Pro Tip: Cold temperatures in protein processing could change the way the ingredient functions in formulations. 

Denaturation has long been seen as an unavoidable side effect of isolating protein before it gets packaged and shipped off to make into final products. This unfolding is commonly thought of as an all or none process, where the protein unfolds rapidly into a random configuration as the result of temperature, shear, pressure or chemical interruption to its structure. 

However, newer models of protein folding show many thermodynamically stable intermediate forms configurations, each with its own unique function, which allows for targeted engineering of protein structure using different levers of denaturation.

In our most recent work, cold denaturation in pea protein was modeled using structural bioinformatic. That process showed that, at low temperatures (~ 15°F), pea protein unfolds and exposes hydrophobic amino acids, which allows for better emulsification properties. This model was confirmed by physicochemical characterization of commercial pea protein isolate in our laboratories.

By comparing the impacts of low temperatures and shear forces independently, we show that shear force decreases the particle size of pea protein and increases the hydrogen bound β-sheet structures, while low temperature increases hydrophobicity. 

These changes were persistent after the protein returned to room temperature, and it was demonstrated that when pea protein is processed at low temperatures, the resulting structure can absorb more oil and may also lead to novel gels or emulsions.

Additionally, the zeta potential, a measure of the electrostatic repulsive forces between proteins, became more negative, indicating the possibility of more stable emulsions formed from cold denatured protein. 

This work suggests that by using cold temperatures on commercially available pea protein isolate, it is possible to change the way it interreacts with other components in food, and similar changes should apply in most plant-based proteins.

In traditional heat processing, ingredient manufacturers need to be concerned about lipid degradation at high temperatures.

However, by using low temperatures that do not breakdown lipids, it may be possible to generate oil/protein complexes that bind more tightly, since the proteins are being processed when they have a large amount of exposed lipid binding area.

This may help ingredient manufacturers create novel fat replacers, emulsifiers, and oil-filled gels that are not possible by any other means of processing.  

Harrison Helmick is a PhD candidate at Purdue University. Connect on LinkedIn and see other his baking tips at BakeSci.com.

His research is conducted with the support of Jozef Kokini, Andrea Liceaga, and Arun Bhunia.