Research Paper Simulation of natural air drying of maize in a typical location of Argentina: Influence of air heating through the fan M. Martinello a, *, S. Giner b,c a Universidad Nacional de Rı´o Cuarto, Ruta 36 Km 601, (5800) Rı´o Cuarto, Argentina b Investigador CICPBA, Lugar de Trabajo, CIDCA-Universidad Nacional de La Plata, Calle 47 y 116, (1900) La Plata, Argentina c A ´ rea Departamental Ingenierı´a Quı´mica, Facultad de Ingenierı´a, UNLP, Argentina article info Article history: Received 13 April 2009 Received in revised form 15 February 2010 Accepted 11 June 2010 Published online 24 July 2010 Current demand for the near ambient dried grains is growing, because this slow process tends to produce less fissures. This is especially important in flint maize. Near ambient drying may also use less energy and reduce greenhouse emissions. It is also called low- temperature or natural air drying can be considered as an alternative process to produce high-quality dried corn. Two operational modes for the low-temperature drying of maize produced in a typical location Argentina were evaluated using simulation: (1) ambient drying, which operates by drawing the air using fans located downstream the grain bed and (2) near ambient drying, which, by blowing the air upstream the grain bed, takes advantage of the air temperature rise through the fan. Drying time and specific energy consumption were calculated by using a simulation program. Air heating through the fan in near ambient drying is a beneficial effect which reduces energy expenditure and process duration The specific energy consumption varied from 0.3 up to 2.6 MJ kg 1 water evaporated. Savings of energy consumption of up to 30% were predicted for the near ambient mode with respect to the ambient mode, and the reductions in drying time were of about 12%. At the location tested (Junı´n, Province of Buenos Aires, Argentina) ambient drying may not be able to reach the target moisture content in April, unlike near ambient drying, which allows the process to be completed. ª 2010 IAgrE. Published by Elsevier Ltd. All rights reserved. 1. Introduction Food industry uses hard red flint maize as raw material to manufacture “corn flakes”. The grain quality parameter required is the ability to produce a high proportion of coarse fractions of maize, called flaking grits, during dry milling. This characteristic depends on grain hardness and size (Robutti, Borra ´ s, & Eyherabide, 1997; Robutti, Borra ´ s, Ferrer, & Bietz, 2000; Robutti, Borra ´ s, Ferrer, Percibaldi, & Knutson, 2000) and, particularly, depends on the predominance of horny over floury endosperm (Watson, 1988). Unlike flint maize, dent maize endosperm is predominantly floury and less suitable for processing into corn flakes. In order to obtain coarse dry milling fractions, the development of fissures must be avoided. For instance the limit between horny and floury endosperms is a fault line that may break under stress, though this may not become apparent to the naked eye because the pericarp is opaque and holds the two types of endosperm together. However, the mechanised transport of fissured grain in augers, or free-fall inside bins may produce a high percentage of broken grains in the final product. * Corresponding author. Fax: þ54 358 4676246. E-mail addresses: mmartinello@ing.unrc.edu.ar (M. Martinello), saginer@ing.unlp.edu.ar (S. Giner). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/issn/15375110 biosystems engineering 107 (2010) 36 e45 1537-5110/$ e see front matter ª 2010 IAgrE. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biosystemseng.2010.06.010