Stability of oregano essential oil encapsulated in double (w/o/w) emulsions prepared with mechanical or high‐pressure homogenization and its effect in Aspergillus niger inhibition

High‐pressure homogenization and mechanical homogenization were used for the production of water‐in‐oil primary emulsions (PE) containing oregano essential oil. Different PE concentrations and homogenization parameters were tested during the production of water‐in‐oil‐in‐water (W/O/W) double emulsions to assess their effect on emulsion stability during 25 days of storage by determining emulsion droplet size and creaming; the antifungal activity of W/O/W emulsions against Aspergillus niger was evaluated. The smallest droplet sizes of W/O/W emulsions were obtained with a mechanical homogenization velocity of 5,800 rpm, formulated with a PE concentration of 20%. The creaming behavior of emulsions during storage followed a second‐order kinetic starting on day 1, presenting maximum values from 15% to 35% and creaming rates from 3.16%/day to 7.3%/day. The antifungal activity of W/O/W emulsions against A. niger was demonstrated. Binary logistic regression was used to predict A. niger inhibition, resulting in being dependent on the creaming behavior of the emulsions. Practical applications Double emulsions are usually employed to protect and release bioactive compounds in a continuous manner. In this work, oregano essential oil (OEO) was encapsulated in W/O/W double emulsions aiming to reach its gradual release toward the in vitro inhibition of Aspergillus niger, which is usually found in vegetables. Results obtained let know that W/O/W emulsions with different droplet sizes can be obtained using mechanical or high‐pressure homogenization in the preparation of W/O emulsions. The droplet size of the W/O/W emulsions determines their creaming rate affecting the antifungal activity of the encapsulated OEO. The antifungal activity can be evaluated by applying a probabilistic model on mold survival during storage. These data allow predicting the in vitro successful inhibition performance of OEO encapsulated in W/O/W emulsions against A. niger .