H. Espinosa-Andrews, G. Paez-Hernandez
Keywords: curcuma longa, nanoemulsion, ultrasonication, microfluidization
Summary:Turmeric curcuminoids are phytopolylphenol pigments of Curcuma longa root used in foods due to their yellow-orange bright shades and to their antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities. They are highly sensitive to pH, light, and oxygen and are water-insoluble compounds. However, their low solubility and low bioavailability are improved using emulsifiers agents as surfactants (tweens or lecithins), proteins (milk or soy proteins), or polysaccharides (gum Arabic). The developing of oil-in-water nanoemulsions comprise high-energy emulsification methods such as high-pressure homogenization, microfluidizers, and ultrasonication. Microfluidizer is a continuous process, where a process fluid is compressed at high pressures (50–400 MPa), and forced through a homogenization chamber, where intense shear and elongation stresses, turbulence, and cavitation are developed. On the other hand, the ultrasonication process applies sound waves of high frequency into the sample using a sonotrode tip produces mechanical vibration and acoustic cavitation that breaks the emulsion droplets under the sub-micron size. The aim of this study was to compare two high-energy emulsification methods for produce curcuminoids nanoemulsions. Materials and methods. Curcuminoids were provided from future foods (Mexico). Hydroxylated soy lecithin EMULFLUID HL 66 was purchased from Cargill (U.S.A.). Medium chain triglycerides were obtained from Gomas Naturales (Mexico). The curcuminoids oil phase (10 mg/mL) was prepared according to the procedure described by Ochoa et al. . A coarse emulsion (volume oil phase = 0.1) was prepared using a high-speed mixer (Silverson, L5M, UK) at 4000 rpm for 2 min. This emulsion was homogenized using a microfluidizer M-110 PS at 20000 psi for 10 passes (NP) (Microfluidics International Corporation, USA). Also, the coarse emulsion was homogenized for 30 min using an ultrasonic processor VCX 750 PB (Sonics & Materials, Inc., Newtown CT.) using a 13 mm stainless steel probe and an amplitude of 40%. The droplet size and polydispersity index of the emulsions were measured using a Zetasizer Nano ZS90 (Malvern Instrument, UK). Results. The coarse emulsion showed a droplet size of 2.38±0.55 µm and a polydispersity index > 0.5. A high energy was required to decrease the droplet size and the polydispersity index of the emulsions under the nanosize. After the microfluidization process, droplets size and polydispersity index values of the emulsion decreased, as the number of passes increased. After ten passes, the droplet size and polydispersity index of the emulsion were 128 nm and 0.20, respectively. The microfluidization droplet size (DSM) was adjusted to the potential law: DSM=172.25*NP^(-0.29). On the other hand, sonication times of 26 min were required to producing nanoemulsions (< 100 nm) with a narrow polydispersity index (< 0.15). In this condition, the energy applied was 46800 J/ml. The ultrasonication droplet size (DSM) was adjusted to the potential law: DSU=252.62*t^(-0.29). Conclusion. The microfluidization and ultrasonication techniques produce fine emulsions with narrow distributions. However, ultrasonication was an effective technique to produce nanoemulsions.