ANALYSIS OF BIOACTIVE COMPOUNDS AND STABILITY OF EMULSIONS (O/W) WITH LEMON ESSENTIAL OIL OBTAINED BY THE BILAYER METHOD

Tahiti lemon essential oil (LEO) is rich in bioactive and aromatic compounds and is widely used by industries due to its chemical and sensory properties. These compounds degrade under ambient conditions. Pectin (PEC) and whey protein concentrate (WPC) present strong potential for interaction and protection of bioactives in the emulsions stabilization. This study evaluated the bioactive compounds, the temperature effect on the rheological properties and stability of bilayer emulsions (O/W) obtained by electrostatic interaction WPC:PEC at ratios 1:1 and 4:1 with 1, 3 and 5% of LEO. The oil was dispersed in WPC (2%w/w) using a  stirrer at 2000 rpm/10 minutes, PEC (2%w/w) was added, stirred 10 minutes again, resulting in the bilayer emulsion. The properties rheological were determined through flow curves, gap (400 µm) and parallel plate geometry at 5, 25, 45 and 65ºC. Also were determined total phenolic compounds (TPC), antioxidant activity by DPPH and antimicrobial activity by disk diffusion. The microstructure was evaluated by optical microscopy after 24 hours/14 days. The DPPH analyse, the emulsions with better results were 1:1-3% (12.8%) and 4:1-1 and 3% (12.9 and 12.7%). In the TPC analysis, the better results were 1:1-5% and 4:1-1% (0.046 and 0.047 mg EAG/mL). The increase in WPC increased TPC, possibly the protein contains aminoacids with phenolic compounds. The antibacterial activity (Staphylococcus aureus) was better at 4:1, probably the bacteria had difficulty for breaking down the proteins, these results were not satisfactory for this strain. Microscopic showed stability and small droplets, after 14 days, occurred a slight increased, but kept stable. Flow curves showed a good adjusted of Power Law Model (R²>0.99), shear-thinning behavior tending to Newtonian. The temperature influenced the apparent viscosity, occurred ​​decreased with temperature increase. These results highlight the emulsions technological potential for applications in the industries, promoting the protection and functionality of bioactives.