## 4 Conclusions  
Processing whey on site provides the ideal solution, particularly for small farms and plants where transport to and processing at a processing facility is cost prohibitive. This not only helps to reduce waste in cheese manufacturing, where whey is a by-product--but it also promotes sustainability. The goal of this study was to manufacture organic fermented whey beverages enriched with the organic fruit juices sea buckthorn or rosehip. Utilizing whey from both cow's and goat's milk, obtained as by-products from the production of curd and aged cheeses, we developed a technology to produce beverages using both unpasteurized sweet or sour whey. The addition of organic fruit juices (sea buckthorn or rosehip juice) improved the physicochemical (higher acidity), and rheological (lower viscosity) properties. Microbiological safety was ensured, with low levels of pathogenic microorganisms detected. All of the tested beverages had a pH lower than 4.6, which is required for fermented dairy beverages. The viscosity of all the fermented beverages was lower than the control samples, as required for such beverages. The incorporation of organically derived fruit juices including sea buckthorn and rosehip has considerable impact in terms of properties, giving the opportunity to modulate beverages rheological properties and mouthfeel, which can lead to consumer satisfaction while optimizing their functional food status. The pH and titratable acidity values offer evidence on the physicochemical characteristics of fermented whey beverages. The fermented whey beverages produced in the present study were fully microbiologically characterized to ensure that they are safe when consumed and effective as a functional food. The results highlighted the need for careful ingredient selection when designing functional dairy beverages with appealing rheological properties and consumer acceptance. The results of this study showed that the manufactured fermented whey beverages have a potential utilization as new products containing fruit juices, that could provide consumers with pleasure and healthful properties when compared to conventional drinks. This line of stock is prepared in response to an increased demand on the part of the consumer for functional foods that provide health benefits beyond basic nutrition. In addition to that, the use of whey output from the production of ripened or cottage cheese makes the most economic and environmentally friendly option. The program would be in line with the destinations of the European Green Deal by helping sustainable production, and the creation of new, health-friendly foodstuffs.  
The authors suggest further research on interaction effects between the type of whey and the addition of fruit juice in determining the physicochemical properties mentioned in this study.  
M.B.: writing--original draft preparation, conceptualization, methodology, investigation, formal analysis, resources, data curation, visualization; R.W.: investigation, data curation, visualization; B.G.S.: writing--review and editing, conceptualization, software, methodology, validation, formal analysis, data curation, supervision, project administration, funding acquisition. All authors have read and agreed to the published version of the manuscript.  
This work was financially supported by the grants of the Ministry of Science and Higher Education in Poland (grant number DWD/6/0210/2022: \"Implementation doctorate\" and grant number MEiN/2023/DPI/2862: \"Research network of life sciences universities for the development of the Polish dairy sector--research project\").  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest.