1. Overview of whey protein
Whey protein is a type of protein extracted from milk using modern advanced technology. It is easy to digest and absorb, has high metabolic efficiency and biological value. The tissue of milk is 87% water and 13% solid, of which 37% is lactose, 30% is fat, 27% is milk protein, and 6% is ash minerals. Only 20% of milk protein is whey protein and 80% is casein. The production process can affect the efficacy of whey protein. Undenatured whey protein extracted by low temperature and membrane ultrafiltration technology has the best activity and efficacy. As new technologies continue to develop their multifunctional properties, whey protein concentrate (WPC) and whey protein isolate (WPI) have become popular functional food ingredients. WPC is obtained by whey, a natural by-product obtained when producing cheese from milk, through clarification, ultrafiltration, secondary filtration, drying and other processes. [1] WPI is a high-purity whey protein obtained through further processing on the basis of WPC. The purity can reach more than 90%, but its price is expensive, 2-3 times that of WPC. But it is easier to digest and absorb.
2. The main components and functional properties of whey protein[2]
The basic ingredients of whey protein are the same as those of milk, but the proportions of each ingredient are different. Depending on the degree of filtration, the protein concentration ranges from 30% to 80%. The main protein components of whey protein are β-lactoglobulin (48%), α-lactalbumin (19%), protease-peptone (20%), immunoglobulin (8%), and bovine serum albumin (5%). ), in addition, it also contains some trace ingredients with biological activity or health care properties, such as lactoferrin, lactoperoxidase, lysozyme, casein macropeptide, fat globule membrane protein, growth factors, etc., which can also be obtained from whey protein separated. It is these ingredients that provide whey protein with excellent application value.
(1) β-Lactoglobulin
Beta-lactoglobulin is the main component of whey protein. It has an optimal amino acid ratio and a very high content of branched-chain amino acids. Branched-chain amino acids are essential amino acids, including leucine, valine, and isoleucine. Among them, leucine has the strongest biological effect. It can be used as a substrate for glutamine and can also be directly used as a cell fuel. Research has confirmed that branched-chain amino acids play an important role in promoting protein synthesis and reducing protein breakdown. Leucine and its oxidation products can also inhibit proteolytic enzyme activity, which is beneficial to muscle protein synthesis and increases lean body mass. During endurance exercise, branched-chain amino acids can block tryptophan from entering the brain barrier and convert it into 5-hydroxytryptamine, thereby enhancing the central nervous system's ability to resist fatigue. According to recent Southeastern Foods research at the University of North Carolina, beta-lactoglobulin is able to preconjugate fat-soluble nutrients such as vitamins A and E.These fat-soluble vitamins must use solvents or carriers to be added to food. Their use in fortifying non-fat foods is a challenge for manufacturers. This research will help further expand dairy products, baked goods, sports nutrition The development prospects of beverages.
(2), α-lactalbumin
Alpha-lactalbumin is also an excellent source of essential and branched-chain amino acids. It is a natural whey protein and the only whey protein component that can bind metals, including calcium. Recent research has even found that it may have anti-cancer properties. In addition, lactalbumin isolated from cow's milk is very similar to human milk in terms of amino acid ratio structure and functional properties, making α-lactalbumin widely used in infant formula. Clinical studies show that infant formulas rich in alpha-lactalbumin are safe.
(3) Immunoglobulin
The immunoglobulins in milk have the same properties as human milk immunoglobulins and also have activity against human diseases. Moreover, these activities resist the hydrolysis of proteases and can completely enter the proximal small intestine to play a defensive role in protecting the small intestinal mucosa.
(4) Lactoferrin
Although lactoferrin content is low, its biological activity is high. This is reflected in the following aspects:
1. Antibacterial properties: Lactoferrin can firmly bind to iron, preventing it from being used by bacteria. It has been reported that lactoferrin has resistance to several human viruses; 2. Iron transfer: iron-saturated lactoferrin Egg whites are an efficient form of iron transfer in the diet. Many nutritional food formulas, such as baby food, sports drinks, women's food, etc., often use lactoferrin to improve the iron balance in the body; 3. Promote cell growth and improve immunity: Lactoferrin can promote intestinal cell growth and also Can restore intestinal digestive function to normal. Recent studies have found that lactoferrin can stimulate the cells of the human immune system and can be used as a supplement for the elderly or people with low immune function; 4. Antioxidant: Lactoferrin has the ability to bind and transfer and catalyze the generation of peroxide free radicals. The ability to free iron and other divalent metal ions, thus effectively inhibiting the oxidation process catalyzed by metal ions. 5. Inhibit the formation of free radicals: Used to remove excess iron that is catalytically formed into free radicals to prevent various hazards caused by oxidation.
Overall, lactoferrin is a functional ingredient that provides health benefits in dairy products and other pharmaceutical products containing probiotic strains.