Occurrence and Development of Off-Odor Compounds in Farmed Hybrid Catfish (Clarias macrocephalus × Clarias gariepinus) Muscle during Refrigerated Storage: Chemical and Volatilomic Analysis

Depuration of Asian Green Mussels Using Chitooligosaccharide-Epigallocatechin Gallate Conjugate: Shelf-Life Extension, Microbial Diversity, and Quality Changes during Refrigerated Storage

The effect of chitooligosaccharide-EGCG conjugate (CEC) at different concentrations (0, 1, and 2%; w/v) and depuration times (DT; 3, and 6 h) on the total viable count and Vibrio spp. count of Asian green mussels (AGMs) was studied. Depurated samples showed a reduction in both microbial counts as compared to fresh AGMs (without depuration) and AGMs depurated using water (CON). A similar TVC was noticed at both DTs; however, a lower VC was attained at a DT of 3, irrespective of CEC concentrations (p < 0.05). AGMs were depurated for 3 h using 1 and 2% CEC (CE1 and CE2, respectively) solutions and stored for 6 days at 4 °C. The CE2 sample showed the lowest microbial counts as compared to fresh AGMs, CON, and CE1 throughout the storage (p < 0.05). CE2 extended the shelf-life of AGMs by 4 days, which was also supported by the lower peroxide value (0.48 mg cumene hydroperoxide/kg sample) and TBARS (0.94 mmol MDA eqv/kg sample) when compared with other samples. Moreover, CE2 had a lower total volatile nitrogen base (TVB; 4.72 mg N/100 g) and trimethylamine (TMA; 3.59 mg N/100 g) on day 4. Furthermore, 2% CEC was able to maintain the DHA content; however, a slightly lower EPA was noticed as compared to the CON. Next-generation sequencing suggested that the CON had a larger microbial community, especially Vibrio sp., than the CE2. All the treated samples showed similar likeness scores to the cooked CE2 and CON on day 0. However, slightly lower likeness was attained when CE2 was stored for 4 days, but the likeness score was higher than the acceptable limit (5). No difference in cooking loss was noticed between CON and CE2 samples on day 0. Nevertheless, cooking loss was increased on day 4. Thus, depuration using CEC solution enhanced the shelf-life of AGMs by 4 days without having negative impact on consumer acceptability and textural properties.

MXene/Hydrogel-based bioelectronic nose for the direct evaluation of food spoilage in both liquid and gas-phase environments

Various bioelectronic noses have been recently developed for mimicking human olfactory systems. However, achieving direct monitoring of gas-phase molecules remains a challenge for the development of bioelectronic noses due to the instability of receptor and the limitations of its surrounding microenvironment. Here, we report a MXene/hydrogel-based bioelectronic nose for the sensitive detection of liquid and gaseous hexanal, a signature odorant from spoiled food. In this study, a conducting MXene/hydrogel structure was formed on a sensor via physical adsorption. Then, canine olfactory receptor 5269-embedded nanodiscs (cfOR5269NDs) which could selectively recognize hexanal molecules were embedded in the three-dimensional (3D) MXene/hydrogel structures using glutaraldehyde as a linker. Our MXene/hydrogel-based bioelectronic nose exhibited a high selectivity and sensitivity for monitoring hexanal in both liquid and gas phases. The bioelectronic noses could sensitively detect liquid and gaseous hexanal down to 10-18 M and 6.9 ppm, and they had wide detection ranges of 10-18 - 10-6 M and 6.9-32.9 ppm, respectively. Moreover, our bioelectronic nose allowed us to monitor hexanal levels in fish and milk. In this respect, our MXene/hydrogel-based bioelectronic nose could be a practical strategy for versatile applications such as food spoilage assessments in both liquid and gaseous systems.

Multiomics reveals the formation pathway of volatile compounds in preserved egg yolk (PEY) induced by NaCl: Based on the model of PEY and salted egg yolk (SEY) treated with/without NaCl

The models of preserved egg yolk (PEY) and salted egg yolk both treated with or without NaCl were performed to explore the effect of NaCl on the characteristic volatile compounds (VOCs) in PEY. 1-hexanol, 2-heptanone, isoamyl acetate, etc., compounds were confirmed as the characteristic VOCs in PEY mainly induced by NaCl and the formation of 1-octanol, 2-pentylfuran, ammonia, etc., characteristic VOCs induced by NaCl may depend on the combined effect of Cu2+ and OH-. Among them, 1-hexanol and 2-heptanone were formed from linoleic acid in PS(18:0_18:2) and oleic acid in PG(22:6_18:1), respectively, through multi-omics and correlation analysis. Meanwhile, 1-octanol may originated from β-oxidation of oleic acid in PS(18:1); 2-pentylfuran and ammonia maybe derived from the derivative of aspartate and the degradation of l-methionine, respectively. Moreover, this study provides a new insight to parse the influence of NaCl with/without other exogenous factors on the formation of VOCs in food products.

Bioactive Compounds and Therapeutics from Fish: Revisiting Their Suitability in Functional Foods to Enhance Human Wellbeing

Global public awareness about fish-based diet and its health/nutritional benefits is on the rise. Fish nutritional profile projects promising bioactive and other compounds with innumerable health benefits for human wellbeing. As various reported researches involving fish/marine-derived molecules reveal promising attributes, and as the position of fish-based nutrients as nutraceuticals continue to strengthen, health challenges still confront communities worldwide, from cardiovascular disease, diabetes, and obesity to hypertension. Thus, further understanding of fish-based nutrient impact as functional foods remains crucial given the diverse prevailing compositional/nutraceutical merits. In this review, therefore, we provide important information regarding bioactive compounds and therapeutics obtained from fish, specific to the context of their suitability in functional foods to enhance human health. This contribution is hereby constructed as follows: (a) fish nutraceutical/therapeutic components, (b) constituents of fish-based nutrients and their suitability in functional foods, (c) fish antioxidant/bioactive compounds to help alleviate health conditions, (d) common human ailments alleviated by fish-based nutrients, and (e) role of fish in mental health and immune system. As increased fish consumption should be encouraged, the potential of the quality proteins, omega-3 fatty acids, and other compounds inherent in fish should steadily be harnessed.

Characterization of Antioxidant Peptides from Thai Traditional Semi-Dried Fermented Catfish

Herein, the antioxidant peptides from a Thai traditional semi-dried fermented farmed hybrid catfish (Clarias macrocephalus × Clarias gariepinus) catfish, Pla Duk Ra, were characterized. After extraction and deproteinization, Pla Duk Ra crude peptide extract (CPE) was fractioned using 2 connected Hitrap Sephadex-G25 columns, yielding two significant fractions, F1 with higher browning intensity (A420) and F2. CPE, F1, and F2 had different amino acid profiles, contents, and sequences evaluated by LC-MS/MS, which could be responsible for their antioxidant properties. F2 contained the highest numbers of hydrophobic amino acid (HBA) (47.45%) and aromatic amino acid (27.31%), followed by F1, and CPE. The peptides with 8–24 amino acid residues were detected in CPE and its fractions. In CPE, F1, and F2, there were 69, 68, and 85 peptides with varied HBA content, respectively. ARHSYGMLYCSCPPND (50% HBA), ALRKMGRK (37.5% HBA), and ANWMIPLM (87.5% HBA) were the most prevalent peptides found in CPE, F1, and F2. Overall, F2 was the most effective at inhibiting free radicals (DPPH● and ABTS●+) and reactive oxygen species (hydroxyl radical, singlet oxygen, and hydrogen peroxide), followed by F1 and CPE. The metal chelation of F1 was, however, superior to that of F2 and CPE. For the stability test, the effects of pH, heating temperature, and in vitro digestion on the DPPH● scavenging activity of F2 were investigated. The activity was boosted by lowering the pH and raising the heating temperature. In the gastrointestinal tract model system, however, roughly 50% of DPPH● scavenging activity reduced after digesting.