Kinetic and thermodynamic stability of paprika nanoemulsions

Abstract

Summary In this study, oil‐in‐water nanoemulsions of paprika oleoresin were prepared by high‐power ultrasound. The influence of hydrophilic lipophilic balance (HLB) value and surfactant concentration on the physical and chemical stability and kinetic and thermodynamic properties were investigated. Kinetic data for thermal degradation of red and yellow fractions of carotenoids in nanoemulsions at 25, 35 and 45 °C of storage were used for estimating entropy and enthalpy of activation using the transition state theory. The mean diameters (Z‐average) of the dispersed particles containing paprika ranged from 48 to 250 nm. The carotenoids in nanoemulsions stability increased as the particle size and HLB value decreased. According to the enthalpy–entropy compensation, the carotenoid red fraction was enthalpy driven, whereas the carotenoid yellow fraction was entropy controlled. These results provide useful information for the design of delivery systems to encapsulate and stabilise lipophilic molecules.

Development of Paprika Oleoresin Dispersions for Improving the Bioaccessibility of Carotenoids

“…The required HLB to produce a stable emulsion is that, which provides the lowest interfacial tension (Malcolmson et al, 1998). When this interfacial tension is achieved, the surfactant concentration is the lowest, which was 1% for all HLB values used in our previous work (Pascual-Pineda et al, 2015). Therefore, the surfactant concentration employed in this work was 1%, with mean particle sizes below 200 nm in all the treatments.…”

“…At a HLB of 15.6, initial particle sizes of 178 and 38.9 nm were obtained for CE and NE, respectively. The higher stability of carotenoids was found at the smaller particle size, possibly because the interface at smaller size reduces the oxygen diffusion, due the curvature interface was similar to the curvature of surfactant monolayer, which provides a barrier against degradation of carotenoids (Pascual-Pineda et al, 2015). Fig.…”

“…For both processes the best barrier against carotenoids degradation was obtained as the HLB value was increased. Recently Pascual-Pineda et al (2015) reported that the rate of chemical degradation of paprika carotenoids encapsulated within nanoemulsions was less as the HLB value was increased. The droplet interface consists of a narrow region, which surrounds the emulsion droplet and contains a mixture of oleoresin, water and emulsifier molecules.…”

“…Conventional emulsions and nanoemulsions were prepared according our previous work using the maximum stability criteria (Pascual-Pineda et al, 2015). All emulsions consisted of paprika oleoresin, mixed surfactant and Milli-Q water.…”

“…These include emulsion-based delivery systems (Ribeiro et al, 2008), liposomes (Socaciu et al, 2000), the entrapment of carotenoids in microspheres (Laos et al, 2007) and production of microcapsules by drying processes (Rascón et al, 2011) as well as carotenoids entrapment within food nanoemulsions stabilized with non-ionic surfactants (Pascual-Pineda et al, 2015) Within the human body carotenoids first undergo solubilization from the food matrix followed by micellization. This refers to their incorporation into micelles, which are molecular aggregates that transport fat-soluble material, making it more accessible by the intestinal epithelium.…”