17 Address all correspondence to Zhigang Yin, yinck@zzuli.edu.cn The Design, Preparation, and Performance Testing of Hand Creams to Slow the Spread of Pathogenic Microorganisms XIAOKANG WANG, ZHIGANG YIN, TAIJUN ZHANG, SHUANG GAO, HENGYU QIAN, TONGYAN ZHANG, RUIJUAN WANG AND JING ZHOU School of Materials and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou, Henan Province, China (X.W., Z.Y., S.G., H.Q., T.Z., R.W., J.Z.) Guangzhou Emperor’s Wisdom Skin Biotechnology Research Institute Co., Ltd, Canton, Guangdong Province, China (T.J.Z.) Acceptance date: December 15, 2021. Synopsis Pathogenic microorganisms spread in every public place, often through human hand contact, thereby endangering health. However, frequent use of disinfecting products to inhibit these microorganisms can cause skin irritation and discomfort. Hand creams that slow the spread of microorganisms are becoming increasingly relevant and necessary for epidemic prevention and control. This article selects a basic formula and adds plant bacteriostatic ingredients to form a hand cream. The minimum inhibitory concentration and bacteriostatic zone tests were used to assess bacteriostatic performance. The mixture of Citrus reticulata peel extract and Lithospermum erythrorhizon extract with a weight ratio of 2:1 exhibited a potent bacteriostatic effect. It was applied to hand cream, compared with commercial products in bacteriostatic tests, and passed the field test. The viscosity, pH, thermal stability, and other physical and chemical properties were tested in addition to a sensory evaluation, skin moisture content test, and transdermal moisture loss test. Using these measures, a hand cream that can effectively slow the spread of microorganisms was obtained. INTRODUCTION People’s daily activities are carried out in environments rich in microorganisms. After coming into contact with human hands, microorganisms can spread extensively even with frequent handwashing. With the normalization of epidemic prevention and control, people’s awareness of the harm caused by pathogenic microorganisms and the need for protection has increased. The use of alcohol-based disinfecting gels and sprays in public places has become more common, effectively reducing the spread of pathogens. However, when used frequently, these materials can cause irritation and even progress to skin problems such as itching, rashes, and allergies. Therefore, a hand cream that effectively prevents the spread of microorganisms while also taking care of your hands is more needed than ever. Three main types of pathogenic microorganisms frequently affect human health: cocci, bacilli, and fungi, for which Staphylococcus aureus, Escherichia coli, and Candida albicans are J. Cosmet. Sci., 73, 17–34 (January/February 2022)

18 JOURNAL OF COSMETIC SCIENCE representative strains, respectively (1). In this study, we selected raw cosmetic materials with antimicrobial properties to engineer a moisturizing hand cream that can also slow the spread of microorganisms. The antibacterial efficacy of the hand creams was determined by investigating their inhibitory effects against the three aforementioned representative microorganisms, while their skin care performance was evaluated by a group of cosmetology students. Taken together, all experimental data support that this hand cream can slow the spread of microorganisms and care for hands. FORMULA DESIGN AND RAW MATERIAL SELECTION FORMULA DESIGN The first step in the formula design was to clarify the product concept: a hand cream that can effectively prevent the spread of common microorganisms. That is, using the product is like wearing a pair of invisible protective gloves that effectively slow the spread of microorganisms while also caring for your hands. Therefore, the product must have a dual function: to moisturize and to disinfect. The targeted selection of an emulsification system and functional raw materials focused on the desired dual function of the product. Commonly used emulsification systems for skin care products are oil-in-water (O/W) and water-in-oil. Among them, the O/W emulsifica- tion system has the advantages of a less greasy feeling, better skin feel, greater stability, and higher water content therefore, we chose the O/W emulsification system for the matrix type. Next, oils, emulsifiers, moisturizers, auxiliary materials (thickeners, antioxidants, preservatives, flavors, and pigments), and bacteriostatic agents were selected (2–11). Oils: jojoba oil, shea butter, isopropyl palmitate, and dimethicone. Emulsifiers: steareth-2 and steareth-21. Humectants: glycerin and allantoin. Auxiliary materials: xanthan gum (thickener) and tocopheryl acetate (antioxidant). To preserve the bacteriostatic properties, no preservatives or flavors were added. RAW MATERIAL SELECTION The key to hindering the spread of pathogens is to inhibit their reproduction and growth many plant materials exhibit these properties. Huang et al. (12) reported the bacteriostatic effects of extracts of Rhus chinensis, Scutellaria, Glycyrrhiza uralensis, and Dictamnus. Wang et al. (13) verified the bacteriostatic effect of a Coptis extract. Ou et al. verified the bacteriostatic effects of extracts of Eugenia caryophyllata, Houttuynia cordata, Reynoutria japonica, Coptis, rhubarb, licorice, and Scutellaria baicalensis. Among them, the combination of Coptis and Scutellaria yields the best bacteriostatic effect (14). Nan et al. (15) verified the bacteriostatic effects of Schisandra vinegar, pomegranate peel, Ficus hirta, and Senecio alcohol extracts, among which Schisandra vinegar has the most potent bacteriostatic effect. Peng et al. (16) verified the bacteriostatic effects of logwood, Sanguisorba officinalis L., Epimedium brevicornu, Coptis, and Radix Paeoniae Alba extracts. Liu et al. (17) verified the bacteriostatic effect of a Thesium chinense Turcz. extract. Angelica, vine tea, Polygonum chinense L., Dai Bai-Jie, Lindera glauca, red peony, Atractylodes macrocephala, Andrographis paniculata, Curcuma phaeocaulis, Gentiana