Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/64—Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
  • C12P7/6436—Fatty acid esters
  • C12P7/6445—Glycerides
  • C12P7/6472—Glycerides containing polyunsaturated fatty acid [PUFA] residues, i.e. having two or more double bonds in their backbone
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/64—Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11B—PRODUCING, e.g. BY PRESSING RAW MATERIALS OR BY EXTRACTION FROM WASTE MATERIALS, REFINING OR PRESERVING FATS, FATTY SUBSTANCES, e.g. LANOLIN, FATTY OILS OR WAXES; ESSENTIAL OILS; PERFUMES
  • C11B1/00—Production of fats or fatty oils from raw materials
  • C11B1/10—Production of fats or fatty oils from raw materials by extracting
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/64—Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
  • C12P7/6409—Fatty acids
  • C12P7/6427—Polyunsaturated fatty acids [PUFA], i.e. having two or more double bonds in their backbone
  • C12P7/6432—Eicosapentaenoic acids [EPA]
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/64—Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
  • C12P7/6436—Fatty acid esters
  • C12P7/6445—Glycerides
  • C12P7/6463—Glycerides obtained from glyceride producing microorganisms, e.g. single cell oil

Definitions

• Arachidonic acid is a major precursor of a wide variety of biologically active compounds, known collectively as eicosanoids, a group comprising prostaglandins, thromboxanes and leukotrienes.
• Arachidonic acid is also one of the components of the lipid fraction of human breast milk and is thought to be essential for optimal neurological development in infants.
• Arachidonic acid has a wide variety of different applications including use in infant formula, foodstuffs and animal feeds.
• WO-A-97/37032 refers to the preparation of a microbial PUFA-containing oil from pasteurised biomass. However, there is no disclosure of deaeration prior to pasteurisation.
• microbial cells can be pasteurised prior to extraction to a PUFA therefrom in the form of an oil.
• POV peroxide value
• AnV anisidine value
• a first aspect of the present invention therefore relates to a process for producing an oil, or a polyunsaturated fatty acid (PUFA), the process comprising:
• the deaeration of the aqueous liquid preferably results in the removal of air, such as entrained, entrapped, undissolved and/or dissolved air.
• the process may therefore effectively be, or comprise, a degassing. It may remove gas (e.g. air bubbles).
• the process will remove oxygen, such as dissolved oxygen (e.g. in an entrapped form, or as bubbles).
• oxygen such as dissolved oxygen (e.g. in an entrapped form, or as bubbles).
• dissolved refers to the gas, such as air or oxygen, being present or dissolved in the aqueous liquid (rather than any gas inside the cells).
• the deaeration process may also result in other gases being removed from the aqueous liquid, for example carbon dioxide.
• the deaeration because it can preferably remove at least part of the dissolved and/or some undissolved oxygen, can result in reduced oxidation. This may mean that the PUFA and/or the oil may be less oxidised, and therefore of better quality.
• a vacuum can be applied above the surface of the aqueous liquid.
• a true vacuum need not always be necessary, instead a preferred method involves a reduction of pressure above the surface of the aqueous liquid, for example while it is in a vessel, such as a fermenting vessel.
• the pressure above the aqueous liquid is less than atmospheric or room pressure, or at least represents a reduction in pressure when compared with the pressure inside the fermentor vessel (or pressure during fermentation). There may thus be a pressure reduction when deaeration is to begin, for example once fermentation has finished.
• the vacuum or reduced pressure may be applied in a separate vessel from the one in which fermentation took place (such as the fermentor). Liquid may therefore be transferred to a vacuum workstation, or a separate container where a vacuum is applied or can be present.
• a vacuum workstation or a separate container where a vacuum is applied or can be present.
• the reduced pressure vessel may have means for increasing the surface area of the aqueous liquid, to assist deaeration.
• the aqueous liquid may take on the form of a film, such as a thin film.
• the aqueous liquid may be forced into a film (such as a thin film) by a mechanical device, for example a nozzle, such as an umbrella nozzle, or a parasol deaerator.
• the aqueous liquid may therefore be forced onto a curved surface while reduced pressure is applied.
• the level of the aqueous liquid inside the reduced vacuum vessel (which will contain the nozzle or curved surface onto which the aqueous liquid is forced) may be from 1 to 2 tenths full.
• the then deaerated aqueous liquid may then be transferred to a pasteurisation or heating vessel or workstation.
• oxygen or (more usually) air is supplied to the aqueous liquid (culture medium or fermentation broth). This is to allow the microbial cells to grow and divide and to biosynthesise PUFAs.
• the aqueous liquid may be stirred.
• the amount of stirring (or stirring rate) may be reduced or slowed, or stopped altogether. Reduced stirring is less likely to cause cavitation, such as on or near the stirring blade or moving surface(s), and is less likely to create bubbles (in the aqueous liquid).
• Mechanical deaeration may also involve reduction in the amount of air or oxygen supplied to the aqueous liquid (fermentation broth, by means of aeration).
• the rate of air or oxygen addition may be slowed, or stopped altogether.
• the rate of air (or oxygen) supply may be reduced to no more than a half, a third, or even a quarter (such as of the rate during fermentation).
• aeration of the liquid may stop or cease before the end of fermentation (e.g. for up to 5, 2 or 1 hours).
• air or oxygen
• the gas is allowed to bubble into the aqueous liquid and this may be by means of a sparger. Deaeration may involve reduction of the rate of air or oxygen supply by means of the sparger.
• Deaeration may also be achieved by vibration where the aqueous liquid is passed through or into a (static) vibration vessel, such as a tube.
• a (static) vibration vessel such as a tube.
• the aqueous liquid maybe deaerated by using a degassing pump.
• the aqueous liquid may be subjected to accelerative forces, for example in a cyclon.
• the liquid may therefore be subjected to centrifugal force which may assist in the deaeration.
• the cyclone may rapidly rotate the aqueous liquid, and subject it to centrifugal force, in a vessel whereby the gases that escape from the liquid may rise, and may be taken out or removed from the top of the cyclone, while the liquid that has been deaerated may flow in the opposite direction (such as downwardly).
• a mechanical vacuum deaerator may be employed to deaerate the aqueous liquid.
• This may be a pump to which a vacuum (or reduced pressure) can be applied.
• Modified (e.g. centrifugal) pumps that can accept reduced pressure, or can generate a vacuum, are commercially available.
• the vacuum pump will have a rotating chamber, where gas bubbles can be removed from the aqueous liquid, for example under the action of centrifugal force.
• a reduction in viscosity may allow gasses in the aqueous liquid to surface more efficiently.
• methods of reducing the viscosity can assist in the deaeration process. This can be achieved by adding another liquid (itself deaerated, or with a lower air/oxygen content than the aqueous liquid), such as water, and so the process may comprise dilution.
• the aqueous liquid is often quite viscous due to the presence of cells and nitrogen and/or carbon sources for assimilation by cells.
• Another method of reducing viscosity is by heating the aqueous liquid. An increase in temperature decreases the solubility of oxygen in the liquid.
• Air or oxygen can be replaced by many a wide range of gases, as long as, preferably, dissolved oxygen is forced out of solution, and can then leave the aqueous liquid.
• An inert gas is preferred, for example nitrogen, or a noble gas, such as helium.
• the gas may be provided above, on top of, the aqueous liquid (such as in the headspace of the fermentor). For example, it may be added or supplied to the headspace above the liquid, for example in a vessel such as a fermentor. Alternatively, the gas can be supplied to the aqueous liquid, for example by bubbling in, or by use of the sparger.
• the preferred gas is nitrogen, although a gas comprising nitrogen (but with a reduced amount of oxygen, such as below 20% or below 10% or 15%, so it is below atmospheric levels) may be employed.
• the substance may be an oxygen scavenger.
• This substance may be brought into contact with the aqueous liquid.
• the chemical may be added to the aqueous liquid, for example while it is in a vessel, such as a fermentor vessel.
• Suitable oxygen reacting materials, including oxygen scavengers are well known in the art, and include alkali metal (such as sodium) sulphite and compounds comprising hydrazine.
• Other (non-chemical) deaeration method(s) may be used if the PUFA or oil is to be used in a foodstuff.
• the aqueous liquid will slowly give up its dissolved gases, such as oxygen and air. Dissolved gases may diffuse out of the aqueous liquid. Thus the gases may gradually, over time, come out of solution.
• gases such as oxygen and air.
• the entrained gas (gas bubbles) can be measured by compressing a sample in a measuring cell.
• the dissolved gas that may be released can be measured by expanding the sample. This simulates a sharp drop in the pressure. As the pressure in the measuring cell is reduced, the solubility of gases decreases, and are released. Thus the volume of the suspension increases.
• the operation can be fully automatic and/or may comprise an on-line gas analyzer, at an appropriate place in the system, suitably after deaeration.
• Deaeration may result in an O 2 content (in the aqueous liquid) of less than 20 or 15 ppm, for example from 2 or 5 to 15 or 20 ppm.
• concentration of the (e.g. dissolved) oxygen may be preferably less than 10, such as less than 5, and optimally less than 2 ppm.
• deaeration takes place so that the concentration of (dissolved) oxygen is less than 0.03 cc/litre (44 ppb), preferably less than 0.005 cc/litre (7 ppb).
• the deaerated aqueous liquid (obtained by deaerating the aqueous liquid comprising the cells according to the invention) may advantageously be subjected to increased pressure and/or increased temperature. Increased pressure and/or increased temperature may for instance be present during heating and/or pasteurising of the cells.
• the process according to the invention comprises subjecting the deaerated aqueous liquid to a pressure of at least 1 bara, preferably at least 1.5 bara, preferably at least 2 bara, preferably at least 5 bara. There is no specific upper limit for the pressure.
• the deaerated aqueous liquid may for instance be subjected to a pressure below 40 bara, for instance below 20 bara.
• the process according to the invention comprises subjecting the deaerated aqueous liquid to a temperature of at least 60° C., preferably at least 80° C., preferably of at least 90° C., preferably of at least 100° C., preferably at least 110° C. There is no specific upper limit for the temperature.
• the deaerated aqueous liquid may for instance be subjected to a temperature below 150° C.
• the deaerated aqueous liquid that may be subjected to the increased temperature and/or increased pressure has the preferred O 2 content and/or preferred concentration of (dissolved) oxygen as disclosed herein.
• Pasteurisation will usually take place after deaeration and/or fermentation has finished. In a preferred embodiment, pasteurisation will finish the fermentation, because the heat during pasteurisation will kill the cells. Pasteurisation may therefore be performed on the fermentation broth (or the cells in the liquid (aqueous) medium), although it can be performed on the microbial biomass obtained from the broth. In the former case, pasteurisation can take place while the microbial cells are still inside the fermenter. Pasteurisation preferably takes place before any further processing of the microbial cells, for example granulation (e.g. by extrusion) crumbling, or kneading.
• granulation e.g. by extrusion
• the fermentation broth may be filtered, or otherwise treated to remove water or aqueous liquid. After water removal, one may obtain a biomass “cake”. If pasteurisation has not taken place, then the dewatered cells (or biomass cake) can be subjected to pasteurisation.
• Pasteurisation can be performed by heating (the cells) directly or indirectly.
• the heating if direct, may be by passing steam into the fermenter.
• An indirect method may use a medium via heat exchangers, either through the wall of the fermenter, or with heating coils, or an external heat exchanger such as a plate heat exchanger.
• pasteurisation will take place in the fermenter vessel in which fermentation has occurred. However, for some organisms (such as bacteria) it is often preferred to remove the cells from the vessel first, and then pasteurise. Pasteurisation may take place before other processing of the organisms, for example drying or granulation.
• Heating or pasteurisation of the cells may be effected at any suitable temperature, preferably at a temperature of least 60° C., preferably at least 80° C., preferably at least 90° C., preferably at least 100° C., preferably at least 110° C. There is no specific upper limit for the temperature.
• the pasteurisation may for instance be effected at a temperature below 150° C. Preferred pasteurisation processes are described in WO 97/37032 and WO-A-04/001021.
• the present invention may involve extracting and/or isolating a PUFA from the (e.g. pasteurised) cells. Preferably this is after deaeration and (optionally) also after pasteurisation.
• the extraction may first start with the addition of an alkali earth metal halide, such as calcium chloride.
• the cells may (then) be subjected to filtration, washing and/or squeezing, in order to generate a wet cake.
• the microbial cells can then be subjected to extrusion, and if necessary the resulting extruded granules or extrudate, subjected to drying.
• the resulting dried granules, or dried biomass can then used to extract one of the PUFAs, preferably an oil containing one or more PUFAs.
• Preferred extraction processes for preparing an oil containing a PUFA from microbial cells are described in International Patent Application Nos. PCT/EP99/01446 (WO 97/36996), PCT/EP97/01448 (WO 97/37032) and PCT/EP01/08903 (WO 02/10423).
• the PUFA can either be a single PUFA or two or more different PUFAs.
• the or each PUFA can be of the n-3 or n-6 family. Preferably it is a C18, C20 or C22 PUFA. It may be a PUFA with at least 18 carbon atoms and/or at least 3 or 4 double bonds.
• the PUFA can be provided in the form of a free fatty acid, a salt, as a fatty acid ester (e.g. methyl or ethyl ester), as a phospholipid and/or in the form of a mono-, di- or triglyceride.
• Preferred PUFAs include arachidonic acid (ARA), docosohexaenoic acid (DHA), eicosapentaenoic acid (EPA) and/or ⁇ -linolenic acid (GLA).
• ARA arachidonic acid
• DHA docosohexaenoic acid
• EPA eicosapentaenoic acid
• GLA ⁇ -linolenic acid
• ARA is preferred.
• the PUFA may be produced by the cells pasteurised in the process of the invention, such as a microbial cell.
• This may be a bacteria, algae, fungus or yeast cell.
• Fungi are preferred, preferably of the order Mucorales, for example Mortierella, Phycomyces, Blakeslea, Aspergillus, Thraustochytrium, Pythium or Entomophthora.
• the preferred source of ARA is from Mortierella alpina, Blakeslea trispora, Aspergillus terreus or Pythium insidiosum.
• Algae can be dinoflagellate and/or include Porphyridium, Nitszchia, or Crypthecodinium (e.g.
• Yeasts include those of the genus Pichia or Saccharomyces, such as Pichia ciferii. Bacteria can be of the genus Propionibacterium.
• the microbial oil may be a liquid (at room temperature).
• the PUFA is in the form of triglycerides.
• at least 50%, such as at least 60%, or optimally at least 70%, of the PUFA is in triglyceride form.
• the amount of triglycerides may be higher, such as at least 85%, preferably at least 90%, optimally at least 93% or 95% of the oil.
• at least 40%, such as at least 50%, and optimally at least 60% of the PUFA is present at the a-position of the glycerol (present in the triglyceride backbone), also known at the 1 or 3 position. It is preferred that at least 20%, such as at least 30%, optimally at least 40% of the PUFA is at the b(2) position.
• the microbial oil may comprise at least 10, 35, 40 or 45% or more of a desired PUFA, such as arachidonic acid. It can have triglyceride content of at least 90%, such as from 92-94%. Typically, the microbial oil will have an eicosapentaenoic acid (EPA) content of below 5%, preferably below 1% and more preferably below 0.5%. The oil may have less than 5%, less than 2%, less than 1% of each of C 20 , C 20:3 , C 22:0 and/or C 24:0 fatty acids.
• the free fatty acid (FFA) content may be no more than 1.0, 0.4, 0.2 or 0.1.
• the oil may have little or no GLA and/or DGLA.
• the microbial oil may be a crude oil. It may have been extracted from the cells by using a solvent, such as an organic liquid, such as hexane or isopropanol.
• the solvent is allowed to percolate over the dried granules.
• Suitable micro-organism granulation and extrusion techniques and subsequent extraction of a microbial PUFA containing oil, are described in WO-A-97/37032.
• the solvent allows one to obtain a crude PUFA containing oil.
• This oil can be used in that state, without further processing, or it can be subjected to one or more refining steps.
• a crude oil is usually one that contains a solvent, such as a solvent used to extract the oil (e.g. hexane, or an alcohol such as isopropyl alcohol) or that has not been subjected to one (or preferably all) of the following refining step.
• a solvent such as a solvent used to extract the oil (e.g. hexane, or an alcohol such as isopropyl alcohol) or that has not been subjected to one (or preferably all) of the following refining step.
• solvent such as a solvent used to extract the oil (e.g. hexane, or an alcohol such as isopropyl alcohol) or that has not been subjected to one (or preferably all) of the following refining step.
• Suitable refining protocols are described in International patent
• the oil can be subjected to one or more refining steps which can include acid treatment or degumming, alkali treatment or free fatty acid removal, bleaching or pigment removal, filtration, winterisation (or cooling, for example to remove saturated triglycerides), deodorising (or removal of free fatty acids) and/or polishing (or removal of oil-insoluble substances). All these refining steps are described in greater detail in PCT/EP01/08902 and can be applied to the steps described in the present application mutatis mutandis.
• refining steps can include acid treatment or degumming, alkali treatment or free fatty acid removal, bleaching or pigment removal, filtration, winterisation (or cooling, for example to remove saturated triglycerides), deodorising (or removal of free fatty acids) and/or polishing (or removal of oil-insoluble substances). All these refining steps are described in greater detail in PCT/EP01/08902 and can be applied to the steps described in the present application mutatis mutandis.
• the resulting oil is particularly suitable for nutritional purposes, and can be added to (human) foods or (animal) feedstuffs. Examples include milk, infant formula, health drinks, bread and animal feed.
• the cells may be any cells from which an oil or a PUFA can be obtained.
• the cells are microbial cells.
• the microbial cells (or micro-organisms) used in the present invention can be any of those described earlier especially in the section concerning PUFAs and microbial oils. They may comprise, or be able to produce, a PUFA or microbial oil, and suitably the PUFA oil may be extracted or isolated from the cells. They may be in filamentous form, like fungi or bacteria, or single cells like yeast, algae and bacteria.
• the cells may comprise micro-organisms that are yeast, fungi, bacteria or algae.
• Preferred fungi are of the order Mucorales for example, the fungus may be of the genus Mortierella, Phycomyces, Blakeslea or Aspergillus. Preferred fungi of the species Mortierella alpina, Blakeslea trispora and Aspergillus terreus.
• yeasts are preferably of the genus Pichia (such as of the species Pichia ciferii ) or Saccharomyces.
• Bacteria can be of the genus Propionibacterium.
• the cells are from an algae, this is preferably a dinoflagellate and/or belongs to the genus Crypthecodinium or Daniella.
• Preferred algae are of the species Crypthecodinium cohnii or Daniella salina.
• the POV of the (microbial) oil is from 3 to 8 or 12.
• lower POV values can be obtained using the process of invention, and these values may be less than 10.0 or less than 8.0.
• the POV can be measured using techniques know in the art, for instance according to AOCS Cd-8-53.
• the unit (for POV) is usually meq/kg.
• the anisidine value of the (microbial) oil is from 5, 6, 7 or 10 to 15, 20 or 25.
• the AnV no more than 20, for example no more than 15. It may be no more than 10 or even no more than 5 or 2.
• AnV values ranged from 5 to15, optimally from 7 to 12.
• the AnV is from 2 or 5 to 12 or 15.
• the AnV can be measured using techniques known in the art, for instance according to AOCS Cd-18-90.
• a further aspect of the invention relates to a composition
• a composition comprising the oil and, where appropriate, or more (additional) substances.
• the composition may be a foodstuff and/or a food supplement for animals or humans.
• the oils may be rendered suitable for human consumption, if necessary, typically by refining or purification of the oil obtained from the microbes.
• the composition may be an infant formula or (human) foodstuff.
• the composition of the formula may be adjusted so it has a similar amount of lipids or PUFAs to normal breast milk. This may involve blending the microbial oil of the invention with other oils in order to attain the appropriate composition.
• the composition may be an animal or marine feed composition or supplement. Such feeds and supplements may be given to any farm animals, in particular sheep, cattle and poultry. In addition, the feeds or supplements may be given to farmed marine organisms such as fish and shell fish.
• the composition may thus include one or more feed substances or ingredients for such an animal.
• the oil of the invention may be a crude or refined oil. It can be sold directly as oil and contained in appropriate packaging, typically one piece aluminium bottles internally coated with epoxy phenolic lacquer, and flushed with nitrogen.
• the oil may contain one or more antioxidants (e.g. tocopherol, vitamin E, palmitate) each for example at a concentration of from 50 to 800 ppm, such as 100 to 700 ppm.
• Suitable compositions can include pharmaceutical or veterinary compositions, e.g. to be taken orally. or cosmetic compositions.
• the oil may be taken as such, or it may be encapsulated, for example in a shell, and may thus be in the form of capsules.
• the shell or capsules may comprise gelatine and/or glycerol.
• the composition may contain other ingredients, for example flavourings (e.g. lemon or lime flavour) or a pharmaceutically or veterinary acceptable carrier or excipient.
• defoamers are known in the art, and then the appropriate defoamer may be deployed, for example tributyl phosphate.
• the defoamer preferably of a hydrophobic nature, and may be insoluble in water. It may comprise a non-polar hydrocarbon chain, for example modified by a polar group.
• Preferred defoamers include silicone oil, paraffin, fatty alcohol alkoxylate and/or a polyglycol.
• Preferred chemical deaerators include aliphatic alcohols, fatty acid esters, fatty acid ethoxylates, fatty acid polyethers and/or fatty alcohols.
• Deaeration may have further benefits, especially if the microbial cells are to be heated, for example they need to be killed or subjected to pasteurisation.
• the cells, or the aqueous liquid may be subjected to high temperatures and/or high pressures during heating or pasteurisation. This can cause gases to suddenly or violently leave the aqueous liquid, for example it may cause cavitation in pumps during microbial cell transfer. This is undesireable as it may cause cell wall disruption, in other words break open the cells. Therefore, a prior deaeration step may reduce possible problems that may arise during high temperatures or pressures, for example during heating or pasteurisation.
• a second aspect of the invention relates to apparatus suitable for conducting the process of the first aspect.
• the second aspect may thus comprise:
• the dearation in (b) may take place while the cells are (still) inside the fermentor.
• the deaeration means may be separate (although optionally connected to) the deaeration means in (b).
• the cells and culture medium e.g. broth
• the deaerated liquid may be transferred or passed to a pasteurisation means, or a vessel in which the liquid (and cells) is pasteurised.
• Each of the means can be positioned in the order specified, in the order of the stages of the process of the first aspect.
• the aqueous liquid may be transferred from a fermentor to a (suitably tubular) heating system.
• the aqueous liquid may be (pre)heated which may in itself cause deaeration.
• the liquid may be heated to a temperature of from 40 to 80°, such as from 50 to 70°, such as from 55 to 65° C.
• the heating (or preheating stage) may therefore be part of the deaeration system.
• Deaeration may be further encouraged by the addition of water (the dilution technique) and/or steam (the gas replacement technique). Either or both of these may occur before (pre)heating.
• the aqueous liquid may be subjected to a further deaeration stage, for example vacuum or pressure reduction.
• the liquid may then be subjected to pasteurisation.
• Fermentation of a fungal biomass was conducted as described previously in the art. The fermentation was conducted in a similar fashion to that as described in WO 97/36996 (see Examples). Fermentation lasted for approximately 150-200 hours. The broth was transferred from the fermentor via a small vessel (capacity 350 litres) to the pasteurisation equipment.
• Trials were performed on fermentation broths from a number of similar fermentations with fermentation times of 150 to 200 hours.
• the dried biomass obtained from the heatshock trials was analysed for TPC (total plate count).
• the results of the TPC did not deviate from the ones measured on the broth pasteurised under standard conditions.
• the broth, once deaerated and pasteurised was used to isolate a microbial/single cell oil containing arachidonic acid (ARA).
• ARA arachidonic acid
• the arachidonic acid crude oil was recovered and analysed.
• the recovery system involved, after deaerating and pasteurising the broth, calcium chloride addition, filtration/washing and squeezing to form a wet cake. This wet cake was then extruded to form an extrudate, which was dried, and the resulting dried biomass subjected to extraction.
• Filtration was used to simulate the membrane filter press.
• a one litre “Seitz” filter was used, with a Sefar Fyltis AM 25116 cloth.
• One litre of the broth was filtered at 0.5 to 1 bar nitrogen. It was then depressurised and 0.6 times the broth volume of washwater added, not disturbing the cake during water addition. The cake was then washed at 0.5 to 1 bar, and the cake allowed to blow dry for about one minute.
• Vacuum filtration was then performed using a Pannevis labscale filtration belt filter using Pannevis cloth material. About 400 to 500 ml of broth was used, filtered to a pressure of 0.45 bara ( ⁇ 0.55 bar vacuum). Then, 0.6 times the volume of broth of washwater was added, and the cake washed at a pressure of 0.45 bara. The cake was then sucked dry.
• the biomass was then squeezed, between plates, until no more water could be removed. This was done by using cheesecloth.
• Extrusion was then performed using a meatgrinder (Victoria) extruder.
• the resulting granules were then dried using a fluidised bed drier, inlet temperature of 50° C., with the flow rate setting on “5” for 30 minutes.
• the dry matter was between 91 and 96%.
• Extraction was then performed, 100 grams of dried biomass being extracted with 500 ml of hexane at ambient temperature for 60 minutes. The hexane was decanted, and the cake washed with 250 ml of fresh hexane at ambient temperature for 30 minutes. The hexane was decanted and added to the previous extracted hexane. The extract was clarified by vacuum filtration using a glass filter.
• Evaporation involved flashing off the bulk hexane in the rotorvapor with a water bath temperature of 60 to 70° C. at 200 mbara for 5 to 10 minutes. The remaining hexane was also evaporated at the same temperature for 10 to 20 minutes at less then 100 mbara. To minimise oxidation the system was depressurised using nitrogen.
• a permanent deaeration system was installed, with an “umbrella nozzle”, at a working pressure of below 500 mbara. Transfer of the fermentation broth from the fermentator to the deaerator was by means of a low shear pump (monho pump).
• the deaeration system after fermentation but before pasteurisation, was installed using an APV deaeration system to mimic a parasol deaerator.
• the fermentor was linked to the deaerator and the broth transferred at a transfer pressure of 0.5 bar.
• the deaerator was connected to a vacuum pump. After passage through the deaerator biomass was sent (via a monho pump) to a holding tank, before being sent for pasteurisation using heatshock treatment equipment (also APV).
• the monho pump had a flow rate of 10 m 3 /hour and the pressure inside the deaerator was 400 mbara.

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