Responsive emulsion gels of glycyrrhizic acid and alanine for cigarette capsules

Abstract

Low-cost and simplified synthesis process of capsule cigarettes for wider application has received more and more attention. Water phase is suggested to be introduced into the oil content of cigarette capsules in consideration of the cost. The stimuli produced during the smoke can contribute to the phase transition with further flavor release. Here, a kind of multiple stimuli-responsive cigarette capsules based on emulsion gels was designed. The oil-in-water emulsion gels stabilized by glycyrrhizic acid (GA) and alanine (Ala) were prepared through simple one-pot emulsification at high temperature (80 °C) followed with a subsequent cooling. The non-covalent network between GA and Ala endowed emulsion gels with temperature and stress responsiveness, while the CO2 responsiveness was realized by the electrostatic complex formed between the amino group of Ala and the carboxyl group of GA. The rheological behaviors of emulsion gels were evaluated, suggesting that emulsion gels with self-recovery property and temperature responsiveness can satisfy the demands of cigarette capsules application such as the long-distance transportation and flavor release during the smoke. It is found that the oil-soluble flavor loaded in the emulsion gels can be controllably released in response to stimuli that generated during the smoking process, therefore reducing the additional introduction of external stimuli. Our work provides a novel strategy for preparing cigarette capsules with simple synthesis, low cost and eco-friendly characteristics.