HEMP-SEED AND OLIVE OILS 243 2.0 ------------------2.0 1.0 1.0 0.0 ----------------0.0 350 400 450 500 550 600 650 700 Figure 1. UV-visible spectrum of hemp seed oil (1998), diluted 1 :2 in maize-germ oil. in oil samples during storage, especially for the 1998 oil. In consideration of this satisfactory performance, we chose the 1998 hemp-seed oil and the olive oil as lipids to formulate emulsions, which were then characterized by stability and rheological profile. FORMULATIVE STUDIES EYE GEL-EMULSION 3 (Table IX) The viscosity range (Table X) denoted that the 0/W emulsions prepared were fairly consistent and quite stable upon heating. Their pH values (Table X) were skin­ compatible. The rheological study of the eye gel-emulsions showed a pseudoplastic behavior with a high yield value for all three oils employed. This behavior is typical of gel systems that are normally highly structured. The gel-emulsion containing extra­ virgin olive oil showed a small hysteresis area and a thixotropic trend.

244 1,6 1 . : f • 1,4 u C C 1,2 1 0,8 0,6 0,4 0,2 - JOURNAL OF COSMETIC SCIENCE - - - - - -- - - --- - -- - - - ---- t - Aat416 nm of hempseed oil -A at671 nm of hempseed oil * A at416 nm of olive oil ..... •A at 671 nm of olive oil 0-+-------.----------------- a 50 100 150 200 UVA irradiation time (min.) Figure 2. Study of the photostability of the chlorophyll contained in hemp-seed and olive oils under UV A irradiation. 2 E 1,8 - -;II( - - - - -• - - - - - - - .,. C 1,6 ca 1,4 .. 1,2 • 1 0,8 • 0,6 0,4 C 0,2 0 ..... ..... 0 50 100 ..... 150 -hempseed oil under UVA irr. ■ olive oil under UVA irr. ..._. -.-hempseed oil under vis. irr - -K - olive oil under vis.irr. 200 irradiation time (min.) Figure 3. Comparative study of the degradation of the chlorophyll contained in hemp-seed and olive oils under UV A and visible irradiation. Table IX Formulation of Eye Gel-Emulsion 3 Prepared with Hemp-Seed Oil and Olive Oil Ingredients Vegetable (hemp-seed or olive) oil Carbopol 1382® NaOH 10% Water Percentage (% p/p) 5 0.25 0.272 94.478