GB2142326A - Growth medium for mushrooms comprising fatty acids derived from tall oil or animal fat - Google Patents

Abstract

A growth medium for mushrooms contains from 0.01 to 10% wt of one or more fatty acids, eg tall oil fatty acids or fatty acids derived from animal fat. The fatty acids may be used in combination with other nutrients, eg aldehyde-treated protein, in which case they act as promoters for the other nutrient and are preferably present in minor proportion with respect to the other nutrient.

Description

SPECIFICATION Nutrients for mushroom culture This invention relates to nutrients for mushroom culture.

Mushrooms are normally grown in compost and it is known that growth may be stimulated by the addition of nutrients. Finding the right nutrient is not necessarily a simple matter, however.

The compost in which the mushrooms are grown will contain other micro organisms, which may compete with the mushroom mycelium for the nutrient. These other micro-organisms may, indeed, contribute to the mushroom growing process by making the compost more suitable for colonization by the mushroom mycelium but if the other microorganisms are over stimulated, the temperature of the compost may rise too high.

Another desirable quality of a nutrient is that it should be released slowly. It is commercially convenient to add the nutrient at spawning (ie when the spawn is added to the compost) or at casing (ie when the compost containing the developing mycelium is covered with peat or soil).

Too rapid a release of the nutrient may cause it to be preferentially utilised by the other microorganisms and so give rise to over heating, which can destroy the developing mycelium and thus reduce yields. Further, since the mushrooms are harvested in a series of flushes, too rapid a release may mean that insufficient nutrient is left to increase the yield of the later flushes.

Protein, particularly denatured protein, has been proposed as a nutrient for mushroom growing and it has also been proposed that a vegetable or fish oil should be mixed with the denatured protein. The vegetable or fish oil has, it is claimed, a synergistic effect and suitable vegetable oils are said to include peanut, safflower, cottonseed, soybean, corn, olive, linseed, rape seed, sesame, wheat germ, sunflower and palm oils.

All these oils, it will be noted, are vegetable seed oils and all are predominantly fatty acid triglyercides with, possibly, small amounts of mono- and di-glycerides. Fish oils are also predominantly triglyercide oils.

The Applicants have now found that fatty acids are themselves nutrients for mushroom growing, particularly as promoters for denatured protein.

According to the present invention a growth medium for mushrooms contains from 0.01 to 10% wt of one or more fatty acids by weight of dry growth medium.

The medium may conveniently be compost.

The present invention includes a method of growing mushrooms in which from 0.01 to 10% wt of one or more fatty acids is added to the growth medium.

The nutrient is preferably added at the time of spawning or, possibly, at the time of casing.

The fatty acid may contain at least four carbon atoms and more typically may have from 14 to 20 carbon atoms. While the fatty acid may be admixed with other fatty materials (eg fatty acid triglyercides, or other fatty esters or fatty alcohols) the fatty acid content is desirably at least 50% wt and, preferably, at least 90% wt.

The fatty acid may be a single fatty acid or a mixture of acids, The acid or acids may be saturated or unsaturated.

The fatty acids may be of synthetic origin but more likely sources are naturally-occuring acids dr acids derived from naturally-occuring materials by known chemical or physical treatments, eg distillation. Particularly suitable fatty acids may, thus be:1. Tall Oil-Fatty Acid Tall oil fatty acids are produced by distillation of Tall Oil resin obtained during wood pulping.

They are liquids with, typically, a free fatty acid content of 99%, 95% of the fatty acids being C18 unsaturated acids.

Further information on Tall oil resin from which the fatty acids are distilled can be found as reference 8819 in the Merck Index.

2. Animal fat derived fatty acids These may be derived from tallow or lard by pressure hydrogenation to split the glycerides followed by removal of the glycerol by vaccum distillation. By variation of the distillation, the proportions and types of fatty acids recovered can be varied. Suitable fatty acids include those produced by Unichema International and sold under the name Dairy Fat Prills by BP Nutrition (UK) Limited. Dairy Fat Prills have a melting point of 51 C minimum and a free fatty acid content of 99% (85% being saturated acids and the fatty acids being predominantly C,6 and C,8 acids).

The fatty acids may be in liquid or solid form and may be added to the growth medium in any convenient way that ensures even distribution of the nutrient throughout the growth medium e.g. thorough mixing. In the case of liquids they may be absorbed first onto an inert porous carrier and added in this form. A particularly suitable inert porous carrier may be vermiculite which may also act to slow the release of the fatty acids as described in UK Patent Application No 8317764.

In the case of solids they may be added as particles. However, as discussed in more detail in UK Patent Application No 8317764 solid fatty acids may also be mixed with an inert porous carrier and added in this form.

The precise amount of fatty acid used may vary according to the conditions of cultivation and the optimum amount may be determined by trial. It may be the sole nutrient or it may be used in combination with other nutrients. It may be particularly useful as a promoter for denatured protein, and more particularly, aldehyde-treated protein.

As indicated earlier, the amount of fatty acid may be from 0.01 to 10% wt by weight of dry growth medium, and preferably from 0.1 to 5% wt.

If used as a promoter for another nutrient, particularly denatured protein, it is preferably used in minor proportion with respect to the other nutrient (ie less than 50% by weight of the other nutrient). The other nutrient may be used in an amount of from 0.1 to 10% wt by weight of dry growth medium.

The invention is illustrated by the following example.

Example A trial was carried out to examine the effect of fatty acids as mushroom nutrients both on their own, and in combination with formaldehyde-treated protein. The results were measured against a control trial using identical conditions apart from the absence of nutrients.

The trial conditions were Compost fill--17 Ibs/sq ft of bed surface area Mushroom mycelium-5.1 5 Ibs/sq ft of bed surface area Bed surface area--8 containers each of 2+ sq ft surface area Mean growth temperature-74'F (25"C) The nutrients used were: 1. Tall Oil Fatty Acid This was produced by distillation of resin obtained during wood pulping. It was a liquid with a free fatty acid content of 99%, 95% of the fatty acids being C18 unsaturated acids.

2. Dairy Fat Prills These were manufactured by Unichema International and sold by BP Nutrition (UK) Limited.

They had the following characteristics and chemical composition: Setting point 52"C Free fatty acids 99% lodine value 12 Saponification value 207 G L C analysis: C12-C14 2% C16 45% C17 2% C18 38% C181 12% C20 1% 3. Formaldehyde-treated Protein The protein was soya bean meal (protein content 48%) which had been ground through a 2.5mm screen and which had been treated with 5000 ppm wt of formaldehyde by weight of soya bean meal.

In some of the trials the Tall Oil Fatty Acid was absorbed on vermiculite by simple mixing to a level of 50% wt of Tall Oil Fatty Acid by weight of the mixture (ie 50% wt Tall Oil Fatty Acid/50% wt vermiculite).

The vermiculite used was obtained from Mandoval Ltd.

The Tall Oil Fatty Acid was adsorbed by the vermiculite without altering the physical characteristics in any way.

The results up to and including the fifth and final flush were Yield % Increase over lbs/ft2 Control control 2.97 3% wt HCHO-treated protein 3.66 23.2 0.24% wt Dairy Fat Prills (DFP) 3.03 2.0 0.96% wt Dairy Fat Prills (DFP) 3.07 3.4 0.12% wt TOFA/Vermiculite 3.30 11.1 0.48% wt TOFA/Vermiculite 3.19 7.4 3% wt HCHO-treated protein + 0.24% wt DFP 4.31 45.1 3% wt HCHO-treated protein + 0.96% wt DFP 4.41 48.5 3% wt HCll0 treated protein + 4.80 61.6 0.12% wt TOFA/vermiculite 3% wt HOHO treated protein + 4.41 45.1 0.48% wt TOFA/vermiculite 3% wt HCHO-treated protein + 0.12% wt DFP + 4.36 46.8 0.06% wt TOFA The weight percentages were by weight of dry compost. The % wt of TOFA refers to the weight of TOFA alone, exluding vermiculite.

Claims (8)

1. A growth medium for mushrooms containing from 0.01 to 10% wt of one or more fatty acids by weight of dry growth medium.

2. A growth medium for mushrooms as claimed in claim 1 wherein the fatty acids have from 14 to 20 carbon atoms.

3. A growth medium for mushrooms as claimed in claim 1 or 2 wherein the fatty acids are tall oil fatty acids.

4. A growth medium for mushrooms as claimed in claim 1 or 2 wherein the fatty acids are derived from animal fats.

5. A growth medium for mushrooms as claimed in any of claims 1 to 4 containing from 0.1 to 10% wt of one or more other nutrients.

6. A growth medium for mushrooms as claimed in claim 5 wherein the other nutrient is aldehyde-treated protein.

7. A growth medium as claimed in claim 5 or 6 wherein the fatty acids are present in minor proportion with respect to the other nutrients.

8. A method of growing mushrooms using a growth medium as claimed in any of claims 1 to 7.