WORLDWIDE USE OF HERMETIC STORAGE FOR THE PRESERVATION OF AGRICULTURAL PRODUCTS (UNABRIDGED VERSION)

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1 Document #: PU2262PV WORLDWIDE USE OF HERMETIC STORAGE FOR THE PRESERVATION OF AGRICULTURAL PRODUCTS (UNABRIDGED VERSION) To be presented at the 9 th INTERNATIONAL CONTROLLED ATMOSPHERE & FUMIGATION CONFERENCE (CAF) Antalya, Turkey, October 15-19, 2012 T. De Bruin 1, P. Villers 2, A. Wagh 3, S. Navarro 4 1 President, GrainPro Philippines, Inc., Subic Bay Freeport Zone 2222, Philippines (ph: )* 2 President, GrainPro, Inc., 200 Baker Avenue, Suite 309, Concord, MA 01742, USA (ph: ) pvillers@grainpro.com, Website: 3 Asia Continent Manager, 463 Kamal Sagar RCF Colony, Bhandup, East Mumbai, India, avinash@grainpro.com 4 Food Technology International Consultancy Ltd., Beit Yohoshua 40501, Israel ABSTRACT In 2012, the use of fully hermetic storage and solar drying to preserve dried commodities such as grains, seeds and high value commodities, including coffee and cocoa, is now practiced in 80 countries. Hermetic storage has proven especially effective in hot, humid climates, as it combats frequent and devastating post-harvest losses. Hermetic storage has also proven effective in preventing the growth of mold-producing aflatoxins, a major public health hazard. This paper discusses the current state of the art, its limitations and the various forms that hermetic storage currently takes in order to meet the needs of all five continents. The most popular application of hermetic storage is the preservation of major grains, such as rice, corn, beans and wheat, as well as seeds and now silage, without refrigeration or chemicals. Key Words: Hermetic Storage, Modified Atmosphere, Long Term Storage, Insect Control, Flexible Storage Structures, Hermetic Bunker, Cocoon, SuperGrainbag, TranSafeliner, Solar Dryer, Silbag, GrainSafe, Collapsible Dryer Case, GrainKeep Center 1. INTRODUCTION The use of fully hermetic storage has grown rapidly since the 2008 CAF conference (Villers et al. 2008), with a marked increase in the number of applications of the technology and answers to scientific questions. Semi-hermetic storage, such as that provided by the Purdue PICS (Purdue Improved Cowpea Storage) bag and the Argentine Silo Bag, also have been used for some applications, primarily in Africa and Latin America. The GrainKeep Center, among other new applications of hermetic storage, has been developed and in essence brings the market to the farmer in commercially operated safe storage centers. 2. NEW FORMS OF HERMETIC STORAGE AND SOLAR DRYERS saw the introduction of a number of new forms of hermetic storage, such as the Silbag, the Collapsible Dryer Case II (CDC II), the GrainSafe, the GrainSafe XL, and the GrainKeep Center (GKC), as described below. Figure 1 SilBag used for cattle farms and dairies THE SILBAG The SilBag is an airtight silage bag that simplifies the process of storing high-quality silage for cattle and dairies. The Silbag eliminates the need for extensive compression because of its airtight, low oxygen, high CO 2 environment. With a capacity of 20 to 90 cbm, the SilBag does not require filling by machine. (See Fig. 1) 1

2 THE COLLAPSIBLE DRYER CASE II (CDC ) To be successful, long-term hermetic storage of grains and seeds requires proper drying to bring moisture content down to or below the critical moisture level, in order to prevent deterioration and condensation in storage. The availability of low cost, portable, rain-protected solar dryers has greatly facilitated and accelerated the drying of commodities before storage. The Collapsible Dryer Case (CDC II), is shown in Figure 2A. During rains, one end is pulled over the other and zipped closed, protecting the grain. Because the CDC isolates grains and seed from an often cold and moist concrete or earth storage, drying is significantly faster. Figure 2A CDC II Collapsible Solar Dryer THE SUPERGRAINBAG IV R The SuperGrainbag IV R is made using a significantly tougher plastic than that of previous SuperGrainbags to provide a high level of insect resistance against Larger Grain Borers and Cowpea Weevils, both of which have been known to penetrate previous, thin plastic membrane walls. (Garcia-Lara, 2012). The experimental set-up used by Dr. Garcia-Lara (Figure 2B) shows co-extruded low permeability SGB IV R filled with fumigated wheat from the field inside a cage, with LGBs and other insects inside the SGB IV-R and also LGBs between the SCG IV-R and the outer cage. Figure 2B Maize filled SuperGrainbag IV R PLAIN POLYETHYLENE VS. MULTI-LAYERED CO-EXTRUDED FULLY HERMETIC BAGS 2012 also saw the emergence of plain polyethylene grain storage bags that, in some cases, are falsely claimed to be fully airtight and equivalent to fully hermetic, coextruded bags such as SuperGrainbags. However, laboratory tests showed that the permeability to oxygen of these polyethylene bags was 2,219 cc/m 2 /per day, whereas the fully hermetic multi-layer bags such as SuperGrainbags with their proprietary barrier layer, have a permeability of 4.28 cc/m 2 /per day. This explains the substantial difference in performance in reducing oxygen to unbreatheable levels and, in coffee, keeping in the volatile gases emanating from green coffee.. THE GRAINSAFE XL The new 10-tonne to 50-tonne GrainSafe XL is a light and portable bulk storage device used for bulk commodities that are found on larger farms. (See Fig. 3) THE GRAINKEEP CENTER (GKC) Many small farmers do not have access to local markets due to inadequate road networks. The GKC (Figure 4) brings the market to the farmer within a 25-km radius, Figure 3 GrainSafe XL for 10- using a spoke-and-hub concept. Figure 4 shows the hub of a GrainKeep Center with to 50-tonne storage Insets showing their satellite hermetic stores at the village level, or the spokes. Two GrainKeep Centers, (also called Village Aggregation Centers (VAC) in Kenya) were opened in early 2011 as public/private partnerships owned and operated by a local entrepreneur (KPMC). In this set-up, the farmer initially brings bags of grain to a small Cocoon in his or her own village for temporary storage; when this local storage unit is full, the bags are transferred to the Center, which also measures aflatoxin levels and provides the farmer with access to simple modern equipment such as shellers, threshers and dryers. The GKC provides safe hermetic storage at an attractive volume, and can thus attract large buyers such as the World Food Program (P4P), who need a single, trusted source that meets their quality standards. Typically, a GrainKeep Center can service about 2,200 farmers with a capacity of 2,000 tonnes. This significantly improves family income for approximately 11,000 family members. The Center also serves as a training center for the farmers own home use and a source of portable hermetic bags (SuperGrainbags). Figure 4 GrainKeep Center - Bringing the Market to the Farmer 3. OTHER IMPROVEMENTS FOR SUCCESSFUL APPLICATION OF HERMETIC STORAGE Hermetic storage relies primarily on the respiration of insects, microorganisms, and the commodity itself (Villers et al., 2006a; Villers et al., 2006b). However, for any dry commodity previously fumigated to control insects, it may take weeks to reduce oxygen levels. Respiration rates of insects and times required for oxygen levels to drop sufficiently are a strong function of initial infestation and ambient temperature. Further, the time it takes to achieve low oxygen levels in hermetic storage of dry 2

3 commodities increases as the temperature drops significantly below 20 C; below this temperature, respiration rates begin to drop dramatically. On the other hand, respiration rates of wet commodities are dictated by the level of moisture content. SUPPLEMENTAL CARBON DIOXIDE AND OXYGEN ABSORBERS In certain applications, when respiration alone is too slow in reducing oxygen levels, the injection of supplemental CO 2 speeds up the process of reducing the O 2 level to critical levels of <3% for insect survival. This method has been shown to be especially beneficial in the storage of peanuts, where the process may otherwise take 30 days or more (Navarro et al., 2012). It has also been used for organic fig storage (Ferizli and Emekci, 2000) and for the fumigation of flowers and books. The insertion of an inexpensive oxygen absorber packet into small hermetic storage systems is more practical for field applications than the injection of CO 2. RESISTING LARGER GRAIN BORER AND COWPEA W EEVILS Dr. Silverio Garcia-Lara at the Technological University de Monterey, Mexico, recently tested successfully a new, more resistant plastic membrane (0.078 mm) (found in the SGB-IV-R) for the prevention of penetration of hermetic storage bags by cowpea weevils (Callosobruchus maculatus (F.) and larger grain borers (Prostephanus truncatus) which have been known to penetrate earlier hermetic and semi-hermetic bag liners. 4. RELEVANT SCIENTIFIC INFORMATION Figures 5 through 8 show the relevant data as to why conventional warehouse storage proves inadequate for multi-month storage in hot/humid environments. INSECT AND MOLD GROWTH Figure 5 shows moisture content versus humidity under equilibrium conditions for a few sample commodities, showing the variability of that relationship. Figure 6 shows Fungus density versus humidity under equilibrium conditions and the resulting illustrated fungal problems in the tropics. Figures 7 and 8 show why insects are such a serious storage problem at higher temperatures and humidity. Figure 5 Relation between equilibrium, moisture content & relative humidity for representative commodities. Figure 6 Relation between fungus density vs. humidity at equilibrium Figure 7 Indian Meal Moth life cycle: days; eggs/lifetime Figure 8 Typical Insect Density vs. Temperature PUBLIC HEALTH AND AFLATOXINS Due to the detrimental effects of high levels of aflatoxins on public health, which includes facilitating HIV and cancer (Williams, 2011), in 2010, 10% of the Kenyan maize crop had to be rejected because of excessive aflatoxin levels. Many countries have restricted permissible aflatoxin levels for human consumption to five to 10 parts per billion. According to the 2011 World Bank report about grain losses in East Africa, Due to the combined effect of aflatoxins and insect infestation, maize post-harvest losses in a number of areas are 25% [for maize]. (World Bank Report, 2011); and according to its 2010 report, Due to the combined effect of aflatoxins and insect infestation, losses in a number of areas, as shown in Figure 9, are 25%. (World Bank, 2010) Figure Report on postharvest losses of maize in East Africa A recent peanut storage study by Dr. Shlomo Navarro (Navarro et al., 2012) suggests that aflatoxin levels in storage can be arrested (but not reversed) by use of hermetic storage with 3

4 oxygen below 3% and carbon dioxide above 15%. Although this experiment is specific to peanuts, it suggests that hermetic storage at low O 2, and high CO 2 levels prevents the subsequent growth of aflatoxins. As noted earlier, the reduction of O 2 to <3% (generally lethal for air-breathing forms of life) through respiration alone, takes longer to suppress significant growth in aflatoxins unless additional CO 2 is injected. Table 1 shows the experimental data after injection of CO 2. In the case of peanuts, the injection of CO 2 in a central location, or, alternatively, the use of an oxygen absorber, can resolve the problem in the field. Table 1 FFA & CFU mold levels for peanuts LIMITATIONS OF HERMETIC STORAGE Hermetic storage relies primarily on the respiration of insects, microorganisms, and the commodity itself. Any commodity that has been previously fumigated and a few others, such as peanuts, may take several weeks to reduce oxygen levels without the injection of supplementary carbon dioxide. Respiration rates of insects and the time required for oxygen levels to drop sufficiently also are a strong function of ambient temperature as well as moisture content. Further, the time it takes to achieve low oxygen levels in hermetic storage, instead of a typical one to two weeks, increases as the temperature drops significantly below 20 o C; after this, respiration rates begin to drop dramatically. However, humidity is kept out and volatiles are kept in so that in Co-Ops like coffee quality is retained for up to one year. 5. EXAMPLES OF HERMETIC STORAGE AROUND THE WORLD GUATEMALA In response to the demand for medium sized hermetic containers with continuous in and out capabilities, GrainPro introduced one-tonne capacity GrainSafes (Figure 10). In 2011, the World Food Program distributed thousands of these GrainSafes to small and medium sized farmers in Guatemala, primarily for storage of maize. The World Food Program selected this approach after investigating other alternatives, including metal silos (tin and rigid plastic silos) that require the use of fumigants. The World Food Program in Guatemala established that farmers preferred the pesticide-free hermetic storage and provided 2,500 of them. Figure 10 one-tonne GrainSafe supplied by World Food Program (WFP), Guatemala, 2012 GHANA The Cocoa Board of Ghana (COCOBOD) now uses several hundred large Cocoons with a capacity of up to 320 tonnes each to store cocoa beans (which are highly susceptible to rancidity through growth of FFAs) prior to exporting them (Figure 12). More recently, they started using TranSafeliners in shipping containers for protection during transport of organic cocoa. They have also used the portable 60- to 90-kg capacity SuperGrainbags. (Jonfia-Essien, 2008b) NEPAL In Nepal, a large number of small farmers use man-portable 69 kg capacity SuperGrainbags. Figure 11 shows a farmer storing her corn in a Co-Op in Mulpani village near Kathmandu, Nepal. 4 Figure 11 Nepalese Woman with SGBs, Mulpani Village near Kathmandu, Nepal

5 AFGHANISTAN The largest scale application of SuperGrainbags for small farmers, funded by USAID, took place in Afghanistan in 2010 and 2011 in Helman Province along with large quantities of rain-protected solar dryers (CDCs). BRAZIL, PERU AND THE PHILIPPINES Large scale storage of maize and rice seeds in Cocoons is also current in Brazil, Peru and the Philippines. Studies on rice seed by the International Rice Research Institute (IRRI) and the Philippine Center for Postharvest Development and Mechanization (PHilMech) in the Philippines have shown that sufficiently hermetic storage can preserve rice seeds for up to a year with almost the same results as in cold storage, but without the energy requirements. (Villers and Gummert, 2009; Sabio et al, 2006). Elimination of insect damage, maintaining initial moisture level, and low oxygen/high carbon dioxide atmospheres resulting from hermetic conditions create ideal conditions for preserving seed germination and vigor. 6. SAFE STORAGE FOR MAJOR CROPS At present, the eight most common commodities stored hermetically are: seeds, rice, corn, wheat, pulses, cocoa, coffee and spices. The application of hermetic storage to five of these is briefly described below. COFFEE The use of hermetic storage for properly dried green or parchment coffee is now widespread and is used in over 25 countries by hundreds of farmers, traders, importers and roasters. About this use, Coffee and Cocoa International wrote: As coffee growers, logistics companies and roasters search for a way to protect high quality coffee during storage and transportation, one particular technique seems to be coming to the fore. Hermetic products are being used around the world to preserve the quality of coffee prior to roasting, and prevent the development of FFAs and OTA in cocoa. (Coffee & Cocoa International, 2011). Green coffee beans can also be transported across intercontinental distances protected hermetically by the TranSafeliners. As indicated earlier, use of hermetic storage for green coffee, either at the bag level using SuperGrainbags, the multi-tonne level using Cocoons, or for intercontinental transfer using TranSafeliners with standard containers, is in use in more than 25 countries from the Philippines to Kenya and Guatemala, in addition to importers and roasters in the importing country. SEEDS The Philippine Center for Postharvest Development and Mechanization (PHilMech), PhilRice and the International Rice Research Institute (IRRI) have extensively studied long term storage of rice seed. They compared 4 methods: hermetic, cold room, air conditioning and unprotected Kraft bags. The published results by IRRI are reproduced below in Table 2, which shows that hermetic storage is superior to all but cold storage to which it is substantially equivalent. In another IRRI study of farmers in Vietnam using hermetic storage in SuperGrainbags, the seed requirements were reduced by one-third. (IRRI, private communication). RICE Rice storage in hermetic containers is now recommended by IRRI for all ricegrowing regions because of improved shelf life (especially for brown rice), and prevention of major aflatoxin growth in storage. (Villers and Gummert, 2009) Table 2 Mean % Germination rate of un-milled paddy seeds Hermetic vs. Alternate Storage MAIZE Hermetic safe storage of maize is now used in many hot, humid climates, as described in African Farming (Anon., 2011) because losses in storage can generally be reduced to less than 1% and growth of aflatoxin levels in storage largely suppressed. COCOA Because of its high oil content, cocoa is especially susceptible to rancidity caused by free fatty acids (FFAs), as well as insect Figure MT Cocoon storing Figure 13 TranSafeliner TM filled with cocoa at COCOBOD, Ghana, 2012 damage. The benefits of safe storage in sacks of Ghanaan Cocoa Board beans inside 20-foot shipping container. hermetic enclosures are well documented (Jonfia-Essien et al., 2008 and 2010). The largest user is the Ghanaian Cocoa Board, which, as mentioned earlier, has adopted 5

6 hermetic storage for Ghana s exports using large Cocoons TM (Figure 12). More recently, they are using TranSafeliners for intercontinental shipments to protect cocoa beans from insect pests and mold growth while on board a vessel (Figure 13). 7. COST EFFECTIVENESS ANALYSIS Cost effectiveness of hermetic technology is an important consideration for all users. Further economic studies of rice seed (Table 3) comparing hermetic with cold room storage, air-conditioned storage and an unprotected control, pointed to hermetic storage as the lowest total cost alternative. (Sabio et al., 2006) Table 3 Cost comparison of using conventional (Ctrl), hermetic (Hs), cold room (Crs) and air-conditioned room (Acrs) storage for preserving Mestizo 1 (PSB Rc72H) hybrid paddy seeds after 9 months (Abridged) (Philippine pesos per 20 kg bag) Among other economic studies is one conducted by Dorman (VolCafe Kenya) on green coffee storage and transport in Kenya. Table 4 below, shows a cost comparison from four ways of protecting coffee for storage followed by intercontinental shipment. Table 5 below (available as Document #: LT2263PV from GrainPro, Inc.) is an interactive Excel worksheet for customers to use with their own numbers to compare return on investment calculations (ROI) and payback in years. The customer must provide up to thirteen variables, as follows: 1) capacity of each hermetic unit; 2) cost of each hermetic unit; 3) useful life of each hermetic unit; 4) fumigation cost; 6) selling price of commodity; 7) cost of qualitative selling price loss; 8) tonnes to be stored at a time; 9) cost of leasing land, if any; 10) maintenance costs; 11) capital cost of alternative; 12) density of commodity stored; 13) number of loads stored per year. Table 4 Comparative Cost Calculations Dorman (VolCafe Kenya) (in USD) 6

7 Table 5 Comparative Economic Analysis Worksheet for proposed new or add-on hermetic storage installation The Excel spreadsheet, using the thirteen variables listed above and applying the formulas shown in columns E and F (column and rows indicated), then calculates cost differences and savings using (conventional) formulas to determine: 1) Return on Investment (ROI) and years to pay back the extra cost of using hermetic storage (if any), as well as capital cost of hermetic storage and yearly net savings; 2) total savings over the hermetic storage lifetime. 8. CONCLUSION Hermetic storage, when sufficiently hermetic, uses insect and microorganism respiration to provides a low oxygen, high CO 2 lethal atmosphere for insects and while preventing mold growth. Hermetic storage increasingly is accepted as the standard for safe, multi-month preservation of high value crops such as seeds, cocoa and coffee. Hermetic storage provides a modern, sustainable, chemical-free, transportable, user-friendly, green and cost effective solution to six previously difficult storage problems: 1) protecting crops from insect infestation; 2) preventing aflatoxin growth; 3) preventing rancidity in commodities; 4) providing safe, long-term storage; 5) eliminating the need for pesticides, fumigants or refrigeration in storage; and 6) protecting seed germination for up to a year. Conventional storage in hot, humid climates, by contrast, has failed to adequately protect stored commodities in multi-month storage. (Villers et al., 2006) We expect that the variety of applications for hermetic storage and their widespread use will continue to grow as people make greater efforts to avoid the use of chemicals and refrigeration, to dramatically reduce storage losses to less than 1% and to lower storage costs. Now, almost 25 years after the introduction of the first hermetic storage systems, countries can better meet their food security requirements, reduce costs, and increase the incomes of their local farmers, while helping to protect consumers from dangerous aflatoxin levels. 7

8 REFERENCES Anon. (2011) Airtight Post-harvest Storage Helps African Farmers. African Farming and Food Processing. Jan/Feb 2011: Aronson S, Raudales R, Trubey R, Villers P (2005) Breakthrough in storing high quality coffee. Tea Coffee Trade J. 177 (11): Coffee and Cocoa International Journal (2011). GrainPro concept finds new adherents in the coffee industry. Vol. 38, No. 3: Ferizli AG, Emekci M (2000) Carbon dioxide fumigation as a methyl bromide alternative for the dried fig industry. Annual International Research Conference on Methyl Bromide Alternatives & Emissions Reductions. Orlando, Florida. 2000, 81. Garcia LS, (2012), unpublished report. Jonfia-Essien WA, Navarro S, Dator JV (2008a) Effectiveness of hermetic storage in insect control and quality preservation of cocoa beans in Ghana. In: Daolin G, Navarro S, Jian Y, Cheng T, Zuxun J, Yue L, Haipeng W [Eds.] Proc 8th Int Conf Controlled Atmosphere and Fumigation in Stored Prod. California Garden Hotel, Chengdu, China. Sept , Sichuan Publishing Group, Sichuan, China Jonfia-Essien WA, Navarro S, Dator JV (2008b) SuperGrainbag: a hermetic bag liner for insect control of stored cocoa beans in Ghana. In: Daolin G, Navarro S, Jian Y, Cheng T, Zuxun J, Yue L, Haipeng W [Eds.] Proc 8th Int Conf Controlled Atmosphere and Fumigation in Stored Prod. California Garden Hotel, Chengdu, China. Sept , Sichuan Publishing Group, Sichuan, China Jonfia-Essien WA, Navarro S, Villers, P (2010) Hermetic Storage: A novel approach to the protection of cocoa beans. African Crop Sci 18(2): Navarro, H, Navarro, S Finkelman, S (2012) Hermetic and modified atmosphere storage of shelled peanuts to prevent free fatty acid and aflatoxin formation. Proceedings of the Conf Int Org Biol Integrated Control of Noxious Animals and Plants (IOBC). Work Group on Integrated Prot Stored Prod Bull. Volos, Greece. July 4-7, Sabio GC, Dator JV, Orge RF, Julian DDT, Alvindia DG, Miranda GC, Austria MC. (2006). Preservation of Mestizo 1 (PSB Rc72H) seeds using hermetic and low temperature storage technologies. In: Lorini I, et al., (eds) Proc 9 th Int Work Conf Stored Prod Prot Campinas, Sao Paulo, Brazil, ABRAPOS, 2006: Villers P, Gummert M (2009) Seal of approval. Rice Today. 8(1): Villers P, De Bruin T, Navarro S (2006a) Development and applications of the hermetic storage technology. In: Lorini I, et al., (eds) Proc 9 th Int Work Conf Stored Prod Prot Campinas, Sao Paulo, Brazil, ABRAPOS: 2006, Villers P, De Bruin T, Navarro S (2006b) Safe storage of grain in the tropics. Feed Technology Update 1(3): 2-7. Villers P, Navarro S, De Bruin T (2008) Recent developments in hermetic storage technology using sealed flexible storage structures. In: Daolin G, Navarro S, Jian Y, Cheng T, Zuxun J, Yue L, Haipeng W [Eds.] Proc 8th Int Conf Controlled Atmosphere and Fumigation in Stored Prod. California Garden Hotel, Chengdu, China. Sept , Sichuan Publishing Group, Sichuan, China Villers P, Navarro S, De Bruin T (2010) New applications of hermetic storage for grain storage and transport. In: Navarro S, Riudavets J [Eds.] Fumigation, Modified atmospheres and hermetic storage, Proc 10 th Int Work Conf Stored Prod Prot, 27 June to 2 July 2010, Estoril, Portugal Julius-Kühn-Archiv, 425, Bundesforschungsinstitut für Kulturpflanzen, Berlin: Williams, JH (2011) Aflatoxin as a public health factor in developing countries and its influence on HIV and other diseases. Human Aflatoxicosis in Developing Countries: A review of toxicology, exposure, potential health consequences and interventions. Peanut Collaborative Research Support Program, University of Georgia. World Bank Report (2011) Report #60371-AFR. April