WO2001026475A1

WO2001026475A1 - Bulk disinfestation of commodities

Info

Publication number: WO2001026475A1
Application number: PCT/US2000/041100
Authority: WO
Inventors: Ted Lafleur
Original assignee: Mars Incorporated
Priority date: 1999-10-13
Filing date: 2000-10-10
Publication date: 2001-04-19
Also published as: AU1819101A

Abstract

A method of bulk disinfestation of commodities that includes the steps of placing bulk amounts of packaged commodities in a refrigerated container, reducing the temperature of the container to an equilibrium temperature of at least below 10 °F; and subjecting the packaged commodities to the reduced temperature in the container for a predetermined time suitable for killing the insects present in the packaged commodities. Alternatively, bulk disinfestation can occur by placing the bulk commodity in a blast freezer having a temperature of at least between -20 to -40 °F and subjecting the bulk commodities to the reduced temperature for about 48 to 72 hours in order to reduce the internal temperature of the commodity to between about -5 to 5 °F.

Description

BULK DISINFESTATION OF COMMODITIES

Field of the Invention

The present invention relates to a method for the bulk disinfestation of commodities and more particularly to a freezing process for the disinfestation of bulk amounts of commodities. Background of the Invention

The potential infestation of packaged foods by insects is a major concern to both merchants and consumers. Over the years, a number of methods have been used for the disinfestation of packaged foods. These methods have included the use of toxic fumigants such as hydrogen cyanide, methanol bromide and hydrogen phosphide. Usage of these and other fumigants over the years became increasingly restricted because of regulatory agencies concern with worker exposure to pesticides, pesticide residue in the agricultural products, fumigant flammability, and contamination of air and water. As a result of these concerns and other regulatory actions, hydrogen phosphide became the fumigant of choice for disinfestation of stored agricultural commodities and products. Even though hydrogen phosphide fumigants are considered relatively safe to use, they are classified for restricted use and therefore they must be applied only under the supervision of certified licensed applicators.

An alternative to toxic fumigants for the disinfestation of agricultural commodities and products is the asphyxiation of insects by means of low oxygen environments. However, this method is considered impractical as a modern means of insect control for agricultural products. Another method considered effective and practical for the control of stored product insects is the use of modified atmospheres. A modified atmosphere occurs when the existing atmosphere within the storage container is purged and replaced with carbon dioxide, nitrogen or combustion gases. Carbon dioxide has been shown to be a particularly effective disinfestant for the control of stored product insects. U.S. Patent No. 5,167,243 describes a method of treatment by carbon dioxide that is accomplished by placing the products in a closed container that is equipped with an exhaust port and a port for administering the carbon dioxide. The time required for complete disinfestation of a container varies from a few days to approximately two weeks in which the rate of insect kill is directly proportional to both the carbon dioxide concentration and temperature. However, because of its potential human and environmental hazards, restrictions are increasingly being placed on the use of both chemical and gas pesticides.

Alternately, the use of extreme temperatures under controlled conditions have also been found to be useful for the eradication of stored product pests. A method of thermal sterilization is described in U.S. Patent No. 3,986,832. There have been many studies that tested the effectiveness of temperatures greater than 95° F and temperatures lower than 55° F on various species of stored food insects (Fields, 1992; Wetters, 1991). Most studies show that as temperature decreases, the rate and percentage of kill for target insects increases. Fields found that insects that have been acclimated to temperatures between 50 to 68° F require lower temperatures and more time to kill than unacclimated insects. Insects develop greater tolerance to cold temperatures as the time of acclimation and rate of temperature decline increases. Lethal temperatures begin at 32° F to acclimated insects and temperatures below 5° F will kill insects in minutes due to the mechanical injury caused by the forming of ice crystals in cellular tissues (Fields, 1992) or by dehydration (Mullen, M.A. and Arbogast, R. T., 1984).

It has been reported that Indianmeal moth (Plodia interpuntella) eggs are killed by a four hour exposure to 2.0° F (Alder, V.E., 1960). It has also been reported that eggs of the Saw-tooth grain beetle (Oryzaephilus surinamensis) and the Red flower beetle (Tribolium castaneum) are killed with a nine hour exposure to 14° F, but the Cigarette beetle (Sioderma serricome) eggs require 62 hours (Mullen, M.A. and Arbogast, R. T., 1979). It has also been found that all stages of the Saw-tooth grain beetle are killed within a 24 hour exposure to temperatures below 5° F (Arbogast, R.T., 1991). Mullen and Arbogast (1979) have determined that the chill time required for elbow macaroni (13.3 lb/ft³ bulk density at room temperature) in a small freezer was about 20 hours to reach 30° F and about 100 hours to reach a target temperature of - 4° F. Under the same conditions, flour ( 25.9 lb/ft³ bulk density), required 25 hours to reach 32° F and 145 hours to reach - 4° F. The Mullen and Arbogast data does point out the differences in time required to cool commodities with greater bulk densities since the flour has approximately twice the bulk density of elbow macaroni and requires an almost 50% increase in time to reach target temperatures. However, due to a variety to factors, the data from this small scale experiment cannot be extrapolated to similar products in substantially larger volumes. Presently, no research has been done on the effect of freezing large volumes of bulk pre-processed or packaged commodities for the killing of stored product insects.

Therefore, the need to eliminate the use of chemicals and gases for disinfestation has created a need for a simple, safe and effective means of disinfesting stored food product. Additionally, the increased use of organic products has created a need for alternative methods as conventional pesticides are not permitted.

It would be desirable to provide a method for the disinfestation of bulk amounts and/or large quantities of packaged agricultural commodities. It would additionally be desirable to provide a method for the remedial disinfestation of large amounts of individual consumer-ready containers. It would also be desirable to provide a method for the disinfestation of organic products that does not require the use of chemicals or gases. It would further be desirable to provide a method of disinfesting bulk amounts of packaged commodities in a mobile storage container. Summary of the Invention The present invention is directed to a method for the bulk disinfestation of commodities. The method consists of placing bulk amounts of packaged commodities in a refrigerated container and reducing the temperature of the container to an equilibrium temperature of at least below 10° F. The packaged commodities are subject to the reduced temperature in the container for a predetermined time suitable for killing the insects present in the packaged commodities. The temperature of the packaged commodities is reduced to an equilibrium temperature of at least below 10° F for a predetermined time, such as about 96 to 288 hours, for effectively killing the insects present in the packaged commodities. Alternatively, bulk disinfestation can occur by placing the bulk commodity in a blast freezer having a temperature of at least between -20 to - 40° F., and subjecting the bulk commodities to the reduced temperature for about 48 to 72 hours in order to reduce the internal temperature of the commodity to below 5° F. Brief Description of the Drawings A better understanding of the invention can be obtained when the detailed description of exemplary embodiments set forth below is reviewed in conjunction with the accompanying drawings, in which:

Figure 1 is a side plan view of a typical truck trailer; Figure 2 is a rear plan view of the truck trailer of Fig. 1; and Figure 3 is graph illustrating the changes in temperature over time and points at which insect vials were retrieved. Detailed Description of the Preferred Embodiment

The present invention is directed to the freezing of bulk and packaged commodities in order to accomplished the disinfestation and control of stored food insects. The application of this method can be used for bulk amounts of pre- processed commodities as they are received by a food processor. The present invention is also directed to a method for the remedial disinfestation of large or bulk amounts of individual consumer-ready packages that have been stored or warehoused for an extended period of time. The amount of individual consumer-ready packages considered to be a large or bulk amount, for example, would be an amount such as six thousand cases of a consumer packaged commodity.

When the pre-processed bulk commodities arrive at the food processor, they are placed in a commercial blast freezer set a temperature of generally about - 20 to - 40 ° F. The bulk commodities are retained in the blast freezer for at least about 48 to 72 hours in order to bring the internal temperature of the bulk commodities down to generally between -5 to 5 ° F.

When individual consumer-ready packages require remedial disinfestation, the bulk amount of packaged commodity is placed in a refrigerated container or storage area for a predetermined time suitable for killing insects present in the packaged commodities. A refrigerated trailer truck can be used as the container in which the bulk amounts of packaged commodities are treated.

Commodities, as the term is known to one skilled in the art, includes goods such as grain, flour, meal, rice, beans, spices, cereal, pasta, dehydrated food mixes, animal feed, pet food kibbles and other similar type products. Bulk commodities can included pre-processed bulk containers such as paper bags holding 25-100 pounds of product and woven bags holding up to 2000 pounds of product. Packaged commodities can include such items as individual consumer-ready packaged food products in which the commodities are packaged in individual containers for both human and animal consumption. Packaged commodities can also include bulk packaged food products in which the commodities are in containers such as 50 to 100 pound sacks for both human and animal consumption. The commodities can also be organic or non-organic as is known to those skilled in the art.

It has been found that a 100% mortality for all stages of insects can be achieved after subjecting pre-processed bulk commodities to a temperature of generally between about - 20 to - 40° F for a predetermined time of about between 48 to 72 hours. The pre-processed bulk commodities, upon arrival at the food processor, are placed in a commercial blast freezer set a predetermined temperature of preferably about - 30° F. The bulk commodities are retained in the blast freezer for generally between about 48 to 72 hours in order to bring the internal temperature of the bulk commodities down to below 5° F, and preferably between -5 to 5° F. After the blast freezing cycle is complete, the bulk commodities can then be moved to a main freezer storage area, having a temperature of generally between - 2 to - 6° F., and kept there until the commodity is needed for processing into a packaged food item. Prior to processing, the commodity needs to re-tempered in a chilled storage area, having a temperature of generally about 30 to 50° F and preferably about 40° F., for a period of time, generally about two weeks, in order to ensure that the commodity is fully defrosted before processing and shipping. The re-tempering will prevent condensation from forming in the packaged product.

It has also been found that a 100% morality for all stages of insects can be achieved after subjecting bulk or packaged commodities to cooling/freezing in a refrigerated container for generally about 96 to 288 hours (4 to 12 days). After about 144 hours of cooling/freezing, a bulk volume of packaged commodity can reach a temperature of 5 to 8° F. A 100% morality for all stages of insects can be achieved with 24 hours exposure at a target temperature of 5 to 8° F. Preferably, cold stored commodities should be warned up to 70° F before freezing, in order to increase susceptibility of the insects to the process. However, due to the variation in commodity packaging, bulk density, possible diapause or acclimation of stored food insects, and capabilities of the refrigeration unit, it is possible that the minimum exposure time to guarantee 100% kill could be as high as 216 hours (9 days).

The method of achieving the bulk disinfestation of commodities includes placing bulk or packaged commodities in a refrigerated container, reducing the temperature of the container to an equilibrium temperature of at least below 10° F and subjecting the commodities in the container to the equilibrium temperature for a predetermined time suitable for killing the insects present in the commodities. Preferably the temperature of the bulk or packaged commodity is reduced to an equilibrium temperature of at least below 10° F for a predetermined time suitable for killing the insects present in the bulk or packaged commodities. The predetermined times suitable for killing the insects present in the commodities, depending upon the above discussed variables, is generally from about 96 to 288 hours. Preferably 100% kill is achieved by subjecting the packaged commodities to cooling/freezing in the refrigerated container from about 144 to 216 hours. This above described method is applicable for both the disinfestation of pre-processed bulk commodities and the remedial disinfestation of packaged commodities.

Any refrigerated container of an appropriately large dimension and having a temperature range of generally about between - 20° F to 50° F can be used. A large refrigeration/freezer container of approximately about 2,600 cubic feet can be used to hold the packaged commodity or preferably the refrigerated container is a refrigerated truck trailer, as is know to one skilled in the art, that has a maximum temperature settings of about - 20° F to 80° F and a storage capacity of generally about 2,680 cubic feet. Example

In one example of the invention, the method of disinfestation was carried out in a Thermo-King truck trailer 10 that had a four cylinder diesel refrigeration unit 12 attached, as shown in Figs. 1 and 2. The maximum temperature settings for this refrigerated truck trailer 10 was about - 20° F to 80° F. The trailer 10 dimensions were 48 ft by 8 ft by 7 ft, equaling approximately 2,688 cubic feet of volume. No special sealing was performed on the trailer 10.

Forty eight pallets 14 were stacked two high in two rows of 12 pallets each within the interior of the trailer 10. All pallets were shrink wrapped, except for sample boxes that were to be retrieved. Cold air was dispersed throughout the trailer 10 via a vinyl conduit on the roof that allowed air to blow out the sides and end of the trailer 10 for about 40 ft of the interior length. The trailer 10 was filled with approximately 6,900 cases of a commodity, in which the cases contained boxes of a powdered soup product. Each individual box contained loose filled grains and single packets of seasoning. The bulk density of the soup mix was about 11.5 lb/ft³ and the cases weighed approximately 30,750 lbs.

The cooling period was divided into 5 three-day periods. For each period a complete set of bioassay vials (containing selected insects) were inserted into a case of product. Within each test case of product, five boxes were selected into which vials of a single species of food pests were inserted. Three life stages of each insect were used and for every stage, except eggs, 10 each of adults, larvae and pupae were put into separate plastic vials with a sufficient quantity of freshly prepared food medium for at least a 15 day survival period. For the egg vials, a large number of adults were allowed to lay eggs onto freshly prepared food medium for two days. This egg medium was then put into the plastic vials. All of the vials were appropriately labeled. A single complete set of vial replicates was made as a control. The control set was monitored for mortality for the entire 15 days and the controls were maintained for the entire test duration in a growth chamber at 28° C, 60% relative humidity (RH), with 17 hours daylight and 7 hours darkness. Thermometers, numbered 1-6, were placed inside the trailer 10 in order to monitor temperature throughout the test. Thermometer #1 was placed inside the door, #2 inside the center of the cases, #3 between the boxes, #4 in the air at low center, #5 in the air at the top of one corner and #6 in the air at the top of the opposite corner, as shown in Figs. 1 and 2. The thermometers were used to display air temperatures and internal temperatures of the product within the cases. The cases of product were received with an internal temperature of 56° F and were allowed to warm up to a start temperature of 75° F in the trailer. The bioassay vials were prepared three days prior to the beginning of the cool down period and were acclimated to 70° F before being placed in the trailer. After the product reached 70 to 75° F, the trailer was reset to - 20° F to begin the freezing process. Temperatures were recorded frequently for the first eight hours to get an accurate rate of decline in temperatures and to determine that the refrigeration unit on the trailer was working properly. Data was collected thereafter three to six times daily.

As illustrated in Fig. 3, the commodity began freezing at 50 hours, indicated as A on the graph of Fig. 3. The vials were retrieved at 72 hours (B), 144 hours (C), 216 hours (D) and at 288 hours (E). The vials were allowed to warm to room temperature for four hours before removing and observing the insects. All insects were counted and observed for activity or life in petri dishes. The egg bioassays were put into petri dishes and incubated at 85° F, 60% R.H. and 17 hours daylight and 7 hours darkness, for a minimum of 14 days to determine viability. The vials were observed 24 and 48 hours later to determine if delayed recovery or development of the eggs had occurred.

The rate of decrease in temperature in the air space was much faster than the decrease of temperature between the boxes and within the cases of product, as shown in Fig. 3. Air space reached freezing temperatures of 32° F at about 10 hours while the product began freezing at about 50 hours. Air temperatures reached a temperature of 0° F at about 73 hours, while the lowest temperature achieved in the product was 3° F at the rear doors of the trailer and 5° F in the center of the trailer. This occurred at about 192 hours from the start of the freezing process. The product was at or below 5° F for the four days between 192 hours (day eight) and 288 hours (day 12). A separate temperature reading at the conclusion of the test showed that at the center of the trailer there was no difference between the temperatures recorded in the first tier of pallets on the outside row and the third tier of pallets in the center of the stacked pallets.

Table 1 includes data regarding the percent mortality observed in the sample vials over the 12 days of the example. The data showed a 100% mortality for all stages of Saw-tooth grain beetle and Confused flower beetle after retrieval from the trailer at 72 hours. This result was obtained after 22 hours of freezing and a low temperature of about 17.5° F. Some movement and delayed development occurred with the Indianmeal moth larvae, the Red flour beetle larvae, and the Cigarette beetle larvae. All other stages of insects showed no movement or development. Data from day 6, 9 and 12 showed 100% mortality in all insect stages and no development from egg hatch occurred 14 days after incubation. Table 2 includes data regarding the percent mortality observed in the control sample vials over the 12 days of the example. As seen in Table 2, there was some mortality for the control insects which is expected due to the random selection of individual insects and from handling. Data in Table 1 was adjusted using Abbott's formula to take in account mortality in the control. Table 1 - Percent mortality observed in test samples over 12 days

Percent Mortality¹

Indianmeal Moth

Time (hrs) 72 144 216 288 n= 10 n=10 n= 10 n = 20

Adults 100 n/a n/a n/a Larvae 83 100 100 100 Pupae Eggs x 2 100 100 100 100

Saw-toothed Grain Beetle

Time (hrs) 72 144 216 288 n= 10 n= 10 n= 10 n = 20

Adults 100 100 100 100

Larvae 100 100 100 100

Pupae - - - -

Eggs No hatch No hatch

Confused Flour Beetle

Time (hrs) 72 144 216 288 n= 10 n= 10 n= 10 n = 20

Adults 100 100 100 100

Larvae 100 100 100 100

Pupae - - - -

Eggs x 2 No hatch No hatch

Red Flour Beetle

Time (hrs) 72 144 216 288 n=10 n=10 n= 10 n = 20

Adults 100 100 100 100

Larvae 2 x 90 100 100 100

Pupae 100 100 100 100

Eggs No hatch No hatch Cigarette Beetle

Time (hrs) 72 144 216 288 n = 10 n = 10 n = 10 n = 20

Adults 100 100 100 100

Larvae 67 100 100 100

Pupae 100 n/a n/a n/a

Eggs No hatch No hatch

¹ Adjusted for mortality on control n/a - data is omitted due to 100% mortality on control

Table 2 - Percent mortality observed in control samples over 12 days Percent Mortality on Control¹

Indianmeal Moth Time (hrs) 72 144 216 288 n = 10

Adults 90 100 100 100

Larvae 40 40 40 40

Pupae - - - -

Eggs x 2 75 75 75 75

Saw-toothed Grain Beetle

Time (hrs) 72 144 216 288 n = 10

Adults 10 10 10 10

Larvae 20 40 40 40

Pupae

Eggs confirmed egg hatch

Confused Flour Beetle

Time (hrs) 72 144 216 288 n = 10

Adults 0 0 0 0

Larvae 0 0 0 0

Pupae - - - -

Eggs confirmed egg hatch

Red Flour Beetle

Time (hrs) 72 144 216 288 n = 10

Adults 0 0 0 0

Larvae x 2 0 0 0 0

Pupae 0 0 0 0

Eggs confiπr ted egg hatch

Cigarette Beetle

Time (hrs) 72 144 216 288 n = 10

Adults 10 50 50 50

Larvae 10 20 20 20

Pupae 30 100 100 100

Eggs confirmed egg hatch

Some mortality is expected due to random selection and handling

Thus, as described above, the present invention provides a method for the disinfestation of bulk amounts and/or large quantities of packaged agricultural commodities. The present invention also provides a method for the disinfestation of organic products that does not require the use of chemicals or gases. The present invention further provides a method for the disinfesting of bulk amounts of packaged commodities in a mobile storage container. One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The inventive method for the bulk disinfestation of packaged commodities described herein are presently representative of the preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the claims.

REFERENCES Alder, V.E.; Effects of low temperature on the eggs of the Angoumois grain moth, the Indianmeal moth and Confused flower beetle; Journal of Economic Entomology; 53:5, pg. 973-74, 1960.

Arbogast, R.T.; Beetles: Coleoptera; Ecology and Management of Food Industry Pests, FDA Technical Bulletin 4, pg. 131-176, 1991.

Fields, Paul; Journal of Stored Product Research; Vol.28:2, pages 89-118, 1992.

Mullen, M.A. and Arbogast, R. T.; Low temperature to control stored food product insects; Insect Management for Food Storage and Processing; American Association of Cereal Chemists; pg. 257-263, 1984.

Mullen, M.A. and Arbogast, R. T.; Time temperature mortality relationships for various stored product insect eggs; Journal of Economic Entomology 72: pg.476- 478, 1979.

Watters, F. L.; Physical methods to manage stored-food pests; Ecology and Management of Food Industry Pests, FDA Technical Bulletin 4, pg. 399-431, 1991.

Claims

CLAIMS What is claimed is: 1. A method of bulk disinfestation of commodities comprising the steps of: a) placing bulk amounts of commodities in a refrigerated container; b) reducing the temperature of the container to an equilibrium temperature of at least below 10° F; and c) subjecting the commodities to the reduced temperature in the container for a predetermined time suitable for killing the insects present in the packaged commodities.

2. The method of claim 1, further including the step of reducing the temperature of the product to an equilibrium temperature of at least below 10° F for a predetermined time suitable for killing the insects present in the bulk amount of commodities.

3. The method of claim 1 , wherein the predetermined time suitable for killing the insects present in the bulk amount of commodities is about 96 to 288 hours.

4. The method of claim 3, wherein the predetermined time suitable for killing the insects present in the bulk amount of commodities is about 144 to 216 hours.

5. The method of claim 1, wherein the infestation is caused by the presence of insects selected from the group comprising Indianmeal moth, Saw- toothed grain beetle, Red flour beetle, Confused flour beetle and Cigarette beetle.

6. The method of claim 1, wherein the bulk amount of commodities include commodities selected from a group comprising pre-processed commodities, individual consumer-ready food products for human consumption, consumer- packaged food products for animal consumption, bulk-packaged food products for human consumption and bulk-packaged food products for animal consumption.

7. The method of claim 1 , wherein the refrigerated container includes a transportable container.

8. The method of claim 6, wherein the refrigerated transportable container further includes a refrigerated truck trailer having maximum temperature settings of about -20°F to 80°F and a storage capacity of generally about 2680 ft³.

9. The method of claim 1 , wherein the commodities are selected from a group comprising grain, flour, meal, rice, beans, spices, cereals, pasta, dehydrated food mixes, animal feed, pet food kibbles, and combinations thereof.

10. The method of claim 8, wherein the commodities further include organic or non-organic commodities.

11. A method of bulk disinfestation of bulk commodities comprising the steps of: a) placing bulk amounts of commodities in a blast freezer having a temperature of generally between about - 20 to - 40° F; and b) subjecting the bulk amounts of commodities to the temperature of generally about - 20 to - 40° F for a predetermined time required to reduce the internal temperature of the commodities between about -5 to 5° F.

12. The method of claim 11 , wherein the predetermined time required to reduce the internal temperature of the commodities to between about - 5 to 5 ° F is about 48 to 72 hours.

13. The method of claim 11, wherein the bulk amount of commodities include commodities selected from a group comprising pre-processed commodities, individual consumer-ready food products for human consumption, consumer- packaged food products for animal consumption, bulk-packaged food products for human consumption and bulk-packaged food products for animal consumption.

14. The method of claim 11, wherein the commodities are selected from a group comprising grain, flour, meal, rice, beans, spices, cereals, pasta, dehydrated food mixes, animal feed, pet food kibbles, and combinations thereof.

15. The method of claim 14, wherein the commodities further include organic or non-organic commodities.