Sodium Alginate and Mustard Protein-Based Emulsion Gels

Abstract

In this study mustard protein and sodium alginate-based emulsion gels were prepared by cold set gelation. The mustard protein isolate used in the study was isolated from defatted mustard meal using alkaline extraction and isoelectric precipitation. The protein content in the isolate was 90.5%. The concentration of oil was kept at 40% in all the emulsion gels having varying proportions of mustard protein and sodium alginate. Formulation of emulsion gel containing protein and sodium alginate in the ratio of 1:4 exhibited a good recovery rate of 91% and emulsion stability of 98%. Temperature sweep test showed that the fabricated emulsion gels were thermally stable. The ratio of mustard protein and sodium alginate significantly affects the characteristics of emulsion gels. Results of rheological analysis showed that PA21(emulsion gels having mustard protein and sodium alginate in the ratio of 2:1) and PA41 (emulsion gels having mustard protein and sodium alginate in the ratio of 4:1) were weak emulsion gels having low emulsion stability, oil binding capacity, and freeze-thaw stability. The protein and alginate content in emulsion gels also affected their color values. An increase in the ratio of protein resulted in the decreased strength of emulsion gels but played a significant role in the stabilization of oil droplets in the gel matrix. The best emulsion gel was selected for the replacement of butter in cookies. The 100% replacement of butter with emulsion gel resulted in harder cookies with low sensorial scores. However, EG50, (cookies having 50% butter substituted with emulsion gels) were considered more comparable with control in terms of textural and organoleptic properties. Moreover, both EG50 and EG100 (cookies having 100% butter substituted with emulsion gels) cookies showed a significant decrease in fat content making them a healthier choice. Therefore, the fabricated emulsion gel can be potentially used in the preparation of low-fat processed food products with potential health benefits.