Effect of wheat germ protein isolate and xanthan gum as egg substitutes on the rheological properties of mayonnaise

Mayonnaise is a kind of oil in water emulsion، that most widely used sauce in the world. Egg yolk is a key ingredient in mayonnaise، due to excellent emulsifying properties. Nevertheless، one main problem with egg yolk is its high cholesterol content، so different attempts have been carried out to develop low cholesterol mayonnaise. The aim of this study was to prepare low cholesterol mayonnaise containing wheat germ protein isolate (WGPI) and xanthan gum (XG) as egg yolk substitutes. The mayonnaise prepared with different composition of WGPI، egg yolk (0-9% of each component) and XG (0-0. 5%)، as formula variables by applying the optimal mixture design approach. Effect of this substitution on rheological characteristics and microstructure of mayonnaise samples were evaluated. The results indicated that all mayonnaise samples exhibited thixotropic shear thining behavior under steady shear tests، which fitted by Power law model and the factors related to this model were specified in the samples. Also، it was observed that mayonnaises exhibited weak- gel like properties، by using dynamic oscillatory shear tests and had significant effects on acquired parameters from frequency sweep test، such as storage modulus، loss modulus and tan delta. According to rheological and microstructure results، the low cholesterol mayonnaise contained WGPI and XG shows similar characteristics to those of a typical mayonnaise. Formulation 10 (71. 5% and 4. 2% egg replacement with WGPI and XG، respectively) shows the most similarity to control sample.