# The Effect of Varying Out Beverage Ratios on the Characteristics of Fermented Dairy-Oat Beverages
## 4 Discussion
In our study, the addition of oat beverage slows down the acidification process in fermented dairy-oat beverages, which may affect their stability and texture. The most intense acidification (lowest pH) occurs in samples with 0-25% oats, suggesting that smaller amounts of oats do not significantly disrupt fermentation. The optimal oat addition range (25-50%) may allow for maintaining a proper fermentation process while enriching the beverage with oat components. With a high oat content (75-100%), fermentation is significantly slower, which may require technological modifications (e.g., longer fermentation time or the addition of starch-degrading enzymes) [6]. Further research is needed on the impact of enzymatic hydrolysis of oat starch on the fermentation process and sensory acceptance of the final product. However, oat components such as \(\beta\)-glucans may contribute to viscosity and water retention, which suggests that alternative structuring agents (e.g., hydrocolloids) could be tested to improve the texture of high-oat formulations. In our study, a higher content of oat beverage causes a gradual darkening, yellowing, and increase in reddish hue. Optimal proportions of milk and oat beverage (25-50%) seem to be the best in terms of maintaining the typical color of a fermented dairy beverage, while avoiding excessive yellowing. Further research should investigate how these color changes affect consumer acceptance and what strategies can help maintain an attractive product color [24]. The limited pH decrease in during low-temperature storage high-oat beverages may affect their microbiological stability and sensory perception, as acidity is a significant factor in shaping the flavor of fermented beverages. A mixture containing 25-50% oat beverage appears to be the optimal solution, as it retains the characteristic features of fermented dairy products while modifying the taste and nutritional values. The study confirmed that an increasing proportion of oat beverage slows the acidification process, as evidenced by the higher final pH values in samples with 75-100% oat content. This is likely due to the lower lactose availability, which serves as the primary fermentable sugar for lactic acid bacteria, as well as the buffering capacity of oat-derived components such as fiber and minerals. Mixtures of cow's milk and oat beverage in proportions of 25-50% seem to be the most advantageous, as they allow for a moderate level of syneresis during cold storage, which may contribute to an acceptable texture. A recent study on the stability of oat-based dairy alternatives also found that a moderate oat ratio provides better consistency and microbial viability [24]. Sensory characteristics such as texture, adhesiveness, and water-holding capacity are influenced by fermentation. High syneresis in samples dominated by oat beverage indicates limited ability to form a stable gel. This is likely due to a lower content of proteins with gelling properties (e.g., casein), which play a key role in water retention in cow's milk [25; 26]. The stability of parameters during low-temperature storage suggests that the fermentation and storage process does not drastically affect syneresis properties, but the presence of oat beverage weakens water retention in the gel structure. For optimal quality of the fermented dairy-oat beverage, recommended oat beverage proportions are 25-50%, which allows for reduced syneresis while maintaining the beneficial sensory characteristics of the product. In our study, an increasing the proportion of oat beverage significantly reduces the product's hardness during low-temperature storage, a result of alterations in the protein composition and structural makeup of the mixture [12]. An optimal balance between hardness and oat beverage content is likely to be found within the 25-50% range, suggesting the possibility of achieving a product with a desirable consistency while retaining the beneficial attributes of both milk and oats.