Makgeolli: Rapid Production of an Alcoholic Beverage from the Fermentation of Rice

Undergraduate microbiology courses offer a perfect opportunity to introduce students to historical food preservation processes that are still in use today. Specifically, food fermentation exercises encourage students to consider other cultures and their food and beverage traditions, in addition to teaching students techniques that can be performed in their own kitchens. In previous semesters of an undergraduate microbiology course we have taught a variety of fermentations through the production of yogurt, sauerkraut, kimchi, and cheese. Student enthusiasm for these food labs led us to explore new fermentations, especially those from other cultures. To this end, a laboratory procedure and worksheets for producing the Korean rice wine makgeolli from fermented rice in the presence of amylase enzyme was developed. Students ferment the rice, bottle the ferment, and those of legal drinking age test the product while completing exercises that challenge them to explore the microbiological concepts of fermentation. Underlying themes of this laboratory activity also include basic concepts of food safety and kitchen cleanliness. The laboratory experiment can be completed in less than two weeks and can be modified easily for students of varying scientific backgrounds. Overall, the intersection of metabolism, food science, cultural diversity, and history excited students and enhanced their understanding of the microbial processes at work in fermentation

Chemical analysis of Hg0-containing Hindu religious objects.

Parad items used in Hindu practices and Ayurvedic medicines contain elemental mercury (Hg0) and have traditionally been used in prayer and to treat a variety of diseases including diabetes, heart conditions, and sexual dysfunction. These items are often referred to as amalgams of silver, and take the form of shivlings, statues of gods, necklaces, and other jewelry. Fourteen parad items were purchased from online vendors in India and the United States and analyzed. All items produced copious amounts of Hg0 vapor, with Hg0 concentrations exceeding 1,000,000 ng/m3 as measured using a Mercury Instruments Mercury Tracker 3000 IP atomic absorption spectrometer. Measured concentrations were highly variable, so a simple qualitative experiment employing a UV-C light source and a thin-layer chromatography plate impregnated with a fluorescent dye that glows green when irradiated at 254 nm allowed for the indirect visualization of the Hg0 being evolved. In addition, all items were screened using a hand-held X-ray fluorescence analyzer to estimate the concentration of Hg, Sn, Pb, As, and Cd on the surface of the item. Select samples were then digested in aqua regia and analyzed for Hg content using a direct mercury analyzer. All samples were found to exceed 20% by mass Hg. The digestates were analyzed using inductively-coupled plasma-optical emission spectrometry and were determined to be between 10-55% by mass Pb and contain up to 0.3% by mass As. While Article 4 of the Minamata Convention on Mercury specifically requires parties to stop importing, exporting, and manufacturing Hg-added products, products used in traditional and religious practices are excluded