Application of guava leaf extract on hard candy to inhibit upper respiratory tract infection caused by bacteria

Guava (Psidium guajava L.) leaf has long been the subject of diverse research initiatives as herbal medicine due to its antimicrobial activity against various bacteria. An Upper Respiratory Tract Infection (URTI) is a contagious infection of the upper respiratory tract, which can be caused by bacteria, i.e., Streptococcus pyogenes and Pseudomonas aeruginosa. In this research, guava leaves were extracted sequentially using solvents with different polarities. Furthermore, this research aimed to determine the antibacterial activity of guava leaf extract against URTI caused by bacteria (S. pyogenes and P. aeruginosa) and to formulate it into hard candy at various Minimum Inhibitory Concentrations (MIC), which were 2 MIC, 3 MIC, 4 MIC, and 5 MIC, to obtain hard candy with the highest antibacterial activity and organoleptic acceptability. To assist in the organoleptic acceptability aspect of the hard candy, lemongrass oil was used in varying concentrations (0%, 0.15%, 0.3%) as a flavoring agent. Results showed that ethanol guava leaf extract had the strongest antibacterial activity against both S. pyogenes (MIC=721.21 ppm) and P. aeruginosa (MIC=3085.91 ppm). Moreover, hard candy added with guava leaf extract at a concentration of 4 MIC and 0.15% lemongrass oil had the highest overall acceptability and antibacterial activity against S. pyogenes (inhibition diameter of 11.92 ± 0.56 mm) and P. aeruginosa (10.77 ± 0.69 mm).