Published in the Journal of Food Hydrocolloids, the study looked at the impact both animal and vegetable sourced proteins had on the rheology (the texture and flow of the batter or dough) and quality of rice based gluten-free muffins.
Soy protein isolate, pea protein isolate, egg white protein and casein were tested and compared to muffins without added protein and also muffins with added vital wheat gluten.
“Both the rheological properties of the batters and the technological characteristics of the muffins obtained are notably dominated by the type of protein used in the formulations,” the researchers found.
“The development of sweet-baked gluten-free product is greatly dependent on the protein source,” they said.
Findings showed that proteins impacted batter behavior and end product attributes like texture, height and moisture content.
“Overall the experimental results showed some common peculiarities within vegetal proteins and the same within animal source proteins,” the researchers wrote.
Given the level of impact proteins have on the gluten-free muffins, the researchers said manufacturers must optimize formulations to ensure a good quality end product.
Batter impacts
At the batter stage, specific gravity (ratio comparison of the batter weight against regular water) and rheological behavior were both impacted by the proteins.
Findings indicated that specific gravity was “significantly affected” by the protein type; with casein protein ensuring the highest value and egg white protein the lowest – the latter indicating that more air was incorporated and retained during mixing, the researchers said.
Animal sourced proteins – egg white and casein – increased the emulsifying activity of the rice flour which in turn decreased the stability of the emulsion, whereas vegetable origin proteins had little impact.
Viscosity was also impacted differently depending on the protein source, the researchers said. Overall, vegetable origin proteins induced a hardening effect on the batters whereas animal sourced proteins led to batters with a less solid like character.
Muffin impacts
The inclusion of added proteins led to “significant differences” in the moisture content of the muffins, findings showed, as well as impact on height and specific volume.
Animal proteins improved volumes the most but egg white protein specifically had the most significant impact on height and volumes, improving both.
Texture parameters were also impacted with added proteins, the study found, increasing the springiness and cohesiveness of the muffins.
Hardness only increased with the inclusion of casein, the researchers said.
“In general, muffins made from animal proteins were springier, more cohesive and chewy than those made from vegetal protein source,” they said.
Crumb color was changed predominantly in relation to the original color of both the rice flour and protein isolates.
Source: Journal of Food Hydrocolloids
Published March 2014, Vol. 35, Pages 150-158
“Establishing the function of proteins on the rheological and quality properties of rice based gluten free muffins”
Authors: ME. Matos, T. Sanz and CM. Rosell