Introduction:Defatted flour of orange seed contains about 26% protein, making it a rich and cost-effective source for producing plant-based proteins and peptides.

Methods:In this study,protein was extracted from the defatted orange seed flour, and then the resulting protein concentrate (76% protein) was hydrolyzed using the enzyme pepsin at various enzyme-to-substrate ratios (1-3%) and time intervals (2-5 hours) at optimum temperature. The hydrolyzed proteins with the best antioxidant properties were selected and applied in the laboratory production of fish sausage containing hydrolyzed orange seed protein. The antioxidant activity (iron ion chelating ability,Thiobarbituric Acid Index(TBA))of the samples was then measured during the storage period.

Results:The results showed that the highest bioactivity was found in the hydrolyzed treatments with pepsin enzyme, specifically in the optimal treatment with a 3% W/W and a hydrolysis time of 3.5 hours. Generally, the use of hydrolyzed protein in fish sausage formulation demonstrated that increasing the concentration of hydrolyzed orange seed protein from 0.5% to 2.5% significantly increased the iron ion chelating activity and decreased the thiobarbituric acid index of the samples. The increase in antioxidant capacity of the sausage with higher concentrations of hydrolyzed protein may be attributed to the antioxidant potential of the hydrolyzed protein itself.

Conclusion:Overall,the formulation of fish sausage containing 1.5% hydrolyzed orange seed protein, as a product with high nutritional value and without preservatives, has the potential for industrial production and market supply and can be used for the production of hydrolyzed proteins and bioactive peptides with suitable quality and high antioxidant properties.