Pro Tip: Protein denaturation can lead to a loss of functionality, but controlling change brings new possibilities for plant- based protein
Have you ever tried to use a bag of gluten and found that it just didn’t lead to the strength that you expected? One possible reason for this is the gluten was denatured due to high heat used as part of the isolation process. When proteins undergo processing with extreme temperatures, or other harsh conditions, it causes them to unfold and take on a new structure. In the case of gluten, this means it can’t form the disulfide bonds during mixing that we look for in a well-developed dough.
To avoid this, ingredient producers use a variety of drying methods to minimize protein denaturation. Freeze-dried gluten retains the best baking properties, but it has not proven economically viable for mass production. Spray drying is generally the best way to dry protein at industry scale given the short time that the protein is held at high temperatures. Unfolding happens in mere milliseconds though, so even spray drying leads to some denaturation.
What if it were possible, however, to use denaturation as a tool to change the structure of a protein in specific ways to gain new functionality? In gluten for baked goods, denaturation inhibits functionality, but in many plant-based proteins, targeted denaturation is one way to improve functional properties, including solubility, emulsification and gelation. Proteins denature when the bonds that hold them together are disrupted by changes in temperature, chemicals, shifts in pH and shear forces. However, each of these levers of denaturation breaks different bonds in the protein structure, which leads to a selective unfolding of the protein. By using specific processing conditions, producers of plant-based protein can engineer its functionality by applying different levers of denaturation.
In our work, we have found that processing pea protein in the presence of ethanol, shear and low temperatures leads to increases in the ability of the protein to form strong emulsions after drying. By selectively modifying protein shape with different combinations of temperature, mechanical force, pH changes and chemicals, ingredient suppliers can produce protein ingredients to help bakers with all of their emulsification and gelation needs.
By viewing denaturation as a tool, instead of something to be avoided, plant-based emulsifiers and gelators can lead to clean label solutions for increased loaf volume, enhanced crust color and even serve as part of an egg replacement strategy.