Brewing conditions and low-temperature storage affect the total phenolics, caffeoylquinic acid content, and antioxidant activity of yerba mate infusion

Herbal infusions exhibit diverse pharmacological effects, mainly attributed to the high content of phenolics (e.g., caffeoylquinic acids (CQAs)). Herein, we evaluated the content of CQAs in the methanolic extracts of model herbs, namely yerba mate ( Ilex paraguariensis ), stevia ( Stevia rebaudiana ), and Pluchea indica , showing that yerba mate had the highest total CQA content (108.05 ± 1.12 mg/g of dry weight). The analysis of yerba mate infusions prepared using different steeping times, dried leaf weights, and water temperature demonstrated that the amount of extracted CQAs was maximized (~ 175 mg per 150 mL) when 6 g of dried leaves were steeped in hot water for 10 min. Ten-day refrigerated storage induced no significant changes in the antioxidant activity and total phenolic and CQA contents of the infusion kept in a brown container but negatively affected the above parameters when kept in a clear container, suggesting the detrimental effect of light exposure. Our findings provide consumers, food scientists, and commercial producers with guidelines for optimizing the preparation and storage conditions of herbal infusions.