# Techno-Functional Properties and Recent Advances in the Manufacturing of Whey Beverages: A Review
## 5 Technological Processes Used in Whey-Based Beverages Manufacturing  
Various technological processes can be employed in the production of dairy beverages, which may impact the properties of the product. These processes can lead to a reduction in the nutritional value of whey proteins, such as denaturation and aggregation, and can also decrease the digestibility and bioavailability of these proteins. Therefore, it is crucial to select an appropriate technology that minimises negative effects on the proteins [74]. At the same time, unconventional technologies are being studied, including intensive ultrasound, cold plasma, microwave, and ohmic heating. The use of high-intensity ultrasound helps preserve the bioactivity of the products. However, when sonication is performed at temperatures below 55 \({}^{\circ}\)C, it may not effectively inhibit microorganisms [75; 76; 77]. A summary of the technological processes used in the production of whey-based beverages is provided in Table 2.  
In practice, both direct and indirect thermal treatments are used. A study by [PERSON] et al. [78] investigated the impact of direct and indirect heat processing (preheating at 70 \({}^{\circ}\)C with final heating at 121 \({}^{\circ}\)C, and preheating at 80 \({}^{\circ}\)C with final heating at 135 \({}^{\circ}\)C, with a final hold time of 30 s and 2 s, respectively) on the properties of whey beverages. The beverages were made from 4%, 6%, and 8% (\(w/w\)) whey protein isolate (WPI). Significant differences were observed between the beverages treated with direct and indirect heating in terms of appearance and organoleptic properties. Beverages treated with direct heating contained less denatured protein, showed lower viscosity, and exhibited fewer changes in volatile compound profiles. Direct thermal treatment is particularly suitable for beverages with higher protein content. [PERSON] et al. [75] compared the effects of short-term thermal treatment and thermosonication on the properties of whey beverages. Beverages treated with thermosonication showed better microbiological quality and higher antioxidant, antihypertensive, and antidiabetic activities. Additionally, there was less degradation of ascorbic acid in the beverage. Whey beverages exhibited the features of better rheological properties and a better volatile compound profile compared to those treated with short-term thermal heating. Ultrasound and thermosonication were compared to pasteurisation in a study by [PERSON] et al. [79]. Both methods are considered non-thermal food processing techniques. During thermosonication with preheating to 55 \({}^{\circ}\)C, the best microbial inactivation of the whey-based beverage was achieved. Beverages treated with ultrasound and thermosonication exhibited better organoleptic properties compared to those treated with pasteurisation. Additionally, no sediment was observed in the beverages, and the colour remained unchanged throughout the experiment. [PERSON] et al. [80] also investigated the impact of high-intensity ultrasound on the properties of whey beverages. Thermosonication at 480 W for 10 min at 55 \({}^{\circ}\)C resulted in improved microbial and sensory properties of the drinks. On the other hand, ultrasound treatment led to an increase in the number of viable microorganisms during the activation process. \begin{table}
\begin{tabular}{c c} \hline \hline
**Technological Process** & **References** \\ \hline Direct and indirect heat processing & [PERSON] et al. [78] \\ \hline Thermosonication & [PERSON] et al. [80] \\  & [PERSON] et al. [75] \\ \hline Ultrasound and thermosonication & [PERSON] et al. [79] \\ \hline High-intensity ultrasound & [PERSON] et al. [81] \\ \hline  & [PERSON] et al. [82] \\  & [PERSON] et al. [83] \\  & [PERSON] et al. [84] \\  & [PERSON] et al. [85] \\ \hline  & [PERSON] et al. [86] \\ Microfiltration & [PERSON] et al. [87] \\  & [PERSON] et al. [88] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Technological processes used in whey-based beverages manufacturing.