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ABSTRACTIn this study, a high-calcium and high-amino acid fish frame hydrolyzate (FFH) was prepared from channel catfish (Ictalurus punetaus) through ultrasound-assisted enzymatic hydrolysis (UAEH). A 4-factor and 3-level Box-Behnken design of response surface methodology was employed to optimize the hydrolysis conditions, where the independent variables were sonication power (W), sonication time (min), enzyme activity (U) and water-substrate ratio (v/w). The degree of hydrolysis (DH) and soluble calcium content (SCC) were used as response factors. The optimal hydrolysis conditions were found to be sonication power (X1) = 492.91 W, sonication time (X2) = 15.01 min, enzyme activity (X3) = 6677.88 U, and water-to-substrate ratio (X4) = 3.56 v/w. Under these conditions, UAEH effectively disintegrated fish frame collagen and converted bound calcium to soluble calcium. Nevertheless, this study investigated the pattern of collagen transformation into short peptides and free amino acids throughout the degradation process. These findings highlight the potential of the FFH from channel catfish to serve as a foundation for creating highly nutritious food additive. The outcomes of this study further enhance the food industry’s ability to capitalize on the nutritional benefits offered by fish frame hydrolyzates. This expansion of health-focused product options and endorsement of the sustainable use of fish by-products harmonizes seamlessly with the industry’s evolving goals of waste reduction and value optimization.

This study aimed to purify and identify a novel antidiabetic peptides from Chinese giant salamander (Andrias davidianus) protein hydrolysate and to evaluate its anti-diabetic properties against α-amylase and α-glucosidase. The isolation was done by gel filtration, reverse phase chromatography (RF-HLPC), and finally peptide and amino acid sequences were identified by LC/MS/MS system. Our results revealed five novel peptides that strongly inhibited α-amylase and α-glucosidase. The peptides’ amino acid sequences were Cys-Ser-Ser-Val (MW = 393.99 Da), Tyr-Ser-Phe-Arg (MW = 570.99 Da), Ser-Ala-Ala-Pro (MW = 343.89 Da), Pro-Gly-Gly-Pro (MW = 325.99 Da) and Leu-Gly-Gly-Gly-Asn (MW = 415.99 Da) possessing α-amylase inhibitory activity IC50 of 13.76 × 103, 10.82 × 103, 4.46 × 103, 4.23 × 103, and 2.86 × 103 µg/mL, respectively; and for α-glucosidase with IC50 of 206.00, 162.00, 66.90, 63.50, and 42.93 µg/mL, respectively. Intriguingly, the peptide LGGGN showed higher inhibition on both α-amylase and α-glucosidase and could be considered as a potential anti-diabetic inhibitor. [ABSTRACT FROM AUTHOR]

The objective of this work was to investigate the effects of sodium replacement on the textural properties and water-holding capacity (WHC) of heat-set freshwater surimi gels. Potassium chloride and calcium chloride were chosen as salt substitutes. The surimi gels presented better water-holding capacity with potassium chloride than the treatments containing calcium chloride. Gel strength and rheological properties indicated that monovalent metal ions could improve surimi gel properties. The contents of chemical interactions, especially disulfide bonds, nondisulfide covalent bonds, and hydrophobic interactions of surimi gels, varied with the addition of salt type and concentration. Furthermore, microstructure observed from scanning electronic microscopy (SEM) demonstrated that surimi gels prepared with monovalent salt presented more compact and denser networks, while more aggregated particles existed in gels with calcium chloride. [ABSTRACT FROM AUTHOR]

This study investigated the effect of chitosan coating (1 and 2%) on the quality of grass carp fillets stored at 4°C for 20 days. During storage, the physicochemical properties (pH, thiobarbituric acid value, total volatile basic nitrogen value, trimethylamine nitrogen value,K-value, water loss, and instrumental texture), microbiology (total viable count and psychrotrophic count), and sensory properties were evaluated. The results showed that chitosan coating could effectively inhibit bacterial growth, improve physicochemical and sensory qualities, and it reduced the deterioration of the quality of grass carp fillets. Compared with fillets without chitosan coating, the shelf life of fillets with 1 and 2% chitosan coating was extended by ~3 and 6–7 days, respectively. [ABSTRACT FROM AUTHOR]

In this study, chitosan flake was micronized in a ball mill to make fine powder. The effects of the milling on properties of chitosan, such as particle size, molecular parameters, bulk density, crystalline structure, color, chemical structure, and solubility, were investigated. Results showed that the volume weight mean diameter (D[4,3]) of chitosan was reduced to 37.53 μm after 8 h of milling and extended milling did not cause a further decrease in particle size. After milling, the viscosity average molecular weight (Mv) of chitosan was decreased, but the degree of acetylation (DD) remained nearly unchanged. The bulk density of chitosan increased with increasing milling time. The crystalline structure of chitosan was destroyed by the milling. The ball-milling treatment deepened the color of chitosan. UV-vis spectra showed that new C=O groups might be formed during the milling process. Further, the micronized powders showed high dissolution rates in simulated gastric juice. [ABSTRACT FROM AUTHOR]