GB2557781B

GB2557781B - Edible fungus

Info

Publication number: GB2557781B
Application number: GB1803978.4A
Authority: GB
Inventors: Macdonald Behrens Christopher
Original assignee: Marlow Foods Ltd
Current assignee: Marlow Foods Ltd
Priority date: 2016-06-27
Filing date: 2016-06-27
Publication date: 2019-10-30
Anticipated expiration: 2036-06-27
Also published as: GB2551964B; GB201611140D0; GB2551964A; TW201809260A; GB201803978D0; GB2557781A; WO2018002579A1

Description

EDIBLE FUNGUS

The invention relates to edible fungus and particularly, although not exclusively, relates to a process for reducing the ribonucleic acid (RNA) content of an edible fungus and edible fungi with reduced RNA content perse.

Mycoprotein, or fungal protein, is used in many food products as a meat substitute. Mycoprotein is often derived from the fungus Fusarium venenatum (formerly classified as Fusarium graminearum) as described in WO95/23843. F.venenatum is grown by continuous or batch aerobic fermentation in a sterilised fermenter in a water and glucose solution with a continuous feed of nutrients. The rapidly growing fungal cells produce nucleic acids, such as RNA. If consumed in food products there is a concern that RNA may be broken down into purines and metabolised to uric acid which may lead to the development of gout and kidney stones.

To produce mycoprotein based food products which are more suitable for human consumption, fungus is heat treated to reduce RNA content. Guidelines indicate the nucleic acid content of a food product should not exceed about 2% by weight. Heat treatment inactivates fungal proteases and inhibitors of ribonuclease (RNAase) thus resulting in a high retention of fungal protein and effective removal of the majority of RNA by active RNAases. The waste products of RNA digestion diffuse through the fungal cell walls into the fermenter broth and are subsequently separated from the mycoprotein solids by centrifugation. WO95/23843 discloses growing Fusarium Graminaerum at 28°C in the presence of a growth medium in a continuous fermenter, with continuous aeration with sterile air containing ammonia gas. Then, to remove RNA, the culture is passed into a continuous stirred tank reactor and steam is injected into the culture to heat shock the culture and increase its temperature to an especially preferred temperature of above 72°C. As a consequence, RNA passes from the fungus to the growth medium and treated fungus, with reduced RNA, can be isolated downstream.

The yield of the process described in relatively low (about 70%). It is an object of the present invention to address this problem.

In addition, the energy required to raise the temperature of the culture to the preferred temperature of above 72°C is significant. It is an object of preferred embodiments of the invention to reduce energy consumption in a process of the type described.

As described hereinafter, biomass separated and/or isolated in a method described herein is different compared to biomass produced in a comparative process. In this regard, the size of filamentous fungus in said biomass is greater than that produced in a comparative process. In addition, it is advantageously found that use of the method leads to an improved yield of biomass compared to the yield produced in a comparative process. Said biomass suitably has any feature of the biomass of the first aspect. Said biomass may include filamentous fungus with filament lengths which are, on average, longer than may be produced in processes different from a comparative process as discussed herein.

According to a first aspect of the invention, there is provided a biomass per se, said biomass comprising a filamentous fungus, wherein said biomass is isolated from a mixture comprising said biomass and a liquid, wherein said liquid comprises particles of filamentous fungus, wherein particles in said liquid have one or more of the following characteristics (measured by laser diffraction as herein described): a median size of less than 1.3 pm, for example less than 1.1 pm; a mean size of less than 1.4 pm, for example less than 1.2 pm; a mode size of less than 1.4 pm, for example less than 1.2 pm; a D (v, 0.1) of less than 0.85 pm; a D (v, 0.5) of less than 1.20 pm; a D (v, 0.9) of less than 1.5 pm, for example less than 1.2 pm; wherein said filamentous fungus consists essentially of cells of Fusarium venenatum A3/5.

Particles in said liquid preferably may include at least two, preferably at least four, more preferably each of the characteristics described.

The median size may be at least 0.5 pm. The mean size may be at least 0.5 pm.The mode size may be at least 0.5 pm. The D (v, 0.1) size may be at least 0.4 pm. The D (v, 0.5) size may be at least 0.4 pm. The D (v, 0.9) size may be at least 0.5 pm.

Suitably the median, mean and/or mode particle sizes of filaments of said filamentous fungus in said biomass is greater than the median, mean and/or mode particle sizes in said liquid.

Suitably, the total weight of RNA in said liquid (within the filamentous fungus or otherwise contained in the liquid) is greater than the total weight of RNA in said biomass.

The total weight of filamentous fungus in said biomass divided by the total weight of filamentous fungus in said liquid is suitably greater than 2.3.

Said biomass may include at least 20wt% water; it may include 30wt% water or less.

Preferably, said biomass includes at least 5kg, for example at least 50kg of filamentous fungus.

Said biomass, said mixture and said liquid may independently have any features described herein.

In an embodiment, the biomass of the first aspect may be produced in a method of reducing the level of RNA in a biomass comprising filamentous fungus, the method comprising the following steps: (i) heating said biomass, downstream of a fermenter in which filamentous fungus is produced, to a first temperature; (ii) subsequently heating the biomass to a second temperature greater than the first temperature to facilitate release of RNA from cells of said filamentous fungus; (iii) separating said biomass comprising filamentous fungus from other components, for example from other components in a mixture produced in step (ii) which suitably contains said filamentous fungus having a reduced level of RNA compared to the level in the biomass heated in step (i).

The first heating of said biomass comprising filamentous fungus downstream of said fermenter suitably comprises heating said biomass to said first temperature as described. The method preferably does not involve any heating (e.g. active heating) of said biomass downstream of said fermenter prior to heating of it to said first temperature.

Heating said biomass in step (i) preferably uses a first heating device. The first heating of said biomass comprising filamentous fungus downstream of said fermenter suitably comprises heating said biomass to said first temperature using said first heating device. Suitably, no other heating device is positioned between an outlet of said fermenter (via which said biomass of filamentous fungus passes downstream) and said first heating device.

The first heating of said biomass in step (i) preferably does not involve direct contact of said biomass with any heated fluid; the first heating preferably does not involve direct contact of said biomass with steam.

In step (i), said biomass may be heated to increase its temperature by at least 20°C, for example by at least 25°C. The temperature may be increased by less than 40°C, for example by less than 36°C.

In step (i), said biomass may take at least 2 minutes, for example at least 2.5 minutes to reach said first temperature, after contact with said first heating device. Said biomass may reach said first temperature in less than 20 minutes, preferably in less than 12 minutes, after contact with said first heating device.

Said first temperature may be at least 40°C, preferably at least 45°C, more preferably at least 50°C, especially at least 55°C. Said first temperature may be less than 68°C, preferably less than 65°C, more preferably less than 63°C, especially 61 °C or less.

Step (i) may be undertaken in a receptacle (A), for example a pre-heat vessel, which suitably has an inlet positioned downstream of said fermenter, there being a conduit (A) positioned between said fermenter and said inlet for transfer of biomass from said fermenter to said receptacle (A).

Heating in step (i) suitably involves contact of the biomass with a heat source which has a maximum temperature which is less than 100°C, less than 95°C or less than 91 °C. Heating may involve contact of biomass with a heat source which has a temperature of at least 60°C, preferably at least 76°C.

Heating in step (i) suitably involves subjecting biomass to a temperature which is no greater than 99°C, preferably no greater than 95°C, especially no greater than 91 °C. Heating may involve subjecting biomass to a temperature of at least 55°C, preferably at least 75°C.

Preferably, step (i) comprises heating said biomass using a solid body which suitably contacts said biomass. Said solid body is preferably arranged to conduct heat to said biomass. When step (i) is undertaken in a receptacle (A), a heat exchanger is suitably associated with said receptacle (A) for transferring heat to said biomass. Step (i) of said method preferably does not involve contact of said biomass with a fluid, for example steam, for heating the biomass to said first temperature.

In step (i), said biomass is preferably heated, at least in part, by a material, for example fluid, which is generated in said process, for example downstream of step (i) and/or downstream of receptacle (A). Preferably, heat is conducted from said fluid to said biomass; and suitably the fluid does not directly contact and/or is not mixed with said biomass. In step (i), said biomass may be heated by a material which is produced by and/or subsequent to heating of the biomass to said second temperature in step (ii). Preferably, said material, for example fluid, which is generated in said process is introduced into a heat exchanger which is suitably associated with receptacle (A) as described.

Preferably, in the method, no additive (e.g. to adjust pH or dilute the biomass) is contacted with the mass of material during its passage from the fermenter to an inlet of receptacle (A), wherein said biomass is heated to said first temperature. Thus, the composition of said biomass in conduit (A) positioned between said fermenter and said inlet of receptacle (A) and in receptacle (A) itself is substantially constant and/or unchanged.

In step (ii) of the method, said biomass may be heated to increase its temperature by at least 2°C, preferably at least 4°C, more preferably at least 6°C. It may be heated to increase its temperature by less than 20°C, preferably less than 15°C, more preferably less than 12°C.

Said second temperature may be at least 60°C, preferably at least 62°C, more preferably at least 64°C. It may be less than 68°C, for example less than 67°C.

Heating of the biomass in step (ii) may involve contact (e.g. direct contact) of a heated fluid, for example steam with the biomass. When step (i) takes place in a receptacle (A), heating in step (ii) suitably takes place downstream of said receptacle (A). It may take place in a conduit (B) which is downstream of and communicates with receptacle (A). Conduit (B) may be arranged to deliver biomass to a RNA removal receptacle.

Heating of biomass in step (ii) preferably utilises steam at greater than 100°C for example at greater than 120°C or greater than 140°Cata pressure of greater than 3barg (300 KPa) or greater than 5barg (500 Kpa).

In the method, said biomass may be held at said second temperature (e.g. within the range 60 to 67°C, for example 64 to 66°C), for at least 10, at least 20 or, preferably at least 30 minutes. It may be maintained at said temperature for less than 2 hours for example less than 1 hour.

Subsequent to step (ii), and suitably downstream of said RNA removal receptacle (when provided), said biomass may be contacted with a heated fluid, for example steam, for example for hygienic reasons.

In step (iii), said biomass may be treated to remove fluid (e.g. primarily water), thereby to produce a biomass which includes a lower level of fluid (e.g. water). After treatment, said biomass may include less than 40wt%, preferably less than 30wt%, for example less than 25wt% water.

Step (iii) may comprise centrifuging said biomass. Step (iii) may comprise isolating dewatered biomass.

The fluid (e.g. comprising water) removed in step (iii) (e.g. supernatant produced by centrifuging as described) may be relatively hot. For example, it may have a temperature of greaterthan 50°C, greater than 60°C or greater than 70°C. The temperature of the fluid (e.g. comprising water) may be less than 90°C. Preferably, the fluid (e.g. comprising water) removed is used to heat the biomass in step (i). It is suitably arranged to heat the biomass to said first temperature. In a preferred embodiment, except for ambient heat, no heat source other than fluid (e.g. comprising water) removed in step (iii) is used to heat said biomass to said first temperature.

When heating said biomass in step (i) uses a first heating device, fluid (e.g. comprising water) removed in step (iii) may be a component of said first heating device.

When step (i) is undertaken in a receptacle (A) with which a heat-exchanger is associated, fluid (e.g. comprising water) removed in step (iii) is preferably directed into said heat exchanger for transferring heat to said biomass. Downstream of said heat exchanger, fluid (e.g. comprising water) removed in step (iii) may be discarded as waste.

Said biomass (e.g. dewatered biomass) may, after separation in step (iii), include less than 82 wt%, for example less than 80 wt% water; and suitably includes at least 18 wt%, preferably at least 20 wt% of mycoprotein (on a dry matter basis).

After step (iii), said biomass (e.g. dewatered biomass) may include less than 2 wt% of RNA on a dry matter basis.

Said filamentous fungus preferably comprises fungal mycelia and suitably at least 80 wt%, preferably at least 90 wt%, more preferably at least 95 wt% and, especially, at least 99 wt% of the fungal particles in said formulation comprise fungal mycelia. Some filamentous fungi may include both fungal mycelia and fruiting bodies. Said fungal particles preferably comprise a filamentous fungus of a type which does not produce fruiting bodies.

Said filamentous fungus preferably fungus selected from fungi imperfecti.

Fusarium venenatum A3/5 (formerly classified as Fusarium graminearum) is described by references IMI 145425; and ATCC PTA-2684 and is deposited with the American Type Culture Collection, 10801 University Boulevard, Manassas, VA.).

Said filamentous fungus in said biomass heated in step (i) may comprise filaments having lengths of less than 1000 pm, preferably less than 800pm. Said filaments may have a length greater than 100pm, preferably greater than 200pm. Preferably, fewer than 5wt%, preferably substantially no, filaments in said biomass have lengths of greater than 5000pm; and preferably fewer than 5wt%, preferably substantially no filaments have lengths of greater than 2500pm. Preferably, values for the number average of the lengths of said filamentous fungus in said formulation are also as stated above.

Said filamentous fungus in said biomass heated in step (i) may comprise filaments having diameters of less than 20pm, preferably less than 10pm, more preferably 5pm or less. Said filaments may have diameters greater than 1pm, preferably greater than 2pm. Preferably, values for the number average of said diameters of said fungal particles in said formulation are also as stated above.

Said filamentous fungus in said biomass heated in step (i) may comprise filaments having an aspect ratio (length/diameter) of less than 1000, preferably less than 750, more preferably less than 500, especially of 250 or less. The aspect ratio may be greater than 10, preferably greater than 40, more preferably greater than 70. Preferably, values for the average aspect ratio of said filamentous fungus (i.e. the average of the lengths of the particles divided by the average of the diameters of the said filamentous fungus in said formulation are also as stated above.

Said filamentous fungus may be grown in said fermenter. It may be grown in a continuous or batch aerobic fermentation. Fermentation may utilise water and glucose and other nutrients.

In step (i) of the method, heating of said biomass is suitably undertaken with said filamentous fungus in the presence of its growth medium. Immediately prior to said heating, the filamentous fungus is preferably in a viable state.

During step (i) of the method, preferably the pH of the biomass is not adjusted by addition of any pH adjusting material, for example acidic or alkaline material. Preferably, during step (ii) of the method, the pH of the biomass is not adjusted by addition of any pH adjusting material, for example acidic or alkaline material Preferably, during step (iii) of the method, the pH of the biomass is not adjusted by addition of any pH adjusting material, for example acidic or alkaline material. Preferably, from heating biomass in step (i) to separating biomass in step (iii), the pH of the biomass is not adjusted by addition of any pH adjusting material, for example acidic or alkaline material. For the avoidance of doubt, steam/water per se is not regarded as a pH adjusting material.

Said method is preferably carried out using an apparatus comprising: (a) said fermenter; (b) a said first heating device for heating said biomass in step (i); (c) a said receptacle (A), for example a pre-heat vessel, there being a said conduit (A) between said fermenter and said receptacle (A) for transferring fluid from said fermenter to receptacle (A); (d) a said conduit (B) which communicates with an outlet of said receptacle (A); (e) a said RNA removal receptacle downstream of said conduit (B); (f) a centrifuge for centrifuging biomass in step (iii), said centrifuge being downstream of said RNA removal receptacle; (g) a conduit for circulating centrate removed from biomass (e.g. by centrifugation) to said first heating device, for example a heat-exchanger, for heating said biomass in step (i).

As described hereinafter, the biomass separated and/or isolated in the method of the first aspect is different compared to biomass produced in a comparative process. In this regard, the size of filamentous fungus in said biomass is greater than that produced in a comparative process. In addition, it is advantageously found that use of the method leads to an improved yield of biomass compared to the yield produced in a comparative process. Thus, the invention extends, in a second aspect, to a product obtained by the process of the first aspect. In the second aspect, there is suitably provided a biomass produced in said method of said first aspect. Said biomass suitably has any feature of the biomass of the first aspect. Said biomass may include filamentous fungus with filament lengths which are, on average, longer than may be produced in processes different from the comparative process of the first aspect and/or as discussed herein.

In an embodiment, a method of making a foodstuff for human consumption may comprise: (i) selecting a biomass made as described herein; (ii) contacting the biomass with other ingredients to define the foodstuff.

Said foodstuff is suitably a meat-substitute. It may be in the form of, for example, mince, burger, sausage or meat-like pieces or strips.

Said other ingredients may comprise any meat-free food ingredients. Said ingredients may include one or more meat-free fillers, flavours, oils, fats, proteins or vegetables.

Said method may comprise packaging the foodstuff, for example in a substantially airtight and/or fluid tight package.

In the method, at least 5kg, for example at least 100kg of said foodstuff may be made.

In an embodiment, a foodstuff comprising a biomass as described and other ingredients may include at least 1wt%, for example at least 5wt% of other ingredients. Said foodstuff may include at least 10wt% water.

Embodiments of the present invention will now be described by way of example only, with reference to the following figures, in which:

Figure 1 is a schematic diagram showing a currently used process for producing mycoprotein paste with reduced RNA levels by direct steam injection;

Figure 2 is a schematic diagram showing the steps involved in producing mycoprotein paste with reduced RNA levels using an alternative process;

Figure 3 is a graph comparing yields of mycoprotein obtained using the processes of Figures 1 and 2 over a period of days;

Figure 4 is a particle size analysis graph for waste centrate produced in the process of Figure 1; and

Figure 5 is a particle size analysis graph for waste centrate produced in the process of Figure 2.

The following material is referred to herein.

Mycoprotein paste - refers to a visco-elastic material comprising a mass of edible filamentous fungus derived from Fusarium venenatum A3/5 (formerly classified as Fusarium graminearum Schwabe) (IMI 145425; ATCC PTA-2684 deposited with the American type Culture Collection, 12301 Parklawn Drive, Rockville Md. 20852). It typically comprises about 23-25wt % solids (the balance being water) made up of non-viable RNA reduced fungal hyphae of approximately 400-750 pm length, 3-5 pm in diameter and a branching frequency of 2-3 tips per hyphal length.

Unless otherwise stated herein, particle size analysis is undertaken by laser diffraction, for example using a Horiba (Trade Mark) LA950WET particle size analyser.

Referring to Figure 1, an existing current, commercially-used process 100 (the full details of which have not been published) for producing a mycoprotein paste involves growing a fungal culture in a pressure cycle fermenter 110 at 27°C in the presence of a growth medium. The culture broth passes from the fermenter 110 through a conduit 111 into an RNA reduction vessel 120. Steam (at 7barg (700 KPa) and 160°C) is injected into the culture broth via a steam injection port 112 in the conduit 111. Steam injection raises the temperature of the culture broth to 60-70°C. Steam injection is performed to reduce the RNA content of the final mycoprotein paste 140.

The RNA reduction vessel 120 is a continuously stirred tank reactor. The culture broth is held in the RNA reduction vessel 120 at the RNA reduction temperature for at least 30 minutes. The culture broth then passes from the RNA reduction vessel 120 to centrifuges 130 via a conduit 121. Steam is injected into the culture broth via a steam injection port 122 in the conduit 121. This injection of steam increases the temperature of the culture broth to 80-90°C for hygienic purposes. The centrifuges 130 are run at 5000g for a period of time. The centrifuges 130 separate the mycoprotein paste 140 and waste liquid centrate. The mycoprotein paste leaves the centrifuges 130 via conduit 131. The waste liquid centrate contains RNA and digestion products of RNA that have passed out of the fungal cells into the surrounding aqueous media. The waste liquid centrate, which at this stage has a temperature of 80-90°C, passes through conduit 132 to a cooler 150 in which it is cooled to 30°C. It then travels through conduit 151 to an effluent treatment plant (ETP) 160 for disposal. The final mycoprotein paste 140 has a nucleic acid content of less than 2% on a dry weight basis.

An alternative process for reducing the level of RNA is shown in Figure 2. Referring to the figure, a fungal culture is grown in a pressure cycle fermenter 210 at27°C in the presence of a growth medium. The culture broth passes through a conduit 211 from the fermenter 210 to a pre-heat vessel 220. The culture is pre-heated to 55-60°C (and maintained at the temperature for about 3 to 8 minutes) by waste liquid centrate which is produced further downstream in the process 200, as described below. The waste liquid centrate is passed through a heat exchanger (not shown) associated with vessel 220; the waste liquid centrate does not contact the culture directly. The pre-heated culture broth then passes along a conduit 221 to an RNA reduction vessel 230. During this passage, steam (at 7barg (700 KPa) and 160°) is injected into the culture broth via a steam injection port 222 in the conduit 221. Steam injection raises the temperature of the culture broth to 64-66°C. The culture broth is held at this temperature in the vessel 230 for at least 30 minutes. The culture broth then passes from the RNA reduction vessel 230 to centrifuges 240 via a conduit 231. During this passage, steam (at 7barg (700 KPa) and 160°) is injected into the culture broth via a steam injection port 232 in the conduit 231. This injection of steam increases the temperature of the culture broth to 80-90°C for hygienic purposes.

The centrifuges 240 are run at approximately 5000g and are arranged to separate the mycoprotein paste 250 and waste liquid centrate. Downstream of the centrifuges 240, the mycoprotein paste 250 passes through conduit 241 and is isolated. The waste liquid centrate, which has a temperature of 80-90°C, passes through conduit 242 to a heat exchanger associated with the pre-heat vessel 220. Thus, the centrate is used to heat the culture broth in the pre-heat vessel 220.

After heating the pre-heat vessel via the heat exchanger, the waste liquid centrate, which at this stage has a temperature of40-50°C, passes through conduit 243 to a cooler 260. The centrate, containing waste RNA and waste RNA digestion products, is cooled to 30°C and travels through conduit 261 to an effluent treatment plant (ETP) 270 for disposal.

The following examples illustrate differences in products produced following processes described above with reference to Figures 1 and 2.

Example 1 - Assessment of yields

The yields of mycoprotein paste 140 and 250 achieved using the Figure 1 and Figure 2 processes respectively were assessed. In this regard, the respective pastes 140 and 250 were dried after isolation by heating to cause evaporation of water. The % solid mycoprotein recovered was calculated by comparing the weight of mycoprotein recovered at 140 and 250 to the weight exiting the fermenters 110 and 210 respectively. Results are presented graphically in Figure 3, wherein the % solids recovered is plotted on the y axis and the time of sample collection (in days) is plotted on the x axis. Example 1(a) (comparative) illustrates the yield obtained using the process described with reference to Figure 1; and example 1(b) illustrates the yield obtained using the process described with reference to Figure 2.

Figure 3 illustrates the increased yield achieved through use of the Figure 2 process (Example 1(b)) compared to the Figure 1 process (Example 1 (a)). The increase in yield is about a 5% increase which is commercially very significant. Furthermore, it is found for both the Figure 1 and Figure 2 processes that the RNA content is less than 1.7% RNA, on a dry weight basis. Thus, use of the Figure 2 process is able to reduce the level of RNA in the mycoprotein paste to an acceptable level and is found to produce a significant increase in yield.

Example 2 - Assessment of centrates produced using the Figure 1 and Figure 2 processes

The centrates produced by centrifugation in Figures 1 and 2 were isolated downstream of centrifuges 130 and 240 and particle size analysis of mycoprotein fragments in the centrate was undertaken.

Results of the particle size analysis for centrate produced as described with reference to the Figure 1 process (Example 1(a)) and produced with reference to the Figure 2 process (Example 2(b)) are provided in Figures 4 and 5 respectively. In addition, the table below details results forthe centrate of the figures 1 and 2 embodiments.

It appears from the Figure 4 and Figure 5 data that the centrate produced in the process described with reference to Figure 1 has a greater number of, and a larger number of, broken

pieces of hyphae than in the centrate produced in the process described with reference to Figure 2. This fact can be used to explain the different yields achieved using the processes of Figures 1 and 2. In this regard, it appears the process described with reference to Figure 1 causes greater damage to mycoprotein filaments (e.g. a greater number of breakages of mycoprotein filaments) compared to use of the Figure 2 process. As a result, more larger fragments of filaments are broken off using the Figure 1 process, compared to use of the Figure 2 process, and such larger fragments are observable in the centrate - hence particle sizes of fragments in the Figure 4 centrate are greater than in the Figure 5 centrate.

It also follows, by inference, that the filaments in the mycoprotein produced in the process described with reference to Figure 2 will be less damaged than those produced by the process described with reference to Figure 1. Thus, it follows that the use of the processes described with reference to Figures 1 and 2 produces mycoprotein pastes which are different (at least in terms of the respective size distributions of the filaments). In addition, as already described, use of the process of Figure 2 advantageously produces an increased yield.

In addition to the advantages of use of the Figure 2 process compared to the Figure 1 process in terms of the yield and filaments sizes, use of the Figure 2 process leads to significant energy savings by using waste liquid centrate in conduit 242 to pre-heat the culture broth in pre-heat vessel 220. More particularly, about 65% less steam is used in the figure 2 method compared to the figure 1 method.

Claims

Claims 1 A biomass comprising a filamentous fungus, wherein said biomass is isolated from a mixture comprising said biomass and a liquid, wherein said liquid comprises particles of filamentous fungus, wherein particles in said liquid have one or more of the following characteristics (measured by laser diffraction as herein described): a median size of less than 1.3 pm, for example less than 1.1 pm; a mean size of less than 1.4 pm, for example less than 1.2 pm; a mode size of less than 1.4 pm, for example less than 1.2 pm; a D (v, 0.1) of less than 0.85 pm; a D (v, 0.5) of less than 1.20 pm; a D (v, 0.9) of less than 1.5 pm, for example less than 1.2 pm; wherein said filamentous fungus consists essentially of cells of Fusarium venenatum A3/5.
2. A biomass according to claim 1, wherein particles in said liquid include each of the characteristics described.
3. A biomass according to claim 1 or claim 2, wherein the median size is at least 0.5 pm, the mean size is at least 0.5 pm and the mode size is at least 0.5 pm.
4. A biomass according to any preceding claim, wherein the D (v, 0.1) size is at least 0.4 pm, the D (v, 0.5) size is at least 0.4 pm and the D (v, 0.9) size is at least 0.5 pm.
5. A biomass according to any preceding claim, wherein the median, mean and mode particle sizes of filaments of said filamentous fungus in said biomass are greater than the median, mean and/or mode particle sizes in said liquid.
6. A biomass according to any preceding claim, wherein the total weight of RNA in said liquid is greater than the total weight of RNA in said biomass.
7. A biomass according to any preceding claim, wherein the total weight of filamentous fungus in said biomass divided by the total weight of filamentous fungus in said liquid is greater than 2.3.
8. A biomass according to any preceding claim, wherein said biomass includes at least 20wt% water; and it includes 30wt% water or less.
9. A biomass according to any preceding claim, wherein said biomass includes at least 5kg of filamentous fungus.
10. A biomass according to any preceding claim wherein particles in said liquid have each of the following characteristics (measured by laser diffraction as herein described): a median size of less than 1.1 pm; a mean size of less than 1.2 pm; a mode size of less than 1.2 pm; a D (v, 0.1) of less than 0.85 pm; a D (v, 0.5) of less than 1.20 pm; a D (v, 0.9) of less than 1.2 pm.