How Seasonal Variations in Cow’s Milk Affects Whey Protein

by Christine Hronec

From time to time, a client will question why their whey protein seems “different.” This has to do with source of cheese that the whey was derived from and the associated method utilized in cheese production as well as the diet of the cows during lactation. The science behind transforming milk to cheese is a complex chemical process. Cow’s milk is rich in a wide range of chemical compounds that can be processed into various dairy products such as cheese, butter, and yogurt. Specifically the milk component involved in cheese production is a soluble protein called casein. The enzyme rennet can be used to catalyze the conversion of casein in milk to para-casein by removing a glycopeptide from the soluble casein. Para-casein further coagulates, in the presence of calcium ions to form white, creamy lumps called the curd, leaving behind the supernatant called the whey.

There is no standard method of cheese making; limitless variations exist for all stages of the process: pre-ripening, curdling, addition of artificial ingredients and salt for flavor, and aging. This variation in processing accounts for the wide range of cheeses commercially available, differing in texture and flavor. The curd can also be processed with other techniques to make a variety of desserts. However, all processes have one thing in common: the separation of the curd from the whey.

Commercially, there are two main approaches for preparing milk for curdling:

Curdling via Microorganisms or, using a strong acid such as hydrochloric acid. The differences in these methods affect the resulting quality of the final cheese. The variations and different types of starting cultures, amount, and process time are what lead to more sophisticated types of gourmet cheeses, where the efficiency related with using a strong acid will generate a commercial grade cheese without much complexity. Regardless of the process utilized to prepare cheese curds whether it is high end or economy cheese, the resulting supernatant or phase separated liquid is where we derive whey protein. It is then ultra-filtered several times and spray dried before becoming the rich, high quality protein supplement known for its benefits in the bodybuilding and general health industries.

Since whey is the byproduct of an organic raw material aka cheese (I use the word organic meaning “natural” not certifying a commercial farming method), there are times that whey protein will be “different” from batch to batch regardless if it made using the same exact formulation. In addition to the cheese curling method, the factor that will affect whey protein color is related to the diet of the cows. Sometimes whey has a more yellow/orange hue as opposed to a light cream/white color. Cheese manufacturers compensate for this variation by adding a food grade titanium dioxide pigment (very common with mozzarella cheese production). Cheeses and whey for that matter that have a more yellow/orange color have the same protein quality; however the cows were fed a diet that contained small amounts of beta carotene which contain annatto pigment. This is the same natural pigment that gives carrots it orange color. The reason cheese looks this way is because pasture fed cows that consume grass have higher beta carotene content due to a diet of fresh grass, where in the winter, cow’s diet consists primary of hay, containing less beta carotene resulting in “whiter” whey. At the end of the day, the nutritional quality is the same of whey regardless of the color; however there is a perception at the lighter colored whey is higher quality when in fact it only means that the cows had less beta-carotene in their diet at the time.

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