The Use of Lemongrass/Lemon Blend Essential Oil Nanoemulsions in Chewy Candy Formulations and Its Evaluation Against Streptococcus mutans and Porphyromonas gingivalis

Lemongrass (Lg) and lemon (Lm) essential oils (EOs) mainly contain citral and limonene, respectively, which are not limited to flavor for food but can also provide antibacterial activity. The information on the enrichment of these combined EOs in chewy candy products has never been documented yet. This study aimed to evaluate the physical-chemical properties and volatile compound of nanoemulsion formulations of Lg/Lm blend EOs as well as the physical-chemical properties, total plate count (TPC), and sensory acceptability of chewy candy formulated with nanoemulsions. Antibacterial evaluations against Streptococcus mutans and Porphyromonas gingivalis were performed for both nanoemulsion and chewy candy. Blending Lg and Lm EOs at ratios of Lg1.85 : Lm2.25 and Lg3.65 : Lm0.45 showed a broadly different constituent of the volatile compound than the ratio with the least amount of Lg (Lg0.05 : Lm4.05) but all the formulations possessed eugenol, β-Bisabolene, and caryophyllene oxide. The combination of Lg1.85 : Lm2.25 produced the nanoemulsion with the lowest particle size but lower zeta potential and emulsion stability. At this ratio, the significant inhibitory activity of the nanoemulsion was found to be 92.40% and 84.14% for S. mutans and P. gingivalis, respectively (p < 0.05). Its application in chewy candy formulation also resulted in the highest inhibitory activity against S. mutans (85%) and P. gingivalis (77.20%). Chewy candy formulated with Lg1.85 : Lm2.25 nanoemulsion was also found to have the lowest TPC of 3.72 log CFU/g. The overall acceptability of the chewy candy was around neutral (3.77) by panelists for its higher color score (4.73) and aroma (4.37) in average to the other samples. This study discovered the potential of Lg/Lm blend EOs nanoemulsion for enhancing the antibacterial effect and improving the texture and color of chewy candy.