Pro Tip: By using Fourier Transform Infrared Spectroscopy, bakers can know which ingredients lead to strong gels, better emulsifiers and if the process is effectively developing gluten.  

During ingredient processing, shear forces, temperature changes and more come together to alter the structure of protein, starch, fiber and lipids. These structural changes all lead to different functional characteristics, but how can you quantify those differences and begin to understand which structures lead to strong gels or better emulsifiers? 

The techniques that can give insight on the physical chemistry and better understand processing changes are called physicochemical experiments, and they are common in materials science laboratories. These techniques have proven invaluable in developing fundamental understanding of the changes food ingredients undergo as the result of processing, and they also help to validate that the process is working. 

One fast and reliable technique that can be used to see structural changes in food ingredients is Fourier Transform Infrared Spectroscopy (FTIR).

All food ingredients are held together by different chemical bonds, and these chemical bonds change when energy is added to them. FTIR takes advantage of this phenomena, measuring how much infrared light is absorbed by a food ingredient at different wavelengths of light. Based on how much vibration occurs, insight on the chemical bonds in the material can be gained. 

In protein-based ingredients, by looking at the wavelengths of light between 1,600 and 1,700 cm-1, it is possible to see the secondary structure. For example, if the protein is high in α-helices, it might also indicate that it is a good emulsifier, and it will present a large peak at a wavelength of ~ 1,650 cm-1. A strong peak at ~1,630 cm-1 is an indicator or β-sheet structures, which are known to lead to stronger gels due to a large amount of hydrogen bonding, and this is shown on the pea protein model and FTIR curve in the figure.

By using FTIR before and after ingredient processing, it is possible to understand how the secondary structure changed and why the ingredient behaves differently. In dough mixing, it has been found that optimally mixed dough is high in β-sheet structures. These structures and high levels of disulfide bonding are part of what leads to the unique strong and stretchy characteristics of well-developed gluten.

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

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