Effect of processing type and compositional change on antioxidant activity of aqueous phase of O/W nano-emulsions during freeze-drying microencapsulation

The primary aim was to observe the effect of processing type and compositional change on the antioxidant activity of the aqueous phase of O/W nano-emulsions during freeze-drying microencapsulation. So, olive oil-in-bitter orange juice nano-emulsions (O/W) were microencapsulated by freeze-drying with chia gum and xanthan gum. Physical (microstructure, droplet size, particle size distribution) and chemical (total antioxidant activity, total phenolic content, and structural characterization; FTIR spectroscopy) properties of different processed nano-emulsions were investigated. Solely freeze-drying of Tween80/Span20, Tween80/SMP, and Tween80/SL nano-emulsions caused a 39%, 13%, and 19% decrease in antioxidant activity accompanied by 65%, 52%, and 64% decrease in phenolic content, respectively. Microencapsulation with xanthan gum increased antioxidant activity of Tween80/Span20, Tween80/SMP, and Tween80/SL nano-emulsions by 17%, 47%, and 120% accompanied by a 5.8, 7.2, and 5.9 times rise in phenolic content, respectively. Microencapsulation with chia gum produced a 7.5, 7.13, and 9.3 times increase in antioxidant activity along with a 9.3, 12.4, and 10.1 times rise in phenolic content of Tween80/Span20, Tween80/SMP, and Tween80/SL nano-emulsions, respectively. Freeze-drying microencapsulation with chia gum and xanthan gum can be an effective method for increasing the antioxidant activity of the aqueous phase of O/W nano-emulsions.