The antioxidant activity of soybean–cow milkyogurt showed significant reduction during 21 days ofrefrigerated storage to 35.29 ± 1.0%. Phenolic contentis the most influential factor to antioxidant activity [44].Soybean has been previously reported to show antiox-idant activity properties associated to isoflavones andpolyphenolic compounds [45,46]. Additionally, milkprotein proteolysis [47] and organic acids production[48] as a result of microbial metabolic activity during fer-mentation and refrigerated storage could be other sourcesof antioxidant activities.