# Techno-Functional Properties and Recent Advances in the Manufacturing of Whey Beverages: A Review
## 1 Introduction
By addressing both the opportunities and challenges, this paper aims to provide a comprehensive understanding of whey's role in the beverage industry and its potential for future applications in manufacturing whey-based beverages. The composition and properties of whey vary according to the type of milk, the type of animal's diet, the technology used to process the milk, and other environmental factors [17]. Whey contains, on average, approximately 93% water. Acid whey possesses a higher ash content. On the other hand, it contains reduced lactose content and hence increased lactic acid, as lactic acid bacteria convert lactose into lactic acid during the curd formation process. In sweet coagulating, the activity of lactic cultures is diminished compared to the coagulation caused by rennet, resulting in a lower concentration of lactic acid in the sweet whey. Importantly, acidic coagulation of casein occurs close to the isoelectric point of milk (pH \(\approx\) 4.6), resulting in a higher degree of milk protein precipitation than in sweet whey. The lower pH of the acid whey results in the dissolution of the colloidal calcium phosphate from the casein micelles, therefore, the calcium content of the acid whey is almost twice as high [13; 14; 16; 18; 19]. As already mentioned, whey was previously considered mainly as waste and was primarily used as part of animal feed. Nevertheless, due to technological developments in the dairy industry and current research, whey is now considered a value-added raw material [5; 18]. Whey contains components with high nutritional value and biological activity. First of all, these are whey proteins, which can have a beneficial effect on growth, metabolism, and health. Lack of protein in the diet causes health problems worldwide, so it is advisable to include foods rich in these nutrients in the human diet. Whey proteins, as globular proteins, contain a high proportion of \(\alpha\)-helix structures. Hydrophilic and hydrophobic amino acids, as well as acidic and basic amino acids, are evenly distributed in their polypeptide chain [20; 21]. fractions of whey proteins are \(\alpha\)-lactalbumin (\(\alpha\)-LA), \(\beta\)-lactoglobulin (\(\beta\)-LG), bovine serum albumin (BSA), immunoglobulins (IG), bovine lactoferrin (BLF), bovine lactoperoxidase (LP), and smaller amounts of glycosacropeptide (GMP) [27]. In addition, sweet whey contains caseinmacropeptide (CMP), which is formed during the breakdown of \(\kappa\)-casein by rennet [28]. Enzymatic hydrolysis of whey protein in the human digestive system, as well as fermentation of milk by starter cultures or hydrolysis by plant or microbial proteases, leads to the release of bioactive peptides. These bioactive peptides then function as signalling molecules and have diverse physiological effects on the immune, gastrointestinal, cardiovascular, and nervous systems. A growing body of scientific evidence supports the valuable effects of whey proteins on human health, including antimicrobial, antioxidant, antihypertensive, antidiabetic, and immunomodulatory effects, while they may also contribute to weight loss and alleviate or inhibit allergic reactions [29; 30]. Lactose in whey plays a crucial role in ensuring optimal magnesium levels and enhancing the digestion of dairy fats and other nutrients within the human body while also not contributing to dental plaque formation. Additionally, the heat treatment of whey leads to the transformation of a portion of lactose into lactulose, which serves as a growth stimulant for bifidobacteria [21; 31]. Water-soluble vitamins found in milk also transfer into whey, although their concentrations fluctuate considerably and are strongly affected by whey storage conditions. Whey comprises significant quantities of riboflavin, folic acid, and cobalamin, with the latter two attaching to whey proteins and frequently persisting in the whey post-cheese manufacture.