Pro tip: use spectroscopy to see process changes

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Pro tip: Using Fourier transform infrared spectroscopy, bakers can find out which ingredients lead to strong gels, better emulsifiers, and whether the process effectively develops gluten.

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

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

A 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. The FTIR takes advantage of this phenomenon by measuring the amount of infrared light absorbed by a food ingredient at different wavelengths of light. Based on the amount of vibration that occurs, insight into the chemical bonds in the material can be obtained.

In protein-based ingredients, looking at the wavelengths of light between 1600 and 1700 cm-1, it is possible to see the secondary structure. For example, if the protein is rich in helices, it could also indicate that it is a good emulsifier and that it will show a strong peak at a wavelength of about 1,650 cm-1. A strong peak at ~ 1,630 cm-1 is an indicator or sheet structures, which are known to lead to stronger gels due to a large amount of hydrogen bonds, and this is shown on the protein model of peas and the FTIR curve in the figure.

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

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

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


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