The Effect of Whey Protein Concentrate, Soy Protein Isolate, and Xanthan Gum on Textural and Rheological Characteristics of Gluten-Free Batter and Cake

The market of gluten-free food products has been growing exponentially in recent years. Consequently, it is necessary to conduct research on the effects of various compounds to enhance the quality of these products. The present study is aimed at investigating the effects of adding whey protein concentrate (WPC) and soy protein isolate (SPI) at three levels (0%, 5%, and 10%) and xanthan gum (XG) (0%, 0.15%, and 0.3%) on the textural and rheological characteristics of gluten-free batter and cake based on rice flour. The results showed that increasing the levels of XG, WPC, and SPI improved the apparent viscosity of the batter samples. The effect of WPC on the apparent viscosity was more pronounced than that of SPI, as the highest value (21.9 Pa·s) was related to the sample containing 10% WPC and 0.3% XG. The loss tangent values of the batter samples, measured at a frequency of 1 Hz, ranged from 0.531 to 0.8 for different levels of WPC/XG and from 0.466 to 0.699 for SPI/XG, indicating a gel-like behavior of the batter samples. The sample containing 10% SPI and 0.3% XG displayed the strongest gel with higher storage modulus (982.112 Pa) and loss modulus (458.039 Pa) compared to other samples. Increasing the levels of XG, WPC, and SPI resulted in higher specific volume, porosity, firmness, and springiness of the samples compared to the control sample (P < 0.05). The addition of WPC, SPI, and XG improved the overall acceptability of the cake samples, with the samples containing WPC/XG combination being the most preferred. Ultimately, the cake sample containing 10% WPC along with 0.3% XG introduced as optimal sample. This formulation not only can enhance the characteristics of gluten-free cake but also meets parts of the nutritional needs of consumers, particularly those with celiac disease.