Protein Preparation
Protein Preparation
Milk is comprised of two different types of protein: whey (20%) and casein (80%). The two types of protein are separated by the addition of acid to the milk, leading to coagulation of the milk. This coagulation causes a separation between the proteins, leaving casein protein on the bottom and whey protein on the top. After this process is completed, whey is removed from the casein through various filtration techniques that also leads to the removal of fat and lactose from the whey.
There are several different forms of whey protein on the market and the difference between each type is in the filtration process used. The more filtration that occurs, the greater the protein content, lower the lactose and fat content, and typically the greater the cost. After the filtration process occurs the milk is evaporated and dried out leaving protein in the form of powder. Whey protein concentrate typically contains 70-85% protein, while whey protein isolate contains 90-98% protein.
There are several various types of protein filtration techniques, each one eliciting a different result. Tovar Jiménez et al., 2012 conducted a study looking at some of these techniques. The techniques used for this study were:
The purpose of this study was to show how each filtration technique effects the nutritional and biological makeup of the protein. The results were as follows:
As expected, each technique produced a different end results, which allows us to discuss the advantages and disadvantages of each process. Ultrafiltration and salt treatment led to the highest protein content; however, the salt treatment technique left behind more sugars and more fat in the protein. One major advantage of the salt treatment is its cost effectiveness. The same is not true for cross filtration. Results from this study demonstrated that ultrafiltration leads to a lower sugar and fat content; however, this technique is much more expensive which is a reason why this technique may not be as advantageous.
One very important detail that I want to be understood is that sometimes it is not just the macronutrient content that is important. Whey protein contains bioactive peptides which serve many purposes with one of their main focuses being enhancing the immune system. Certain filtration techniques can denature or destroy these bioactive peptides. During this study, lactoferrin (LF) and immunoglobulin (Igs) were monitored to test for denaturation. Lactoferrin exhibits antibacterial, antifungal, antiviral, antiparasite and antitumor activities. It is protective with regard to intestinal epithelium, promotes bone growth and accelerates recovery of the immune system function in immunocompromised animal (Zimecki et al., 2007). Immunoglobulins can provide a boost to the immune system as well. Jimenez found that the ultrafiltration technique also produced better results in maintaining LF and IGs, demonstrating that denaturation did not occur.
The results from this study suggest that the best method for filtering whey protein could be ultrafiltration due to its production of a high protein content, low fat and sugar content, and preservation of bioactive peptides. Whey protein that has been exposed to ultrafiltration can be found in the form of whey protein isolate. The one major disadvantage to this form of whey protein is the increase in cost compared to other types of whey protein such as whey protein concentrate.
Tovar Jiménez, Xóchitl, et al. "Traditional methods for whey protein isolation and concentration: effects on nutritional properties and biological activity." Journal of the Mexican Chemical Society 56.4 (2012): 369-377.
Zimecki, Michal, and Marian L. Kruzel. "Milk-derived proteins and peptides of potential therapeutic and nutritive value." J Exp Ther Oncol 6.2 (2007): 89-106.
