GB2180529A - Osmoprotectant particles and method of making the same - Google Patents

Abstract

An osmoprotectant particle for use in enhancing fungus growth and particularly for use with edible mushrooms. The osmoprotectant particle includes a carrier particle (12), either a protein or a neutral material and a plurality of osmoprotectant microdroplets (14) containing lecithin and betaine or choline which are attached to a plurality of recesses (16) formed about the carrier particle. Denaturation of the protein and/or control of a surface-to-volume ratio restricts access to the microdroplets such that only mushroom mycelia occurring in the later flushes will be able to utilise the phospholipid droplets. A method is provided for producing the osmoprotectant particles utilising either the protein carrier particle or the neutral carrier particle.

Description

SPECIFICATION Osmoprotectant particles and method of making the same This invention relates generally to nutrient additives for biological systems and more specifically to an additive for enhancing and prolonging mushroom growth and extending cropping, and to methods for producing such an additive.

Millions of pounds of commercially produced, edible mushrooms are grown and consumed annually in the United States. Commercial mushroom production is divided into several stages, with the first stage being the preparation of the media or compost upon which the mushrooms will grow. The compost is prepared by an aerobic fermentation process in outdoor piles at temperatures in excess of 165"F (74"C). The compost is then subjected to an indoor pasteurization process and cooled below 80"F (27"C). At this point the compost is inoculated with mycelia which have been separately grown on a grain substrate such as rye or millet. This process is known as "spawning". The mycelia are allowed to colonize the compost for a two to three week period following the inoculation.Subsequently, the compost is covered with a thin layer of peat moss and a calcium carbonate buffer. This process is called "casing" and the peat moss layer is called the casing layer. Approximately twenty days after casing, the mushroom begins to produce the fruiting bodies or sporophores which are harvested and sold commerically as the edible mushrooms.

Because disturbing the spawn after it has been cased can have detrimental effects upon the production of fruiting bodies, the most advantageous time for the mushroom grower to add exogenous components to the compost is at the time of spawning, when such components may be freely admixed with the compost. However, it is not desirable to have some types of materials, such as delayed release nutrients, biologically available until later in the crop (i.e. at the time of fruiting). Mushrooms are grown in a series of crop cycles called "breaks" or "flushes". A typical mushroom compost preparation will produce three, four or five such flushes occuring at about one week intervals. However the later flushes tend to produce lesser amounts and lower quality mushrooms.

The prior art has been directed toward the development and preparation of adjuvants intended primarily as delayed release nutrients to supply the mycelia with a food source prior to and during the first flush. For example, U.S. Patent 4,420,319 discloses a combination mushroom spawn activator and delayed release nutrient particle which shortens the period of time required for the spawn to reach fruition. U.S. Patent 4,370,159 discloses a nutrients particle which is timed to provide the maturing mycelia with high value foodstuff near the time of the first fruition.

An additional problem is present during the later flushes which has not yet been addressed by the art. It is well-known that the osmotic potential of the compost and casing layer increases during the later periods of the crop cycle, primarily during the third, fourth and fifth flush. The increase in osmotic potential is brought about by the secretion of metabolites and salts from the large biomass of mycelia growing in the casing layer and in the compost. As a response to this adverse biochemical environment, the mycelia cells synthesize ergosterol, a cholesterol-type compound that is deposited in the cell membrane. Ergosterol synthesis has been noted in a paper by R. B. Holtz and D. E. Smith, presented at the proceeding of the Tenth International Congress of the Science and Cultivation of Edible Fungi, Part 1, 1979, page 437.The cell membrane, which is the primary regulator of metabolite transport into and out of the cell, becomes less permeable due to the ergosterol formation. This reduction of transport acts as a defense mechanism to protect the cell. However, reduced transport also means reduced mycelia activity and subsequently reduced production of mushroom fruiting bodies. Therefore, the yield of mushroom tissue declines both in quality and quantity in the later breaks because the mycelia cannot supply the expanding fruiting bodies with biochemical raw materials for cell synthesis and with water for cellular expansion.

It has been reported in the literature, for example, by Le Rudulier and R. C. Valentine, Trends in Biochemical Science, Volume 7, page 431, osmoprotective compounds, such as betaine and glycyl-choline. The importance of this fact is that the organism must take up and/or synthesize osmoprotectant compounds at the time of osmotic stress. To provide these compounds prior to this time would not result in osmoprotectant activity, rather the compounds would enter other metabolic pathways and be used for other purposes.

Recent experiments with bacteria have shown that the addition of these osmoprotective compounds to nutrient media can encourage growth even in situations where the salt content of the media exceeds the tolerance for normal growth. (See Le Rudulier, Strom, Dandekar, Smith and Valentine, Science, Volume 224, page 1064, 1984). Choline and betaine have been shown to protect cultures of E. Coli against osmotic stress in high salt media. In higher plants, betaine has been shown to protect a root symbiont, Rhizobium meilloti as a free living organism and in the form of a nodulated seedling.

None of the prior art has however, shown that betaine and choline would have a similar effect in higher fungi, specifically Basidiomycetes. Furthermore, none of the prior art has applied the results of these studies toward the development of a functional osmoprotectant for fungi, which may be added to a commercial mushroom spawn and which would viably protect the later flushes against the effects of increased osmotic stress.

Accordingly, it is an object of the present invention to provide a protective additive which will ameliorate the effects of osmotic stress in mushroom cultures and, to this end, there is provided an osmoprotectant particle for enhancing fungus growth comprising: a carrier particle having a plurality of recessed attachment sites; and a plurality of osmoprotectant droplets, smaller in size than the carrier particle and having a core of a phospholipid material surrounded by a layer of an osmoprotectant material, the said droplets being attached to the recessed attachment sites of the carrier particle.

One embodiment of the invention comprises an osmoprotectant particle for enhancing fungus growth comprising: a protein carrier particle having a plurality of recessed attachment sites; and a plurality of having a plurality of recessed attachment sites; and a plurality of osmoprotectant droplets, smaller in size than said carrier particle and having a core of a phospholipid material surrounded by a layer of an osmoprotectant material, said droplets being attached to said plurality of recessed attachment sites to be substantially surrounded by the carrier particle such that release of said osmoprotectant droplets occurs only during the later flushes of a mushroom broken down by mycelia of earlier flushes.

Another embodiment of the invention comprises an osmoprotectant particle for enhancing fungus growth comprising: a plurality of neutral carrier particles having a plurality of recessed attachment sites; and a plurality of osmoprotectant droplets, smaller in size than said neutral carrier particles and having a core of a phospholipid material surrounded by a layer of an osmoprotectant material, the said droplets being attached to said recessed attachment sites of the neutral carrier particle, the plurality of neutral carrier particles being coagglomerated in a matrix whereby a combined osmoprotectant particle is formed.

Briefly, a preferred embodiment of the present invention includes a particle comprising a plurality of droplets of an osmoprotectant material such as betaine or choline which are compounded with a carrier material such as protein or a neutral material. The particle also includes from about one-half to three percent lecithin which serves to orient the betaine or choline on the carrier particle and as a source of biologically available choline. The final product is dried to contain about six to eight percent water, and may also include a thin wax containing to further control the delayed release of the osmoprotectant materials.

It is a further object of the present invention to provide a simple and efficient method for preparing such osmoprotectant additive particles and, in this aspect, the invention provides a method of producing an osmoprotectant additive comprising: preparing a plurality of carrier particles, each having a plurality of recessed interior and exterior attachment sites for receiving a plurality of osmoprotectant droplets; preparing a suspension of osmoprotectant and carrier by mixing together an osmoprotectant material and the carrier particles and blending the resultant mixture; homogenizing the blended mixture of osmoprotectant droplets with the carrier particles whereby said osmoprotectant droplets attach to said plurality of recessed attachment sites on the carrier particles; and drying the resultant product to approximately six to seven and one-half percent moisture by weight.

If the carrier particle is a protein particle, a denaturing agent may be added in order further to control the delayed release of the osmoprotectant.

If the carrier particle comprises a neutral material, the carrier particles are coagglomerated with approximately 1 to 3% starch, and subsequently dried.

A thin wax coating may also be added to the surface of either particle to further control the delayed release of the nutrient.

The resulting particle may then be added either to the compost for mushrooms or be directly brought into contact with immature spawn prior to planting.

An advantage of an osmoprotectant embodying the present invention is that osmotic stress in the media is reduced, thus improving nutrient uptake.

Another advantage is that the osmoprotectant may be added either at the compost stage or at the spawn stage and is released at the appropriate time.

A further advantage is that mushroom yield and quality is improved during the later flushes.

Yet another advantage is that the osmoprotectant particle may be produced simply and efficiently using readily available materials.

In order that the invention may be readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-sectional view of idealized osmoprotectant particle utilising a protein carrier; Figure 2 is a flow-chart diagram of a method for preparing the osmoprotectant particle of Fig.

1; Figure 3a is a cross-sectional schematic view of an idealised alternative embodiment of the osmoprotectant particle; Figure 3b is a cross-sectional schematic view of an idealised combination particle of the alternative embodiment of the present invention; and Figure 4 is a flow-chart diagram of a method for preparing the alternative embodiment of the osmoprotectant particle of Figs. 3a and 3b.

Fig. 1 represents an idealized cross-sectional schematic view of an osmoprotectant particle 10.

It may be seen from Fig. 1 that the osmoprotectant particle 10 is generally spherical in shape and includes two discrete components, namely a protein carrier particle 12, and a plurality of osmoprotectant droplets 14. The protein carrier particle 12 serves as a matrix for the osmoprotectant droplets 14 and is irregular in shape. The exterior surface of the carrier paticle 12 is convoluted and includes a plurality of recessed attachment sites 16, which provide loci for the attachment of the lipid droplets 14 to the protein carrier 12.

The osmoprotectant droplets 14 are generally spherical in shape and substantially smaller than the protein carrier 12. Typically, the droplets 14 range from one hundred and twenty-five to two hundred and fifty microns in size. Each droplet 14 comprises a micro-droplet of lecithin 18 which is surrounded by an osmoprotectant material 20, comprising a layer of either betaine or choline. The lecithin microdroplet 18 serves to orient the osmoprotectant material 20 on the surface of the microdroplet 18 in order to make the osmoprotectant 20 more readily available to the mushroom mycelia. The lecithin microdroplet 18 also serves as an additional source of biologically available choline to maintain membrane permeability.

It may be noted that if the osmoprotectant material 20 is chosen to consist of choline, the choline is preferably added as lecithin. Thus, the droplet 14 can be conceptualized as essentially a single component droplet rather than a dual component droplet. An additional advantage of lecithin is that being a phospholipid conjugate of choline, it releases the choline to the mycelia more slowly than if the osmoprotectant material 20 was pure choline.

Other compounds can also serve as the osmoprotectant material 20 and generally consist of amino acid conjugates. Such materials include glycine betaine, betaine aldehyde, trimethyl-amino butyrate, dimethyl glycine, proline and proline-betaine.

While a number and variety of proteins may be used as the protein carrier particle 12, the protein utilised in the particle 10 is by a by-product of say protein manufacture. This may be produced as an end product of soy protein isolate manufacture. This protein material is highly insoluble and forms a very absorbant grit-like material. Commercially available soy protein in this form may be obtained from a number of sources, including for example Ralston Purina and Archer Daniel Midlands, in a variety of particle sizes, between twenty and one hundred mesh (Tyler sieve).

Because the protein 12 is a folded linear arrangement, a number of attachment sites for the osmoprotectant droplets 14 are present at various locations about the protein, both internal and external. Thus, the phospholipid droplets are protected from early mycelia attack by the convolutions of the tertiary structure of the protein carrier particle 12. To further isolate the osmoprotectant droplets 14, a denaturant is added to create a plurality of cross links 22 which are represented in idealized fashion in the particle 10 of Fig. 1.

The osmoprotectant particles 10 can be used as an additive at the time of spawning, either alone or on conjunction with a delayed release nutrient such as, for example those disclosed in U.S. Patents 4,370,159 and 4,420,319. The osmoprotectant particle 10 should be admixed to the compost at the time of spawning, and is distributed throughout the compost by any of the several mechanical mixing processes as known in the art. Such mechanical mixing processes are necessary to adequately disperse the particles. The optimum concentration of the osmoprotectant 10 can be expressed as a percentage of the dry weight of the compost per square foot of bed area. By this computation, the optimum concentration for particles of the osmoprotectant 10 is between eight-tenths and one and two-tenths percent. This gives an effective concentration of approximately .001 molar on a dry weight basis.

The osmoprotectant particle 10 will not change the conditions of the spawn run or period between casing and first harvest of the mushrooms. The only cultural changes to be expected will be somewhat higher compost temperatures during the later breaks or flushes. The osmoprotectant particles 10 give the mushroom mycelia the ability to remain biologically active during the later period of the crop crycle when the soluble salts from metabolic activities during the cropping period are at their highest concentration by giving the cell the ability to balance the osmotic pressure inside the cell with that of the environment. It has been proposed that some osmoprotectants may also serve as stabilizers of proteins and enzymes that may lose their function as a result of osmotic stress.

Fig. 2 represents a schematic flowchart of a method for preparing the osmoprotectant particle 10. The process starts with the preparation of the soy protein carrier, in which soy beans 30 are subjected to a grinding, defatting and extraction stage 32 wherein soluble proteins, minerals and carbohydrates 33 are removed leaving a soy protein material 34 which is between twenty and thirty percent protein. These protein materials are highly insoluble and absorbant, and form a grit-like material which may be selected to have a particle size between twenty and one hundred mesh. An osmoprotectant 36 comprising, in the particle 10, either betaine or choline is mixed with the soy protein 34 to form a suspension 38 which is approximately one-tenth to three percent osmoprotectant 20, fifteen to thirty percent moisture, and sixty-five to ninety percent soy protein 34.The suspension 38 is subjected to a blending step 40 utilising either a conventional ribbon blender or a V-type (Patterson-Kelley) blender. Blending times are usually approximately twenty minutes depending on the type of blender. If choline is chosen as the osmoprotectant material 20, it is added directly as lecithin. If other osmoprotectant materials 20 are selected, from one half to three percent lecithin is also added. The lecithin is represented by the broken-lined box 39 of Fig. 2. The blended mixture next undergoes a homogenization step 42 utilising a conventional homogenizer, ultrasonic disintegrator, or a high speed, high-shear blender. An aqueous solution of about one percent potassium permanganate 43 is added to the homogenized mixture to increase the total added moisture to approximately thirty percent.The potassium permanganate acts as an oxidative denaturant to the protein to further restrict mycelia access to the phospholipid droplets.

Finally, the homogenate is subjected to a drying step 44 wherein the product is dried in a fluid bed-type dryer yielding the finished osmo-protectant particle 10. Product temperature is regulated to be between 140 and 160"F (between 60"C and 71"C). This typically requires an inlet temperature of approximately 250"F (121 C) and a residence time of about three minutes.

An alternative embodiment of the osmoprotectant particle is illustrated in schematic in Figs. 3a and 3b and designated by the general reference character 70. Those elements of the osmoprotectant particle 70 which are common to the preferred embodiment carry the same reference numeral distinguished by a prime designation. The particle 70 is illustrated in Fig. 3b and is combination particle comprising a plurality of carrier particles 72 each of which is comprised of a relatively biologically inert material specifically, a non-protein material which is not subject to denaturization.The material selected to comprise the carrier particles 72 should include a plurality of surface of internal convolutions 16' and may consist of, for example, carboxymethylcellulose, a clay material mold under the trade name Kaolin, diatomaceous earth, silicates such as vermiculite, and various cross-linked polysaccharides. Attached to the neutral carrier particle 72 are a plurality of osmoprotectant droplets 14', each comprising a lecithin microdroplets 18' and a layer of an osmoprotectant material 20', namely betaine or choline. As with the particle 10, if choline is chosen as the osmoprotectant material 20', it is added directly as lecithin and the droplet 14' is essentially a single layer. The neutral carrier particle 72 is relatively inert. Thus, the droplets 14' cannot be further isolated by a denaturing process.Therefore, the delayed release of the osmoprotectant materials supplied by the particle 70 is accomplished by regulation of particle size which decreases the surface to volume relationship and thus slows assimilation of the particle 70 by the mycelia. The neutral carrier particle 72 is accordingly chosen to be approximately one hundred and fifty times larger than the osmoprotectant droplets 14'. Isolation of neutral carrier particles 72 plus attached osmoprotectant droplets 14' to form the combination particle 70, which includes a plurality of neutral carrier particles 72, the osmoprotectant droplets 14' attached thereto, and an encapsulation of a starch 76. The combined particle has a surface to volume ratio of between twenty-four hundredths and eighteen hundredths square millimeters per cubic millimeter to control release at the third break.It is to be noted that this range may be varied depending on the release time desired. It is to be further noted that the above surface to volume range presently appears to be optimal, but other ranges can also be used to practice the invention.

The droplets 14' may be further isolated from the mushroom mycelia by surrounding the combination particle with a thin layer of a neutral wax 78.

Fig. 4 represents a schematic flow chart diagram for a method of producing the combination osmoprotectant particle 70. The process is begun by mixing a neutral carrier material 80 with one tenth to three percent of the osmoprotectant material 82, for example, betaine or choline, to form a suspension 84. Approximately one half to three percent lecithin, represented by the broken-lined box 85, may be added to the suspension 84 where choline is not the osmoprotectant 20'. The neutral carrier material may be, for example, carboxymethylcellulose, a fine clay, various silicates such as diatomaceous earth and vermicuiite or various cross linked polysaccharides, and makes up about sixty-five to ninety percent of the suspension 84. The suspension 84 is blended at blending step 86 for approximately twenty minutes using apparatus as described for the particle 10. Next is a homogenization step 88 wherein the blended suspension is homogenized in, for example, a conventional homogenizer, ultrasonic disintegrator, or a high speed, high shear blender. Following homogenization, the particles are subjected to an agglomeration step 90. The agglomeration step 90 comprises introducing the homogenate into an agglomerator, which may be, for example, a fluid-bed type, tower-type or a KG-Schugi mixer agglomerator, and spraying the homogenate with a solution 92 of between one to three percent soluble starch. The agglomeration process increases the particle size from approximately one hundred mesh to a size of between twenty and sixty mesh by agglomerating a plurality of particles 72 to form the combination particles 70, and increases the final moisture to between twenty-eight and thirty-four percent.Following the agglomeration step 90, the combination particles 70 undergo a drying step 94 wherein the- particles are dried in a fluid-type bed dryer to reduce final moisture of the product between six and seven and one-half percent. The temperature of the dryer should not exceed approximately 100 F (38"C) due to the nature of the starch solution 92. If desired to additionally isolate the osmoprotectant droplets 14' from the mushroom mycelia, the dried combination particles 70 may be subjected to a waxing step 96 (illustrated by broken lines), wherein a thin coating of a neutral wax 78, such as a paraffin, is applied to the combination particles 70. The wax 78 can be solubilized in a neutral solvent such as a low boiling petroleum and sprayed into the fluid bed agglomerator at ambient temperature.

The solvent can then be removed from the particle by carefully heating the air stream to approximately 100 F (38"C) for about three minutes. While paraffins or solvent-soluble hydrocarbon derivatives are preferred, other waxes, such as microcrystalline waxes, could also be applied via a solvent solution. Emulsifiable synthetic waxes could be emulsified in an aqueous solution, blended with the product and dried. The drying process would remove residual moisture. The paraffin and low-melting-point waxes could also be applied by heating to the melting point, and spray-coating on the particles 70.

Example 1 The production of mushroom tissue occurs in breaks or flushes which occur approximately one week apart. A typical mushroom crop continues for five breaks, after which point the yields have diminished to a point where recovery of the crop is no longer economically feasible. The quality, usually represented by size, colour and firmness, also deteriorates as a function of prolonged cropping time. One of the primary reasons for this deterioration in yield is the inability of the mycelia to transport nutrients and water from the compost encasing layer and to translate them to the site of growth of the fruiting body. Experiments with spawn grown in submerged cultures have shown that the normal growth at 80"F (27"C) will cease after a period of twenty eight days. These cultures were grown in shake flask culture or in fermentors.When betaine or choline and/or lecithin were added to these cultures after twenty-eight days growth continued for a period totalling thirty seven days.

Osmoprotectant materials were prepared as described above for the preferred embodiment and with the following specific percentages: Soy Material 83.2% Lecithin .6% Betaine-HCI 0.1 % Water 16 % Potassium Permanganate 0. 1% The particles were admixed to the compost along with a delayed release nutrient comprising a microencapsulated phospholipid material in a protein matrix, substantially as described in U.S.

Patent 4,370,159 issued to Holtz. Yield data showed a forty-two percent increase in the yield of the fourth break as compared to a control, representing a total yield increase of twenty-two hundreths pounds per square foot.

The osmoprotectant particles 10 and 70 of the present invention are of particular value in that they are specific for mushroom mycelia of the later stages or breaks, thus providing the osmoprotectant activity at the cropping point wherein it is needed most. The delay of the release is accomplished by the denaturization of the protein carrier particle 10 and by controlled agglomeration of the combined particle 70, such that the osmoprotectant particle provides a metered resistance to biological degradation. During the initial development of each flush, the mushroom mycelia are not sufficiently mature and vigorous to be able to penetrate the carrier particles to reach the phospholipid material absorbed thereonto. During the later phases of growth of each flush, however, the mycelia will begin to break down the protective layers surrounding the phospholipids.By selection of protein size and degree of denaturation in the embodiment 10, and by selection of surface to volume ratio and amount of wax coating in the embodiment 70, mycelia access to the phospholipid materials can be regulated such that mycelia access to the phospholipids will not occur until approximately the third or fourth flush. After this point, sufficient breakdown in the carrier particles will have occured such that the phospholipid materials are readily available to the mycelia of the remaining flushes. The phospholipid materials are readily accessible and give the mushroom mycelia cell the ability to balance the osmotic pressure inside the cell with that of the environment.

The various components of the particles of the preferred embodiment have been described in terms of readily available and inexpensive materials. Those skilled in the art will recognize that proteins other than soy bean may be utilised and that additional phospholipids will serve equally well. The various steps of the method for preparing the osmoprotectant particles may be varied slightly without materially effecting the result. Furthermore, the specific ingredients and ratios utilised in the method may be altered to accomplish specific desired purposes.

Claims (20)

1. An osmoprotectant particle for enhancing fungus growth comprising: a carrier particle having a plurality of recessed attachment sites; and a plurality of osmoprotectant droplets, smaller in size than the carrier particle and having a core of a phospholipid material surrounded by a layer of an osmoprotectant material, the said droplets being attached to the recessed attachment sites of the carrier particle.

2. An osmoprotectant particle for enhancing fungus growth comprising: a protein carrier particle having a plurality of recessed attachment, sites; and a plurality of osmoprotectant droplets, smaller in size than said carrier particle and having a core of a phospholipid material surrounded by a layer of an osmoprotectant material, said droplets being attached to said plurality of recessed attachment sites to be substantially surrounded by the carrier particle such that release of said osmoprotectant droplets occurs only during the later flushes of a mushroom broken down by mycelia of earlier flushes.

3. An osmoprotectant particle according to claim 2, wherein the osmoprotectant material is chosen from the group consisting of betain, choline, lecithin, glycine betaine, betaine aldehyde, trimethyl-amino butyrate, dimethyl glycine, proline and proline-betaine; and the phospholipid material is lecithin.

4. An osmoprotectant particle according to claim 2 or 3, wherein the said plurality of recessed attachment sites comprise surface and internal convolutions, and said droplets and further surrounded by a plurality of protein cross-links.

5. An osmoprotectant particle for enhancing fungus growth comprising: a plurality of neutral carrier particles having a plurality of recessed attachment sites; and a plurality of osmoprotectant droplets, smaller in size than said neutral carrier particles and having a core of a phospholipid material surrounded by a layer of an osmoprotectant material, the said droplets being attached to said recessed attachment sites of the neutral carrier particle, the plurality of neutral carrier particles being coagglomerated in a matrix whereby a combined osmoprotectant particle is formed.

6. An osmoprotectant material is chosen from the group consisting of betaine, choline, lecithin, glycine betaine, betaine aldehyde, trimethylamino butyrate, dimethyl glycine, proline and proline-betaine; and the phospholipid material is lecithin.

7. An osmoprotectant particle according to claim 5 or 6, wherein a surface to volume ratio of the combined particle is chosen to be in the range of twenty-four hundredths square millimeters per cubic millimeter to eighteen hunderdths square millimeters per cubic millimeter.

8. An osmoprotectant particle according to any one of claims 5 to 7, wherein the said matrix includes a starch.

9. An osmoprotectant particle according to any one of claims 5 to 8, wherein the combined particle further includes a coating of a neutral wax substance.

10. An osmoprotectant particle according to any one of claims 5 to 9, wherein the neutral carrier particles comprise a biologically inert material.

11. A method of producing an osmoprotectant additive comprising: preparing a plurality of carrier particles, each having a plurality of recessed interior and exterior attachment sites for receiving a plurality of osmoprotectant droplets; preparing a suspension of osmoprotectant and carrier by mixing together an osmoprotectant material and the carrier particles and blending the resultant mixture; homogenizing the blended mixture of osmoprotectant droplets with the carrier particles whereby said osmoprotectant droplets attach to said plurality of recessed attachment sites on the carrier particles; and drying the resultant product to approximately six to seven and one-half percent moisture by weight.

12. A method according to claim 11, wherein lecithin is added to the suspension prior to blending.

13. A method according to claim 11 or 12, wherein the carrier particles comprise a soy protein which has been ground, defatted and stripped of impurities; the osmoprotectant droplets comprise a material chosen from the group consisting of betaine, choline, lecithin, glycin, betaine, betaine aldehyde, trimethyl-amino butyrate, dimethyl glycine, proline, and proline-betaine; and potassium permanganate is added to the blended mixture prior to drying to further denature and cross link the soy protein carrier.

14. A method according to claim 11 or 12, wherein the carrier droplets comprise a biologically inert material; said osmoprotectant droplets comprise a material chosen from the group consisting of betaine, choline, lecithin, glycine betaine, betaine aldehyde, trimethyl-amino butyrate, dimethyl glycine, proline, and proline-betaine; and the blended particles are agglomerated prior to drying utilising a one to three percent starch solution.

15. A method according to any one of claims 11 to 14, wherein the dried particles are coated with a layer of a neutral wax to further restrict mycelia access thereto.

16. An osmoprotectant particle for enhancing fungus growth substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

17. An osmoprotectant particle for enhancing fungus growth substantially as hereinbefore described with reference to Figs. 3a and 3b of the accompanying drawings.

18. A method of producing an osmoprotectant additive substantive as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

19. A method of producing an osmoprotectant additive substantially as hereinbefore described with reference to Fig. 4 of the accompanying drawings.

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