240 JOURNAL OF COSMETIC SCIENCE Table II Physicochemical Characteristics of the Vegetable Oils Considered Hemp-seed Hemp-seed Parameters oil (1998) oil (1999) Olive oil Relative density (d204) 0.925 0.924 0.916 Rotational viscosity at 18.6 s- 1 (mPa s) 40 37.5 60 Capillary viscosity (mPa s) 40.420 Refractive index (RI) 1.4735 1.4760 1.4665 Table III Acidity Indices and Percentage of Oleic Acid in the Vegetable Oils Considered IA Oleic acid(%) Hemp-seed oil (1998) 3.85 (±0.46) 1.93 (±0.18) Hemp-seed oil (1999) 14.10(±1.31) 7.13 (±0.95) Values in parentheses are standard deviations, determined on four samples. Extra-virgin olive oil 55 1.4665 Olive oil 0.44 (±0.02) 0.22 (±0.01) IA = aliquot (in mg) of KOH O. lM necessary to neutralize the fatty acids that are free in 1 gram of fat mass. hemp-seed oil (1998 and 1999) had free acidity above 1 %, the upper limit for the "extra-virgin" category (EEC Regulations), while the acidity of olive oil was below the limit. Hemp-seed oil (1999) had a significantly higher free-fatty-acid content, although it was younger, probably due to the different method (Baglioni) employed for crushing the seeds. The acidity index of the commercial olive oil was in agreement with that declared on the label. PEROXIDE NUMBER Peroxide numbers, expressed as milliequivalents of 02 per 1000 grams of fat mass, were found to be 5 .15 for the 1998 hemp-seed oil and 1. 5 7 for the 1999 hemp-seed oil. Both kinds of oil had peroxide values below the limit of 10 established for "extra virgin" oil. Moreover, the peroxide numbers of both hemp oils were lower than 20, the threshold limit for edible oils. CONJUGATED DIENES AND TRIENES Results of UV characterization are reported in Table IV. Absorptivity differences at 232 Table IV K232 and 11K Values of the Oils Considered, Dissolved in 0.1 % 1-Butanol Hemp-seed Hemp-seed oil (1998) Hemp-seed Extra-virgin oil (1998) (after 24 h at 40°C) oil (1999) Olive oil olive oil K232 2.58 (±0.23) 2.66 (±0.11) 2.12 (±0.12) 2.72 (±0.08) 2.20 (±0.09) 11K 0.025 (±0.003) 0.030 (±0.001) 0.025 (±0.001) 0.075 (±0.002) 0.0 Values in parentheses are standard deviations, determined on four samples.

HEMP-SEED AND OLIVE OILS 241 nm and at 262, 268, and 274 nm (ilK) were used to measure the increase in conjugated dienes and trienes, respectively. Both for the two kinds of hemp-seed oil and the commercial olive oil, K232 and ilK values were above the limits set for "extra virgin" oils. The absorptivity (0.1 % oil in 1-butanol) at 232 nm and the ilK value increased with temperature, as is shown for the hemp-seed oil (1998), heated for 24 hours at 40°C. Tables V and VI report the results of the spectrophotometric analysis carried out to evaluate whether the polymeric vehicles Sepigel 305 ® and Carbopol 1382® enhance the formation of conjugated dienes and trienes in vegetable oils in which they are dispersed. The combined results (Tables V and VI) show that both hemp-seed oils and the com­ mercial olive oil had much higher oxidative stability when dispersed in the Sepigel 305 ® than in the Carbopol 1382® system. IRRADIATION TEST Table VII shows the results of the irradiation test. Olive oil was much more photostable Table V UV-Visible Characterization of Oils Dispersed in Sepigel 305® System (emulsion 1) Hemp-seed Hemp-seed Extra-virgin Hemp-seed oil (1998) oil (1999) Olive oil olive oil oil (1998) (after 24 h (after 24 h (after 24 h (after 24 h (before heating) at 40°C) at 40°C) at 40°C) at 40°C) K232 2.80 (±0.21) 4.45 (±0.18) 4.23 (±0.10) 3.51 (±0.14) 3.51 (±0.09) J).K 0.015 (±0.003) 0.020 (±0.001) 0.020 (±0.004) 0.020 (±0.003) 0.020 (±0.003) Values in parentheses are standard deviations, determined on four samples. Table VI UV-Visible Characterization of Oils Dispersed in Carbopol 1382® System (emulsion 2) Hemp-seed Hemp-seed Extra-virgin Hemp-seed oil (1998) oil (1999) Olive oil olive oil oil (1998) (after 24 h (after 24 h (after 24 h (after 24 h (before heating) at 40°C) at 40°C) at 40°C) at 40°C) K232 2.76 (±0.13) 2.90 (±0.16) 4.04 (±0.18) 4.04 (±0.23) 2.55 (±0.17) J).K 0.010 (±0.001) 0.015 (±0.002) 0.030 (±0.006) 0.030 (±0.006) 0.010 (±0.004) Values in parentheses are standard deviations, determined on four samples. Table VII K232 and J).K Values of the Vegetable Oils after 2 Hours of UVB Irradiation Hemp-seed oil ( 1998) 5.54 (±0.11) 0.015 (±0.001) Hemp-seed oil ( 1999) 8.92 (±0.30) 0.035 (±0.005) Values in parentheses are standard deviations, determined on four samples. Olive oil 3.07 (±022) 0.095 (±0.002)