Canola oil, cold pressed

de Morais, Jacqueline Moreira, et al. Journal of dispersion science and technology, 2006, 27(7), 1009-1014.

The aim of this study was to evaluate the effects of commonly used hydrolyzable raw materials in pharmaceutical and/or cosmetic formulations, including surfactants, salts/cations and salts/anions, on the potential and droplet size distribution of rapeseed oil/water nanoemulsions. The results showed that the additives affected the interfacial structure of the droplet emulsions without affecting the macroscopic stability. The zeta potentials obtained before and after the tests indicated that the emulsion stability was not entirely dependent on electrostatic stability. Therefore, these nanoemulsion systems obtained by an emulsion inversion method with a pair of nonionic surfactants could be used to develop pharmaceutical and/or cosmetic dosages that require high levels of hydrolyzable active substances.
Preparation of emulsions
· Emulsions were prepared using the emulsion phase inversion (EPI) method. A surfactant blend of PEG-40 castor oil (3.58% w/w) and sorbitan oleate (2.42% w/w) was used, totaling 5.0% w/w and yielding an HLB of 8.8. Both surfactants were dissolved in the canola oil phase (5.0% w/w). The oil and aqueous phases (90.0% w/w) were heated to 70 ± 2°C and then slowly mixed at 400 rpm until reaching room temperature (25 ± 2°C).
· The phase inversion temperature (PIT) of the surfactant blend (Surfom R-400w and Span 80w) was previously determined to be above 90°C by measuring conductivity changes in an O/W emulsion upon heating. Additives were incorporated into the O/W emulsions at concentrations of 0.1%, 0.5%, and 1.0% (with an additional 0.25% for the cationic surfactant to identify the charge reversal point). Additives were added immediately after emulsion preparation, and analyses were conducted 48 hours later to allow for equilibrium adsorption of dissociated ions onto the O/W interface.

Winkler-Moser, et al. European Journal of Lipid Science and Technology, 2014, 116(5), 606-617.

This study aimed to investigate how tocopherol (TOH) homologues (α- and γ-TOH) interact in a sequence of water-in-oil (o/w) emulsions made with rapeseed oil (CO) and soybean oil (SBO), the obtained data that could be applied to decide the correct level and proportion of tocopherol for protective emulsions based on oil type. It was examined the oxidative stability of α- and γ-TOH levels on their own and in mixtures in relation to the CO and SBO TAGs' fatty acid profiles in two batches of water-in-oil (o/w) emulsions treated with increased oxidative pressure (50°C in the dark).
Key conclusions
· The overall formation rates of hydroperoxide and hexanal were found to be lower in CO compared to SBO.
· In CO emulsions, γ-TOH acted as a more potent antioxidant than α-TOH, with their combined effect proving to be additive.
· In SBO emulsions, on the other hand, at lower concentrations α-TOH was more antioxidant while at higher concentrations γ-TOH was.
· This α- and γ-TOH interaction was synergistic at low concentrations, but switched to additive or antagonistic effect at higher concentrations, depending on the ratios and concentrations of the two tocopherols.
· In both CO and SBO emulsions, the effectiveness of α-TOH diminished at elevated concentrations, while the efficacy of γ-TOH increased with higher concentrations.