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Summary: Brown stain is a major problem for tuna during storage. This study aimed to investigate the impact of antioxidants on myoglobin oxidation and the promotion of metmyoglobin (MetMb) reduction in tuna slices. Response surface methodology (RSM) was used to optimise the formula of the compound antioxidant in yellowfin tuna (YFT) slices, with the percentage of MetMb as the response value. The ratios of ε‐polylysine, sodium lactate and D‐sodium ascorbate were 0.43%, 2.21% and 2.71%, respectively. The interactions between sodium lactate and D‐sodium ascorbate had a greater impact on the percentage of MetMb. Then, verification experiments were conducted, and the results revealed that the samples treated with compound antioxidants had higher a* values, total sulfhydryl content, Ca2+‐ATPase activity, total reducing activity (TRA) and MetMb‐reducing activity (MRA) and lower percentages of MetMb and carbonyl contents than did the control samples. It also helps to maintain the stability of the NADH/NAD+ ratio, which contributes to facilitating MetMb reduction. The results showed that the compound antioxidant significantly inhibited myoglobin oxidation, promoted the reduction of MetMb in tuna slices and significantly enhanced the myoglobin stability of refrigerated YFT slices. [ABSTRACT FROM AUTHOR]

The objective of this research was to investigate the impact of inoculating autochthonous starter cultures on the alterations in microorganisms, biogenic amines, nitrite, and N-nitrosamines in Chinese traditional fermented fish products (CTFPs) during in vitro human digestion. The results revealed that gastric digestion significantly (p < 0.05) inhibited the proliferation of lactic acid bacteria, yeast, Staphylococcus, and Enterobacteriaceae, whereas various microorganisms proliferated extensively during small intestine digestion. Meanwhile, small intestine digestion could significantly increase (p < 0.05) levels of putrescine, cadaverine, and tyramine. The reduced content observed in inoculated fermentation groups suggests that starter cultures may have the ability to deplete biogenic amines in this digestion stage. Gastric digestion significantly (p < 0.05) inhibited nitrite accumulation in all CTFPs samples. Conversely, the nitrite content increased significantly (p < 0.05) in all groups during subsequent small intestine digestion. However, the rise in the inoculated fermentation groups was smaller than that observed in the spontaneous fermentation group, indicating a potentially positive role of inoculated fermentation in inhibiting nitrite accumulation during this phase. Additionally, gastric digestion significantly (p < 0.05) elevated the levels of N-nitrosodimethylamine (NDMA) and N-nitrosopiperidine in CTFPs. Inoculation with L. plantarum 120, S. cerevisiae 2018, and mixed starter cultures (L. plantarum 120, S. cerevisiae 2018, and S. xylosus 135 [1:1:1]) effectively increased the degree of depletion of NDMA during this digestion process. [ABSTRACT FROM AUTHOR]

Summary: The impact of κ‐carrageenan on the physicochemical structural characteristics of ready‐to‐eat (RTE) Antarctic krill surimi gel (AKSG) was investigated. The modifications in chemical bonding, protein secondary structure, protein composition and microscopic morphology were compared in both gels with and without κ‐carrageenan. According to the findings, adding 4% (w/w) κ‐carrageenan could reduce the cooking loss of AKSG significantly (P < 0.05), enhance the WHC and textural quality of AKSG and RTE AKSG and increase the amount of hydrophobic and disulfide bonds so that the secondary structure of Antarctic krill proteins could be shifted to the β‐sheet. However, there was little impact on the composition of the protein molecules according to the SDS‐PAGE. In addition, the usage of κ‐carrageenan significantly alleviated the disruption of the protein gel network caused by high‐temperature and high‐pressure treatments (P < 0.05). Therefore, applying κ‐carrageenan could effectively enhance the gel quality of RTE AKSG. [ABSTRACT FROM AUTHOR]

Summary: Textural deterioration is a severe problem in fish industry. In order to study the role of structural proteins in refrigerated grass carp, myofibrillar proteins and collagen degradation were investigated at different stages. Results revealed that connective tissues of fish muscle disintegrated from day 1, failing to hold muscle myotomes together, with a decrease of shear force. Meanwhile, collagen solubility increased from day 1 and degradation of nebulin was observed after 3 days, while there was no obvious change in the bands of myosin heavy chain and actin. Furthermore, Pearson coefficient analysis revealed that insoluble collagen (ISC) and nebulin were significantly correlated with shear force. Negative correlation was established between drip loss and contributing factors (ISC, titin and nebulin). All results suggested that textural loss of post‐mortem grass carp fillets was mainly mediated by the degradation of collagen and to a lesser extent by myofibrillar proteins at the early storage. [ABSTRACT FROM AUTHOR]

Summary: Silver carp myofibrillar proteins (MP) with different moleculars states were constructed by the addition of NaCl and fracture degree of muscle fibres. Results showed that salt‐dissolved MP (P+) under unfrozen and oxidised state showed higher oxidation degree with higher carbonyl (3.42 nmol mg−1) and dityrosine contents (25.98 a.u.) (P < 0.05) compared with saltless‐polymeric MP (P) and salt‐induced swelling MP (F+) due to addition of salt and broken muscle fibres. After oxidative and freeze–thaw process, P+ group also exhibited more cross‐linking as evidenced by turbidity (0.73), solubility (64.96%) and SDS‐PAGE, but unordered aggregates in P group increased probably due to severe frozen denaturation. Moreover, F+ group of salt‐induced swelling MP from intact muscle fibres suffered less structural damages with higher fluorescence intensity (668.41 a.u.) and higher α‐helix contents (15.56%). Overall, Fish‐ Hua of salt‐dissolved MP had a higher oxidation level and NaCl contributed to improve freeze–thaw stability of MP during freeze–thaw process. [ABSTRACT FROM AUTHOR]

BACKGROUND: Excessive sugar consumption has been linked to type 2 diabetes, obesity and other diseases. Therefore, it is indispensable to reduce sugar of food. However, the sensory characteristics of food are affected after sugar reduction (SR). Currently, SR has been reported in drinks, jams, candies, and other fruit related or sweet foods; but salty or protein related foods have not been explored, therefore there is a big gap that needs to be filled. RESULTS: Sensory scores of initial sweetness and sweetness reduced by 0.26 and 0.12 in 10% SR dried fish mince product compared with control, and there was a small difference between 25% SR (3.33) and 40% SR (3.09) samples. It also showed that 10% SR sample had a small reduction in sweetness value and free sugar content by 3.5% (0.42/11.9) and 7.8% (2.12/27.06) compared with control; while values in 25% SR sample decreased sharply but were not much different from 40% SR sample. Electronic nose results showed that SR had a small effect on odor. Texture analysis showed that texture properties of 25% SR sample were significantly different from control. CONCLUSIONS: Dried fish mince product with below 10% SR had a small difference on the sensory characteristics and there was a big change when SR was more than 20%. Dried fish mince product with 25% SR and 40% SR had no significant difference. SR had a small effect on odor, but had a great effect on texture properties, especially over 20% SR. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Adding appropriate exogenous substances is an effective means to improve the quality of freshwater fish surimi. The present study investigated the effects of chicken breast on the gel properties of mixed minced meat products. RESULTS: With the increase in the proportion of chicken breast, the breaking force of mixed gels gradually increased. When the addition ratio was 30:70, the gel strength of mixed gels had the highest strength of 759.00 g cm−1 and also the highest water holding capacity of 87.36%. Compared with surimi gels (0:100), the hardness, adhesiveness and chewiness of mixed gels were significantly improved. The increase in the proportion of chicken breast increased the thermal stability of the mixed sol and improved the rheological properties of the mixed sol. When the proportion was 40:60, the area of immobile water (A22) in the mixed gel increased significantly, and the highest A22 was 3463.24. The hydrophobic interactions and disulfide bonds in the mixed gel were significantly increased as a result of the addition of chicken breast. The results of microstructure, electrophoresis and Raman spectroscopy indicated that the addition of chicken breast promoted the cross‐linking of the proteins in mixed gels, which facilitated the transformation of the protein secondary structure from α‐helical to β‐folded structure, thus forming a more uniform and orderly network structure. CONCLUSION: These results suggest that improving the gel properties of silver carp surimi by use of chicken breast has practical implications for the development of new blended products for surimi processing. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Alcoholism is a serious public health problem, and the abuse of drinking seriously damages the health of people. Chitosan oligosaccharides (COSs) are small‐molecule oligosaccharides with amino groups that have many unique properties. The neuroprotective effect of COS on alcohol‐induced hippocampal injury in Sprague–Dawley (SD) rats was investigated. The discrimination ratio of the COS group in the Y‐maze experiment was 59.3% higher than that of the ETOH group. Meanwhile, the discrimination index was less than 0 in the ETOH group but greater than 0 in the COS group during the object recognition test. The cells in the COS group were more tightly arranged than those in the ETOH group. Proteomics was used to identify differentially expressed proteins in the hippocampus. There were 27 differentially expressed proteins in the COS and ETOH group for further bioinformatic analysis. There are three enriched pathway categories, namely, primary immunodeficiency, hedgehog signaling, and sulfur relay system. Next, sonic hedgehog signaling pathway‐related proteins were verified through western blotting. The protein expression level of β‐arrestin‐2 in the COS group was 2.85 times higher than that in the ETOH group. This work may contribute to understanding the underlying mechanism of the neuroprotective effect of COS against alcohol‐induced hippocampal injury in SD rats. [ABSTRACT FROM AUTHOR]