Effect of broad bean (Vica faba.L) protein concentrate and xanthan gum on the properties of rice batter and cake.

Nowadays, replacing gluten is one of the challenging issues in cereal field. Since gluten-free products do not have desirable textural and sensory characteristics, using compounds such as proteins and gums can help to improve the quality of them. Proteins and hydrocolloids can mimic the viscoelastic properties of gluten to some extent. Legumes are important and inexpensive food resources rich in protein and can compensate for the lack of lysine amino acid in cereals. Thus, they are considered as a good food supplement for cereals. Broad bean is one of the legumes rich in protein (25-32% protein) and is considered as a suitable source for the production of protein concentrate. Xanthan gum is also one of the most effective hydrocolloids used in gluten-free products. The aim of this research work is to evaluate the effect of broad bean protein concentrate (BPC) and xanthan gum on physicochemical properties of rice batter and cake.

In the present study, BPC was extracted by acidic-alkaline method and was then added to the batter formulation at three levels of 0, 7.5, 15 % with xanthan gum at three levels of 0, 0.15, 0.3%. Physicochemical properties of the batter including specific gravity and viscosity were evaluated. Physicochemical and sensory properties of cake including porosity, volume, baking loss, hardness and sensory properties were evaluated.

Results of the batter analysis showed that viscosity was reduced by increasing the amount of BPC and xanthan and no significant difference was observed in specific gravity of samples. Results of the cake analysis revealed that hardness was increased and porosity, volume and baking loss were reduced by increasing the amounts of BPC and xanthan. Results of the sensory evaluation showed that there was no significant difference between the treatments in the parameters of crust and crumb color, hardness and porosity; and the panelists assigned lower score to the treatments containing 15% of bean protein concentrate (BPC) regarding the texture and flavor. In terms of total acceptance, the panelists assigned the highest score to the control sample and the sample containing 7.5% broad bean protein concentrate (BPC) and 0.3% xanthan.

In general, high amounts of broad bean protein concentrate (BPC) and xanthan gum led to a significant increase in batter viscosity which resulted in an increase in hardness and a decrease in volume and porosity of the cake by creating high water absorption, but led to a decrease in baking loss of the cakes, which is economically favorable. According to the obtained results, cake with 7.5% BPC and 0.3 % xanthan was the best treatment in terms of sensory and quality characteristics.