Use of fumigation for managing grain quality

 

 

Somiahnadar Rajendran* and Venkata-rao Sriranjini

Central Food Technological Research Institute, Mysore, India

 

 

 

Abstract

Purpose of the review: Fumigation is a vital tool for grain protection against insect and mite pests and quality maintenance. Methyl bromide and phosphine, the principal fumigants, have been facing threats on environmental (ozone depletion) and biological (insect resistance) grounds, respectively. Hence, there have been major developments on the judicious use of phosphine and intensive search on alternative fumigants for grain protection. Recent advances on fumigation for managing grain quality are reviewed in this paper.

Main findings: Due to increased tolerance and development of resistance by stored grain insects, the target concentration of phosphine for effective treatment of grains has been increased (eg, 1,000 ppm for a 7-day treatment). To serve the dual purpose of preventing grain contamination with residual aluminium phosphide and for controlling phosphine-resistant insects, techniques for direct application of gaseous phosphine from cylinder and on-site generator sources have been developed. Rapid penetration into commodities, low to moderate level of sorption by food grains and quick aeration after the treatment have been demonstrated as the favourable properties of sulphuryl fluoride, a new grain fumigant. Reports on the effect of carbonyl sulphide, a promising alternative fumigant, on grain quality (eg, germination and tainting) are conflicting. Improved methods to apply ethyl formate alone and in mixture with CO₂, have been developed. Ethyl formate appears to be a promising fumigant for on-farm storage and space treatments, while ethane dinitrile has shown promise as a devitalising agent for grains.

Directions for future research: Intensive studies are required to exploit natural plant products for grain fumigation. Studies are also necessary to optimise ethyl formate application techniques for on-farm storage. Efficacy of new fumigants against mites in stored grain needs attention. Furthermore, there is a need to ensure quality supply of the fumigants as the impurities present have been noted to be harmful to the produce.

 

Keywords: fumigation; stored grains; insect control; grain quality

 

Stewart Postharvest Review 2007, 6:9

Published online 01 December 2007

doi: 10.2212/spr.2007.6.9