The recent uptick in consumption of plant-based beverages has forced companies to modify production methods to further optimize the process. The objective of this study was to evaluate how groat type, water to grain ratio, and extraction method affect the quality and composition of oat beverage. Wet milling and the use of an amylase treatment produced significantly (p<0.05) higher values of degree Brix, solids, and total starch within the beverage base. Stabilized groats produced the highest value of total starch of 61.97%. Microbial analysis revealed that amylase treated products had a much lower colony forming units per gram (CFU/g), when compared to dry and wet milling. To produce an oat beverage with ideal rheological and composition values, the beverage must be derived from heat treated groats, a grain to water ratio of 1:4, and must undergo an α-amylase treatment.