WO1995017816A1

WO1995017816A1 - Pest repellent

Info

Publication number: WO1995017816A1
Application number: PCT/US1994/014432
Authority: WO
Inventors: Dan K. Comer; Martin F. Berry; Anthony J. Monfredi; Chel W. Lew
Original assignee: The Pillsbury Company
Priority date: 1993-12-30
Filing date: 1994-12-29
Publication date: 1995-07-06

Abstract

The present invention includes a process for deterring pests from food stored in packages. The method includes providing a pest repelling agent, encapsulating the pest repelling agent to form an encapsulate having a core component and a shell component and applying the encapsulate to a package. The present invention also includes the encapsulates having a core component with the pest repelling agent and a shell component.

Description

PEST REPELLENT

BACKGROUND OF THE INVENTION

The present invention relates to a process for deterring pests from infesting food products for extended periods of time. The present invention is also related to particles that deter pests from infesting the food products.

The development of non-refrigerated, storage stable packaged food products has revolutionized the food industry. Eliminating a need for special food storage conditions such as refrigeration has made it possible for commercial food manufacturers and distributors to store food products for up to several years until the food products are needed for distribution and sale. This permits bulk production and distribution to match changing demands in the marketplace.

With increased non-refrigerated food storage capabilities, there has, unlortunately, been a corresponding increase in pest infestation of stored food products. Because the food products are stored for longer periods of time, simple wearing down of the food packaging materials or gradual migration of food components to the exterior surfaces of the packaging makes the stored food products particularly attractive to pests. Such stored food pests include mite species such as Tyrophagus putrescentiae, among others.

Of the multitudes of pests known to infest packaged food- products, mite species represent an extremely costly sector. Mite-infested food products are completely unsalvageable and must be destroyed to prevent infestation of adjacent packages. Furthermore, food products near the original infestation site are also often adversely affected to the point of being unfit for use. Mite infestation is a common problem associated with warehouse storage of packaged food products, particularly when climactic factors favor mite growth and reproduction.

The problem of pest infestation of stored food products is seen mostly in the storage of dry or intermediate-moisture food products. These food products are typically packaged in paper or plastic bags, containers or wrappers. These packaging materials have not been successful in excluding pest infestation of food products because of problems with package integrity. For example, paper bags are susceptible to insect infestation through the stitch holes used to seal the bags, incomplete glue or heat seals, and abrasion and tears occurring through handling. Paper and paperboard are in addition subject to absorption of food components by the paper, thereby exposing attractants to the outside surface of the package, which is subject to pest infestation. The use of paperboard boxes has similar drawbacks, such as incongruous flaps which permit product fines to create trails of food which attract pests further into the package. Furthermore, these types of packaging are more susceptible to adulteration from outside sources, such as spilled oil or water, which weakens the packaging material and provides an attractive site for pest infestation. The use of plastic coverings, such as cellophane wrappers, is also not immune to pest infestation through, for example, tears in the wrapper or spaces in between the sealing edges of the wrapper.

It is therefore evident that protecting stored food products from pest infestation has been and continues to be a major concern for commercial food manufacturers. Current methods for dealing with pest infestation include treating the food packaging materials with pest-repelling compounds. For example, Laudani et al. in the Proceedings of the Florida State Horticultural Society, vol. 69, pp. 191-195, describe treating paper bags with insecticides to protect the food products contained therein from insect infestation. The insecticides used to treat the bags included synergized pyrethrum, methoxychlor and lindane. The food products thus packaged remained insect free for up to twelve months.

Another method of dealing with pest infestation of stored food products has been to include pest repelling agents in the food product itself. Numerous repelling agents, or allomones, are known for a large variety of food-infesting pests. For example, Rodriguez et al in Recent Advances in Acarology. vol 1, pp. 251-261 (1979) describe several flavoring compounds having various effects on the growth and behavior of acarid mites. Some of the flavoring compounds tested attracted mites to the food product, while others repelled mites from the food product. Terpenoid compounds were among those found to have a repelling or allomomc effect on mite behavior.

A different approach to solving the problem of pest infestation is to prepare the food products with pest repelling agents as ingredients of the food formulation. There have been problems associated with this approach as well. The first and most obvious consideration is the safety of the repelling agent in food products. Another overriding concern is the effect of the repelling agent on the organoleptic qualities of the food product. In addition to these overriding problems, from a practical standpoint, the pest repelling agent must be present uniformly throughout the food product to have the desired effect. The food product must be packaged in a way such that the repellant effect of the pest repelling agent is preserved and does not escape from the food product through, for example, evaporation or dehydration. Furthermore, the pest repelling agent must be selected such that it is not physically or chemically inactivated during food processing. Attempts have been made to provide storage-stable dry or intermediate moisture food products that are resistant to pest infestation.

For example, Mehring et al., U.S. Patent Number 4,298,624, describes a method for repelling mites in intermediate moisture pet foods by incorporating within the food product fatty acids of chain lengths ranging from C₄ to C₁₀, and their amide, ester and salt derivatives of the fatty acids.

SUMMARY OF THE INVENTION

A process of the present invention for deterring pests from stored food includes providing an edible pest repelling agent, encapsulating the pest-repelling agent to form an encapsulate having a core component and a shell component, and applying the encapsulate to food packaging materials, thereby deterring pests from approaching the package. The process further includes incorporating the edible pest repelling agents into the food itself. The present invention also includes an encapsulate having a core component having an edible pest repelling agent and a shell component that coats the core component. The encapsulate may be applied to packaging materials, food products or to both packaging materials and food.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the experimental design of Example III.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A process for deterring pests from food stored in a package includes providing an edible pest-repelling agent, encapsulating the edible pest repelling agent to form an encapsulate having a core component and a shell component, and applying the encapsulate to the package storing the food. The present invention also includes a pest-repelling encapsulate having a shell component and a core component where the core component includes an edible pest-repelling agent. The process and product of the present invention resolve a long standing problem of how to utilize pest deterring features of an edible pest repelling agent such as a terpene that is quite volatile, over a long period of time and throughout a food storage package while still maintaining organoleptic qualities of a food product. The process and encapsulate of the present invention deter infestation of pests such as mites in packaged foods, particularly of dry and intermediate moisture, for periods of time in excess of one year without destroying odor or flavor of the food stored.

used herein, the expression "storage-stable" refers to products that are capable of being stored at approximately ambient temperatures and low and intermediate moisture levels. "Food packaging material" refers to any material suitable for packaging food, such as paper or plastic which can be used in the form of bags, wrappers or more rigid containers. "Pests" refers to any life form not desired in food products, including insects such as mites and their larvae and debris.

The pest repelling agents used in the process and encapsulates of the present invention may be selected from any repelling agent suitable for use in food or food packaging materials. In one embodiment of the present invention, edible repelling agents that include terpenes are used. One source of terpenes includes citrus oils. Citrus oils include oils derived from lemons, grapefruit, limes, kumquats, tangerines, oranges and other members of the genus Citrus. Specific examples of terpene compounds found in citrus oils include citral, limonene, /3-sinensal and nootkatone, among others. In a preferred embodiment of the present invention, citral is the pest repelling agent.

Citral is an extraction of lemon grass oil that includes two geometric isomers, neral (1) and geranial (2). Structures of these isomers are illustrated as follows:

The concentration of the neral geometric isomer in citral from natural sources may range from about 33 percent by weight to about 40 percent by weight. The concentration of the geranial geometric isomer may range from about 56 percent to about 64 percent by weight of the citral obtained from natural sources.

The pest repelling agents that are edible, such as citral, are encapsulated in the core component of the encapsulate and food grade encapsulating agents are included in the shell component. The encapsulates may be applied to an interior of food packaging material facing the food stored. The encapsulates may also be applied to an exterior surface, facing the outside environment. The encapsulates may additionally be applied to food products stored within the packaging material.

Within the core component of the encapsulate, the citral obtained from natural sources, orange oil or combination of citral and orange oil may be incorporated in either a liquid phase or a solid phase with preservatives such as BHT and BHA. BHA is a mixture of 2-tert-butyl-4- methoxyphenol and 3-tert-butyl-4-methoxyphenol. BHT is 2,6-di-tert-butyl-4-methylphenol. In one embodiment, the concentration of BHT is about 0.05 percent by weight of the core component. The concentration of BHA is also about 0.05 percent by weight, and the concentration of citral is about 99,90 percent by weight of the core component. In one preferred embodiment, the citral-based core component is about 50% by weight of the encapsulate.

The shell component of the encapsulates of the present invention may be selected from any of a wide variety of food-grade encapsulating agents. Included in this category are cellulose and cellulose derivatives, gums, oils and glycerides. Based on the wide variety of suitable encapsulating agents available, specific encapsulating agents can be selected to meet the particular needs of the packaged food product during transportation and storage. In a preferred embodiment, gums such as sodium alginate and carrageenan are used.

Additional shell components include polyvinyl alcohol, film forming starches and plasticizers such as corn syrup solids, sorbitol and glycerol. The encapsulating shell and core materials must be able to withstand conventional processing conditions.

In one preferred embodiment, the shell component of the encapsulate includes gelatin in a concentration of about 54.99 percent. The gelatin is of a Bloom Type A and is manufactured by the Hormel Company of Austin, Minnesota. The shell also includes starch in a concentration of about 44.99 percent by weight. In one embodiment, the starch is a Capsul^® starch, manufactured by National Starch and Chemical Co. of Bridgewater, NJ. The Capsul^® starch is an encapsulating starch dextrin. The shell component also includes a sodium benzoate preservative in a concentration of 0.1 percent by weight. In one embodiment, the preservative is manufactured by Monsanto Chemical Co. of St. Louis, MO. The shell component may also include Atmos 300^® or Tandum 552^® surfactants or wetting agents manufactured by Atlas Chemical Co. of Miami, FL in a concentration of 0.01 percent.

Preferably, encapsulating materials of the shell and core form encapsulates having a diameter ranging from approximately about 150 to about 500 microns in size. In one embodiment, about 51.6 percent of the capsules fall within a size range of about 100 to 355 microns. The remaining weight of the capsule population falls within a size of 355 to 500 microns. It is contemplated, however, that encapsulates may be of substantially the same size.

In one embodiment, the shell component has a thickness within a range of about 10 to 20 microns for encapsulates having a total core payload of 50 to 60 weight percent of the encapsulate. The shell component of the encapsulates permits a graduated controlled release of the pest repelling agent over a one to three year period. In particular, the pest repelling agent slowly permeates through the shell, eventually escaping to the atmosphere. Additionally, some shell additives or plasticizers may slowly solubilize, thereby releasing the volatile pest repelling agent core through the shell to the external environment. The size distribution of the encapsulates may be such that the core component of the smaller encapsulates may permeate before the core component of the larger encapsulates. This may occur because the surface area is much greater for smaller encapsulates than larger encapsulates.

The shell component is also susceptible to rupture with application of pressure. Once ruptured, the pest repelling agent of the core is released. It is believed that when packages that include the encapsulates are lifted and then repositioned within a warehouse or in transit, that larger encapsulates burst because of the package movement. The bursting of the encapsulates and the corresponding large release of pest repelling agent is believed to deter pests from approaching the bags.

The encapsulated pest repellents can be formed using various encapsulation techniques such as centrifugal extrusion as described in U.S. Patent No. 4,764,317 to Anderson, et al. Other encapsulation methods include methods taught by Lew et al. in U.S. Patent No. 5,246,636. One centrifugal extrusion process includes a device having a centrifugal extrusion encapsulation head. Materials for the shell and core layers are fed into the head wherein the encapsulates are formed and expelled. As the head rotates, nodes form on extruded "rods" or "nozzles" of the head. Eventually, the nodes break off as encapsulates. The size of the encapsulates produced is a function of the feed rate, the rotational speed of the head, and the nature of the shell and core materials. The shell component of the encapsulates is then dried and hardened by chemical reaction, solvent extraction, solvent evaporation, cooling or a combination of these techniques. The encapsulates are then collected for use.

In a preferred embodiment, the encapsulates are collected in a starch stream. One preferred starch is Dry flow^® starch, a hydrophobic capturing and drying starch manufactured by National Starch and Chemical Corp. of Bridgewater, NJ. The starch stream acts as a cushion that prevents encapsulate breakage as the encapsulates are transported in a production process. The encapsulates thus prepared may be applied to food packaging materials, rendering the packaging materials unattractive to pests. Applications may be performed by coating the encapsulates by methods such as spraying, dipping and brushing the encapsulates onto the packaging materials. Other applications include incorporating the encapsulates into the packaging material itself as it is being manufactured. For example, the encapsulates may be added to the pulp compositions used to make paper bags for food packaging. The encapsulates may also be applied to a package as part of a glue seal. Other conventional methods for applying the encapsulates to packaging materials may be used depending on the encapsulation materials and methods used.

The encapsulates may be applied on any or all of an interior of the package, exterior of the package or the product enclosed within the package. The interior of the package contacts the product and the exterior of the package faces the outside environment. Preferably, encapsulates applied to the exterior of the package are concentrated at the bottom of the package, most likely to contact a floor.

Once treated with the encapsulates, the packaging materials may be filled with food products using conventional packing methods. Alternatively, food products can be put into the packaging materials prior to application of the encapsulates. The latter procedure is preferred as the package containing the food product can be sealed and then treated with the encapsulates, avoiding any additional loss of the encapsulates to handling prior to filling the package with food product.

The present invention further provides for the incorporation of encapsulates directly into the food product prior to packaging. The encapsulates are preferably added to food that has been prepared. However, it is also contemplated that the encapsulates are prepared in a manner whereby the shell- and core-forming materials of the encapsulates are able to withstand food manufacturing processes such as heating, cooling- shearing, extruding and the like, with the core materials remaining within the encapsulate. The core-forming materials, including the pest repelling agents, are selected to ensure that food processing does not alter or reduce the pest repelling abilities. The resulting food product, containing the encapsulates, has pest repelling properties that render the food product pest free for up to about 3 years under ambient storage conditions. Described below are specific embodiments of the encapsulates and process of the present invention. These embodiments are presented for illustrative purposes only and not to limit the present invention. EXAMPLE I PREPARATION OF ENCAPSULATES

Encapsulates having pest repelling core materials and shell forming materials were prepared according to the following formulation. All values are given as a weight percent of the entire encapsulate unless specified otherwise.

Shell Composition:

Gelatin 300A 16.5%

CAPSUL^® 13.5

Sodium Benzoate 0.1

Atmos 300^® 0.1

Water 69.8

Core Composition

Citral 100.0%

The shell materials were heated to a temperature of about 120° to about 130°F prior to extrusion, while the core materials were extruded at room temperature.

The encapsulates were prepared by centrifugal extrusion with the extruder head operating at about 2100 RPM. The encapsulate materials were extruded through a nozzle having an internal diameter of 0.020 inches for the shell materials and 0.009 inches for the core materials. The extrusion stream for the shell material had a weight-based flowrate that was substantially the same as a weight-based flowrate for the core extrusion stream.

The resulting encapsulates were collected using Dry Flo® Starch. The encapsulates were preferably dried with intermittant heat at about 120 degrees F to a moisture of about 9 to 14 percent by weight. EXAMPLE II PREPARAΗON OF ENCAPSULATES

Encapsulates were prepared as described above but with a different core material. The core material used in this example had the following formula:

Core Composition

Citral 50.0%

Orange Oil 50.0

The core materials were cold pressed and concentrated two¬ fold prior to being brought to room temperature and coextruded with the shell materials.

EXAMPLE m MITE REPELLANT ACnVTTY OF ENCAPSULATES

Encapsulates prepared according to Example I were tested for their repelling effect on mite populations. The mite cultures used in this Example were Acarus siro L. and Tyrophagus putrescentiae.

The cultures were maintained using standard procedures. Prior to testing, mites were held at about 70°F for about one day for "feeding mite" tests and for one week for "starved mite" tests.

The mites were thereafter removed from their culture jars, placed on pieces of white paper, onto which a sample of the encapsulate had been placed. The mites were placed at a measured distance from the encapsulate, and their migration relative to the encapsulates was measured over time.

Figure 1 shows the experimental layout of this Example. Table 1 shows data that were collected using this experimental design using Tyrophagus putrescentiae. The test conditions were uncontrolled, but the te perature range for testing was 70°F plus or minus 5°F with the relative humidity range from 50% to 85%.

Twelve replications were made with a citral sample such as is described in Example I, which meant that each quadrant such as shown in Figure 1 was used three times. All testing was performed in a semi-dark situation created by covering the test area with a box.

To perform the test, an unknown number of mites was released at the release point as shown in Figure 1. The test area was then covered with the box in order to darken the area. Each test lasted for five minutes at which time the position of all mites were counted and placed in one of four categories. Mites found in area 1 were the most attracted mites. Mites found in area 2 were slightly attracted. Mites found in area 3 were repelled and mites found in area 4 displayed no reaction.

A measure of repellency was achieved by adding the number of mites attracted to areas 1 and 2, and dividing by the number of mites repelled in area 3, and multiplying by 100. This figure was a percent repellency for each test. The mites failing to respond were not considered in the evaluation. The division of the mites attracted into two categories was utilized as a method of assessing that there was a real repellant action involved. In nearly every case, the number of mites in area 1 was only a small fraction of those observed in area 2. The percent of positive repellency for each test are presented in Table 1.

The data shown in Table 1 was subjected to analysis by the

New Duncan's Multiply Range Test as described by Steel, R.G.D. and J.H. Torrie in Principles and Procedures of Statistics (1960) published by

McGraw Hill of New York. No control or comparison sample was run as the citral had been determined to be a repellant for this mite. The data in Table 1 shows that each of the samples showed an average percent repellency falling within a range of about 62.2% to 79.3%.

TABLE1

Percent Oi : Mites Repelled

Reps. #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12

1. 57.1 83.3 66.7 81.6 77.0 62.5 80.5 66.9 72.5 82.0 61.6 76.5

2. 68.0 86.7 71.5 93.0 76.2 71.5 64.3 67.2 78.2 87.5 88.0 76.5

3. 73.3 74.1 88.0 68.4 75.6 54.1 77.8 65.5 87.4 77.3 47.2 65.6

4. 83.3 72.4 78.9 74.3 72.4 68.4 72.7 75.4 81.2 68.2 58.9 68.5

5. 50.8 69.2 75.5 71.6 65.7 56.8 57.8 79.3 73.4 92.3 64.8 64.7

6. 89.0 68.0 68.1 86.8 71.4 67.3 77.0 77.0 85.5 73.6 74.7 77.8

7. 75.5 46.4 83.6 72.7 38.3 66.7 71.4 73.7 77.3 70.5 71.9 72.4

8. 73.3 56.8 73.6 69.8 84.8 68.4 70.0 56.8 87.0 81.3 86.0 58.7

9. 66.7 64.5 65.9 76.6 78.3 49.0 52.4 71.9 64.8 81.5 57.6 75.0

10. 72.2 81.5 67.6 51.3 92.6 70.4 72.3 67.6 61.3 83.1 68.0 77.9

11. 70.1 77.2 77.6 78.6 69.6 58.6 51.5 62.5 69.0 73.3 68.9 87.1

12. 72.8 64.3 57.7 81.2 65.1 53.1 74.5 77.0 75.0 80.6 78.9 71.3

EXAMPLE IV PACKAGING HAVING ENCAPSULATES INCORPORATED

Encapsulates such as are described in Example I were provided. Cardboard boxes were filled with a dog food of intermediate moisture and were sealed using hot melt glue. Prior to filling with dog food, six of the boxes were assembled with a cold glue using the following variations:

1. Two types of control boxes were prepared having one of two quantities of cold glue. Both types of control boxes were free of citral encapsulates. For one type, identified as "C" group, 0.5 grams of cold glue was deposited in a 2 inch by 6 inch area at the bottom of each box. For the second type, one gram of cold glue was applied to the packages in the 2 inch by 6 inch area. This type is designated as "Cl". 2. In a second group of test boxes, encapsulates were applied t an interior surface of each box facing food stored in the box. The encapsulate came in contact with the dog food product. For this group, about 1 gram of citra encapsulates having a weight percent of 50% citral was applied to the interio surface of each box near the bottom of the box. One segment of this test grou had about 0.5 grams of cold glue applied in a thin rectangular monolayer measurin about 2 inches by 6 inches at the bottom of the box. This group is designated "B" A second segment of this test group had about 1 gram of cold glue applied in th thin rectangular monolayer and this group is designated as "Bl". 3. For a third test group of boxes, the encapsulates were applie to an exterior surface of each box, not in contact with the product and facing th outside environment. The encapsulates applied to this test group were of abou 50% citral by weight and were applied in a quantity of 1 gram to the exterio surface. The encapsulates were applied to a bottom flap of the box. Along wit the encapsulates, a 0.5 gram quantity of cold glue was applied in a thin rectangula monolayer measuring 2 inches by 6 inches. Boxes having this configuration ar designated "A" in Table 2. For a second segment within the third test group, a amount of glue of one gram was applied in the thin rectangular monolayer. Thi group is designated "Al". As can be seen from Table 2, the packages having encapsulate applied had fewer mites under the box after the box was dropped into a nest o mites than the control groups. The packages having encapsulates applied to th external surface of the box had a better performance than boxes havin encapsulates applied to the internal surface. TABLE 2

SET SMALL GLUE LARGE GLUE % % LEVEL 0.5g glue LEVEL l.Og glue MΓΓES UNDER MTTES UNDER BOX BEFORE BOX AFTER

DROP DROP

CONTROL C NO CITRAL Cl NO CITRAL 21-23% 18-23% CAPSULES

INTERNAL B INTERNAL lg. Bl INTERNAL lg. 8-10% 18-23% CAPSULES CAPSULES

EXTERNAL A EXTERNAL lg. Al EXTERNAL lg. 2-4% 4-5% CAPSULES CAPSULES

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A method for deterring pests from food stored in a packag comprising: providing an edible pest-repelling agent; encapsulating the pest-repelling agent to form an encapsulate, havin a core component and a shell component; and applying the encapsulate to the package storing the food.

2. The method of claim 1, further comprising adding the encapsulat to the food.

3. The method of claim 1 wherein the encapsulates are applied to th package after food has been added to the package.

4. A composition for deterring pests from food stored in packages, sai composition comprising pest-repelling agents and encapsulating agents.

5. The composition of claim 4, wherein said pest-repelling agents ar terpenes.

6. The composition of claim 4, wherein said encapsulating agents ar selected from the group consisting of cellulose derivatives, gums, waxes, oil glycerides and mixtures thereof.

7. A food comprising encapsulated pest-repelling agents.

8. A package material suitable for packaging food for storag comprising encapsulated pest repelling agents.

9. An encapsulate comprising: a core component that includes a pest repelling agent in concentration effective for deterring pests; and a shell component that encloses the core component in th encapsulate, the shell component having a thickness of abou 10 to 20 microns wherein the pest repelling agent in the cor component permeates the shell component.

10. The encapsulates of claim 9 wherein the core component has a weigh percent of about 50 to 60 percent of the encapsulate weight.

11. The encapsulate of claim 9 wherein the pest repelling agent is terpene.