**2. Components and types of whey proteins**

Acid whey, which has a pH of 5.1 or less, is made by acidifying milk directly, as is used in the production of cottage cheese. After rennet-coagulation, sweet whey with a pH of 5.6 or higher is produced, as it is used in most cheese-making processes around the world [3]. Whey protein (protein not precipitated by acid or rennet) accounts for about 0.6 to 0.7 percent of total milk content and accounts for about 20% of overall milk proteins. Whey proteins are high in nutrients that are beneficial to wellbeing of humans. α-lactalbumin, β-lactoglobulin, lactoferin, lactoperoxidase, immunoglobulins, and glycomacropetide are among the proteins present in it [4]. Percentage of each component of whey protein is mentioned in **Table 1**.

The development of processing techniques, particularly those based on selectively permeable membranes, has allowed a range of whey protein constituents to emerge as common food additives in the last two decades. The membrane based processing techniques results in ultrafiltration (UF) to concentrate proteins and diafiltration (DF) to eliminate most lactose, minerals and low molecular weight components and hence producing versatile whey products with distinct qualitative and quantitative profiles of proteins, minerals, lipids, sugars and whey


#### **Table 1.**

*Approximate concentration of proteins in whey in different species.*

**Figure 1.**

*Types of whey proteins; this classification is based on protein processing and refining [18, 19].*

*Bio-Molecular Characteristics of Whey Proteins with Relation to Inflammation DOI: http://dx.doi.org/10.5772/intechopen.99220*

protein concentrate (WPC). There are WPC that produce 35, 50, 65 and 80% (w/w) protein, subject to their concentration. When the protein content reaches 90% (w/w), a whey protein isolate (WPI) is made, that is a high-grade and pure protein concentrate. When added to foods, each of these compounds function as carriers for the stimulation of a variety of biological characters. When whey is heated, α-LA denatures quickly, allowing the fraction to be divided by precipitation [14]. Whey protein hydrolysate (WPH) is the "predigested" type of whey protein since it has already passed through partial hydrolysis, which is needed for the body to consume protein. WPH is easier to absorb than the other two types of whey protein [15–17]. Flow sheet of all types of whey proteins is mentioned under **Figure 1**.

### **3. Physiological and biological roles of whey proteins**

Whey protein is high in bioactive peptides, which can help with chronic disease control by nutrition. The conventional and evolving implications of whey proteins are elaborated in below para [20, 21].

Whey proteins and their constituents have been found to have a variety of health advantages. In a study, bovine whey proteins showed positive impacts on the lipid profile in serum and liver, including overall lipid and triglyceride alteration and reduction [22]. Enzymatic breakdown (natural digestion in the GI tract, enzyme mediated hydrolysis, milk fermentation) of whey proteins produces antihypertensive peptides (ACE-I) [23]. Whey proteins derivatives like short chain and peptides resistant to water have been shown in studies to reduce blood pressure and stress hypertension by increasing ACE inhibitory action [24, 25]. Whey proteins are a predecessor or foundation of glutathione (GSH) that performs oxidation against reactive oxygen species (ROS), responsible for tissue harm, especially in the central nervous system's neurons and glial cells [26]. Whey proteins are unusual in their capacity to increase glutathione (GSH) levels in different tissues that optimizes the functionality and structure of the immune system [27]. GSH defends cells from free radical destruction, contaminants, chemicals, infection, and UV exposure as part of antioxidant defense mechanism of body [28]. GSH levels are usually low in people who have cancer, HIV, persistent fatigue syndrome, or other immune-suppressing diseases [29]. GSH levels drop with age, and it's thought to play a role in diseases like Alzheimer's, cataracts, Parkinson's, and arteriosclerosis. Whey proteins provide a number of health benefits, including improving the acquired immune system. The most active fractions were whey protein extracts from β-lactoglobulin and α-lactalbumin, which had an additive impact on neutrophils, making them more sensitive to a subsequent stimulus [30]. Supplementing athletes with whey protein during rigorous endurance training can help them boost the immunity in between and afterward of workout and physical activity [29, 30]. In infants, an improved immune response may aid in the prevention of bacteriological and pathological syndromes, as well as illnesses including gastroenteritis. Thus, including whey proteins in one's diet can benefit people of all ages, not just those with a weakened immune system [31]. Whey protein has been shown to prohibit the progression of pathogenic bacteria, suggesting that it may be used to regulate the development and reinfection of *E. coli* (O157:H7)*, Listeria monocytogenes, and Salmonella typhimurium* in ready to eat meat by using WPI as a defensive film covering ingredient [32–35]. Rises in the levels of alanine in plasma and aspartate aminotransferase activities, production of lactate dehydrogenase, and bilirubin concentration that refers to hepatitis indicators, as well as hyaluronic acid concentration which is fibrosis marker can be suppressed by a whey protein-rich diet [36, 37].

The active ingredient of whey protein found to have a vital role in growth and development of bones as well as a possible healing impact on osteoporosis by stimulating osteoblasts [38, 39]. The biochemical role of peptides in whey protein is as food additives is to improve calcium absorption (by preventing calcium phosphate formation) and avoid bone disorders [40]. Branched-chain amino acids (BCAAs) are well-known in whey proteins. While the need for BCAAs rises with endurance activity, whey protein may be used to supplement these BCAAs during the healing process to boost protein synthesis and muscle development [41]. Since both whey and skeletal muscle almost have identical amino acid profiling, it is highly effective to speedup muscle protein synthesis [42]. As a result, whey protein, by its necessary amino acids, aids in the production of skeletal muscle protein and the avoidance of sarcopenia (muscle wasting) after strenuous exercise [43, 44]. Current researches depicts that whey proteins may help athletes with resistance training boost their lean body mass and efficiency [45]. Increased brain tryptophan and serotonin activities boost cognitive function in stress-prone subjects because of efflux of whey protein in α-lactalbumin [46]. In milk, glycomacropeptides (GMPs) and whey protein concentrate may help probiotic bacteria like *bifidobacterium lactis* development. Gut wellbeing has been seen to be improved by a variety of probiotic bacteria [47]. Cancer prevention is essential. Whey protein in the diet can lower serum C-peptide levels and duodenal SREBP-1c mRNA profusion, as well as lessen the risk of duodenal tumors [48, 49]. Growth stimulator established in whey proteins showed positive impacts on various mammalian cells of the culture media. These growth stimulators work by suppressing protein degeneration and enhancing synthesis of protein and DNA inside the cells. As a result, whey protein can aid in tissue regeneration as well as the prevention of psoriasis and ulcers [50]. Incorporating whey protein concentrates and glycomacropeptides (GMPs) into the diet may increase satiety and reduce food consumption. GMP that activates cholecystokinin (CCK), which is a hormone to suppress hunger, is shown to have variety of important roles in gastrointestinal activity, including food intake control [51]. Various other proteins, in the patients suffering from type 2 diabetes, established to be overtaken by whey proteins for the improvement of postprandial lipemia, when taken as a complement to a fat-rich diet, likely due to the development of less chylomicrons or improved clearance of chylomicrons [25, 52] as shown in **Figure 2**.

#### **Figure 2.**

*Biological roles of whey proteins summarized from different literature [53–60].*
