Status of Free Radicals in Indian Monsooned Coffee Beans γ-Irradiated for Disinfestation BRIJ BHUSHAN,* ,† RAJEEV BHAT, § AND ARUN SHARMA † Food Technology Division, Bhabha Atomic Research Centre, Mumbai, India, and Department of Applied Botany, Mangalore University, Mangalagangothri, Mangalore 574 199, Karnataka, India Free radicals in two cultivars of Indian monsooned coffee beans, γ-irradiated for hygienic and quarantine purposes, were examined by entrapping the small amount of samples in potassium chloride powder in ESR quartz tubes. In contrast to a prominent free radical signal at g ) 2.002, observed in spermoderm (silver skin) and cotyledon (whole seed without skin) parts of normal coffee beans, the same was not discernible in monsooned coffee bean parts of both cultivars. The ESR signal was found to be more prominent in the spermoderm than in the whole seed portion of the normal coffee beans. Common practices of roasting and powdering were found to generate quantitatively more free radicals in coffee beans than γ-irradiation alone. Phenols, contributing maximally to observed free radical signals in coffee beans, were significantly different in normal and monsooned coffee beans. These observations on insignificant free radical population in irradiated monsooned coffee beans may be attributed to their inherent possession of high water activity, favoring decay of free radicals produced. Textural studies with monsooned coffee beans, before and after mild heat treatments, supported these findings. KEYWORDS: Specialty coffee; monsooning; radiation processing; hygienic and quarantine treatments INTRODUCTION Monsooned coffee is a “specialty coffee” of India, which has gained worldwide recognition for its unique taste, flavor, and cup quality. This coffee is in great demand and is preferred by consumers, particularly in the Scandinavian countries, Italy, France, Japan, and, now, the United States as a base for espresso coffee. Monsooned coffee is prepared according to an unscientific but traditional method adapted during the past 50 years at the coffee-curing works situated in the coastal towns of Mangalore and Tellicherry in Karnataka and Kerala states of India, respectively. Monsooning is a process wherein the dry processed “A” grade (6-7 mm size grade) coffee beans belonging to Arabica (Coffea arabica Linnaeus) and Robusta (Coffea cane- phora Pierre ex Froehner) coffee varieties are exposed to the moist winds of the monsoon season in open warehouses (godowns), situated at the coastal belt for a period of 6-7 weeks. During such processing, coffee beans, being highly hygroscopic, are allowed to absorb moisture from an initial level of 9-10% up to 18-22% (1). Due to this absorption of atmospheric moisture, the coffee beans bloat to double their original size accompanied by the bleaching of natural color. The beans acquire a totally different taste and flavor similar to that of an aged coffee. The coffee beans thus processed are marketed as “Indian Monsooned Malabar Coffee” (2). Radiation processing is increasingly being accepted as one of the most effective and economic methods available today to treat agricultural and horticultural commodities for hygienic purposes and for overcoming quarantine barriers in international trade (3, 4). No other method of food processing has undergone such a thorough assessment of safety as the method of radiation processing, and the pertinent details have been provided in many excellent reviews (5, 6). Of late, a number of studies have been carried out to identify the chemical changes, mainly related to the generation of free radicals and radiolytic products, in different foods and food components after exposure to ionizing radiation (7-10). Although a few studies have been reported recently, until now no scientific information has been available on the status of free radicals in monsooned coffee beans (1, 2, 11). Because Indian Monsooned Malabar Coffee has good scope for export in better markets under the new WTO regime, the present studies were undertaken to assess the status of free radicals in monsooned coffee beans, exposed to quarantine doses of γ-irradiation, and to evaluate their quality parameters. Such information is required not only to remove misconceptions from consumers’ minds but also to provide suitable information to law enforcement authorities responsible for regulating the trade in food commodities. MATERIALS AND METHODS Coffee Beans. Arabica and Robusta monsooned coffee beans, conforming to the standards set by the Coffee Board, Government of * Author to whom correspondence should be addressed (telephone +91-22-25592533; fax +91-22-5505151 or +91-22-5519613; e-mail bbhushan@apsara.barc.ernet.in). † Bhabha Atomic Research Center. § Mangalore University. 4960 J. Agric. Food Chem. 2003, 51, 4960-4964 10.1021/jf030187o CCC: $25.00 © 2003 American Chemical Society Published on Web 08/06/2003