Liposomes loaded with betel leaf (Piper betle L.) extract: Antibacterial activity and preservative effect in combination with hurdle technologies on tilapia slices

Betel (Piper betle L.) leaf ethanolic extract (BLEE) has shown to possess antibacterial activities. However, the use of BLEE is still limited due to the instability and remaining chlorophylls even after dechlorophyllization. Encapsulation using liposomes might enhance its stability and reduce the color of BLEE, but antibacterial properties of liposomes have not been elucidated. Hence, this study was conducted to determine the antibacterial activity of liposome loaded with BLEE (L/BLEE). Microbial challenge tests using the selected bacteria (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Shigella sonnei) were also conducted to evaluate the preservative properties of L/BLEE at different concentrations combined with modified atmosphere packaging (MAP) and non-thermal plasma (NTP) treatment on tilapia slices stored at 4 degrees C. Antibacterial activity of BLEE was enhanced (p < 0.05) after loading into liposomes, as witnessed by lower (p < 0.05) MIC and MBC than those of the unencapsulated BLEE. L/BLEE also showed larger inhibition zones, lower triphenyl-2H tetrazolium chloride (TTC) dehydrogenase activity, and higher release rates of K+ and Mg2+ ions (p < 0.05) of bacteria. Additionally, scanning electron microscopic (SEM) images showed deformations and perforation on cell walls of bacteria after treatment with L/BLEE. L/BLEE at 400 ppm combined with MAP (CO2: Ar: O2 = 60: 30: 10) and NTP (80 KV-RMS for 5 min) exhibited the highest inhibition effect (p < 0.05) toward all the challenged bacteria over 15 days of storage at 4 degrees C. The use of L/BLEE at 400 ppm combined with MAP and NTP treatments could preserve tilapia slices for up to 12 days.

Automated summary

This study found that liposomes loaded with Betel leaf ethanolic extract can enhance its antibacterial activity and effectively inhibit various bacterial strains. Combined with modified atmosphere packaging and non-thermal plasma treatment, it can prolong the preservation of tilapia slices effectively.