JOURNAL OF COSMETIC SCIENCE 412 are mixed with a given oil, the HLB value is presented as the optimum ratio that provides optimum emulsifi cation (14–18). UHTXLUHG +/% +/%UHTXLUHG L L I q œ , where fi is the mass (or weight) fraction of the oil i. The required HLB values are used not only to calculate the required HLB values of the oil phase but also to estimate the values of each component of the oil phase. HLB values are known to be affected by signifi cant errors. Therefore, the required HLB values should be determined experimentally (19,20). Experiments were conducted using three types of essential oils from Jeju Island and Jeju horse fat (HF). Citrus unshiu fruit oil (CUFO) has antibacterial activity against the main causes of acne (21). Citrus unshiu peel oil (CUPO) has physiological activities, such as antioxidant and antibacterial activities (22). Camellia japonica seed oil (CJSO) has a wrinkle improvement effect by inhibiting matrix metalloproteinase activity and by inducing human type I procollagen synthesis (23). In addition, Camellia japonica seed oil is known to have a dietary effect by reducing low-density lipoprotein choles- terol level and increasing high-density lipoprotein cholesterol level (24). HF could be used as cosmetic and pharmaceutical materials with anti-infl ammatory effects by re- ducing of erythema and Immunoglobulin E level and recovering of histopathological features of skin (25). In the present study, to determine the required HLB value of essential oils, the method of Orafi diya and Oladimeji was used in which stable emulsions were based on minimum droplet size and maximum turbidity (1). To verify our results, we also carried out related experiments using liquid paraffi n as a reference standard. MATERIALS AND METHODS MATERIALS Liquid paraffi n (paraffi n oil, Sigma-Aldrich, St. Louis, MO), sorbitan sesquioleate (Rheodol AO-15V, Kao, Tokyo, Japan HLB = 3.70), polysorbate 60 (Rheodol TW-S120V, Kao, Tokyo, Japan HLB = 14.90), and polysorbate 20 (Rheodol TW-L120V, Kao HLB = 16.70) were used. Citrus unshiu fruit oil (Human Island, Jeju, Korea), Citrus unshiu peel oil (Human Island), horse fat (Ecotech, Bucheon, Korea), Camellia japonica seed oil (CJSO, Daebongs, Incheon, Korea), and pure water (k 3 μS/cm, Pure RO 130, Human Corporation) were used. See Tables 1 and 2. Table I Description of Raw Materials Used INCI name Science name Manufacturing method Specifi c gravity (d20/20) Refraction indexa Citrus unshiu fruit oil Citrus unshiu Markovich Steam distillation 0.856 1.471 Citrus unshiu peel oil Citrus unshiu Markovich Cold press 0.862 1.470 Horse fat Horse fat Fermentation 0.860 1.469 Camellia japonica seed oil Camellia japonica L. Cold press 0.911 1.467 a Refractometer (NAR-1T, Atago, Japan). INCI, International Nomenclature Cosmetic Ingredient.

DETERMINATION OF REQUIRED HLB VALUE 413 M ETHODS P REPARATION OF EMULSIONS T he volume of the O /W emulsion prepared was 50 mL and contained 1 wt% surfactant, 3 wt% of essential oils or HF, and 96 wt% pure water. The surfactants, sorbitan sesquio- leate (HLB = 3.70) and polysorbate 60 (HLB = 14.90), comprised 1 wt% of the total blend concentration used in the O /W emulsions. A series of emulsions with HLB values were prepared by blending the emulsifi ers together in different ratios (1). We can calcu- late the HLB of the mixed surfactants using the following formula (12,14): PL[ WRWDO +/% +/% D D E E & & & q q+/% where Ca and Cb are the quantities of surfactants (%) an d HLBa and HLBb are the HLB values of surfactants. Af ter mixing the surfactant with essential oil, the mixture was kept for 2 h at a tempera- ture control of 45°C in a screw cap bottle to prevent the essential oil from volatilization and was placed in an ultrasonic cleaner (JAC-3010, KODO, Seongnam, Korea) for 20 min and mixed well. After addition of purifi ed water, the solution was vortexed for 1 min using a vortex mixer (vortex genie-2, Scientifi c Industries Inc., Bohemia, NY), and then stored at room temperature for 1 week. X: Sorbitan sesquioleate (HLB = 3.70) + polysorbate 60 (HLB = 14.90), Y: Sorbitan ses- quioleate (HLB = 3.70) + polysorbate 20 (HLB = 16.70), Z: Polysorbate 60 (HLB = 14.90) + polysorbate 20 (HLB = 16.70) Table II Main Composition Content for Two Citrus unshiu Oils INCI name Main composition content (%)a Citrus unshiu fruit oil dl-Limonene (92.51), gamma-Terpinene (0.68), alpha-Pinene (0.53) Citrus unshiu peel oil dl-Limonene (91.97), gamma-Terpinene (3.48), alpha-Pinene (0.69) a Gas chromatograph mass spectrometer (GCMS-QP2010 plus, Shimadzu, Japan). INCI, International Nomenclature Cosmetic Ingredient.