Pro Tip: Differential scanning calorimetry can be used to identify when key reactions occur in protein and starch, leading to a better understanding of plant-based protein processing and gelation.

Maintaining the highest quality product is an ongoing challenge in every bakery, and keeping control of temperature is a critical factor. From mixing to packaging, there are countless points where temperature matters, but the oven is one crucial step to know what reactions occur at different temperatures.

When baked goods go into the oven, heat is transferred from the outside of the dough piece in, and as the temperature rises, protein denatures (~60°C to 95°C) and starch swells with water as it loses its crystalline structure and gelatinizes (~60°C). Achieving these reactions at the right times are crucial for producing bread that has a tight crumb structure and sufficient volume, but how can you establish the temperature where these reactions occur, and how do they change with your formula?

The easiest way to find out is using differential scanning calorimetry (DSC). DSC is a well-established technique that can provide insight on starch gelatinization in the oven and retrogradation during shelf life, but it is also used to study protein denaturation and structure. What these things have in common is that reactions occur because of the energy stored in starch or protein, and DSC can quantify that energy, providing insight on when the starch or protein undergoes key reactions.

Figure 1: A –diagram of a differential scanning calorimeter. A sample pan is compared to a reference pan as the chamber is heated, and the difference between the heat going to these two pans is recorded in the computer; B – Representative DSC curve for protein denaturation showing the enthalpy and temperature of denaturation (shaded green area); C – Representative DSC curves showing a larger endothermic peak in aged bread, caused by starch retrogradation (crystallinity).

 

DSC works by putting a small amount of protein, starch or any other material in a hermetically sealed pan and placing it on a pedestal in a closed chamber. A reference pan is prepared with no sample and is placed on a second pedestal. As the chamber is heated, the temperature of each pan is monitored, and if the pan with material requires more heat to maintain a constant temperature, that means that the material is taking on more energy, appearing as an endothermic peak on a graph.

In protein, the temperature where this peak appears is the temperature of denaturation, and the integral of the peak is the enthalpy of denaturation. These values are important for anyone interested in making gels from plant-based protein since gelation can only occur if the protein denatures, allowing for structural rearrangement and establishing a new solid structure. For example, the two primary proteins in eggs denature around 65°C and 84°C, but in many plant-based proteins, these temperatures can be as high as 85°C to 95°C. However, temperature and enthalpy of denaturation increases in the presence of both salt and sugar, is impacted by pH and also depends on how fast that temperature is reached.

Using DSC, it is possible to learn how the conditions in your baked goods impact the temperature of denaturation of the proteins used so that adjusting the processing ensures that high enough temperatures are reached at the right time to make strong gels in egg-free baked goods.

Harrison Helmick is a PhD candidate at Purdue University. Connect 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.