JP2714483B2 - Natamycin treatment of dried whole grains - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method of treating dried whole grains with natamycin to control and / or prevent the growth of yeast, filamentous fungi and other fungi.

It is desirable to store the whole dried grain under conditions that minimize microbial attack with toxin formation. Fungal assaults are particularly troublesome because fungi have a strong propensity to attack grains and the toxicity of mycotoxins produced by certain fungi. Probably the most prevalent, grain-aggressive mycotoxin-producing microorganisms are filamentous fungi, especially Fusarium, Penicillium and Aspergillus.

Storing in silos has not been entirely successful for long-term storage of kernels or raw pasture, where mitotoxin production must be limited. For example, a common practice with silos is the storage of high moisture lintels that are fermented to increase the acidity of the lintel, where the acidity is controlled but the toxins (ie, the metabolism of certain fungi) The formation of a significant amount of (toxin released by activity) is not prevented.
Fermentation is disadvantageous in that it reduces the feed nutritional value of the stored forage.

The use of antibiotics to control the growth of microorganisms on live grass stored in silos has been suggested because long-term storage in silo storage in the normal humid environment typically requires high concentrations of antibiotics. Not generally done.

It has long been recognized that whole grains need to be dried before storage in order to directly and almost completely prevent the attack of any organisms on the high moisture grains. However, drying alone does not achieve long-term adequate protection of whole grains, such as from harvest to harvest.

Recently, a commonly accepted method of protecting kernels from storage losses is to treat the kernels with propionic acid. Propionic acid is typically sprayed onto the grain at a rate of 1 to 5 pounds per ton of grain. This process does not lead to complete success, especially for long-term storage. Propionic acid is volatile and evaporates. In addition, propionic acid is corrosive to the treatment equipment and is damaged, especially if the pump is not made of expensive corrosion-resistant metal. More importantly, propionic acid does not effectively control certain filamentous fungi, fungi, yeasts, etc. that attack kernels during storage.

Natamycin is generally known to be useful as an antifungal agent. Natamycin is one of the antifungal agents of the polyene family. This family is characterized by a macrolide ring of carbon atoms closed by lactone formation and has a series of conjugated double bonds. Members of this family are categorized by the number of double bonds and whether the compound contains glycoside-linked carbohydrates. Compound natamycin is a tetraene with a molecular weight of about 666, generally has a molecular formula which corresponds to C ₃₃ H ₄₇ NO _13, carbohydrate residues linked glycosidically contains mycosamine. Natamycin exhibits an isoelectric point of pH 6.5. The structure of natamycin has two configurations, an enol structure and a keto structure.

It is an object of the present invention to provide an improved method for storing dried whole grains. In particular, the present invention relates to a method of treating kernels with polyene to reduce damage associated with fungal attack.

Although particular emphasis has been placed on the use of natamycin in the processing of dried whole grains, the present invention relates to any member of the polyene family that is effective in controlling and / or reducing fungal contamination during storage of dried whole grains. Is intended to encompass the use of

SUMMARY OF THE INVENTION The present invention provides control of dried whole grains from fungal contamination and / or
Or to protect, the process achieved by the use of polyene antibiotics, in particular natamycin, and the products produced thereby. The present invention also controls and / or prevents the contamination of whole dried kernels with mycotoxins released by fungi. The present invention allows dry whole grains to be stored for long periods of time, substantially free of fungal contamination. The polyene may be sprayed, mixed, etc. on the dried whole grain by any technique suitable to provide the whole grain with the polyene in an effective manner.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the treatment of stored dry whole grains with small amounts of antibiotics from the polyene family, such as natamycin. The presence of the polyene prevents fungal attack, for example growth of fungi, molds, yeasts, etc., as well as possible contamination with mycotoxins. The present invention also allows for very long-term storage of the grain and improves the quality of the grain that is ultimately retrieved from storage (eg, the retrieved grain is substantially free of fungal contamination).

According to the invention, the term polyene antibiotics is released by fermentation of Streptomyces species and is one or two of the recognized classes of antibiotics particularly effective against fungi.
The above members are defined and mean. Equivalent polyene derivatives such as esters, salts and the like are also included.
Further, other pharmaceutically acceptable derivatives of natamycin, which are effective in controlling and / or preventing fungal contamination,
It can be used to practice the invention. Generally, the preferred polyene for use in the present invention comprises natamycin. Because natamycin usually provides long-term antifungal protection at relatively low non-toxic concentrations, so natamycin is economical for long-term grain storage.

"Biologically effective amount" means antifungal control appropriate for the intended use of the stored grain, i.e., the growth and growth of the grain against fungi, molds, yeast, etc. over the entire storage period. It is defined as being present in an amount sufficient to provide adequate protection from mycotoxin contamination and maintaining activity for a sufficient amount of time.

"Grains" refers to one or more kernels that are stored in the dry state for an extended period of time, e.g., from harvest to spring for seed kernels or from harvest to harvest for continuous production of processed grain foods. Defined and means it. In particular, monocotyledonous grains used for human foods and animal feeds such as cereal foods, seeds and the like are intended, for example, corn, goose corn, oats, barley, rice, rye, wheat, pasture seeds, canola and sunflower seeds , Soybeans and the like.

"Whole grain" is defined and means a grain having substantially complete hull surrounding the grain, substantially free of crushing or other disruption. For example, the term whole grain refers to corn and / or
Alternatively, it is defined as and encompasses individual grains such as corn. However, the term does not include many conventional animal feeds (eg, bird feeds) where individual grains have been crushed or broken and the protective epithelium of the grains has been broken.

"Storage" is defined as the technique of holding a grain in its dried whole grain form for an extended period of time, i.e., 1-2 weeks, months or more. Storage takes place in large grain warehouses, bins, bags and the like. In an important aspect of the invention, the storage is intended to substantially maintain the grain in its initial state of storage without significant changes or contamination due to microbial attack.

"Drying" is defined as drying the kernels by sun or heat to reduce the initial moisture content of at least about 30% by weight to about 15% or less, usually about 7%.

By "non-toxic" is meant the concentration of polyene and the substances used therewith according to the invention for effective biological protection of the grain. Non-toxic does not include unacceptable amounts of toxic chemicals from polyenes or mycotoxins from fungal invasion.

Polyenes (eg, natamycin) are useful in an amount of only about 5 g to at least about 50 g per ton, in which amount they are effective in controlling fungal attack or invasion, while foods consumed by animals and / or humans (Eg animal feed) is non-toxic. From about 5.5 ppm to at least about 55, based on the weight of dry kernels to be treated
Natamycin concentrations of ppm are non-toxic and are biologically effective at protecting the grain for two months or more against significant fungal infestation and / or mycotoxin contamination. However, the precise dosages that are sufficiently effective for fungi depend on the particular storage conditions. If storage conditions are favorable for fungal metabolic activity, relatively large amounts of polyene will be required. Warm, humid, with a neutral pH,
Storage conditions, such as containing oxygen and containing metabolizable substrates, require relatively large amounts of polyene to be effective for protection from fungi. The amount of polyene required to prevent fungal growth and / or potential toxin contamination may be less than that required to treat an existing fungal outbreak. It is therefore advantageous to treat the whole grain immediately after drying.

In addition, fungi tend to attack whole-grain flaws that allow fungi to enter the interior regions of the kernel (eg, the interior of the kernel contains starch and sugars that can be consumed by the fungus). . For example, the grain may be injured during drying, transport, etc., to render the grain more susceptible to fungal attack. In particular, dried whole grains may contain or develop enough cracks in the epithelium to allow fungi to penetrate.
Also, grain germ (eye) is particularly susceptible to injury,
Thus, even if the epithelium is not cracked, it will be attacked by fungi.
If the fungal attack on stored kernels is widespread, the entire contents of the storage container will need to be treated (for example, the presence of fungi and their toxins will make all kernels in large grain warehouses completely intact). Appropriate).

The preferred form of the polyene is a crystal. However, in the practice of the present invention, any morphological condition that is effective against fungi is acceptable. The polyene used in the present invention is
It can exist in one or more hydrated forms (eg, mono- and trihydrates). The trihydrate form is advantageous in some embodiments of the invention due to its stability.

Natamycin is an acceptable polyene for the practice of the present invention and as such is essentially insoluble in water. Certain non-toxic, bioequivalent derivatives of natamycin are water-soluble. Natamycin and / or water-soluble bioequivalent derivatives can be added to the kernel in any convenient manner that provides the desired polyene to the dried whole grain in a manner that is biologically effective against fungi. Supplied. For example, polyene (one or more) may be aerosol,
It can be applied (spray, mixing, coating, etc.) as fume, mist, powder, aqueous suspension, solution and the like. Excessive wetting of dry kernels should be avoided (eg, moisture increases the growth rate of invading fungi). Typically, polyenes are transported during the delivery or transportation of the grains to storage facilities, for example,
Supplied when transferring to large grain warehouses, bins, bags, etc. Care must be taken to ensure that the polyene is applied such that it is dispersed (eg, uniformly) and remains throughout the grain throughout storage.

In one aspect of the invention, the polyene is suspended in a non-toxic liquid carrier and sprayed on dried whole grains. If a non-toxic liquid carrier is used for the application of the polyene, the liquid carrier should generally not be a solvent for the polyene. However, certain biologically effective and / or pharmaceutically acceptable polyene derivatives that are soluble in non-toxic liquid carriers can also be used alone and / or with natamycin. Suitable non-toxic liquid carriers consist of at least one of the following groups: alcohols such as methanol, water and the like. In addition to the non-toxic liquid carrier, it is advantageous to include a non-toxic wetting agent or surfactant in the suspension. Non-toxic wetting agents tend to increase the effectiveness of polyenes by making it easier to coat suspensions and / or dry whole grains into cracks.

In another aspect of the invention, the polyene is comminuted or ground into a powder to increase its surface area.
As the surface area increases, the effectiveness and ability of the polyene to disperse uniformly throughout the dried whole grain increases (eg, relatively small particles of natamycin can be easily mixed directly with whole grain for storage).

It was a surprising finding that when the kernels were stored in a generally dark, dry environment, the safe shelf life became less relevant to the treatment concentration. For example, if kernels stored in a dark, dry environment were applied to all kernels in an amount that provided adequate antifungal protection for about two months,
Even for significantly longer storage periods (eg, from harvest to harvest), it is not necessary to use more natamycin.
For example, if a suspension consisting of natamycin, a non-toxic liquid carrier and a wetting agent is sprayed onto the grains to be stored and can be stored in a dark dry environment for at least about two weeks, it will decrease, if not prevent, fungal attack. It should be expected. This of course presupposes that natamycin is chemically stable under stored conditions.

In certain embodiments of the present invention, it is advantageous to use the polyene with other processing steps and / or materials. For example, the polyene suspensions described above can include other substances such that multiple dry grain treatments are performed simultaneously. More importantly, the polyene treatment of the present invention does not interfere with the subsequent processing of the treated whole grain or use in the final product (eg, whole grain treated according to the present invention may be removed from storage). ,
It can be processed into flakes, grits, etc. as it is).

Without wishing to be bound by any theory or explanation, polyenes are active or effective on fungi but not on bacteria. One explanation would be that fungi contain ergosterol in their membranes (but not bacteria).

In general, the fungus will continue to grow until it contacts natamycin if the environment is appropriate. The logical mechanism of the action of polyene is the binding of the polyene molecule to ergosterol present on cell membranes of fungi, filamentous fungi, yeasts and the like. Complex formation with ergosterol is evidenced by the neutralizing effect of ergosterol addition on the antifungal activity of polyenes against fungi. It is believed that the true complex of the polyene and the fungal cell membrane alters the permeability of the membrane. Polyenes are relatively large molecules that cause an increase in surface pressure, which triggers the relocation of ergosterol present in the membrane, which results in a change in the permeability of the cell membrane and an osmotic shock. This osmotic shock is usually sufficient, if not abolished, to disrupt the metabolic activity of the fungus (eg, polyene causes irregular fungal growth, sporulation).

An important aspect of the present invention is that very small amounts of polyene, such as natamycin, effectively prevent excessive contamination with mycotoxins during storage of whole grains.
This is extremely important when the grains are used in food products, especially human food products such as cereal food products. In this case, the polyene compound must be compatible with human and / or animal consumption. The polyenes used in the present invention are highly non-toxic to humans and animals. In general, polyene ingested by animals (eg, cows, birds, pigs, etc.) does not usually remain in animal meat.
Thus, polyenes are not harmful to humans when consuming animals that have consumed feed containing them. In contrast, animals exposed to fungi have fungi and / or their toxins incorporated into the meat. Such fungi and / or toxins are harmful to humans consuming the meat of our animals, and the present invention is used as a technique to prevent and / or control the significant exposure of these animals to fungi. (Eg, polyene treatment of whole grains, which are ultimately milled for animal feed, prevents and / or controls exposure of animals and / or humans to fungi). Thus, in one aspect, the present invention controls and / or controls the fungal attack on whole grains that feed the animals so that the animals being processed are not contaminated by fungi, their toxins and / or antifungal agents. It is possible to prevent it.

While certain aspects and embodiments of the present invention have been described in detail above, it is to those skilled in the art that the present invention encompasses, in addition to these examples, many combinations, equivalents and modifications. Is self-evident.

Claims (1)

(57) [Claims] 1. Drying the whole grain to a moisture content of less than 15%, treating the dried grain with natamycin at 5.5-55 ppm based on the weight of the grain, and drying the grain so treated A method of substantially eliminating fungal contamination of kernels, comprising storing in the environment.