GB2402865A

GB2402865A - De-infestation of agricultural produce

Info

Publication number: GB2402865A
Application number: GB0313968A
Authority: GB
Inventors: Clive Edward Jewers; Matthew James Jewers
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-06-16
Filing date: 2003-06-16
Publication date: 2004-12-22
Anticipated expiration: 2023-06-16
Also published as: GB2402865B; GB0313968D0

Abstract

De-infestation of an agricultural food material comprises: a treatment chamber b through which a controlled flow of the food material to be deinfested passes; a heat supply 22 to maintain the temperature of the atmosphere in the treatment chamber to within a predetermined temperature range, wherein the duration of time for which the food material in the flow is exposed in the treatment chamber to the atmosphere therein is controlled to be within a predetermined time range, wherein the predetermined and controlled temperature and time periods are selected to de-infest the food product and to preserve the essential properties of the food product. The atmosphere is preferably air at a a temperature of 80 - 300{C, and the time period is preferably 6-15 seconds.

Description

DE-INFESTATION METHOD AND APPARATUS s

This invention relates to a method and apparatus for cleaning cereals, oilseeds, legumes and grasses and more particularly, to a method and apparatus for de- infesting cereals, oilseeds, legumes and grasses.

lo It is well recognised that cereals, oilseeds, legumes and grasses need to be cleaned and treated before storage. Conventionally, organophosphates have been used to de-infest insects from food products such as grain, but throughout many countries in the world, the use of organophosphates is being discontinued.

An outright ban of organophosphates for this purpose is expected shortly.

In Europe, the greatest infestation problem faced is presented by insects which live on the surface of the cereal. In more temperate and tropical climates, the greatest problem is from boring insects which occupy the core of stored cereals, thereby damaging the cereal and limiting its use to animal feed. Clearly, so damaged cereals cannot be used for human food consumption. Accordingly, downgrading the use of the cereal means providing a less valuable product - a direct result of infestation.

Another approach using chemicals for de-infestation purposes uses phosphene as gas but its use is not always practical and presents the user with handling difficulties, storage problems and the like.

Presented with the particular problem of de-infesting grain from boring insects that occupy the core of the grain, research has been undertaken which offers a non-chemical alternative to the fumigation process mentioned above. The research concentrates on solving this difficult problem using heat over a long time period, of many hours, which although de-infesting the grain satisfactorily, leaves the grain damaged and limits its use to animal feed. Such treatment may s also damage the grain's germination properties meaning such treated gain cannot be used as seed. It should also be noted that the fumes from the heating process come into contact with the grain which is undesirable.

High temperature de-infestation techniques have been proposed in grain stores lo where the grain is stored for periods of days to months, exposing insects at more than 63 C for one minute or 50 C for a few hours to control completely infestation. However, such long time periods where the product remains static cannot be tolerated where grain is to be deinfested prior to storage or other processing. As previously mentioned, higher temperatures, whilst de-infesting the grain, cause the grain to lose its essential properties by effectively cooking the grain through to its core and are therefore to be avoided.

In many cases, it is desirable to avoid use of contact insecticides or fumigation.

It is an object of the present invention to seek to provide an apparatus and method for de-infesting cereals, oilseeds, legumes and grasses which does not rely upon contact insecticides or fumigation and which does not damage the cereals, oilseeds, legumes and grasses but which can be readily and simply implemented. 2s

Accordingly, one aspect of the present invention provides a deinfestation apparatus for Reinfesting an agricultural food material comprising: a treatment chamber through which a controlled flow of the food material to be deinfested passes; a heat supply to maintain the temperature of the atmosphere in the treatment chamber to within a predetermined temperature range, wherein the duration of time for which the food material in the flow is exposed in the treatment chamber to the atmosphere therein is controlled to be within a predetermined time range. s

Another aspect of the present invention provides a method of Reinfesting an agricultural food material comprising: passing a controlled flow of the food material through a treatment chamber; heating the atmosphere in the treatment chamber to within a predetermined temperature range; exposing the food lo material in the treatment chamber to the atmosphere therein for a time duration within a predetermined time range, the exposure de-infesting the food material and preserving the essential properties of the food material.

In order that the present invention may be more readily understood, Is embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-section through an apparatus embodying the present invention; and Figure 2 is a schematic block diagram of an apparatus embodying the present invention.

The invention is described below with particular reference to grain de- as infestation but the principles and parameters of operation hold true for other agricultural foodstuffs such as cereals (wheat, barley, oats, triticale, maize and sorghum), oilseeds (oilseed rape, linseed, soya and sunflower), legumes (peas and beans) and grasses.

Referring to Figure 1, an apparatus 1 embodying the present invention for de- infesting grain comprises a grain handler 2 and a heat treatment unit 3.

s Turning firstly to the grain handler 2, this comprises a conventional hopper 4 into which is received a supply of infested material such as grain, cereals, oil seeds, pulses or other food materials.

The hopper 4 feeds vertically downwardly into a geared paddle 5 which lo controls the volume flow of food material to a treatment zone comprising a chamber 6 with a series of cascading baffles 7,8 projecting from alternate side walls of the chamber. The chamber 6 terminates in an elongate outlet 9 which drops the treated food material into a screw action worm conveyor 10.

Between the elongate outlet 9 and the conveyor 10, the outlet 9 opens out into a settling chamber 11 from which airborne particles are evacuated through an exhaust outlet 12 to a disposal furnace 13 - see Figure 2.

The treatment zone and more particularly the chamber 6 has permeable side walls 14, 15 preferably in the form of a wire mesh which allow an airflow to JO pass through one side wall 15 of the chamber 6, through the chamber 6, and out the opposite side wall 14 of the chamber, effectively transverse of the chamber.

The transverse airflow is substantially normal to the flow of food material through the chamber 6 along and down the baffles 7,8.

:5 The heat treatment unit 3 comprises a heat exchanger consisting of a metal chamber 20 having an inlet 21 and an outlet 22. The chamber 20 is heated from below through the wall of the chamber 20 by thermostatically controlled burners 23, the fumes from which are exhausted away from the chamber 20 and do not, at any time, enter the chamber 20. The inlet to the chamber 20 is provided with a constant volume flow fan 24 which drives a supply of air into the chamber 20 which is being heated by the burners 23. The air is heated as it passes through the chamber 20 to a temperature at the outlet 22 of the chamber in the region of 80 C to 300 C and more preferably, 150 C to 200 C. The outlet 22 feeds directly into the grain treatment chamber 6 passing through the mesh side wall 15 of that chamber.

Referring now to Figure 2, the airflow through the apparatus is shown schematically being driven by the constant volume flow fan 24 through the heat lo exchanger 20, through the treatment zone 6 and out from the treatment zone to a filter 30 and then routed back around to the inlet 21 to the chamber 20 via a return pipe 31 in a substantially closed circuit. The fumes from the burners 23 are exhausted away from the heat exchanger 20 and do not enter the closed circuit.

The exhaust 12 from the grain handler 2 is preferably fed to a disposal furnace 32. It is envisaged, as shown in Figure 2, that the disposal furnace and the burners 23 for the heated exchanger may be one and the same. Of course, the disposal furnace 32 can be configured as a spearate element to the burners 23.

so Again, it should be stressed that the fumes and bi-products generated by the burners 23 are not exhausted into the chamber 20. The chamber 20 holds only heated air and, although that heated air may carry contaminants after passing through the treatment zone 6, any such contaminants are filtered out by the filter 30 immediately downstream of the treatment zone 6 so that the air being Is returned to the chamber 20 is clean air and does not carry any significant particulate matter. The use of the substantially closed circuit minimises the energy requirements for heating the air in the chamber 20.

In operation, the temperature of the air exiting the chamber 20 into the treatment zone 6 is maintained preferably between 150 C to 200 C. The temperature can be increased to as high as 300 C or as low as 80 C but the period of time for which the grain is exposed to these high temperatures must s also be carefully controlled. Accordingly, the drop time which it takes a single grain to pass down through the treatment zone 6 is controlled by determining the length of the path through the treatment zone 6 along the staggered baffles 7,8. Preferably, the length of the path is such that grain would take between 6 to 15 seconds but more preferably, 7 to 12 seconds, to pass along and down the lo baffles 7,8 through the treatment zone, in which zone the grain is exposed to the airflow from the chamber 20.

Particular examples for wheat and barley (cereals) are now given.

Example 1: Maintaining the temperature in the treatment zone 6 at 300 C and Is subjecting grain to that temperature for a duration of 7 seconds, does not damage the grain nor does there appear to be any significant effect on the subsequent possibility of that grain germinating - i.e. the grain properties are maintained.

Example 2: Maintaining the temperature in the treatment zone at 150 C and So subjecting grain to that temperature for a duration of 10 seconds, does not damage the grain nor does there appear to be any significant effect on the subsequent possibility of that grain germinating - i.e. the grain properties are maintained.

as Exposure to these high temperatures (80 C to 300 C) for a short time period (6 to 15 seconds) is comfortably adequate to kill the insects infesting the grain thereby ensuring that insects, their larvae and eggs are destroyed safely without damaging the essential so-called "grain" properties of the product such as germination, glue, oil, starch, protein and hagburg. At the same time, the previously harmful admixture of insects and their produce are removed in a vacuumed air flow via exhaust 12 to be incinerated. Similar controlled temperatures and time periods apply to the other foodstuffs listed: cereals, oilseeds, legumes and grasses.

The clean, treated, food material is conveyed away by the worm conveyor 10 to be cooled.

Thermostatic control of the temperature in the treatment zone 6 is effected lo within a 5 C range by switching the burners 23 on and off under control of a thermostat located in the treatment zone 6.

It should be noted that the careful selection of controlled heat (80 C to 300 C) for a short time period (6 to 15 seconds) means that the food product is externally heated but the inner core is certainly not heated to the same extent, thereby preserving the essential properties of the food product.

In preferred embodiments of the invention, the baffles 7,8 may also be perforated to encourage airflow therethrough. To increase or decrease the time for which a particular piece of grain is exposed to the controlled temperature, the number of baffles and their orientation can be varied. Thus, to decrease the drop time, baffles can be removed or to increase the drop time more baffles can be added, interleaving with existing baffles. Further, the slope angle of individual baffles 7,8 can be increased to decrease the drop time and vice versa.

The action of the grain descending down and along the baffles 7,8 through the treatment zone 6, disturbs the skin of the grain so that impurities are knocked from the grain and made airborne, akin to the step of winnowing grain, and preferably carried away by the heated air through the perforated chamber walls.

Other particles which follow the path down the chamber 6 are light enough when falling into the settling chamber 11 to be airborne and vacuumed away through the exhaust outlet 12 whilst the grain, being that much heavier than the airborne particles, falls to the conveyor 10 for subsequent storage or other treatment steps.

It should be noted that even if any impurities remain attached to the grain, these impurities will have been de-infested by their exposure to the short time period heat burst in the treatment zone so as to be rendered inert and not a cause of lo subsequent infestation in the stored product.

It should be appreciated that there is a safe temperature range for any given food material and a time range for which the given food material should be exposed to the safe temperature.

In the present specification "comprises" means "includes or consists of" and "comprising" means "including or consisting of".

The features disclosed in the foregoing description, or the following claims, or so the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any I combination of such features, be utilised for realising the invention in diverse forms thereof. I

Claims

CLAIMS: 1. A de-infestation apparatus for Reinfesting an agricultural food

material comprising: a treatment chamber through which a controlled flow of the food material to be Reinfested passes; a heat supply to maintain the temperature of the atmosphere in the treatment chamber to within a predetermined temperature range, wherein the duration of time for which the food material in the flow is exposed in the treatment lo chamber to the atmosphere therein is controlled to be within a predetermined time range.
2. An apparatus according to Claim 1, wherein the treatment chamber comprises a vertically oriented chamber having a top and a bottom, a food Is material inlet being provided at the top and a food material outlet being provided at the bottom.
3. An apparatus according to Claim 2, wherein one or more baffles are interposed between the inlet and the outlet to increase the path length between so the inlet and the outlet taken by the flow of food material.
4. An apparatus according to any preceding claim, wherein one or more I burners heat a flow of gas directed through the treatment chamber.
5. An apparatus according to Claim 4, wherein the treatment chamber has one or more sidewalls configured to allow the passage of gas therethrough.
6. An apparatus according to any one of Claims 1 to 3, wherein the atmosphere in the treatment chamber is radiantly heated by one or more burners.
7. An apparatus according to any one of Claims 4 to 6, wherein the combustion products of the one or more burners are not exhausted through the treatment chamber.
8 An apparatus according to any preceding claim, wherein the lo predetermined and controlled temperature and time periods are selected to de- infest the food product and to preserve the essential properties of the food product.
9. An apparatus according to Claim 8, wherein the predetermined time period is 6-15 seconds.
10. An apparatus according to Claim 9, wherein the predetermined time period is 7-12 seconds.
1l. An apparatus according to any one of Claims 8 to 10, wherein the predetermined temperature range is 80-300 C.
12. An apparatus according to Claim 11, wherein the predetermined temperature range is 1 50-200 C.
13. An apparatus according to any preceding claim, wherein the apparatus is part of a substantially closed circuit, air flow passing through the treatment chamber being returned for subsequent reintroduction to the treatment chamber.
14. A method of Reinfesting an agricultural food material comprising: passing a controlled flow of the food material through a treatment chamber; heating the atmosphere in the treatment chamber to within a predetermined temperature range; exposing the food material in the treatment chamber to the atmosphere therein for a time duration within a predetermined time range, the exposure de- infesting the food material and preserving the essential properties of the food material.

15. A method according to Claim 14, wherein the predetermined time period is 6-15 seconds.

16. A method according to Claim 15, wherein the predetermined time period Is is 7-12 seconds.

17. A method according to any one of Claims 14 to 16, wherein the predetermined temperature range is 150-300 C.

so 18. A method according to Claim 17, wherein the predetermined temperature range is 150-200 C.

19. A Reinfestation apparatus and method substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

20. Any novel feature or combination of features disclosed herein.

Amendments to the claims have been filed as follows 1. A de-infestation apparatus for Reinfesting an agricultural food material comprlsmg: s a treatment chamber through which a controlled flow of the food material to be deinfested passes; a heat supply to maintain the temperature of the atmosphere in the treatment chamber to within a predetermined temperature range by radiantly heating the atmosphere in the treatment chamber, wherein the predetermined and controlled lo temperature and time periods for which the food material in the flow is exposed in the treatment chamber to the atmosphere therein are selected to de-infest the food product and to preserve the essential properties of the food product.

2. An apparatus according to Claim 1, wherein the treatment chamber Is comprises a vertically oriented chamber having a top and a bottom, a food material inlet being provided at the lop and a food material outlet being provided at the bottom.

3. An apparatus according to Claim 2, wherein one or more baffles are interposed between the inlet and the outlet to increase the path length between the inlet and the outlet taken by the flow of food material.

4. An apparatus according to any preceding else - , Herein one or more burners heat a flow of gas directed through the treatment chamber.

5. An apparatus according to Claim 4, wherein the treatment chamber has one or more sidewalls configured to allow the passage of gas therethrough.

6. An apparatus according to any one of Claims 1 to 3, wherein the atmosphere in the +.lea+.lllent challlDcl is radian'- heated by one or more burners.

s 7. An apparatus according to any one of Claims 4 to 6, wherein the combustion products of the one or more burners are not exhausted through the treatment chamber.

8. An apparatus according to any preceding claim, wherein the lo predetermined time period is 6-15 seconds.

9. An apparatus according to Claim 8, wherein the predetermined time period is 7-12 seconds.

10. An apparatus according to any preceding claim, wherein the predetermined temperature range its 80-300GC.

11. An apparatus according to Claim 10, wherein the predetermined temperature range is 1 50-200 C.

12. An apparatus according to any preceding claim, wherein the apparatus is part of a substantially closed circuit, air flow passing through the treatment charnlbel being re+ullled for subseyuerlt reilltloductioll to Me keatll.cut chllLcl.

13. A method of Reinfesting an agricultural food material comprising: passing a controlled flow of the food material through a keatrllerl+ chamber; radiantly heating the atmosphere in the treatment chamber to within a predetermined temperature range; lit exposing the food material in the treatment chamber to the atmosphere therein _ À À . . a. À A._ _ _ 1 J _.. _ _: ._ _ À .._. ...._ _ _ À1_ _ _.... _1 vi a LllllG QUiaLlOll Wllllll a pIGUGLillllllU Lulls lulls, LllG ApOUlG ue infesting the food material and preserving the essential properties of the food material.

l 4. A method according to Claim l 3, wherein the predetermined time period is 6-15 seconds.
15. A method according to Claim 14, wherein the predetermined time period lo is 7-12 seconds.
16. A method according to any one of Claims 13 to 15, wherein the predetermined temperature range is 150-300 C.
17. A method according to Claim 16, wherein the predetermined tPmnPrntllre rn,, is 1 5n nQo

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18. A Reinfestation apparatus and method substantially as hereinbefore described with reference to and as shown in the accompanying drawings.