A naturally-occurring white-colored protein found in milk, casein makes up around 80% of the proteins found in cow's milk. It is a complete protein in itself, as it contains all the essential amino acids such as leucine, lysine, valine, isoleucine, phenylalanine, threonine, methionine, and tryptophan. It is used in the form of protein powders/supplements. It is also used in the production of cheese, adhesives, paint, plastics, etc.
Caseinates are protein products that are obtained by neutralizing the acid casein curd with a strong alkali. The type of caseinate formed will vary, depending on the alkali. A reaction between acid casein curd and calcium oxide/calcium hydroxide (to pH 6.8 to 7.6) or sodium hydroxide (to a pH of about 6.8) gives rise to the formation of calcium caseinate or sodium caseinate, respectively. These protein products are usually spray dried.
Structure and Properties of Sodium Caseinate
Casein is produced by the process of acid precipitation of fresh pasteurized skim milk. When an acid is added to milk, an isoelectric precipitate called acid casein is formed at the pH of 4.7 (pH at which a protein molecule has a net charge of zero). While making cheese, casein is precipitated by adding an acid or enzyme rennin. Casein precipitates out of the milk in the form of a curd. The curd is treated so as to remove fat, lactose, or other milk solids to get pure casein. Whey, another protein found in cow's milk, is the watery residue that gets separated from the curd. Both casein and whey have a high protein efficiency ratio.
It must be noted that acid casein curd is insoluble in water. It cannot be used in this form in food products. However, neutralizing the acid casein curd with an alkali changes its nature. For instance, neutralizing acid casein with sodium hydroxide gives rise to the water-soluble form of caseinate.
For the formation of sodium caseinate, acid casein reacts with sodium hydroxide. The following equation represents the neutralization of acid casein with an alkali. Here R represents casein protein.
H + Na+-
OH = R-COO-Na + H2
Sodium caseinate is odorless, and comes in the form of white or pale yellow granules or powder. It comprises the following amino acids:➠
According to the Food and Drug Administration (FDA), sodium caseinate is not a dairy product, in spite of being derived from milk. As per the FDA, the protein content has been changed to such an extent that it doesn't need to be considered as a dairy product.
Uses and Benefits
Since casein contains all the essential amino acids, it is a complete protein with a high nutritional value. Its protein efficiency ratio (PER) is high. PER is the ratio of body weight gain in grams (in specified time) to the amount of protein (in grams) consumed. Both whey and casein have a high PER of 3.2. This means that these proteins are easily absorbed by the body. This is the reason why casein/whey and their byproducts are added to infant foods and amino acid supplements. While sodium caseinate is not used as a food by itself, it is widely used in the food industry. However, it is only used as a supplement or ingredient in small proportions for either increasing the nutritional value of the food item or changing the physical properties of certain food products. It has the following applications in the food industry.
Besides improving the nutritional value of flours and baked goods, it also helps improve the texture, especially in food items such as donuts, muffins, and waffles. In case of deep-fried food items, it absorbs the extra fat. It acts as a binding agent for processed meats.
Being an excellent stabilizing and emulsifying agent, it is often used in beverages such as milk shakes. It enables the fat to remain suspended in water-based products, which is why it is often used in coffee creamers and ice creams. Moreover, it also imparts a thick texture and white color, which in turn provides a creamy look. Thus, it is also used as a coffee whitener. It acts as a stabilizing agent in case of ice creams. It is also used in wines due to its coagulant properties. It causes fine particles to coagulate with the protein. As a result, these can then be easily filtered out.
It is used in the following products:➠
Nutritional supplements (Protein bars or powders)➠
Bakery mixes and glazes➠
Sauce mixes and gravy➠
Side Effects or Risks Involved
Though the FDA doesn't place sodium caseinate under the category of dairy, as the addition of sodium hydroxide or other products used during the production change its properties, those who are allergic to milk or dairy products must watch out for any untoward effects. After all, it is made from casein. Moreover, reports in the Journal of Agricultural and Food Chemistry suggest that the byproducts of the process of the addition of sodium hydroxide to casein could be harmful. When ingested in large quantities, it could burden the kidneys.
Some individuals might even be allergic to casein, which breaks down to produce the peptide casomorphin, which in turn might cause an allergic reaction. The onset of the symptoms of an allergic reaction is due to the release of histamine by the mast cells. The common symptoms of an allergic reaction include hives, skin rashes, nasal congestion, runny nose, sneezing, wheezing, coughing, etc. In severe cases, the affected individual might experience swelling of the face, mouth, tongue, lips, and throat. Anaphylaxis is a life-threatening allergic reaction wherein the affected individual experiences symptoms such as swallowing and breathing difficulties, abdominal pain, cramps, vomiting, diarrhea, hives, angioedema, etc.
Further research is needed to prove that the use of sodium caseinate could aggravate the symptoms of autism. Also, concerns have been raised about the presence of glutamic acid, which is found in monosodium glutamate (MSG). A food additive used to enhance flavor, MSG was linked to symptoms such as headaches, flushing, sweating, facial pressure or tightness, numbness, tingling or burning sensation in the face, neck and other areas, rapid heart palpitations, chest pain, nausea, weakness, etc. However, there is a lack of definitive evidence to substantiate the link between these symptoms and the use of MSG.
On a concluding note, sodium caseinate is used in small amounts to modify the properties of certain food items. It is also used in certain supplements. However, if one does experience adverse reaction after the use of products containing this caseinate, it would be best to avoid such products.