Effect of High Hydrostatic Pressure Treatment on Urease Activity and Inhibition of Fishy Smell in Mackerel (Scomber japonicus) during Storage.

In this study, the physicochemical changes related to fishy smell were determined by storing high hydrostatic pressure (HHP)-treated mackerel (Scomber japonicus) meat in a refrigerator for 20 days. The inhibition of crude urease activity from Vibrio parahaemolyticus using HHP treatment was also investigated. The mackerel meat storage experiment demonstrated that production of trimethylamine (TMA) and volatile basic nitrogen (VBN), the main components of fishy smell, was significantly reduced on the 20th day of storage after the HHP treatment compared to the untreated mackerels. The results demonstrated that the increased ammonia nitrogen rates in the 2000, 3000, and 4000 bar, HHP-treated groups decreased by 23.8%, 23.8%, and 31.0%, respectively, compared to the untreated groups. The enzyme activity of crude urease was significantly reduced in the HHP-treated group compared to that in the untreated group. Measurement of the volatile organic compounds (VOCs) in mackerel meat during storage indicated that the content of ethanol, 2-butanone, 3-methylbutanal, and trans-2-pentenal, which are known to cause off-flavor due to spoilage, were significantly reduced by HHP treatment. Collectively, our results suggested that HHP treatment would be useful for inhibiting the activity of urease, thereby reducing the fishy smells from fish and shellfish.

Effect of locust bean gum-sodium alginate coatings incorporated with daphnetin emulsions on the quality of Scophthalmus maximus at refrigerated condition.

In this study, the microbiological, physicochemical, and flavor changes of turbot (Scophthalmus maximus) coated with a composite active coating of locust bean gum (LBG) and sodium alginate (SA) supplemented with daphnetin emulsions (0.16, 0.32, 0.64 mg·mL-1) were determined during 18 days of refrigerated storage (4 ± 1 °C). Results showed that LBG-SA coatings containing 0.32 mg·mL-1 daphnetin emulsions could significantly lower the total viable count (TVC), psychrophiles, Pseudomonas spp. and H2S-producing bacteria counts, and inhibit the productions of off-flavor compounds including the total volatile basic nitrogen (TVB-N), trimethylamine (TMA) and ATP-related compounds. 32 volatile compounds were identified by solid phase microextraction combined with gas chromatography-mass spectrometer method (SPME-GC/MS) during refrigerated storage and the treated turbot samples significantly lowered the relative content of fishy flavor compounds. Further, the LBG-SA coatings containing daphnetin could also delay the myofibril degradation of the turbot samples. These results indicated that the LBG-SA coatings with 0.32 mg·mL-1 daphnetin were a potential alternative way to improve the quality of turbot during refrigerated storage.

Fishy Odor and TMA Content Levels in Duck Egg Yolks.

The differences between the trimethylamine (TMA) content levels in duck and chicken egg yolks under normal dietary conditions were compared. Moreover, the association between the polymorphisms of the duck FMO3 gene and TMA content levels in duck egg yolks was analyzed. Then, to detect the mutations associated with the fish-flavor trait, duck populations were selected for a high-choline diet experiment, which was followed by full-length sequencing of the FMO3 exons. The results showed that the TMA content levels in duck eggs (3.60 µg/g) were significantly higher than those in chicken eggs (2.35 µg/g) under normal dietary conditions (P < 0.01). With regard to the high-choline diet, the average TMA content levels in duck egg yolks (9.21 µg/g; P < 0.01) increased significantly. Furthermore, 5 SNPs reported in Ensembl database were detected in duck FMO3 exons. However, no mutation loci were found to be significantly associated with the TMA content levels in duck egg yolks. Besides, duck liver FMO3 mRNA expression levels were not associated with the TMA content levels. The results indicated that excessive TMA deposition in duck eggs is one of main factors causing the fishy odor in duck eggs, and the addition of choline in the ducks' diets was responsible for inducing an increase in the TMA content levels in duck eggs. PRACTICAL APPLICATION: Our study can help to diminish the fishy taste in duck eggs by reducing the amount of supplemented choline. Furthermore, this study laid a solid foundation for revealing the genetic factors involved in the fishy odor in duck eggs.

Effects of dietary rapeseed meal supplementation on cecal microbiota in laying hens with different flavin-containing monooxygenase 3 genotypes.

To evaluate the effect of dietary rapeseed meal (RM) supplementation on cecal trimethylamine and bacteria in laying hens with different flavin-containing monooxygenase 3 (FMO3) genotypes, a 3 × 2 2-factorial arrangement was employed using FMO3 genotypes (AA, AT, and TT) and dietary RM (0 and 14% of diet) as the main effects. At 50 wk of age, 36 hens of AT genotype and 36 hens of TT genotype were randomly allotted to one of the 2 dietary treatments, and each dietary treatment consisted of 3 replicates with 6 birds each. A total of 12 hens with AA genotype were allotted to one of the 2 dietary treatments that consisted of 3 replicates with 2 hens. Hens were fed 0% RM in a corn-soybean (SM) diet for one wk before the 6-week feeding trial period. Dietary RM supplementation increased trimethylamine (TMA) concentrations in both egg yolks (P < 0.0001) and cecal chyme (P < 0.0001). Dietary RM supplementation increased bacterial abundance and diversity (P < 0.0001). Weighted UniFrac, Nonmetric Multidimensional Scaling, and analysis of similarity (R-ANOSIM = 0.1516; P-value = 0.014) indicated distinct clustering was dependent on diets rather than FMO3 genotypes. Twenty-four phyla (most dominant, Bacteroides, Firmicutes, and Proteobacteria) and 229 genera were identified in the cecal samples. Compared with the SM diets, RM diets increased the proportion of Firmicutes (P = 0.004), Proteobacteria (P = 0.006), and Firmicutes:Bacteroides (P = 0.001), and some low-abundance phyla (P < 0.01), whereas the abundance of Bacteroides was lower (P = 0.0002). The abundance of 42 genera varied with dietary types. Six phyla and 35 genera were positively correlated with TMA concentration in the cecal chyme. In conclusion, the major TMA-producing bacteria in cecal were from Firmicutes and Proteobacteria phyla. The major TMA-producing bacterial genera could be from the genera that positively correlated with TMA concentration.

The Metabolite Trimethylamine-N-Oxide is an Emergent Biomarker of Human Health.

Trimethylamine-N-oxide (TMAO) is a low molecular weight metabolite whose production is dependent on metabolism of its precursors choline, carnitine, creatinine, betaine or lecithin by host gut microbes resulting in the synthesis of trimethylamine (TMA), which is subsequently oxidized to TMAO via hepatic flavin monooxygenase (FMO). TMAO is associated with microbial dysbiosis and is being studied for its linkage with cardiovascular disorders. In addition, dysregulated levels of TMAO have been linked with renal diseases, neurological disorders and cancer. Here we discuss the enzymatic and metabolic landscape that results in TMAO production, and in addition, collate data from numerous clinical studies that have assessed TMAO as a biomarker for various disease conditions. We also summarize the interaction of TMAO with modern and traditional drugs that together affect circulating TMAO levels in the human body.

Gold nanoparticle-enhanced target for MS analysis and imaging of harmful compounds in plant, animal tissue and on fingerprint.

Gold nanoparticle-enhanced target (AuNPET) was used for detailed investigation of various materials of biological origin - human fingerprint, onion bulb and chicken liver. Analysis of these objects was focused on toxic and harmful compounds - designer drug containing pentedrone, diphenylamine in onion and potentially cancerogenic metronidazole antibiotic in liver. Detection of large quantity of endogenous compounds from mentioned objects is also shown. Most of analyzed compounds were also localized with MS imaging and relationship between their function and location was discussed. Detected compounds belong to a very wide range of chemical compounds such as saccharides, ionic and non-ionic glycerides, amino acids, fatty acids, sulfides, sulfoxides, phenols etc. Fingerprint experiments demonstrate application of AuNPET for detection, structure confirmation and also co-localization of drug with ridge patterns proving person-drug contact.

Relation between the activity of anaerobic microbial populations in oil sands tailings ponds and the sedimentation of tailings.

Oil sands tailings ponds contain a variety of anaerobic microbes, including methanogens, sulfate- and nitrate-reducing bacteria. Methanogenic activity in samples from a tailings pond and its input streams was higher with trimethylamine (TMA) than with acetate. Methanogens closely affiliated to Methanomethylovorans hollandica were found in the TMA enrichments. Tailings sedimentation increased with methanogenic activity, irrespective whether TMA or acetate was used to stimulate methanogenesis. Increased sedimentation of autoclaved tailings was observed with added pure cultures under methanogenic, as well as under nitrate-reducing conditions, but not under sulfate-reducing conditions. Scanning electron microscopy and energy-dispersive X-ray spectroscopy indicated the presence of microbes and of extracellular polymeric substances in tailings particle aggregates, especially under methanogenic and nitrate-reducing conditions. Hence different classes of microorganisms growing in tailings ponds contribute to increased tailings aggregation and sedimentation. Because addition of nitrate is known to lower methane production by methanogenic consortia, these observations offer the potential to combine lower methane emissions with improved microbially-induced tailings sedimentation.

Quality assessment of salted, modified atmosphere packaged rainbow trout under treatment with oregano essential oil.

UNLABELLED: The present study evaluated the effect of oregano essential oil (EO) on fresh salted, packaged (45%CO(2)/5%O(2)/50%N(2)) rainbow trout fillets and stored for a period of 21 d at 4 °C. Treatments included the following: M1 (control without added EO), M2 (EO 0.2%, v/w), and M3 (0.4%, v/w). Populations of lactic acid bacteria (LAB), H(2)S-producing bacteria (including Shewanella putrefaciens), Enterobacteriaceae, and Pseudomonas spp. reached higher final numbers in control (M1) than for M2 and M3 samples. Under treatments M2 and M3, total volatile basic nitrogen (TVBN) and trimethylamine nitrogen (TMAN) values were lower than for M1 samples, whereas lipid oxidation, as judged by determination of thiobarbituric acid values (TBA), did not occur during the refrigerated storage period. Interestingly, treatment M2 resulted in a shelf-life extension of 7 to 8 d for the fresh trout fillets, whereas treatment M3 proved unsuitable (due to strong odor) for trout fillet preservation, as determined by sensory evaluation. PRACTICAL APPLICATION: The use of an essential oil such as oregano oil in fresh fish preservation may be considered an alternative "natural" additive, enhancing the sensory characteristics and extending the shelf life of the product.

Gel strengthening effect of wood extract on surimi produced from mackerel stored in ice.

The effect of ethanolic kiam wood extract (EKWE) and commercial tannin (CT) on the gel properties of surimi produced from mackerel (Rastrelliger kanagurta) stored in ice for different times (0 to 12 d) was studied. During 12 d of iced storage, pH, total volatile base (TVB), trimethylamine (TMA), and trichloroacetic acid (TCA)-soluble peptide contents as well as thiobarbituric acid-reactive substances (TBARS) of mackerel mince increased while myosin heavy chain (MHC) band intensity decreased continuously (P < 0.05). The result suggested that deterioration, protein degradation, and lipid oxidation proceeded with increasing storage time. For corresponding surimi, TVB and TMA were almost removed and TBARS and TCA soluble peptide contents were decreased. Conversely, MHC became more concentrated. Decreases in gel-forming ability of surimi were observed when fish used as raw material were stored in ice for a longer time, regardless of EKWE or CT addition. Whiteness of surimi gel decreased and expressible moisture increased especially when the storage time increased. However, superior breaking force and deformation of surimi gel with 0.15% EKWE or 0.30% CT added, compared to those of the control gel were observed during the first 6 d of the storage. Thereafter, EKWE and CT had no gel enhancing effect on surimi. Therefore, freshness was a crucial factor determining gel enhancing ability of EKWE or CT toward mackerel surimi.

Nonlinear four-way kinetic-excitation-emission fluorescence data processed by a variant of parallel factor analysis and by a neural network model achieving the second-order advantage: malonaldehyde determination in olive oil samples.

Four-way data were obtained by recording the kinetic evolution of excitation-emission fluorescence matrices for the product of the Hantzsch reaction between the analyte malonaldehyde and methylamine. The reaction product, 1,4-disubstituted-1,4-dihydropyridine-3,5-dicarbaldehyde, is a highly fluorescent compound. The nonlinear nature of the kinetic fluorescence data has been demonstrated, and therefore the four-way data were processed with parallel factor analysis combined with a nonlinear pseudounivariate regression, based on a quadratic polynomial fit, and also with a recently introduced neural network methodology, based on the combination of unfolded principal component analysis, residual trilinearization, and radial basis functions. The applied chemometric strategies are not only able to adequately model the nonlinear data but also to successfully determine malonaldehyde in olive oil samples. This is possible since the experimentally recorded four-way data, modeled with the above-mentioned advanced chemometric approaches, permit the achievement of the second-order advantage. This allows us to predict the analyte concentration in a complex background, in spite of the nonlinear behavior and in the presence of uncalibrated interferences. The present work is a new example of the use of higher-order data for the resolution of a complex nonlinear system, successfully employed in the context of food chemical analysis.

Investigations on the effects of rape oil quality, choline and methionine concentration in diets for laying hens on the trimethylamine content of the eggs, on trimethylamine metabolism and on laying performance.

An experiment was conducted to study the effects of graded levels of choline addition (0, 500, 1000 and 4000 mg/kg diet) in laying hen diets prepared either with degummed or refined rape oil on the performance, sensory properties and trimethylamine (TMA) contents of the eggs. Furthermore, the diets containing no supplemented choline or 4000mg choline/kg diet were tested with adequate or inadequate methionine supply (4.2 vs. 2.8 g methionine/kg diet). TMA metabolism and N-balance were measured for the latter diet types, but only with the diets containing refined rape oil. Therefore, a total of 12 and 4 diets were tested in the feeding (n = 60) and balance study (n = 9). Laying performance (23 -75 weeks of age) was not significantly influenced by increasing choline additions with the exception of feed-to-egg mass ratio which decreased significantly linearly (P(linear) = 0.003). However, a significant interaction between choline addition and laying month was detected which was caused by a depression of performance of the unsupplemented control group occurring from the sixth laying month. The most obvious effect of an inadequate methionine supply was a temporary drop in performance between the third and sixth laying months. The mean TMA-concentration in pooled egg yolks [microg/g] increased with dietary choline concentration [mg/kg] in an exponentially related fashion (y = 1.14 + 4E(-10) x x(2.71), r2 = 0.962) and suggested only a minor influence of total dietary choline on TMA content up to approximately 2000mg choline/kg. Individual TMA-concentrations varied greatly from 0.4 - 1.5 microg/g, from 2.2 - 34 microg/g and from 18.4 - 75 microg/g for eggs with a normal, aberrant and heavily aberrant odour, respectively. It is concluded that a total choline concentration of at least approximately 1500 mg/kg is necessary to maintain a maximal laying performance. An inadequate methionine supply cannot be compensated by an increased addition of choline. Neither degummed nor refined rape oil influenced the TMA content of eggs.

Hypersaline stress induces the turnover of phosphatidylcholine and results in the synthesis of the renal osmoprotectant glycerophosphocholine in Saccharomyces cerevisiae.

The role of phosphatidylcholine turnover during hypersaline stress is investigated in Saccharomyces cerevisiae. In the wild-type strain, 2180-1A hypersaline stress induced the rapid turnover of phosphatidylcholine, a major membrane lipid. Yeast cells were grown in the presence of [14C]-choline to label phosphatidylcholine. Upon shifting the cells to medium with 0.8 M NaCl, phosphatidylcholine levels were diminished by c. 30% within 20 min to yield glycerophosphocholine, a methylamine osmoprotectant that has been previously identified in renal cells. High-performance liquid chromatography studies showed that osmotically mediated glycerophosphocholine production was enhanced if 10 mM choline was added as a supplement to synthetic dextrose medium with 1.6 M NaCl, but glycine betaine was not detected. Enhanced glycerophosphocholine production also correlated with improved growth in media containing 1.6 M NaCl and choline. Enhanced growth is specific to methylamines: salt-stressed cells supplemented with 10 mM choline or glycine betaine showed enhanced growth relative to unsupplemented control cultures, but other additives had no effect on growth or adversely affected it. Nutritional effects are ruled out because yeast cannot use choline or glycine betaine as carbon or nitrogen sources in normal or high-salt medium. Finally, enhanced growth in hypersaline media with choline or glycine betaine is dependent on the choline permease Hnm1. These results in yeast highlight a similarity with mammalian renal cells, namely that phosphatidylcholine turnover contributes to osmotic adaptation via synthesis of the osmoprotectant glycerophosphocholine.

Precursors of N-nitroso compounds in some Nigerian medicinal plants.

Twenty-seven tropical plants of medicinal importance were analysed for primary and secondary amines by chemiluminescence detection on a Thermal Energy Analyzer (TEA) modified for use on 'nitrogen mode' following derivatization with benzene sulphonyl chloride (BSC) and gas chromatographic (GC) separation of their sulphonamides. Nitrite was determined by colorimetry at 540 nm after diazotization with sulphanilamide and coupling with N-(1-naphthyl)ethylenediamine to form an azo dye. Nitrate was determined as nitrite following on-line reduction by granulated cadmium. Dimethylamine in the range of 0.5 ppm to 18.2 ppm was detected in 96% of samples, while pyrrolidine ranged between 0.7 ppm and 12.78 ppm in 14 samples. Isobutylamine, methylamine and ethylamine were the most ubiquitous primary amines. Largest number of secondary amines (four) was found in Azadirachta indica (Neem) while largest number of primary amines (six) was detected in Azadirachta indica and Tamarindus indica (Tsamiya) which also contained the highest amount of total primary amines (148.8 ppm). Nitrate and nitrite were seldom found in plant extracts whose pH were generally below 7.0. These findings suggests that early exposures to precursors of N-nitroso compounds via medicinal plants might contribute to total risk posed by environmental carcinogens in Nigeria.

Composition, preservation, and use of sea clam viscera as a protein supplement for growing pigs.

Use of surf clam viscera as an animal feed was assessed by measuring nutrient content, susceptibility to spoilage, preservation with organic acid, and replacement value for soybean meal when fed to growing pigs. Viscera exiting the processing plant averaged 88% moisture and 71% CP in DM. Amino acid contents (51% in DM) and profiles were similar to those of soybean meal. Storage and feeding quality of wet viscera could be maintained up to 3 wk by adding formic or propionic acid (3.5%, wt/wt). Pigs readily ate corn-based diets containing wet viscera preserved with propionic acid. Growth rate was similar for pigs from 18 kg to market weight (92 kg) when soybean meal and(or) clam viscera were fed as protein supplements. However, cooked loin roasts from pigs fed one-half or all supplemental protein from viscera (5 or 10% viscera in diet DM) had distinctive fishy aromas. To produce acceptable pork, future studies must identify lower dietary levels or withdrawal periods for viscera.