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In this experiment, head wastes were prepared and enzymatically hydrolyzed using alcalase (2.4 L) enzyme. The hydrolysate was fractionated by ultrafiltration with 10 kDa molecular weight cut-offs and the desired fraction was encapsulated following ion coagulation method (chitosan and triphosphate (TPP)) in nanochitosan capsules. Encapsulation process was optimized based on different ratios of chitosan:TPP and different concentrations (1, 5 and 10 mg/ml) of peptidic fraction. Finally, the degree of hydrolysis and the length of the peptides obtained from enzymatic hydrolysis were determined. The nanocapsules were examined for size, zeta potential and polydispersity index (PDI) using dynamic light scattering (Malvern, England). Structural and surface morphology studies including scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) of capsules produced under favorable conditions were also performed. Particle size was measured in various concentrations and treatments in the range of 30 to 150 nm. The best results were obtained in the treatment of 2: 1 ratio of chitosan to polyphosphate and concentration of 10 mg / ml. The size, dispersion index, zeta potential and size of nanocapsules in the optimal conditions were 0.375, 2020 and 30.13 nm, respectively, and storage conditions at -20 °C had no effect on the quality of nanocapsules. Based on the efficiency study, it was found that fraction with a concentration of 10 mg/ml is well encapsulated by chitosan with an efficiency of 91.04 ± 0.18 percent. The results showed that chitosan-TPP could be used for nanocapsulation of bioactive peptides with an approximate molecular weight of less than 10 kDa.

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Given the concerns regarding the use of synthetic antioxidants in the food industry, it seems necessary to identify and use substances containing natural antioxidants. Protein-containing wastes are one of these substances from which antioxidant compounds can be extracted in various ways. The aim of this study was to compare and comprehensively evaluate the antioxidant activity of bioactive peptides produced from three sources of waste including fish (FPH), poultry (PPH) and shrimp (SPH) with flavourzyme enzyme. Therefore, post-production bioactive peptides from these three sources were compared in term of all common and uncommon antioxidant tests in the food industry. The results showed that the peptides produced from these three sources (with the same enzyme and degree of hydrolysis) were different in terms of antioxidant activity. In free radical scavenging activity tests of DPPH and ABTS, linoleic acid peroxidation inhibition and metal chelating power, SPH was significantly higher than the other two proteins (p<0.05). The values of these four indices in SPH were measured 87.45±1.38%, 79.26±0.59%, 94.56±1.62%, and 71.49±0.37 %, respectively. There was no significant difference between SPH and FPH regarding ferric ion reducing power and hydroxyl free radical scavenging activity (p>0.05). Also, FPH and PPH did not show significant differences in terms of ABTS free radical scavenging activity index (69.15±0.85% and 68.44±1.93% respectively). In general, based on the results of the tests, in the present study, bioactive peptides produced from shrimp wastes (SPH) had the highest antioxidant activity. Peptides from fish wastes hydrolysis (FPH) was ranked second. In almost all tests, the lowest antioxidant activity was related to poultry wastes peptides (PPH).