412 JOURNAL OF COSMETIC SCIENCE ratio at R = 7:3. The second group composed of olive and camelina oils exhibited an optimal ratio at 8:2. To understand what is the link between the vegetable oils inside the two groups, we deter- mined three oil properties at 25°C: surface tension, viscosity, and density (Table III). Sun- flower, olive, apricot, and camelina oils had surface tension around 33 ± 0.7 mN·m−1. Only rapeseed oil exhibited a slightly higher surface tension around 35.4 mN·m−1 and was statis- tically different from the other vegetable oils (Table III). Therefore, in terms of the surface tension, a link was not found between the two groups found previously. For the viscosity, sunflower oil had the highest viscosity around 70.2 mPa.s. Camelina oil had the lowest one around 52.7 mPa.s. Olive and apricot oil had close values around 62.5 and 60.8 mPa.s, respectively. Rapeseed oil had a value around 56.1 mPa.s. Again, we found no link between the two groups obtained previously and the viscosity of the different oils. Moreover, all the vegetable oils had the same density from statistical analysis around 0.9 showing that the density was not the key parameter giving rise to the different oleogel properties as a function of the oil. In contrary to previous study on oleogels based on γ-oryzanol and β-sitosterol, which have shown that the viscosity of the oil phase affected the final gel strength of the oleogels, no link was observed in the case of the BO/BA system (35). A key parameter described in the literature to affect the oleogel properties is the percent- age of unsaturated fatty acids in oils (33). We compared the fatty acid chain unsaturation composition for all vegetable oils with oleogel properties (Table I). We observed that for the first group formed by the sunflower, apricot and rapeseed oils, there was no link between the oil compositions in terms of unsaturation of fatty acid. For example, sun- flower oils contained 27.2% of oleic acid and 58,7% of linoleic acid, whereas apricot oil contained 60% of oleic acid and 29.1% of linoleic acid. In the same way, for sunflower oil with optimal R = 7:3, the total percentage of unsaturation in oils was around 86.9 wt.% and it was close to 86 wt.% for camelina oil with an optimal ratio for R = 8:2. Another parameter already mentioned in the literature which could play a role on the oleogel properties was the fatty acid chain length composition of the vegetable oil (39). We compared the fatty acid chain length composition of vegetable oils with the oleogel properties (Table I). We observed that for the first group formed by the sunflower, apricot, Figure 5. Schematic phase diagram for BO/BA oleogelator system in oil. One phase region is indicated by 1φ, and two phases region is indicated by 2φ. S corresponds to solid and L to liquid. Platelets crystals are drawn: pure BO in red, mixed BO/BA crystals in red and blue dashed, and pure BA in blue.

413 THE EFFECT OF VEGETABLE OIL COMPOSITION Table II SAXS and WAXS Average Value for d-Spacings Measured for Oleogels in Olive, Apricot, Camelina, or Rapeseed Oils with Various Ratios of Behenyl Alcohol:Behenic Acid (BO:BA): (a) 10:0, (b) 8:2, (c) 7:3, (d) 5:5, (e) 3:7, (f) 2:8, (g) 0:10. The Nature of Crystals Deduced from SAXS/WAXS Results is Indicated: Pure BO, Pure BA, or Mixed Crystals BO/BA. R = 10:0 Oleogel SAXS d-spacing (Å) WAXS d-spacing (Å) Type of crystals Sunflower 57.1, 48.3 4.3, 4.1, 4.1, 3.9, 3.7, 3.6 Olive 57.1, 52.4 4.3, 4.2, 4.1, 3.9, 3.7, 3.6 Apricot 57.1, 48.3 4.3, 4.2, 4.1, 3.9, 3.7, 3.6 Pure BO Camelina 57.1, 48.3 4.3, 4.2, 4.1, 3.9, 3.7, 3.6 Rapeseed 57.1, 49.1 4.3, 4.2, 4.1, 3.9, 3.7, 3.6 R = 8:2 Oleogel SAXS d-spacing (Å) WAXS d-spacing (Å) Type of crystals Sunflower 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Olive 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Apricot 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Mixed BO/BA Camelina 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Rapeseed 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 R = 7:3 Oleogel SAXS d-spacing (Å) WAXS d-spacing (Å) Type of crystals Sunflower 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Olive 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Apricot 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Mixed BO/BA Camelina 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Rapeseed 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 R = 5:5 Oleogel SAXS d-spacing (Å) WAXS d-spacing (Å) Type of crystals Sunflower 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Olive 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Apricot 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Mixed BO/BA Camelina 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 Rapeseed 57.1 4.6, 4.5, 4.0, 3.8, 3.6, 3.5 R = 3:7 Oleogel SAXS d-spacing (Å) WAXS d-spacing (Å) Type of crystals Sunflower 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 Olive 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 Apricot 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 Mixed BO/BA Camelina 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 + pure BA Rapeseed 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 R = 2:8 Oleogel SAXS d-spacing (Å) WAXS d-spacing (Å) Type of crystals Sunflower 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 Olive 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 Apricot 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 Mixed BO/BA Camelina 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 + pure BA Rapeseed 57.1, 48.3 4.6, 4.5, 4.3, 4.1, 4.0, 3.8, 3.7, 3.6 R = 0:10 Oleogel SAXS d-spacing (Å) WAXS d-spacing (Å) Type of crystals Sunflower 48.3 4.4, 4.3, 4.1, 4.0, 3.7 Olive 52.4, 48.3 4.4, 4.3, 4.1, 4.0, 3.7 Apricot 48.3 4.4, 4.3, 4.1, 4.0, 3.7 Camelina 69.8, 48.3 4.4, 4.3, 4.1, 4.0, 3.7 Pure BA Rapeseed 52.4 , 48.3 4.4, 4.3, 4.1, 4.0, 3.7