pH-responsive citral microcapsules with tannic acid-Fe^III coordination complexes

Area of Science:

• Food Science and Technology
• Materials Science
• Chemical Engineering

Background:

• Citral is a key aromatic compound in food and beverages, prized for its lemon-like scent.
• Limited application of citral due to rapid evaporation and susceptibility to oxidation.
• Need for effective encapsulation strategies to improve stability and controlled release.

Purpose of the Study:

• To develop and characterize citral microcapsules using tannic acid-Fe(III) coordination complexes (citral@TA-Fe(III)).
• To investigate the morphology, structure, loading capacity, pH-responsive release, oxidative stability, and sensory profile of the microcapsules.
• To evaluate the antimicrobial efficacy of the developed citral microcapsules.

Main Methods:

• Synthesis of citral microcapsules via tannic acid-Fe(III) coordination.
• Characterization of microcapsule morphology and structure using electron microscopy.
• Quantification of citral loading, assessment of pH-responsive release kinetics, oxidative stability tests, and sensory evaluation.
• Antimicrobial activity testing against *Staphylococcus aureus* and *Escherichia coli*.

Main Results:

• Citral@TA-Fe(III) microcapsules exhibited a core-shell structure with an average size of 528.16 nm.
• High citral loading capacity of 12.79% was achieved.
• Microcapsules demonstrated pH-responsive release, with sustained release at neutral pH and rapid release under acidic conditions.
• Excellent oxidative stability and retained sensory profile were observed.
• Effective inhibition of *S. aureus* and *E. coli* growth, enhanced under acidic conditions due to citral release.

Conclusions:

• Tannic acid-Fe(III) coordination complexes provide an effective method for encapsulating citral.
• The developed microcapsules offer enhanced stability, controlled pH-responsive release, and antimicrobial functionalities.
• This approach holds potential for expanding the applications of hydrophobic unsaturated aroma compounds in various industries.