J.E. DONAHAYE, S. NAVARRO, S. ANDALES, ANGELITA M. DEL MUNDO, FILIPINAS CALIBOSO, GLORY SABIO ANGELINA FELIX, MIRIAM RINDNER, A. AZRIELI and R. DIAS
ABSTRACT
Two laboratory studies were carried out to evaluate the influence of hermetic storage on the quality conservation of paddy at different water activities. Five moisture content (M.C.) levels of paddy were used, namely, 14, 15, 16, 17 and 18% w.b., approximately corresponding to the following water activities: 0.75, 0.80, 0.85, 0.88 and 0.90 aw. Quality evaluations were carried out after five storage periods, namely: 0, 1, 2, 3, 4 weeks for the first experiment and seven storage periods, namely 0, 1, 2, 3, 4, 5, 6 months for the second experiment. The entire study was undertaken at room temperatures of ~ 29¼ to 30&186;C prevailing in the Philippines. Cooked rice aroma, taste, tenderness, cohesiveness, color and gloss were found to be negatively correlated with moisture content (m.c.) and storage duration of the paddy. The poor acceptability and preference-scores for cooked milled rice samples from paddy stored hermetically at 16% to 18% m.c. was primarily dictated by the presence of fermented smell in these samples. In the raw form, wholeness of grains and color were found to have a significant negative correlation with m.c. and storage duration. Analysis of microfloral loads and bacteria revealed an increase in bacterial counts for the paddy held at 17% and 18% m.c.
Field trials using sealed flexible storage structures of 10 tons capacity were undertaken. It was clearly demonstrated that the rates of oxygen depletion in hermetically sealed 18% m.c. paddy could prevent mold proliferation. The effects of hermetic storage upon paddy quality were also evaluated using cooking and acceptability parameters obtained after 1, 3 and 6 months of storage. The findings indicated that after 1 month, quality of sealed paddy stored at 18% m.c. had not deteriorated perceptibly. However, further evaluations made on paddy stored hermetically for 1, 3 and 6 months under both laboratory and field conditions confirmed that after the first month of storage the quality of moist paddy (16-18% m.c.) deteriorated progressively and the grain was no longer acceptable to the taste panels.
J.E. DONAHAYE, S. NAVARRO, GLORY SABIO, MIRIAM RINDNER, A. AZRIELI AND R. DIAS
ABSTRACT
A sealed structure (the 'Volcani Cube'¨) that provides protection to grain without the use of chemical pesticides was used in these experiments. A major advantage of the Volcani Cube is that it can be used to safely store grain outdoors where no suitable storage buildings are available. Under tropical conditions, when grain is stored in the open with no shade, ambient diurnal temperature fluctuations, can create temperature gradients within the stack that cause convection currents to carry moisture to the upper layers of grain. To overcome this effect, an upper insulating layer of bags containing straw or husks was employed. Under tropical climates this solution enables safe storage of maize and paddy for periods of up to 3 months; for more extended periods the top moistened layer of husks should be replaced with dry material. In a search to develop an alternative inexpensive and convenient method of insulating the stack from diurnal temperature fluctuations, the use of a shade screen placed above the cube was investigated. This material described as a knitted thermal screen is formed from aluminum coated high-density polyethylene threads. Trials conducted with Volcani Cubes in tropical and subtropical climates showed that grain is protected under sealed storage by maintaining the number of live insects below the threshold of economic damage without the need for pesticides. For dry paddy, it was shown that after 5 months storage under a reflective cover, no perceptible increase in moisture content was found at the top of the stack and the grain remained in good condition.
S. NAVARRO, J.E. DONAHAYE, MIRIAM RINDNER AND A. AZRIELI
ABSTRACT
Dates grown in Israel served as a model to demonstrate the feasibility of storing dried fruit under CO2 atmosphere. A controlled atmosphere of 60-80% CO2was used within a 151 m3 plastic chamber partially filled with 30 tonnes of dates stacked in crates on pallets. The dates were stored in the chamber in bulk (in boxes of 10 kg or crates of 400 kg on pallets) or packed (250 g capped plastic cups) on pallets containing dates of vars. 'Hallawi', 'Hadrawi', 'Zahidi', 'Derei' and 'Ameri'. Dates were sampled before closing the chamber, after one month and after 4.5 months at the end of storage. The following were investigated: presence of insects and molds; skin sloughing; sugar formation; water activity (aw); and color changes (only on var. Zahidi). At the initial purge phase the desired CO2 concentration was obtained in the chamber within one hour by introducing the gas under high pressure. An intermittent maintenance phase was then applied for 4.5 months using approximately 0.8 kg CO2 per day. At the end of storage, quality of the treated dates was compared to controls stored at -18¡ C. No significant difference was found between the treated dates and controls. The insect population was effectively controlled. This technology is proposed for the treatment of stored dates to control pests and maintain quality.
C.P.F. DE LIMA
ABSTRACT
Oaten hay for animal feed, is shipped to Japan and other countries from Australia after methyl bromide or phosphine fumigation. However for environmental as well as health and safety reasons these techniques require alternatives. Trials were conducted to develop alternatives using 2% PH3 in CO2 (Phosphumeâ) and CO2 alone. Approximately 300 containers of 67 m3 were used. In addition treatments were carried out in pallet sized units for break-bulk shipment. The pests fumigated were mainly stored-product insects. Quality control procedures were developed through moisture measurement in the field, before harvest and through the drying and baling stages. Techniques were developed to (a) increase the packing density without affecting product quality, (b) improve gastightness, and (c) reduce fumigant dosage. A quality assurance process was developed to reduce quarantine inspections while achieving the highest standards of shipped produce. Economic analysis showed a benefit / cost between 30 and 44 depending on the measures adopted. The techniques developed could be used for the treatment of other durable commodities in developing countries.
CECILIA V. DE DIOS, MARIA FINESA A. COSICO, D.D. JULIAN, J.V. DATOR, ELVIRA M. MARTINEZ AND R.L. TIONGSON
ABSTRACT
A pilot trial was conducted on the adoption of hermetic storage using Volcani Cubesâ for long-term storage of milled rice at the National Food Authority (NFA) Warehouse in Cabanatuan City, N.E., Philippines. The storage cubes consist of an upper and a lower section of plastic sheeting zipped together to provide an hermetic seal. The objective of this trial was to evaluate the preservation of milled rice in the cubes without employing fumigants in a tropical climate. Nine stacks of milled rice imported from Vietnam were kept in Volcani Cubes; three untreated control stacks were used as reference. Initial infestation was extremely low due to the recent fumigation of the test commodity. After 3, 6 and 11 months of continuous storage, oxygen concentrations in the Volcani Cubes dropped to 11.4%, 5.4% and 2.7% respectively. The hermetic conditions suppressed insect development and, where the atmospheres contained sufficiently low levels of oxygen, mortality of insects was achieved. The modified atmospheres were able to retard insect growth and development, as evidenced by weak and abnormal progeny of Rhyzopertha dominica. This is further supported by the decrease in live insect counts. The quality of rice stored under hermetic conditions in the cubes remained high throughout the storage period. In contrast, the untreated control stacks stored in a normal warehouse atmosphere were heavily infested after three months of storage. Between 4 and 6 months of storage, 6 out of the 9 stacks in Volcani Cubes showed insect holes presumably inflicted by R. dominica, but damage to the commodity was negligible. Further refinements were suggested for this environment- and user-friendly hermetic storage technology for the quality preservation of milled rice without the use of fumigants, in the Philippine climate.
J. van S. GRAVER AND S. PRATT
ABSTRACT
To further investigate the technique used in China of retarding phosphine evolution from solid aluminium phosphide formulations by enclosing the tablets in plastic bags placed inside the fumigation enclosure, we monitored phosphine production under laboratory controlled conditions. An apparatus comprising a computer-controlled sampling manifold and an electrochemical sensor was used to continually determine and log phosphine concentrations. Commercial 3 g phosphide tablets were placed in glass dishes that were then covered with plastic of known water permeability and sealed inside chambers where they were exposed to gentle streams of humidified air (70% r.h.). A computer controlled the monitoring of the PH3 concentrations of the effluents, so that the attenuation in PH3 production with respect to uncovered tablets was determined. The effect of plastic thickness on PH3 evolution was examined, where it was found that even very thin plastic (10 mm) drastically reduced the rate of PH3 evolution. The rate of production of the gas was only partially dependent on the number of tablets within the enclosed dishes. Lastly, the surface area of the permeable plastic was shown to affect the rate at which PH3 was produced.
We discuss the utility of the Òdelayed evolutionÓ technique in relation to the need to prolong exposure periods for effective PH3 fumigations.
C. REED
ABSTRACT
Phosphine monitors with electrochemical cells and data-loggers were used to describe movement of phosphine gas escaping from fumigated grain in upright concrete grain bins. The monitors were placed in ground and below ground enclosed areas, outside the elevator, and at bin-top locations to characterize phosphine concentrations. A monitor suspended from the bin roof recorded the fumigant concentration in the air inside the bin and above the grain. Data were taken at each location at 15-minute intervals during 23 separate fumigation events at 15 grain elevators in Kansas, USA. The predominant direction of gas movement was upward through the fumigated grain. In several cases, phosphine concentration in the grain headspace increased and decreased daily, reaching its maximum at mid-morning and its minimum at late evening. The pattern was consistent with the theory that chimney effects produce a generally upward airflow through the grain, with the rate of air movement influenced by the temperature differential between the grain and the ambient air. Enclosed areas at the bin-top level or above were more likely to contain phosphine concentrations greater than 0.3 ppm than were enclosed areas at ground or below ground levels. Significant wind effects were observed in several cases.
SYLVIA ALLEN
ABSTRACT
This paper describes the use of inert dust for the control of storage pests by the bulk grain handling industry in Australia. Inert dusts are used in three main ways, as structural treatments, capping treatments and surface admixture treatments. Structural treatments of chemical insecticides, where they were used, have been largely replaced with use of the inert dust, DryacideÒ, that can be blown onto surfaces dry or sprayed as a slurry. Capping treatments are used in combination with flow-through fumigation of phosphine (SIROFLOÒ) where a thin layer (100 g m-2) of DryacideÒ is applied by blowing dust across the surface of the grain bulk. The purpose of the dust layer is to ensure phosphine gas is retained at insecticidal concentration in the surface layers of the grain bulk by retarding the loss of phosphine to the headspace. Surface admixture treatments are used in combination with aeration. In this application, DryacideÒ is mixed into the top 0.3 m of grain to protect against insect re-invasion of the grain bulk surface, and to reduce or possibly eliminate some existing populations.
G.N. MBATA AND T.W. PHILLIPS
ABSTRACT
Prospects of low pressure, simulating vacuum, in disinfestation of stored-products were investigated in the laboratory by examining the mortality of developmental stages and adults of three stored-product insects, Tribolium castaneum (Herbst), Plodia interpunctella (Hubner) and Rhyzopertha dominica (F.) exposed to 32.5 mm Hg at 25, 33, 37 and 40°C; and the eggs of T. castaneum, P. interpunctella, R. dominica and Ephestia cautella (Walker) to 50, 75, 100, 200 and 300 mm Hg at 22.5, 30 and 37.5&186;C. In preliminary studies, adults of the three species were found to be very susceptible to low pressure and complete mortality was obtained within 3 h exposure to low pressure at 25°C. The adults were therefore excluded from further investigation. Among the species investigated, developmental stages of R. dominica were found to be most tolerant to low pressure while developmental stages of P. interpunctella and E. cautella were the most susceptible. The egg stage was the most tolerant stage while larval stages were most sensitive to low pressure. The egg stage investigated at several low pressures showed that very low pressure (50, 75, and 100 mm Hg) produced mortality earlier than moderate pressures of 200 and 300 mm Hg. Higher temperatures of 30, 37.5 and 40&186;C lowered LT99 for all the species and their life stages exposed to low pressure and this was most pronounced for developmental stages of R. dominica that were tolerant at the lowest exposure temperature of 25&186;C. Sensitivity of eggs to low pressure was high when they were freshly laid, and up to a certain time-frame depending on species, and then increased again before hatch.
C. NEWMAN, G. RUSSELL, W. SHORE, D. GOCK AND R. RYAN
ABSTRACT
SIROFLOÒ fumigation technology was invented in Australia in the 1980Õs, for the purpose of fumigating grain in bulk using gaseous phosphine. Until recently the technology has been adopted in relatively few other countries because of the difficulties associated with the registration of gaseous phosphine products, despite the fact that their active ingredients are chemically identical to the less pure solid phosphide formulations that are in common use worldwide. However In the last two years, significant moves have been made to broaden the international market for SIROFLO technologies and gaseous phosphine products. Grain Tech Systems Pty Ltd (GTS) is a small Australian company that has participated in this process by introducing the technologies to the PeopleÕs Republic of China. This paper briefly describes some of the projects that have been undertaken by GTS in China, and some of the emerging grain fumigation technologies that are being developed in competition with GTS.
S. NAVARRO, J.E. DONAHAYE, R. DIAS, A. AZRIELI, MIRIAM RINDNER,
T. PHILLIPS, R. NOYES, P. VILLERS, T. DEBRUIN, R. TRUBY AND
R. RODRIGUEZ
ABSTRACT
It was demonstrated that the response of insects to low pressures is temperature and moisture dependent. Trogoderma granarium quiescent larvae were considered the most resistant storage insects tested, a 172-h exposure to 25 mm Hg being necessary for their control at 30&186;C. To control them within a 145-h exposure time it was necessary to increase the temperature to 35&186;C.
The encouraging reports led to the idea of developing a transportable system to render the technology a practical tool for the control of insect pests. Two sets of experiments were carried out using a 15 m3 capacity plastic container termed the ÒGrainPro CocoonsªÓ or ÒVolcani Cube¨Ó. This container is made of a flexible liner and characterized by its transportability. The first test was carried out in Foxboro MA, USA using an oil-lubricated vacuum pump (3 hp) to reduce the pressure to 25-mm Hg within 25 min. Then the pressure was maintained between 25 and 29 mm Hg for 17 days. Three sets of bioassay replicates were retrieved on day 3, 10, and 17 of treatment. Complete mortality of test insects was observed after the 3-days exposure to vacuum. The second test using vacuum was carried out in Israel using a similar set-up for the vacuum pump and the Volcani Cube. The purpose of these tests was to evaluate the technology so as to contribute to improved performance. Vacuum was maintained within 22 and 75 mm Hg for over 25 days.
M.G. ANDRADA, C.G. ALINGOD, M.E.S. LIM, MARIA FINESA A. COSICO, AND ELVIRA M. MARTINEZ
ABSTRACT
The NFA continuously searches for alternative pesticides that are cost effective. It had embarked on a research project to evaluate other commercially available fumigant formulations in the market such as Quickphos, which is suggested to be as effective as Phostoxin, the one currently used by the agency for PH3 fumigations. Data obtained from an analysis of variance showed that as regards technical performance, Quickphos, when applied either in single or double dosage, exhibited the same effect as Phostoxin in the control of stored-product insects such as Rhyzopertha dominica, Sitophilus spp., and Tribolium castaneum, yielding 100% mortality. Regardless of the dosage used, gas concentration generated by Phostoxin was significantly higher than Quickphos. The gas concentration of a double dose of both fumigants was significantly higher than a single dose. The peak gas concentrations attained at different monitoring times did not differ significantly between the two fumigants tested. Furthermore the interaction of dosage and time in relation to gas concentration revealed a wide variety of responses with one variable having a more pronounced effect than the other. Economics-wise, Quickphos is cheaper than Phostoxin. The agency will be able to realize a substantial savings especially on fumigation, if the former is used in the administration of pest control.
C.J WATERFORD AND P.P ASHER
ABSTRACT
Trial results are presented of two types of phosphine (PH3) generator designed to use a new formulation of aluminium phosphide. A quick release generator, designed to deliver up to 6 kg of PH3 over five hours to rapidly establish an effective concentration in sealed storage, was tested in three trials in which 3 kg of PH3 was generated. A slow release generator, designed to provide controlled rates of PH3 production, was tested at 4 g h-1 and 8 g h-1. These rates can be maintained for sixteen days to service active fumigation techniques, which supply a relatively constant flow of fumigant in air at an effective concentration and small positive pressure to the fumigated store. This is sufficient to prevent dilution to ineffective fumigant concentrations by wind and temperature effects that can cause air ingress and gas loss. Maintenance applications could also use this type of generator to offset gas loss due to leaks, wind and diurnal temperature effects. Recirculation techniques could use a combination of the two types of generator, the quick release to rapidly establish and distribute the fumigant throughout the storage and the slow release to maintain this concentration for the remainder of the fumigation.
M.G. ANDRADA, MARIA FINESA A. COSICO, AND ELVIRA M. MARTINEZ
ABSTRACT
This research project was conducted with the primary purpose of searching for alternative fumigants that are cost effective and might be used by the agency in its nationwide adoption of the SEFUST method or CAST (controlled atmosphere storage technology) for the NFA's stock management operations. The project compared the performance of the fumigant formulation (Phostoxin) in present use by the agency against an alternative formulation (Quickphos) under the SEFUST method for a 6- month storage period. It focused its observations on the effect on the quality changes of milled rice such as percent damaged grains, percent discolored grains, percent moisture content, rice kernel whiteness, and insect-damaged kernels. Results revealed that SEFUST did not significantly affect the overall quality of the milled rice except for moisture content. Generation of the PH3 concentration of the fumigant formulations was also measured and compared and showed that Phostoxin PH3 generation is significantly higher than that of Quickphos. Furthermore, the PH3 concentration at the top of the pile is not significantly different from the bottom of the pile for both fumigant formulations. The project also addressed the application cost of the two fumigant formulations under this method.
P.V. HERRERA JR., M.G. ANDRADA, AND ELVIRA M. MARTINEZ
ABSTRACT
A validation study was conducted to determine the adoptability into the operations of the NFA of the SEFUST using PH3 as a fumigant in corn storage. A comparative analysis of the costs incurred in utilizing SEFUST vs the existing conventional storage practice of the NFA was undertaken. The comparison between the two systems from a financial perspective showed a relatively low initial investment for the conventional storage as compared to the SEFUST. For a longer period of storage, however, the conventional storage would incur a higher cost because of the expensive pest control methods under the routine basis as normally practiced. SEFUST provides potentially cost-effective control in terms of the benefit viewed in the longer run. With regards to its technical viability, the SEFUST for corn storage using PH3 as a fumigant showed satisfactory results in terms of effective control of infestation and prevention of re-infestation.
R.P. ESTIGOY
ABSTRACT
The strategies of technology transfer of two outdoor storage technologies, the Volcani Cube¨ (Israeli technology) and the local sealed plastic enclosure (Australian technology) for use under Philippine conditions were considered. Deterioration and loss of large quantities of grains during and after harvest are major concerns in the local grain industry. Inadequate storage facilities expose grains to natural elements and pests. One of the interventions to curb losses was the introduction of these two technologies after they were found to be economically and technically feasible and socially acceptable in the Philippines. These technologies were introduced in 1997. The Volcani Cube is a heat-welded 0.833 mm thick polyvinyl chloride (PVC) plastic liner with zipper and tension straps. It has varying capacities of 5, 10 and 20 tonnes. The sealed local plastic enclosure is also heat-welded 0.4 mm PVC with a capacity of 6 tonnes. Both technologies are now being promoted in the grain industry. They can adequately protect dry paddy and corn from insects, rats, birds and rain water damage for three months. The outdoor storage technology is an alternative storage technique adaptable both at on-farm and off-farm levels, which can be used by farmers' cooperatives and small-scale grain millers and handlers. Major technology transfer activities conducted include the provision of a linking mechanism to credit facilities, information and educational campaign, dissemination through tri-media (audio, visual and printed forms of communication), technology demonstration and forum, training of end-users and extension workers, industry assistance and industrial extension. A total of 200 units of the outdoor storage technology have been set up nationwide under a special industry assistance project.
P. WILLIAMS AND R. RYAN
ABSTRACT
ECO2FUME¨ is a cylinder gas formulation of phosphine that was developed for the grain industry for use in SIROFLO¨ systems. ECO2FUME can be applied rapidly and can readily be used to top up PH3 concentrations during a fumigation, a feature used in SIROFLO. It avoids problems with unexpended residues of PH3-generating compounds, which can occur when using solid PH3-generating formulations. These attributes give ECO2FUME the potential for treatment of produce requiring shorter duration fumigations than those used for grain. Research on the development of alternatives to methyl bromide for disinfestation of cut flowers for export, led to the registration of ECO2FUME for this purpose in Australia in March 1999. Fumigation requirements are an exposure time of 15 h with an initial PH3 concentration of 1 g m-3 and a minimum temperature of 15&186;C. Further work is in progress on produce with much longer shelf life than flowers and for which longer exposure times of up to 48 h have been used. The potential for use of ECO2FUME for disinfestation of oranges infested with larvae of the Queensland fruit fly Bactrocera tryoni, has been demonstrated. It has been shown to be effective in controlling eggs, larvae and pupae of the lightbrown apple moth Epiphyas postvittana, on pears, and larvae of the codling moth Cydia pomonella, in apples without injuring the produce.
R. CAVASIN, B. MCSWIGAN, R. RYAN AND D. GOCK
ABSTRACT
The use of this cylinder source of phosphine (PH3) fumigant has gained government approvals and industry acceptance as the fumigant of choice for a variety of applications around the world. ECO2FUMEÒ has many advantages over traditional PH3 fumigation, including ease of application, precise PH3 concentration control, and reduced risk use. In addition, ECO2FUME is non-flammable, generates no waste, and is environmentally friendly. This paper provides an up-to-date review of the existing and pending country approvals, and the global activities on progress to expand the use of this important source of PH3 fumigant gas. Among the many activities that are reviewed are the SIROFLOÒ and SIROCIRCÒ techniques developed in Australia, the experimental fumigation of empty ship holds in Canada, and on-site blending of PH3 in carbon dioxide techniques used in Australia and China.
B. BRIDGEMAN, R. RYAN, D. GOCK AND P. COLLINS
ABSTRACT
Methyl bromide (MB) is relied on to maintain insect free grain exports from Queensland Australia. The eminent demise of this fumigant has been the catalyst for the trials conducted at the Globex International Gladstone Port Terminal using high doses of phosphine (PH3) at 1 mg/L, 2 mg/L and 3 mg/L. The trials compared on-site mixing of ECO2FUME and Phosphine/air mix to existing conventional technologies. Modifications to the existing MB fumigation system were minimal and although procedures to carry out this work had to be compiled during the trials, the fumigations were successful. The efficacies of the trial fumigations were assessed using bioassays of mixed age cultures of several species of target insects with typical levels of PH3 resistance.
Results indicated that at 25-27&186;C, fumigation with PH3 at 750 ppm for 5 d was successful in controlling all stages of target pests tested. The mobile stages were totally controlled within 3 d, while control of eggs and pupae required a further 1.5 to 2 d. The trials indicated that although the fumigation time could not be reduced to below 5 d, at 25&186;C, the cost of fumigant was substantially reduced when compared to MB. The cost of using liquefied forms of PH3 compared well to all other formulations and the fumigation duration could be reduced by 2 days without compromising efficacy. The other significant advantages of the systems under trial, were that complete dosing and distribution of the fumigant into the bin took 60 - 80 min and clearance of the fumigant to below detectable levels was reduced to less than 6 h. The systems using liquefied PH3 do not require disposal of spent residues.
Grainco Australia has begun implementation of a high dose PH3 capability at all Globex Ports and further research and development of PH3/air mixing is a priority.
C. H. BELL, B. B. HARRAL, S. T. CONYERS AND B. E. LLEWELLIN
ABSTRACT
In silo bins modified atmospheres can easily be applied via the aeration system in the bin floor, but dosing of floor-stored bulks is less straight forward. All treatments rely on sheeting to achieve a high level of seal. A propane burner is a suitable atmosphere source provided that the exhaust gas can be cooled before entry into the grain.
In maintaining the atmosphere under a continuously running gas input from such a generator, care needs to be taken to avoid internal circulation of pockets of high oxygen levels, which can persist for long periods even in the absence of adverse weather conditions. Experiments on the distribution and location of gas input points, variation of gas input flow rates, and manipulation of the degree of sealing achieved at different locations round the periphery of the bulk, are described as part of a back to back study between mathematical modelling and practical gas application and monitoring in a floor store.
The maintenance flow rate for a box-shaped bulk was similar to that of a silo bin of similar capacity, calculated as 4.965 + (0.0110 x tonne weight of bulk) m3/h. Maintenance flow rates for sloping bulks were higher. When the distribution of leak sources was biased towards one end of the store, the replacement atmosphere was best introduced at the opposite end. This advantage was reduced when the sites of leakage were more generally distributed.