pH-responsive citral microcapsules with tannic acid-Fe coordination complexes.

Citral is one of the most important aromatic ingredients in foods and beverages for its distinct lemon-like odor. However, the fast evaporation and oxidation limit these applications. Herein, citral microcapsules were constructed by tannic acid-Fe coordination complexes (citral@TA-Fe). The morphologies, structure, citral loading amount, pH responsiveness, oxidative stability and olfactory sensory evaluation were investigated. The obtained citral@TA-Fe microcapsules presented core-shell structure with the average size of 528.16 nm. Citral loading amount was 12.79 %. Citral release exhibited pH-responsiveness with a sustained release rate at neutral pH and a fast release under acidic condition. Citral microcapsules retained excellent sensory profile due to the antioxidant capsule shells. Citral@TA-Fe microcapsules efficiently inhibited bacteria (S. aureus and E. coli) growth, and the performance is enhanced under acidic condition by citral pH-responsive release. This work may open a new path for hydrophobic unsaturated aroma compounds encapsulation, widening their applications with multifunctionalities.