Improving encapsulating efficiency, stability, and antioxidant activity of catechin nanoemulsion using foam mat freeze-drying: The effect of wall material types and concentrations

Abstract

This study investigated the effect of wall material types and concentrations on hygroscopicity, solubility, encapsulation efficiency (EE), flavonoid recovery (FR), and antioxidant activity of catechin nanoemulsion (CaNE) powder produced by foam mat freeze-drying. CaNE containing 0.4 g/100 g green tea catechins was ultrasonically fabricated and foamed with hydroxypropyl methylcellulose, as a foaming agent, and three different types of wall materials (maltodextrin [MD], gum arabic [GA], or a mixture of MD and GA [M + G]), at two concentration levels (5 and 10 g/100 g), before being freeze-dried at −50 °C for 48 h. The wall materials increased the hygroscopicity of CaNE powder while improving its water solubility by up to 92%. CaNE containing GA and M + G had higher EE and FR values than that containing MD. MD and M + G samples had higher antioxidant activity than GA. The antioxidant activity of the powder decreased as the concentration of wall material increased. CaNE powder with high EE and FR values, good solubility, and high antioxidant activity can be obtained when using M + G at 5 g/100 g. The findings are significant in providing an efficient method for developing CaNE powder as an effective ingredient for functional foods or beverages.