Identification and characterization of metal-chelating bioenhancer peptide derived from fermented Citrullus lanatus seed milk

Preparation of Calcium-Binding Peptides Derived from Mackerel (Scomber japonicus) Protein and Structural Characterization and Stability Analysis of Its Calcium Complexes

The purpose of this study was to prepare mackerel peptides (MPs) with calcium-binding capacity through an enzyme method and to investigate the potential role they play in improving the bioavailability of calcium in vitro. The calcium-binding capacity, degree of hydrolysis (DH), molecular weight (MW), and charge distribution changes with the enzymolysis time of MPs were measured. The structural characterization of mackerel peptide-calcium (MP-calcium) complexes was performed using spectroscopy and morphology analysis. The results showed that the maximum calcium-binding capacity of the obtained MPs was 120.95 mg/g when alcalase was used for 3 h, with a DH of 15.45%. Moreover, with an increase in hydrolysis time, the MW of the MPs decreased, and the negative charge increased. The carboxyl and amino groups in aspartic (Asp) and glutamate (Glu) of the MPs may act as calcium-binding sites, which are further assembled into compact nanoscale spherical complexes with calcium ions through intermolecular interactions. Furthermore, even under the influence of oxalic acid, MP-calcium complexes maintained a certain solubility. This study provides a basis for developing new calcium supplements and efficiently utilizing the mackerel protein resource.

The degradation of chicken feathers by Ochrobactrum intermedium results in antioxidant and metal chelating hydrolysates and proteolytic enzymes for staphylococcal biofilm dispersion

The increase in the generation of chicken feathers, due to the large production of the poultry industry, has created the need to search for ecologically safer ways to manage these residues. As a sustainable alternative for recycling keratin waste, we investigated the ability of the bacterium Ochrobactrum intermedium to hydrolyze chicken feathers and the valorization of the resulting enzymes and protein hydrolysate. In submerged fermentation with three different inoculum sizes (2.5, 5.0, and 10.0 mg of bacterial cells per 50 mL of medium), the fastest degradation of feathers was achieved with 5.0 mg cells, in which a complete decomposition of the substrate (96 h) and earlier peaks of keratinolytic and caseinolytic activities were detected. In the resulting protein hydrolysate, we noticed antioxidant and Fe2+ and Cu2+ chelating activities. ABTS scavenging, Fe3+-reducing ability and metal chelating activities of the fermentative samples followed the same trend of feather degradation; as feather mass decreased in the media, these activities increased. Furthermore, we noticed about 47% and 60% dispersion of established 7-day biofilms formed by S. aureus after enzymatic treatment for 5 h and 24 h, respectively. These findings highlight the potential use of this bacterium as an environmentally friendly alternative to treat this poultry waste and offer valuable products.

Nutritional and in vitro antioxidant activity analyses of formulated soymilk dessert

Soymilk (SM) is nutritionally nearly equal to milk from cows and is free of cholesterol, gluten, and lactose. This study's objective was to formulate a cholesterol-free soymilk dessert (SOD) and compare it's to commercial desserts (CODs). Results indicated that the CODs contain substantial amounts of cholesterol while SOD does not. Soymilk dessert has more protein, and vitamin E than CODs, but less fat and calcium. In addition, the result also highlighted that SOD has higher number of amino acids compared to CODs. The total antioxidant, flavonoids and phenolics content of SOD were significantly higher than CODs. Furthermore, the in vitro antioxidant activity of SOD and CODs by DPPH and ABTS methods revealed that the IC50 of SODs significantly (p < 0.001) lower than CODs, and lower IC50 indicated the higher free radical scavenging power of SODs than CODs. These findings indicated that this non-dairy SOD may provide beneficial protein, as well as minerals, and antioxidants to support the body's various physiological functions.