# The Effect of Varying Out Beverage Ratios on the Characteristics of Fermented Dairy-Oat Beverages
## 5 Conclusions  
This study comprehensively evaluated the impact of varying proportions of oat beverage in cow's milk on the physicochemical, textural, sensory, and microbiological properties of fermented dairy-oat beverages. For the first time, this research conducted a detailed analysis of the interactions between oat components and milk proteins during fermentation, providing novel insights into the mechanisms influencing the quality of the final product. The results unequivocally indicate that the addition of oat beverage significantly modifies the chemical composition, fermentation process, and quality characteristics of the beverage. With increasing oat beverage content, a decrease in protein, fat, and lactose content was observed, accompanied by an increase in total carbohydrate content. Importantly, this study demonstrated that a higher proportion of oats slows down fermentation, as evidenced by higher pH and slower lactose breakdown. The finding may be crucial for optimizing the production process. The fermentation process was slower in higher oat concentrations, resulting in milder acidification, which could be beneficial for consumers preferring less acidic products. The textural analysis revealed that with increasing oat beverage content, the beverages became darker, more yellowish, and acquired a reddish hue. Increased syneresis was also observed, indicating a weakening of the gel structure and a lower water-holding capacity. These changes highlight the need for formulation optimization to balance sensory appeal and stability. An innovative aspect of the research is the detailed determination of the influence of the milk-to-oat ratio on the stability of fermentative bacteria (lactobacilli and streptococci), providing new data on their adaptive abilities in altered environmental conditions. A key achievement of the study is the identification of the optimal range of proportions of cow's milk and oat beverage (25-50% oat content), ensuring the best balance between microbiological stability, desired texture, and sensory properties. The obtained results can be applied in the development of new, improved formulations of fermented dairy-oat beverages, tailored to the needs of consumers seeking innovative and functional food products. These findings are relevant for the food industry, as they provide a foundation for the development of innovative fermented dairy-oat beverages with enhanced functionality and consumer appeal. The obtained results can be used by food producers to develop new, innovative oat-based products with optimized nutritional, sensory, and stability properties, meeting the needs of various consumer groups. Further research may be needed to determine whether the findings can be generalized to other oat beverage types or starter cultures. Further research also should focus on the impact of the addition of enzymes (e.g., lactase, amylase) on improving fermentation and reducing lactose in dairy-oat beverages, as well as on assessing consumer acceptance and possibilities of modifying the product color. Moreover, studies assessing alternative oat beverage formulations or different starter cultures could provide deeper insights into improving product quality and market potential. Conceptualization, M.Z. and D.Z. ; methodology, M.Z., E.K. and T.F. ; validation, M.Z. and D.Z. ; formal analysis, M.Z., E.K. and T.F. ; investigation, M.Z., E.K. and T.F. ; resources, M.Z. and D.Z. ; data curation, M.Z. and D.Z. ; writing--original draft preparation, M.Z., D.Z., E.K. and T.F. ; writing--review and editing, M.Z., D.Z., E.K. and T.F. ; visualization, M.Z. and D.Z. ; supervision, M.Z. ; project administration, M.Z. ; funding acquisition, M.Z. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. The authors confirm that the data supporting the findings of this study are available within the article.