Optimization of encapsulation of fish protein hydrolysate and fish oil in W1/O/W2 double emulsion: Evaluation of sensory quality of fortified yogurt

In this study, water-in-oil-in-water (W-1/O/W-2) double emulsions were prepared in which fish protein hydrolysate as W-1 phase and fish oil as O phase were used within a complex of whey protein concentrate (WPC) and inulin. The double emulsions were optimized in terms of the release, creaming index, encapsulation efficiency, and encapsulation stability using the response surface methodology. The coefficients of determination were higher than 0.880 for all the response variables and the independent variables had significant effects on all responses. The optimum levels of the independent variables were as follows: 2:1 w/w ratio of wall/core, 2.12:1 w/w ratio of WPC/Inulin, and 6.28% polyglycerol polyricinoleate. For the sensory analysis, natural yogurt was fortified with microcapsules obtained from a freeze-dried W-1/O/W-2 emulsion with an optimized formulation. The visual appearance of the yogurt was not affected by the microcapsules and addition of a flavoring agent for masking fish oil flavor was recommended. Practical applications Thermodynamic instability of double emulsion let to investigate different production condition in order to produce stable emulsion. In this case, response surface methodology has been broadly used to optimize the conditions of different procedures. In this study, optimization of wall/core weight ratio, WPC/inulin weight ratio and emulsifier concentration was developed to achieve minimum amounts of the release and creaming index and maximum amounts of the encapsulation efficiency and encapsulation stability. At the second step, yogurt were fortified by optimized microcapsules and the sensory analysis did not show significant differences in rancid and bitter taste during eating between the control and the fortified sample.