Influence of Surfactant on the Thermal Behavior of Marigold Oil Emulsions with Liquid Crystal Phases

Abstract

Vegetable oils have been largely consumed owing to the interest of pharmaceutical and cosmetic industries in using natural raw materials. The production of stable emulsions with vegetable oils challenges formulators due to its variability in composition and fatty acids constitution within batches produced. In the present work, it was studied that the influence of the size of carbon chain and the number of ethylene oxide moieties of the surfactant on the thermal behavior of eight emulsions prepared with marigold oil stabilized by liquid crystal phases. Differential scanning calorimetry (DSC) was used to determine the thermal behavior of the emulsions. The ratio of bound water was calculated, being between 29.0 and 42.0%, confirming the extension of the liquid-crystalline net in the external phase. Changing the lipophilic surfactant from Ceteth-2 to Steareth-2, there was an increase in the temperature of phase transition of the liquid crystal influencing the system stability. Calorimetric study is very useful in understanding the performance of liquid crystals with the increase of temperature and to estimate emulsions stability.

Evaporation in the Water, Polyethylene Oxide, and Polypropylene Oxide System

“…Most food emulsions contain L a or L b phases, [12] and Professors Santos and Pedro have recently pointed out their importance for pharmaceutical emulsions. [13,14] The transformations found in the initial investigation of emulsion [11] evaporation could be deduced from the phase diagram, in spite of the obvious fact that the phase diagram reflects equilibrium conditions, while the evaporation is a kinetic process. The potential deviation from equilibrium conditions due to kinetic factors may be alleviated by focusing the phase diagram approach [15][16][17] on systems in which the main body of the vapor originates from the continuous phase or the evaporation from a bicontinuous structure, in which the diffusion rates of the compounds are of a similar magnitude as in the continuous phase.…”

Nanotechnology-based drug delivery systems and herbal medicines: a review

“…The authors concluded that the number of ethylene oxide moieties was not as significant as the carbon chain. 83 Following the trend of using natural compounds in systems containing nanostructured LCs, Santos et al proposed using vegetable oils from plants native to Brazil during evaluations for the formation of lamellar LC crystalline phases. The following vegetable oils were used: andiroba (Carapa guyanensis) Aubl (Meliaceae), apricot (Prunus armeniaca) (Rosaceae), avocado (Persea americana Mill) (Lauraceae), Brazil nut (Bertholletia excelsa Bonpl) (Lecythidaceae), Buriti (Mauritia flexuosa) (Arecaceae), cupuassu (Theobroma grandiflorum Willd.…”

Green tea glycolic extract-loaded liquid crystal systems: development, characterization and microbiological control

“…They also offer some protection against photo-or thermal degradation and can promote increased water retention in the stratum corneum, providing increased skin hydration. Finally, LCSs promote the sustained release of active substances and physicochemical stability of emulsions (Formariz et al, 2005;Santos, Rocha Filho, 2007).…”

“…They also offer some protection against photo-or thermal degradation and can promote increased water retention in the stratum corneum, providing increased skin hydration. Finally, LCSs promote the sustained release of active substances and physicochemical stability of emulsions (Formariz et al, 2005;Santos, Rocha Filho, 2007).Liquid crystals are not generally employed in formulations of microbiological preservatives because they have large amounts of surfactants that suppress the growth of micro-organisms. Moreover, the high concentration of oil limits water access, which is one of the main causes of antimicrobial action (Oliveira et al, 2007).…”