The use of hydrolyzed protein from Rainbow trout waste (Oncorhynchus mykiss) as a stabilizer and a relative substitute for fat in yogurt

Abstract

Introduction: In this study، the effect of hydrolyzed protein prepared from Rainbow trout waste in order to exploit these food sources and reduce environmental waste and improve the quality of yogurt has been investigated. Materials & methods: hydrolyzed protein was prepared from Rainbow trout waste using alcalase and protamax enzymes، and yogurt samples were prepared at concentrations of 1 and 5.1% of hydrolyzed protein and a control sample without hydrolyzed protein powder. The degree of hydrolysis and solubility of the hydrolyzed protein were investigated. Results: The degree of hydrolysis of Rainbow trout waste was 49.6±1.58% and the hydrolysis protein solubility was 91.3±2.25%. The results of the parameters measured on yogurt indicate that adding hydrolyzed protein to yogurt decreased the pH (P<0.05) and using hydrolyzed protein decreased the water content and increased the viscosity and consequently the water holding capacity with the concentration of hydrolyzed protein increased and the highest increase in water retention capacity was related to the treatment with 1.5% of hydrolyzed protein (P<0.05). The control sample had the lowest viscosity and the highest water content. According to the sensory evaluation results ،
it was observed that the addition of hydrolyzed protein to the samples had a positive effect on the sensory properties of the taste، smell and texture of the prepared yogurt، but the replacement of the hydrolyzed protein had a negative effect on the color of the yogurt at high concentrations. Conclusion: It can be concluded that improving the traditional properties of yogurt by replacing hydrolyzed protein prepared from Rainbow trout waste with fat can make optimal use of fish waste.