19 TESTING OF HAND CREAMS macrophylla, forsythia, Zhi Mu, honeysuckle, dandelion, and other plant extracts have also been found to possess bacteriostatic properties in recent years (18–23). S baicalensis extract (12,14): S baicalensis Georgi is a perennial medicinal plant. The most valuable part is the root and its primary components are baicalein and wogonin. These also act as the main effective ingredients in the S baicalensis extract. Although their pharmacological effects and molecular structures differ, they all have anti-inflammatory and bacteriostatic properties. Lithospermum erythrorhizon extract (24,25): The effective ingredients with bacteriostatic properties are acetylshikonin and shikonin, which inhibit the growth of both S aureus and E coli. L erythrorhizon extract contains plant pigments and thus appears purple, which makes products more colorful and eye-catching. Sophora flavescens extract (26): The main ingredient is matrine, which has potent anti- inflammatory and bacteriostatic properties. Citrus reticulata peel extract (27–29): The main active ingredients are flavonoids, which not only have strong broad-spectrum bacteriostatic properties but also confer aromaticity. Therefore, they are also used as fragrances and antioxidants. Based on these studies and the color, smell, solubility, and compatibility of the raw materials, S baicalensis extract, L erythrorhizon extract, S flavescens extract, and C reticulata peel extract were selected for incorporation into test hand creams with bacteriostatic properties. METHODS MAIN MATERIALS AND EQUIPMENT The raw materials and experimental equipment used in this study are listed in Tables I to IV. EXPERIMENTAL METHODS Hand cream preparation. According to the hand cream formula in Table V, the Phase A, B, and C raw materials were weighed into separate beakers. Phase A was dissolved at room temperature before the temperature was slowly raised to 80°C. Phase B was heated evenly close to 80°C. The sample was then put into the rotor, and the speed was adjusted to dissolve the ingredients evenly. After mixing Phase A and Phase B, the sample was homogenized at 13,000 r min−1 for 5 min. The system temperature was reduced to 45°C before the Phase C raw material was added. The sample was then homogenized at 7,000 r min−1 for 3 min, cooled to room temperature, and bottled. Bacteriostatic performance test. The tested strains were S aureus ATCC 6538, C albicans ATCC 10231, and E coli ATCC 8099. The compositions of each medium were as follows. Tryptone soy agar medium: tryptone 1.5%, soy peptone 0.5%, sodium chloride 0.5%, agar 1.6% tryptone soy broth medium: tryptone 1.5%, soy peptone 0.5%, sodium chloride 0.5% sandcastle agar medium: glucose 40 g, peptone 10 g, agar 20 g, distilled water 1,000 mL and sandcastle liquid medium: glucose 40 g, peptone 10 g, distilled water 1,000 mL. S aureus and E coli were cultured with tryptone soy agar and tryptone soy broth while C albicans was cultured with sandcastle agar and sandcastle liquid. The neutralizer components were 0.3% lecithin, 2% Tween 80, and 0.3% sodium thiosulfate.

Table I Raw Materials Used in the Hand Creams Serial number Raw material name Specification (w, %) Source Remarks 1 S baicalensis extract 86 Guangzhou Omega Biotechnology Co., Ltd. Cosmetic grade 2 L erythrorhizon extract 90 Changchun Chenyu Biomedical Technology Co., Ltd. Cosmetic grade 3 S flavescens extract 10 Guangzhou Zhaoxi Biological Technology Co., Ltd. Cosmetic grade 4 C reticulata peel extract 73 Guangzhou Zhaoxi Biological Technology Co., Ltd. Cosmetic grade 5 Jojoba oil 98 Shandong Yousuo Chemical Technology Co., Ltd. Cosmetic grade 6 Shea butter 99 Shandong Yousuo Chemical Technology Co., Ltd. Cosmetic grade 7 Isopropyl palmitate 99 Shandong Yousuo Chemical Technology Co., Ltd. Cosmetic grade 8 Dimethicone 99 Shandong Yousuo Chemical Technology Co., Ltd. Cosmetic grade 9 Steareth-2 99 Shandong Yousuo Chemical Technology Co., Ltd. Daily chemical grade 10 Steareth-21 99 Guangdong Sunkiss Chemical Technology Co., Ltd. Daily chemical grade 11 Glycerin 99.7 Shandong Yousuo Chemical Technology Co., Ltd. Daily chemical grade 12 Allantoin 99 Shandong Yousuo Chemical Technology Co., Ltd. Daily chemical grade 13 Xanthan gum 99 Shandong Yousuo Chemical Technology Co., Ltd. Food grade 14 Tocopheryl acetate 99 Shandong Yousuo Chemical Technology Co., Ltd. Cosmetic grade 20 JOURNAL OF COSMETIC SCIENCE