Casein Supplements - Caseinated Calcium, Micellar Casein and Hydrolyzed

Caseins represent the most abundant protein fraction of milk, whose nitrogen content is divided into four components:

• casein : a family of phosphoproteins that make up the prevailing protein fraction of milk (about 2/3 of the nitrogenous substances present in that of cow). They constitute the insoluble protein fraction of milk, which precipitates (coagulates) at pH 4.6 and / or due to the addition of rennet. They are therefore fundamental in the cheese-making processes (from which the cheese is obtained). The casinos boast a good biological value due to the excellent composition in essential amino acids.
• Serum-proteins (or whey proteins or whey protein): they abound in the residual whey from cheesemaking and are distinguished by the very high biological value. They constitute the soluble protein fraction of milk at pH 4.6 and represent 17% of the total nitrogen content of the vaccine. During the heating of the milk the whey proteins are denatured while the casein micelles only undergo small changes.
• Proteins with enzymatic activity (antibacterial like lysozyme, immunological like immunoglobulins and lactoperoxidase, trophic like lactoferrin which favors the absorption of iron, digestive like proteases and lipases ...). These proteins have no purely nutritional purpose, but due to their actions they contribute to improving the state of health.
• Non-protein nitrogen : urea is the main non-protein nitrogenated compound in milk; its values ​​depend on the animal's state of health.

Good sources of caseins are represented by mature cheeses, while whey proteins abound in dairy products produced with whey, such as ricotta. The two protein fractions are also present in many protein supplements.

Nutritional characteristics of caseins

DEEPENING

In milk the caseins are mostly in the form of micelles, large spherical protein aggregates dispersed in the milky mass with the hydrophilic part facing outwards and the hydrophobic part concentrated in the inner "core". Understanding these aspects is important to understand the different properties of casein supplements.

Casein micelles are the result of the association of other smaller spherical particles, the submicelle. Each submicella is composed of many casein molecules, but they are not all the same. In fact, 4 different proteins are known: αs1-casein, αs2-casein, β-casein and k-casein. The first three are strongly hydrophobic and tend to precipitate in the presence of calcium; k-casein is instead made up of two different parts, one more hydrophobic and one more hydrophilic: the hydrophobic portion of k-casein integrates perfectly with the other caseins, while the hydrophilic part turns towards the outside of the micelle, in contact with the surrounding liquid environment; a sort of shield is thus formed that protects the other caseins from contact with the calcium ions (which would cause them to precipitate). Furthermore, this shield is negatively charged and this causes the various micelles to repel each other.

The micelle contains small amounts of lactose and mineral salts such as calcium and phosphorus, which have the function of stabilizing its structure. Outside them we find serum, containing lactose, whey protein and small organic ions.

The size of the micelles varies according to the type of milk; in that of women, for example, they have a smaller diameter than those of cow's milk and this makes the human casein more digestible. The proteases of the stomach, in fact, must separate these micelles before attacking and digesting the proteins concentrated in them; in this sense, the increase of the specific surface (smaller micelles) facilitates the digestive action. Similarly, in the dairy industry smaller micelles mean a faster and more consistent curd.

With the addition of rennet (proteolytic enzymes), the k-casein is broken in two, its protective action is lost and the various caseins instead of repelling, aggregate and form the curd. With acidification, on the other hand, the negative charge of the micelles is lost, with a consequent tendency to aggregation.

BIOLOGICAL VALUE

From the point of view of the amino acid composition, caseins are rich in proline and phosphorylated amino acids, while they are relatively poor in sulfur amino acids (especially cystine). For this reason, considered individually, they have a good but not optimal biological value. Instead, they contain greater amounts of glutamine, arginine and phenylalanine than whey. In this regard it is interesting to note once again the "wisdom" of nature, given that in the food in its entirety the amino acids lacking in caseins are compensated for by the richness in the sulfur amino acids of the whey proteins.

The sportsman who takes casein protein supplements should not, however, worry about the relative lack of sulfur dioxide, as it is necessary to consider the protein intake of the diet globally rather than dwell on the single feeder. The sulfur amino acids are well represented in fish and meat, especially in connective tissues, which generally abound in the sportsman's diet.

DIGESTIBILITY '

Because of their nature and the tendency to form micelles (which are very resistant to heat and dehydration, therefore they can be found in protein supplements), caseins are known to represent a "slow absorption" protein source. Compared to whey proteins, therefore, caseins are digested and absorbed more slowly, ensuring a more delayed entry of amino acids into the bloodstream. For the same reason, at the same dosage, they have a lower insulin index and a greater satiating power.

From all these premises comes the advice to take casein supplements away from training and / or before going to sleep for the night, in order to stimulate protein synthesis and limit the catabolic phenomena induced by prolonged nighttime fasting.

Compared to whey proteins, caseins tend to give more viscous and sticky solutions (lower solubility).

CONTENT IN MINERALS

The concentration of calcium is higher in caseins than in whey proteins. However, much depends on the extraction techniques adopted.

Caseinato Calcium (or Soccer Caseinate)

A caseinate is a casein made soluble (in water) by the addition of alkalis; this solution is then dried by the spray-dry process or on cylinders.

At a neutral or acidic pH, caseins are relatively insoluble in water and are therefore easily separable from other milk proteins, lactose and minerals.

To produce the calcium caseinate supplements, the caseins of the skimmed milk are then precipitated with acids up to its isoelectric point (pH 4.6); then proceed with a repeated washing with water and new acid rain to eliminate excess lactose and salts. At this point, by adding a solution of calcium hydroxide and injecting steam, the precipitated casein is subjected to a rise in pH which turns it into a viscous solution of calcium caseinate, then dried on cylinders or by a process called spray-dry.

Similar to whey proteins obtained by ion exchange, calcium caseinate has a high degree of purity; in fact it contains a higher percentage of protein, greater solubility in water, less fat, less lactose and less sodium. For these characteristics it should therefore present a more rapid digestibility, while the negative aspects would derive from the partial protein denaturation induced by chemical treatments.

Micellar Casein

They are obtained through the use of physical, semi-permeable or ion-selective filters, the type of which influences the "purity" degree of the casein supplement. Similar to whey proteins, two main techniques are known, microfiltration and ultrafiltration. The selectivity of these filtration processes (favored by forces such as pressure, electrical potential or concentration) determines the degree of purity (understood as the residual percentage of fats, lactose and mineral salts); in general, micellar proteins represent a less pure protein source compared to calcium caseinate, characterized by higher percentages of fat, lactose and sodium. However, it should be pointed out that the improvement of production techniques is likely to shortly lead to a reduction in the gap with calcium caseinate, reaching levels of purity that can be superimposed with the advantage of non-protein denaturation. The main value of micellar caseins derives from the preservation of the original micellar structure, which preserves its biological function (instead altered by the chemical processes used to obtain calcium caseinate). The addition of soy lecithin can improve its solubility, obtaining products generally indicated as instant micellar caseins.

Hydrolyzed Casein

These supplements are obtained by subjecting the caseins to enzymatic digestion, which breaks down the peptide bonds of the proteins, reducing them to more easily digestible and absorbable fragments. In this way many of the distinctive characteristics of caseins are lost compared to whey proteins: digestion times are reduced (theoretically) and insulin stimulation increases, therefore the only substantial difference remains the amino acid profile. Even if these statements do not seem to take a theoretical turn, not always what seems obvious based on the physiology of protein metabolism is then confirmed by scientific studies; for example, some studies have shown that both casein hydrolysates and serum proteins do not appear to have significant differences in terms of digestion / absorption time compared to intact proteins.

Hydrolyzed caseins have better solubility characteristics and a much higher cost.

Finally, in the table we compare the nutritional values ​​and the amino acid profile of calcium caseinate, of micellar caseins and whey proteins.