using an Electronic Tongue.

To evaluate the taste of ordinary muscle from white-fleshed fish, we used GC-MS metabolomic analysis to characterise the compounds therein, and correlated the obtained data with taste measurements from an electronic tongue. Prediction models using orthogonal partial least squares were produced for different taste attributes, and the primary metabolic components correlated with the taste attributes were identified. Clear differences were observed in the component profiles for different fish species. Using an electronic tongue, differences in tastes were noted among the fish species in terms of sourness, acidic bitterness, umami and saltiness. The obtained correlations allowed the construction of good taste prediction models, especially for sourness, acidic bitterness and saltiness. Compounds such as phosphoric acid, lactic acid and creatinine were found to be highly correlated with some taste attributes. Phosphoric acid in particular showed the highest variable important for prediction (VIP) scores in many of the taste prediction models, and it is therefore a candidate marker to evaluate the tastes of white-fleshed fish.

Analysis of N(ε) -ethyllysine in human plasma proteins by gas chromatography-negative ion chemical ionization/mass spectrometry as a biomarker for exposure to acetaldehyde and alcohol.

BACKGROUND: N(ε) -ethyllysine (NEL) is a major stable adduct formed by the reaction of acetaldehyde (AA) with lysine residues in proteins. However, its occurrence and levels in biological specimens and its relationship with AA/alcohol exposure-associated disorders have not been fully elucidated. In this study, we have developed a sensitive and specific method to quantitate NEL levels in human plasma proteins. METHODS: The method consists of (1) purification of the protein fraction of interest by Sephadex G-15 to remove low molecular substances, (2) hydrolysis of proteins with Pronase E in the presence of stable isotope-labeled internal standards, (3) derivatization of amino acids with pentafluorobenzyl (PFB) bromide, and (4) quantification of the PFB derivatives of NEL and l-lysine using gas chromatography-negative ion chemical ionization/mass spectrometry in a selected ion monitoring mode. RESULTS: Using the above method, the NEL levels in human plasma proteins obtained from 10 each of control subjects and alcoholic patients were measured. NEL was detected in all samples analyzed, the average level of NEL in the plasma proteins of alcoholic patients (1.17 ± 0.36 NEL/1,000 l-lysine) being significantly higher than that of control subjects (0.26 ± 0.07 NEL/1,000 l-lysine). CONCLUSIONS: The method could be applied to molecular epidemiological studies to investigate possible associations between the NEL levels in human tissue proteins and human diseases associated with exposure to AA and alcohol.

Chemoprevention of azoxymethane/dextran sodium sulfate-induced mouse colon carcinogenesis by freeze-dried yam sanyaku and its constituent diosgenin.

The effects of sanyaku, a traditional Chinese medicine [freeze-dried powder of the yam tuber (Dioscorea)], and its major steroidal saponin constituent, diosgenin, on colon carcinogenesis were investigated. Male ICR mice were subjected to a single intraperitoneal injection of azoxymethane (AOM; 10 mg/kg body weight) followed by administration of 1.5% dextran sodium sulfate (DSS) in drinking water for 7 days to establish carcinogenesis. Commercial diosgenin or sanyaku, which contained diosgenin at 63.8 ± 1.2 mg/kg dry weight, was given in the diet at 20, 100, or 500 mg/kg for 17 weeks. Groups of mice that received diosgenin or sanyaku at all doses yielded significantly less number of colon tumors compared with the AOM/DSS-treated mice. Occurrence of colonic mucosal ulcer and dysplastic crypt induced by AOM/DSS treatment was also significantly decreased by the administration of diosgenin and sanyaku, which was in accordance with the significant reduction of AOM/DSS-mediated increases in expression of inflammatory cytokines such as IL-1ß by diosgenin and sanyaku. Furthermore, elevated levels of serum triglyceride in the AOM/DSS-treated mice tended to be reduced in mice given diosgenin and sanyaku. Microarray and real-time reverse transcriptase PCR analyses revealed that diosgenin administration increased 12-fold the expression of lipoprotein lipase, which may contribute to reduced serum triglyceride levels. Other genes altered by diosgenin included those associated with antioxidative stress responses and apoptosis, such as heme oxygenase-1, superoxide dismutase-3, and caspase-6. Our results imply that the Chinese medicine sanyaku and the tubers of various yams containing diosgenin as food could be ingested to prevent colon carcinogenesis in humans.