PU2044PV0310-3
TM
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PU2044PV0310- 3C-Unabridged Version
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UNABRIDGED VERSION of paper presented at the 10th International Working Conference on Stored Product Protection (IWCSPP), Estoril, Portugal, June 2010
New Applications of Hermetic Storage for Grain Storage and Transport P. Villers1*, S. Navarro2, T. de Bruin1 President, GrainPro, Inc. 200 Baker Avenue, Suite 309, Concord, Massachusetts 01742, USA email:
[email protected] • Tel: +1- 978-371-7118 • website: www.grainpro.com] 2 Senior Consultant, Food Technology International Consultancy Ltd., Beit Yehoshua 40501, Israel. 3 President, GrainPro Philippines Inc. Subic Bay Freeport Zone 2222, Philippines. Tel: +63-47-252-7884,
[email protected] 1
Abstract Recent evolution of pesticide-free post harvest hermetic storage for dry commodities as now used in 81 countries for the storage of grain and other commodities is described. Results of studies on the protection of seeds, rice, maize, wheat, pulses, cocoa and coffee are presented. Flexible plastic structures have been developed and applied to long-term storage. A growing number of types of such hermetic containers now exist especially for tropical conditions. Types of hermetic containers include: 1) SuperGrainbags™, 60kg to 2-tonne flexible portable containers; 2) GrainSafe II™, bulk storage for household or farm use and daily withdrawal of grain of 1-tonne to 2 -tonne capacity; 3) Cocoons™, flexible enclosures of 5- to 1,050-tonne capacity designed for storage at the farmer-cooperative and small trader level or larger commercial and strategic storage facilities; 4) Hermetic Bunkers™ for long term storage in bulk of 10,000- to 20,000-tonnes; 5) TranSafeliners TM provide quality preservation, insect control, and prevention of condensation during shipment of bagged commodities in containers across intercontinental distances. Recent storage applications and the growing use of hermetic liners for intercontinental shipments of a variety of commodities are described. Key performance parameters for safe storage, prevention of mold growth and insect control for dry and moist commodities are discussed. Economic analyses are provided for representative applications, for a variety of commodities, including rice, maize and cocoa. Key words: Hermetic Storage, Hermetic Silo, Modified Atmosphere, Long Term Storage, Cocoon™, Quality Preservation, Insect Control, Flexible Storage Structures, Hermetic Bunkers™, SuperGrainbags™, TranSafeliners™. 1.0 Introduction First introduced in the late 1980s, hermetic storage (HS) can now replace older post harvest storage methods. It is used in more than 80 countries, primarily for grains such as rice, maize, wheat, pulses and high value commodities such as coffee and cocoa, as well as seeds of many types. Hermetic storage has become a replacement for older storage methods, particularly in hot, humid climates because of its “green”, chemical-free technology, control of moisture content, avoidance of pesticides and of need for refrigeration. It can achieve 100% “kill” of insects and control of molds and free fatty acids (FFAs). Hermetic storage features flexibility of installation (indoors or outdoors), portability, and attractive cost. The simple principle involved in hermetic storage is to control moisture and allow depletion of oxygen with increase in CO 2 through respiration of both the commodity and insects. Typically at room temperature or above this creates an unbreathable, low oxygen atmosphere within a few days, and reduces storage losses to 20 ppb) of aflatoxins. Laboratory tests of high moisture maize (up to 37.7%) stored under hermetic conditions were found free from aflatoxins.” Current applications of hermetic storage: 6.0 Key Application Areas: The five most important areas of today’s commercial use of hermetic storage are as indicated earlier: for seed protection, and storage of rice, maize, pulses, cocoa and coffee. In addition, there are a number of less commonly used applications such as those for storage and disinfestation of figs (Ferizll & Emekci 2000), narcissus bulbs, and even disinfestation of archeological artifacts, using injection of CO2 or N2. Provided below is further information on some of these applications. 6.1 Cocoa According to the Transport Information Service (TIS 2009), cocoa bean moisture content higher than 8% corresponds to the rapid mold growth threshold of 75% relative humidity. It is thus recommended to insist on water content of 6% or less when transporting cocoa beans in containers. Safe storage of cocoa presents a number of challenges including insect infestation, the growth of cancer-promoting aflatoxins and the growth of free fatty acids (FFAs). The Ghana Cocoa Board (“Cocobod”) successfully stored cocoa in 150-tonne Cocoons for 9 weeks (Jonfia-Essien, 2008a). They also evaluated the storage of cocoa beans in hermetic SuperGrainbag™ (SGB) liners inside conventional jute bags of 70kg. After 30-days of storage, 100% mortality of populations of insects was observed in all cocoa beans stored in all SGB liners except one single bag in which a few individual insects were alive (Jonfia-Essien, 2008b). Currently cocoa is stored hermetically in Brazil, Indonesia, and Ghana. Data was shown for insect control and for quality preservation of stored cocoa beans by employing a novel approach through the use of biogenerated modified atmospheres as a methyl bromide alternative. The respiration rates of cocoa beans at equilibrium relative humidity of 73% at 26ºC in hermetically sealed containers depleted the oxygen concentration to
