Novel intelligent films containing anthocyanin and phycocyanin for nondestructively tracing fish spoilage.

Potential pH-responsive films were developed based on incorporating anthocyanin, phycocyanin, and a mixture of anthocyanin-phycocyanin (at a ratio of 3:1 v/v) within composite gelatin (1.5 g / 100 g film solution)/soybean polysaccharide (2.5 g / 100 g film solution) matrices. FTIR and SEM assessments certified the incorporation of the pigments into the film matrices. All the colorimetric films were highly sensitive when exposed to headspace ammonia, except the phycocyanin-incorporated film. Moreover, the fabricated intelligent films were conducted to trace the spoilage process of grass carp. An obvious relationship between the color (L*, a*, b*, ΔE) of indicators and pH, TVB-N, bacterial growth, ATP-related compounds, and K-value of the fish was observed. The film incorporated with mixed Ipomoea nil extract and phycocyanin possessed the best color variations (dark orange, pink, dark blue) with the degree of fish spoilage. Therefore, this intelligent film can be considered a promising sensor for monitoring fish freshness non-destructively.

Efficacy of freeze-chilled storage combined with tea polyphenol for controlling melanosis, quality deterioration, and spoilage bacterial growth of Pacific white shrimp (Litopenaeus vannamei).

This study aimed to investigate melanosis, quality attributes, and bacterial growth of freeze-chilled Pacific white shrimp (Litopenaeus vannamei) during 6 days of chilled storage, as well as the preservative effects of tea polyphenol on shrimp. The results showed that freeze-chilled storage retarded the growth of bacteria and the accumulation of putrescine in shrimp. The growth of spoilage bacteria Photobacterium and Shewanella were inhibited. However, freeze-chilled storage aggravated melanosis and lipid oxidation. The total volatile basic nitrogen (TVB-N) slightly accumulated in the thawed shrimp. The incorporation of tea polyphenol preserved freeze-chilled shrimp. Melanosis and lipid oxidation of shrimp were alleviated. The accumulation of biogenic amines, TVB-N, hypoxanthine riboside, and hypoxanthine were retarded. Meanwhile, the growth of spoilage bacteria Pseudoalteromonas, Photobacterium, Psychrobacter, and Carnobacterium were inhibited. Based on sensory analysis, the shelf-life of chilled, freeze-chilled, and freeze-chilled tea polyphenol shrimp were 4 days, 3 days, and 6 days, respectively.

Effect of grape seed extract on quality and microbiota community of container-cultured snakehead (Channa argus) fillets during chilled storage.

Herein, the effects of grape seed extract (GSE) on the microflora and biochemical changes of container cultured snakehead (Channa argus) fillets during 11 days of chilled storage were investigated. The sensory analysis, the total number of viable colonies, the total amount of volatile basic nitrogen, and k-value analysis revealed that GSE retarded the deterioration of snakehead fillets. The degradation of inosine 5'-monophosphate and the accumulation of inosine and hypoxanthine in the GSE group were slower than these in the control group. Moreover, GSE treatment effectively decreased the accumulation of putrescine, cadaverine, and histamine. Illumina-MiSeq high throughput sequencing results showed that GSE inhibited the growth of Aeromonas on snakehead fillets. Based on the microbial enumeration, sensory analysis, and k-value, GSE prolonged the shelf life of fillets for 3 days, suggesting its potential for snakehead fillets preservation.

Effects of pomegranate peel extract on quality and microbiota composition of bighead carp (Aristichthys nobilis) fillets during chilled storage.

This study aimed to investigate effects of aqueous pomegranate peel extract (APPE) and ethanolic pomegranate peel extract (EPPE) on microbiota and changes in quality of bighead carp (Aristichthys nobilis) fillets stored at 4 °C. The results showed that pomegranate peel extract (PPE, which includes both APPE and EPPE) retarded the deterioration of sensory quality and flesh color, inhibited the growth of spoilage bacteria, and attenuated the production of biogenic amines, total volatile basic nitrogen (TVB-N), and the degradation of ATP-related compounds. Moreover, EPPE performed better in color attributes and biogenic amines, but APPE was more effective in retarding the increase of TVB-N and K-value. High-throughput sequencing results showed that microbial composition of all samples became less diverse as storage time increased. For the control group, Acinetobacter was predominant in the middle-period of storage, while Pseudomonas, Aeromonas, and Shewanella became predominant at the end of storage. Additionally, PPE decreased the relative abundance of Acinetobacter in the middle-period of storage, and thus changed the microbial composition. Based on our assessments of quality and microbial analysis, PPE prolonged the shelf-life of bighead carp fillets for about 2 days, and it has the potential to become a promising preservative in aquatic products.

Effect of glazing and rosemary (Rosmarinus officinalis) extract on preservation of mud shrimp (Solenocera melantho) during frozen storage.

In this study, glazing with water and rosemary (Rosmarinus officinalis) extract were applied on frozen mud shrimp (Solenocera melantho) and stored at -20 °C for 24 weeks. Quality loss and protein and lipid changes of shrimp were evaluated by total volatile basis nitrogen (TVB-N), drip loss, moisture distribution, sulfhydryl content (SH), disulfide bond, intrinsic fluorescence intensity, lipid content, free fatty acids (FFA), peroxide value (PV), fluorescent compounds and sensory characteristics. Results showed that unglazed mud shrimp exhibited significant quality decline after 16 weeks of frozen storage. Glazing treatment significantly reduced quality loss, protein degradation, and lipid oxidative damage of shrimp during the 24 weeks of frozen storage, compared to the unglazed control sample. Glazing with rosemary extract was more effective in controlling quality changes in frozen mud shrimp with lower TVB-N, drip loss, PV, FFA and higher lipid content and sensory scores.

Application of Illumina-MiSeq high throughput sequencing and culture-dependent techniques for the identification of microbiota of silver carp (Hypophthalmichthys molitrix) treated by tea polyphenols.

This study evaluated the antimicrobial effects of tea polyphenols (TP) on changes in microbiota composition and quality attributes in silver carp fillets stored at 4 °C. During storage, TP treatment was found to be effective in enhancing sensory quality, inhibiting microbial growth, and attenuating chemical quality deterioration. Meanwhile, the composition of microbiota of silver carp fillets was investigated using culture-dependent and culture-independent methods. Initially, compared to the control, TP obviously decreased the relative abundance of Aeromonas, which allowed Acinetobacter and Methylobacterium to become the dominant microbiota in TP treated fillets on day 0. The controls, 0.5% TP-treated fillets, and 1% TP-treated fillets were rejected by sensory panelists on days 8, 12, and 12, respectively. At the time of sensory rejection, Aeromonas, followed by Acinetobacter and Pseudomonas, became the main spoilers in the control on day 8. However, TP treatment inhibited the growth of Aeromonas and Acinetobacter significantly. Consequently, Aeromonas followed by Pseudomonas and Shewanella became the predominant microbiota in all TP-treated fillets on day 12. Therefore, TP improved the quality of fillets during chilled storage, which was mainly due to their modulating effects on microbiota that resulted in the change in pattern and process of spoilage in fillets.

Evaluating the effects of IADHFL on inhibiting DPP-IV activity and expression in Caco-2 cells and contributing to the amount of insulin released from INS-1 cells in vitro.

Dipeptidyl peptidase-IV (DPP-IV) is a serine exo-peptidase that can inactivate incretins by removing N-terminal dipeptides. Currently, inhibiting the DPP-IV activity is a common treatment for type 2 diabetes (T2D). The goal of this study is to investigate whether IADHFL, a novel DPP-IV inhibitory peptide identified from bighead carp (Hypophthalmichthys nobilis), has the potential to modulate T2D. IADHFL remained stable after simulated gastrointestinal digestion and significantly decreased the activity and expression of both soluble and membrane-bound DPP-IV after 24 h and 48 h of treatment. Intact peptide absorption was observed, but a percentage of the peptide was degraded while passing through a monolayer of Caco-2 cells. In addition, a double-layered cell model showed that the peptide could increase insulin secretion from INS-1 cells after glucose treatments of 2.8 mM and 16.7 mM. Finally, IADHFL could regulate the expression levels of genes associated with insulin secretion and T2D in INS-1 cells.

The anti-photoaging effect of antioxidant collagen peptides from silver carp (Hypophthalmichthys molitrix) skin is preferable to tea polyphenols and casein peptides.

Applying antioxidants to attenuate skin photoaging has received great attention. In this study, antioxidant collagen peptides (ACPs) with different activities were prepared using different proteases, called high (HCP), medium (MCP) and low antioxidant collagen peptides (LCP). The effects of ACPs, tea polyphenols (TP) and casein peptides (CP) on the photoaged skin of mice were evaluated and compared. Ingestion of ACPs significantly alleviated UV-induced abnormal alterations of skin components and antioxidative indicators in both serum and skin (p < 0.05). In addition, HCP had the best effect on protecting skin from photoaging among the three collagen peptides, with no significant differences between MCP and LCP (p > 0.05). TP and CP, with higher antioxidant activity in vitro, only significantly increased hydroxyproline content (only in the TP group) and CAT activity and decreased protein carbonyl content at week 2, showing a much weaker effect than that of the ACP groups. The histological analysis result further demonstrates that ACPs exerted a stronger beneficial effect on normalizing skin structure and collagen arrangement than TP and CP. Accordingly, ACPs have potential for nutraceuticals as anti-skin-photoaging ingredients.