Heating Stability of Whey

Heating Stability of Whey
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Transforming foods into healthy foods

Over the past few years, the popularity of health and fitness has risen dramatically and therefore the use of supplements has followed. This has led to a number of interesting, innovative and different ways to transform foods into healthy foods. This may be through increasing the protein content, adding an active ingredient, increasing nutrient density etc. Whey protein is the most popular supplement used, and therefore it is no surprise that this has been incorporated into a number of these recipes. However, adding whey protein to foods and drinks which require heating can result in the protein denaturing and the amount of protein the body can readily utilise will be reduced.

Whey protein is one of the best sources of protein

Whey protein is one of the best sources of protein due to its high leucine content, fast digestibility and low amount of carbohydrate and fat. However, the properties of whey protein make it one of the most sensitive sources of protein to heat. This poses a particularly big challenge when you want to take advantage of the beneficial components of whey protein and use it within a more convenient, innovative and different format.

Heating whey protein causes it to denature

Heating whey protein causes it to denature as a result of the protein structures unfolding followed by aggregation. This results in a number of protein-protein interactions which change the overall structure. Some of these changes are reversible (covalent) whereas other interactions are not reversible (non-covalent). Therefore heating whey protein can change its structure and characteristics permanently (denatured). These changes can affect the way in which whey protein behaves in solutions of altering pH (a careful consideration to make in flavoured beverages, or those with citric acid added). The denaturing process can also alter the viscosity of the whey protein, causing your finished recipe or food to have an alternative texture and likely become thicker and more stiff.

The protein – protein interactions can also change and break the bonds between protein portions of whey protein, such as the bond between two molecules of Beta-Lactoglobulin. This will ultimately change the whole structure of the protein and the protein will become denatured. As some portions of the whey protein become denatured and altered, the amount of protein that is readily useable by the body decreases, resulting in a recipe or drink that is lower in protein that initially thought.

Denaturing begins to occur at 70˚C

Denaturing and protein aggregation begins to occur at 70˚C within whey protein concentrate (Parris et al 1991) and the extent to which it denatures increases with time and temperature. Further to the denaturing of protein, damaging effects on amino acids are found at higher temperatures of 80 – 140˚C (deWit et al 1983). This would be the typical temperature of boiling water, or cooking temperatures for your high protein foods and drinks.

Due to this information, we have made a point of making a heat stable whey protein available to our customers and only using this heat stable source of whey protein within our formulas and recipes that require heating such as Complete Protein Coffee™, Complete Hot Chocolate™, Complete Protein Porridge™. We also have this source of protein available as an individual ingredient, Hydrolysed Whey Protein Isolate, so that customers who want to make their own foods and protein recipes can still do so as they please.

References

deWit et al, 1983, Effects of various heat treatments on structure and solubility of whey proteins, Journal of Dairy Science, 67 (11) p2701-2710

Parris et al, 1991, Thermal Denaturation of Whey Proteins in Skim Milk, Journal of Agricultural and Food Chemistry, 39 (12) p2167-2170

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