Co-partition and stabilization of polyphenols with low partition coefficient (Log P＜3) in emulsified oil droplets mediated by peppermint essential oil

Emulsion-based carriers have been widely studied for the co-encapsulation of active ingredients with different partition coefficient (Log P). However, it is challenging to encapsulate active ingredients with low Log P values in emulsified oil droplets. In this study, (-)-epigallocatechin gallate (EGCG, 160 µg/g*emulsion, Log P 2.38) and resveratrol (Res, 320 µg/g*emulsion, Log P 2.57), as models with low Log P, were co-encapsulated in emulsified oil droplets for the first time by peppermint essential oil (PEO) mediation. During storage process, EGCG and Res consistently remain co-located inside the emulsified oil droplets. However, both EGCG and Res migrated towards the inner layer of the interface of emulsified oil droplets along with PEO. Res exhibited better stability compared to EGCG, while the degradation of EGCG occurred within the emulsified oil droplets. Furthermore, when co-localized with Res, the degradation rate of EGCG slowed down. PEO did not degrade during storage, and over 98 % of PEO was encapsulated within the emulsified oil droplets. This is the crucial reason for maintaining the stability of SC-stabilized emulsion and achieving high encapsulation efficiency of active ingredients. This provides a green and simple strategy for co-encapsulation of active ingredients with Log P lower than 3.0 within emulsified oil droplets.