RICESORB® FOR LOOSE FACE POWDERS 293 properties and stability of loose face powders containing RiceSorb® in comparison to those containing talcum. EXPERIMENTAL METHODS MAT ERIALS RiceSorb® (100 % natural GMO-free rice starch), cosmetic grade, was supplied by Chanjao Longevity Company Limited, Bangkok, Thailand. Tamarind fruit pulp extract (powder), food grade, was purchased from Fuyang Bestop Import and Export Ltd., Anhui, China. The fruit pulps (sour type) without seeds were subjected to a solvent extraction method (water). The spray drying process was used to prepare the tamarind fruit pulp extract powder. Talcum, other white materials (e.g., zinc oxide and zinc stearate), and preservatives were purchased from P.C. Drug Center, Bangkok, Thailand. Ethanol (95% v/v) was supplied by KSP Octatech, Songkhla, Thailand. All chemicals were pharmaceutical grade, except where specifi ed. INVESTIGATION OF PHYSICOC HEMICAL PROPERTY OF RICESORB® Certain characteristics of RiceSorb® were evaluated as follows: morphology, bulk density, fl owability, and pH compared with those of talcum. These properties of raw materials affected the properties of the fi nished product, loose face powders. Morphology investigation. T he morphologies of RiceSor b® and talcum were evaluated by using a scanning electron microscope (SEM) [model Quanta 400 (SEM-Quanta), FEI Company, Brno, Czech Republic] equipped with an Everhart–Thornley detector. For better resolution and image quality improvement, the samples were coated with a thin layer of gold using a sputter coater (SPI Supplies, West Chester, PA). The SEM analysis was performed under a high vacuum condition (1.3 × 10−2 Pa) at 20.00 kV. Bulk density. The bulk density of powders can be measured by determining the volume of the powder sample (known weight) which has been passed into a graduated cylinder. This was performed to check the uniformity of the bulk powder materials. The samples were passed through a sieve (60 mesh), if they were agglomerated. The powder samples were weighed (30 g) and gently poured into 100-ml cylinders without tapping according to USP 41 and NF 36 (10). The untapped apparent volume of the powder was read to the nearest graduated unit, and the bulk density was calculated as given in equation 1. The bulk density was used to esti- mate the fl owability of powders and to check the uniformity in bulk powder materials. weight of the powder g Bulk density bulk volume ml (1) Flow property. The fl ow of po wde r samples was t ested using a glass funnel with fi xed height (fi xed funnel method). The base upon which the cone formed was fi xed with a diameter of 10 cm [radius (r) = 5 cm]. The powder samples were gently passed through a glass funnel until a powder cone was formed. The height (h) of the cone was measured, and the angle of repose (θ) was obtained using equation 2. The degrees of angle of repose can characterize the fl ow behaviors of powders. For example, when the angle of repose is

JOURNAL OF COSMETIC SCIENCE 294 more than 66°, the fl ow is considered to be very very poor on the other hand, if the angle of reposes is between 31° and 35°, the fl ow is considered to be good (10). tan( ) h r (2) pH measurement. pH values of Ric eSo rb® and talcum were measured based on Thai Industrial Standards (TIS) 443-2525-cosmetics: skin powder (11) of loose face powders. The pH mea- surements of powder samples were performed by preparing a suspension of each powder sample. The procedures were started by weighing a sample (10 g), transferring into a 150-ml beaker, and adding 90 ml of freshly boiled and cooled distilled water. Within 5 min of preparation, the pH values of the water phase were measured by a SevenCompact S220 pH/Ion meter (Mettler Toledo Co. Ltd., Schwerzenbach, Switzerland). If necessary, a fi ltration process was performed when the powder particles were not wetted by water. PREPARATION OF LOOSE FACE POWDERS The f ormulation of loose face powders i s composed of a variety of constituents to obtain satisfactory fi nished products. It is achieved by blending different materials which have various required properties together. Generally, the basic ingredients of loose face powder formulations are talcum, titanium dioxide, zinc oxide, kaolin, starches, magnesium car- bonate, zinc stearate, and magnesium stearate (2). In the current study, the formulations used to prepare loose face powders are given in Table I. The ratios of talcum and RiceSorb® were 4:0, 3:1, 2:2, 1:3, and 0:4 for the formulations F0, F1, F2, F3, and F4, respectively. No fragrance was added to the formulations. The white base powder ingredients were m ixed together using a mortar and a pestle by a geometric dilution technique. The blended white powders were passed through a 250- μm sieve. Later, each formulations, F0 through F4, were incorporated with powder of tamarind fruit pulp extract (white powder bases 90% w/w and tamarind fruit pulp ex- tract 10% w/w). The formulations of face powers with tamarind extract were named as FT0, FT1, FT2, FT3, and FT4, respectively. CHARACTERIZATION OF LOOSE FACE POWDERS Th e test samples were freshly prepared fo rmulations and formulations under the stability study. The physicochemical investigation of the loose face powders included appearances Table I Formulations of Loose Face Powder (White Base Powder ) Ingredient % w/w F0 F1 F2 F3 F4 Talc (adhesion and slip) 80 60 40 20 — RiceSorb® (absorbency, covering power, and blooming) — 20 40 60 80 Other white base materials 19.8 19.8 19.8 19.8 19.8 Preservatives 0.2 0.2 0.2 0.2 0.2