Miller Magazine Issue: 120 December 2019

83 ARTICLE MILLER / DECEMBER 2019 age. Aeration systems can be operated for 10 to 15 minutes every two to three hours to allow interstitial air space to reach equilibrium with the concentration of the fumigant in the grain. Thus, the aeration system can be operated several times to ventilate the stor- age. Storage odors also can develop in a grain bulk due to hot spots containing insects or moldy grain. Sour odors result from anaerobic activity in the pro- cess of fermentation at high MCs (above 18% for ce- reals). At moderate moisture levels (14% to 18% MC for cereals), musty odors in grain are usually caused by the growth of certain molds. Other odors occa- sionally found in grain are considered commercially objectionable foreign odors (COFO) because they are odors that are foreign to grain and render it un- fit for normal commercial usage. Most odors can be reduced using aeration; however residual odors may linger after repeated aeration cycles. Commercial ap- plications based on pilot laboratory studies have used aeration combined with ozone treatment to reduce off odors in grain. PRESERVATION BY CHILLING OF GRAIN BY REFRIGERATED AIR Aeration using ambient air may not be sufficient to control fungi on moist grain protect grain against mites and insects, control self-heating of grain, or preserve the germination capacity and quality of stored grain in warm climates, or when warm grain is stored immediately after harvest. In answer to these situations, refrigerated-air units for chilling grain have been developed for commodities that can justify the added expense of refrigerated aeration cooling. In this type of aeration process, ambient air is condi- tioned by passing it through the evaporator coil and a secondary reheat coil of the refrigeration unit, and then blowing the chilled air into the grain bulk via the existing aeration system. Passage through the sec- ondary reheating coil is designed to adjust the air rel- ative humidity to 60–75% to match the target MC of the dry grain. The amount of reheating and the final air temperature are adjustable by the operator to achieve the desired aeration conditions. Refrigerated aeration has been used for cooling dry grain in subtropical climates when ambient temper- atures are too high for successful insect control by aeration with untreated air (Hunter and Taylor, 1980; Navarro et al., 1973). Refrigeration involves consider- able investment, but together with the dehumidified air method, it could provide answers to the practica- bility of aeration for safe commercial storage in trop- ical climates. Asia’s largest animal feed event For more information, please visit: www.victamasia.com BITEC Bangkok, Thailand 24 - 26 March, 2020 VICTAM ASIA is firmly established as the event dedicated to the animal feed processing industry within Asia. Co-located with VICTAM ASIA is GRAPAS ASIA, the event for the grain and rice processing industries. VIV Health & Nutrition, the event for feed, pharma & genetics in the animal protein production, will also be co-located with VICTAM Asia 2020. Victam Corporation T: +31 33 246 4404 E: expo@victam.com W: www.victaminternational.com See us on Twitter, Facebook, LinkedIn and Google+ or scan the QR code Supported by Thailand Convention and Exhibition Bureau (TCEB)