Pro Tip: Understanding lentils’ protein structure can make it a good candidate to replace egg and dairy proteins in sweet goods.
Pulses are a trendy category of legumes defined by low oil content and high levels of protein. Common examples include peas, chickpeas and lentils. These proteins share several similarities in their structures.
The predominant protein fractions in each are globulins which are subdivided on their sedimentation coefficients into 7S trimers and 11S hexamers. Together, these proteins make up about 70% to 80% of the total protein in the seeds.
Despite similar structures, each plant-based protein has its own unique functionality. The structure of lentil protein leads to favorable functionalities that can be utilized in the baking industry when compared to other pulses.
Lentils typically have more protein than other pulses, and the method of extraction significantly impacts how the protein behaves in baked foods. This high protein content makes lentils an attractive option for producing high-protein baked foods.
Lentil protein is also amongst the most digestible of any pulse and contains high levels of polyphenolic antioxidants, making lentils a good choice for health-conscious consumers. The polyphenolic anthocyanins in particular give lentil protein isolate a naturally red color that can be used as a source of natural color in baking applications as well.
Important functionalities such as solubility are similar to other pulses, where the protein is most soluble around pH 3 and pH 8 and insoluble near pH 4.5. In general, proteins form the strongest and most stable emulsions when they are also the most soluble. Therefore, if the pH of a new product can be held in these ranges, the emulsions may also be more stable during processing.
Considering other important protein functionalities, such has how much oil or water the protein can absorb, lentils often outperform other plant-based protein with the ability to bind more oil and water. This is in part due to a favorable balance of hydrophobic and hydrophilic amino acids that come together to form a surface with regions to interact with both water and oil. In terms of dough rheology, this leads to an increase in peak values when adding lentil protein to wheat flour and mixing with a farinograph.
The ability to bind more water also leads to more viscous batters when producing aerated sweet goods, such as angel food cakes.
However, thicker and emulsified batters, such as muffins and cakes, show minimal changes in viscosity when replacing egg white proteins with lentil protein isolate. The ability to bind large amounts of both oil and water, and adsorb to oil droplets, also leads to well-emulsified batters with lower bake loss than formulas with egg proteins.
The water-holding capacity also promotes more water in the products during storage, which should be considered when controlling mold in these products.
Lentil protein has been shown to lead to denser sweet goods, which could be partially addressed by changing the mixing procedure. For example, most proteins including lentils, form emulsions slower than emulsifiers naturally present in eggs, such as lecithin. As such, a premixing step to form an emulsion, which is then mixed into the batter in a second stage, may help the formation of a well aerated and emulsified batter.