Haibin Wang

Excessive oxidation of protein and lipids in pork leads to quality degradation and loss of nutrients. Kappa‐selenocarrageenan (Se‐K) can not only be used as a selenium enhancer but also as an antioxidant. To explore potential antioxidants that could be applied to pork, the effect of Se‐K on myofibrillar protein (MP) and lipid oxidation was investigated. The results demonstrated that Se‐K could scavenge hydroxyl radicals, DPPH radicals, and ABTS radicals. It was found that Se‐K inhibited the formation of carbonyls and decreased the loss of sulfhydryl groups of MP. Se‐K also inhibited cross‐linking, aggregation, unfolding, and structural transformation of MP and repressed the increase in surface hydrophobicity. Additionally, Se‐K enhanced the emulsibility, textural properties, and water‐holding capacity of MP. We also found that Se‐K delayed the increase in acid value, peroxide value, and thiobarbituric acid reactive substances value. Furthermore, Se‐K inhibited the degradation of unsaturated fatty acids, especially linoleic acid. Overall, Se‐K was effective in inhibiting MP and lipid oxidation and could be a potential antioxidant for pork.

The Enshi black pig is a Chinese native breed known for its rich nutrition content and high quality, which has notable traction in the consumer market. In this study, the potential impact of the main commercial cuts from Enshi black pork carcasses (ham, loin, and belly) on the bacteria community of spoiled meat under refrigerated storage (4 °C) was assessed by using a high-throughput sequencing method. Moreover, the spoilage potential of isolated strains from spoiled pork was investigated. The results demonstrated significant differences (p < 0.05) in bacterial community diversity and composition among spoiled ham, loin, and belly samples. Linear discriminant analysis effect size (LEfSe) analysis revealed a total of 20 significantly different potential bacterial biomarkers, with the dominant genera of Pseudomonas, Psychrobacter, Shewanella and Carnobacterium. Additionally, C. divergens THT1-5, isolated from spoiled ham samples, displayed cold adaptation and higher spoilage potential in Enshi black pork. These findings are helpful for identifying key factors contributing to spoilage in Enshi black pork and developing strategies to inhibit bacterial growth during preservation.

As a popular form of fruit consumption, fresh-cut watermelon is of great convenience for its consumers. Owing to the lack of comprehensive knowledge about the quality changes of fresh-cut watermelon during its shelf life, guidelines and standards are unavailable currently. To clarify the deterioration process and its underlying mechanism in fresh-cut watermelon, the sensory parameters, metabolomics, and microbial community of fresh-cut watermelon during a three-day storage at both room temperature (RT) and refrigerator temperature were systematically studied in this work. Results revealed that the whole property of the watermelon stored at refrigerator temperature kept stable, while pulps stored at RT had substantially deteriorated after 36 h. The decay was reflected in the significant decrease in soluble solid contents, firmness, pH, and color parameters in the sensory perspective. At the metabolic level, significantly declined malate, citrate, uridine, uridine 5-monophosphate, and amino acids, and increased ethanol and lactate contents, were observed as deterioration markers, which partially resulted from the activities of pyruvate dehydrogenase and alcohol dehydrogenase and the burst of genera Enterobacteriaceae and Leuconostocaceae. This study unveiled the underlying mechanisms of quality changes in fresh-cut watermelon under its primary storage conditions to provide fundamental information and potential clues for its quality control and preservation.

Protein degradation occurs during the processing of dry‐cured ham, which has important influences on the flavor and quality of products. The aim of this work was to study the degradation kinetics of myofibrillar proteins (MPs) and sarcoplasmic proteins (SPs) extracted from the biceps femoris muscle during the processing of Xuan'en ham. A relationship between protein degradation and the flavor formation was found. During the processing of Xuan'en ham, MPs and SPs were mainly degraded in the salting stage and incipient fermentation. Accompanied by protein degradation, the content of carbonyl group in SPs increased gradually, but in MPs, it first increased and then decreased. Interconversion between sulfhydryl and disulfide bonds was investigated during this processing. Oxidation, degradation, and thermal effects significantly affected the surface hydrophobicity of proteins. More than one hundred volatile compounds have been identified at each stage of ham preparation. Among them, organic acids were the predominant group, followed by hydrocarbons, aldehydes, alcohols, ketones, and esters.

Summary: Effects of refrigerated (3.5 ± 0.5 °C), iced (0 ± 0.5 °C) and superchilled (−3.0 ± 1.0 °C) storage on quality of crayfish (Procambarus clarkii) were evaluated by monitoring the water migration, microbial contamination, biogenic amines accumulation, and nucleotides catabolism during 21 days. The results indicated that superchilling was effective in accelerating the rate of water migration and reducing total volatile basic nitrogen, trimethylamine, total viable bacteria, Enterobacteriaceae and psychrotrophic bacteria of crayfish. Meanwhile, significant (P < 0.05) lower putrescine, cadaverine and tyramine contents were observed in superchilled sample (SS), whereas histamine concentrations were at lower levels (0.76–2.31 μmol g⁻¹) in all treatments. In addition, the predominant nucleotides degradation pathway in crayfish was the conversion of inosine monophosphate, which was accumulated massively (3.74 µmol g⁻¹) in SS at the end of storage. According to the dynamic changes of inosine and hypoxanthine contents, the shelf life of SS was prolonged to 15 days.

High salt content is one of the major problems for stewed products. To help address this issue, the effect of salt reduction on water migration in stewed ducks was investigated through diverse approaches, including water activity (Aw) and water‐holding capacity (WHC) assay, as well as low‐field nuclear magnetic resonance (LF‐NMR) and scanning electron microscopy (SEM) observation. Our results showed that Aw value remained stable, while centrifugal loss decreased, and cooking loss increased significantly ( p < 0.05). The analysis of NMR indicated that, during the marinating stage, the proportion of immobilized water increased from 86.86%–89.66% (sodium chloride group) and 90.51% (salt‐reduced group), respectively. After 2 h, the free water content became 0, and then became stable until the end of marinating. In the stewing stage, at the beginning 20 min, relaxation time of immobilized water decreased to about 35 ms and the ratio of immobilized water significantly reduced ( p < 0.05) by 5.38% (sodium chloride group) and 5.95% (salt‐reduced group), respectively. Free water peak was detected upon stewing of 10 min, and 20 min later, there was no significant difference in the proportion of free water ( p > 0.05). In general, no significance was observed in water behavior and microstructure of stewed duck meat between the salt reduction group and sodium chloride group. In addition, SEM analysis revealed that marinating could expand the muscle fiber gap to accommodate more immobilized water. However, the fiber was looser at the initial stage of stewing and then became more compact. Practical Application: This work demonstrates potentially feasible to produce salt‐reduced duck products.