Reduction of Microbial Contamination in Kaolin from Belitung Island, Indonesia

Abstract

Kaolin is one of the minerals produced in Indonesia with Belitung island as the biggest deposition site in the country. It has been widely used as paper coating, paper filling, paint extender, ceramic ingredient, rubber filler, plastic filler, ink extender, cracking catalysis, fiberglass, cement, adhesives, enamels, pharmaceuticals, crayon, and molecular sieves. 1 Furthermore, several techniques have been employed to improve its quality, such as separation with the magnetic field, which helps to reduce magnetable minerals as well as improve the brightness. 2 This separation technique has also been used for purification through the elimination of metallic contaminants, such as Fe2O3 3 . Several studies have reported the application of bleaching of clay using organic acid, microbial culture media, and oxalic acid-rich media from the cultivation of Aspergillus niger with biodiesel processing waste as culture medium. 4-8 Calcination of kaolin is often carried out to improve its quality, as well as reduce the usage of titanium oxide in the paper and paint industries. The process is performed at different temperatures, such as 650°C, 1050°C, or 1300°C to produce meta-kaolin, mullite, or refractory grog, respectively. Calcination also increases whiteness, hardness, electrical properties, adsorption capacity, alter size, and shape of particles. 9,10 Low-grade kaolin can be improved by removing Fe(III) impurities using the iron-reducing bacteria, where its whiteness increased, while the redness decreased after treatment. [11][12][13][14] Kaolin is widely used in pharmaceutical, cosmetic, and food industries, where it serves as an abrasive, absorbent, anticaking, bulking, and opacifying agent. Although microbial contamination is not regulated in Pharmacopoeia, certain cosmetic industries require kaolin with limited microbe content.

Formulation, Physical Quality, and Microbial Contamination Tests of Anti-Acne Cream from Longan (Euphoria longan [Lour. Steud.]) Seed Extract

“…9 These plant-derived secondary metabolites can impede bacterial attachment to surfaces, thereby preventing the formation of mature biofilms and inhibiting bacterial growth. 25 Anti-acne cream was made using the antibacterial capabilities of longan seed extract against Propionibacterium acnes. To test if the chemicals included in the extract kept their efficacy in the manufactured product, the antibacterial activity of an anti-acne cream was reassessed.…”