Formula Optimization of a Low‐fat Food System Containing Whey Protein Isolate‐ Xanthan Gum Complexes as Fat Replacer

ABSTRACT Whey protein isolate‐xanthan gum complexes (WPXC) have the potential to significantly reduce fat use in various products. However, their stability and functionality have not been extensively studied, particularly in neutral pH products. The objective of this study was to evaluate WPXC as a fat replacer in cake frostings and sandwich cookie fillings with reduced‐fat content (160 or 80 g/kg fat). Response surface methodology was used to analyze the effect of WPXC on the viscosity and textural response attributes of samples and to optimize the low‐fat formulations. It was found that WPXC had a positive effect ( P > 0.001), providing acceptable viscosity and texture attributes to the low‐fat samples. A significant moisture‐WPXC interaction ( P > 0.001) revealed that the optimum moisture‐WPXC ratio varied, depending on the targeted texture. This ratio was about 8:1 for cake frostings and about 5:1 for sandwich cookie fillings. Optimal formulations were found, and samples meeting the desirability specifications presented textural and melting profiles similar to those of the control products. However, for the production of sandwich cookie fillings, the use of other ingredients (for example humectants and emulsifiers) must be considered to maintain a low water activity (A w ) and prevent moisture migration to the cookie shell.