the preparation of the oil is carried out by direct pressing of a biomass containing lc - pufas and production of a first press oil . in order to increase the lc - pufa yield , the biomass cake obtained from the direct pressing is brought into contact with a carrier oil and the mixture is subjected to pressing in order to obtain a second press oil . the two pressed oils are then mixed in variable proportions so as to obtain an lc - pufa concentration which is appropriate for the specific application . the mixture is then subjected , where appropriate , to physical refining and the desired oil is thus obtained . physical refining , in the context of the invention , is aimed at a reduction in the phospholipids and the free fatty acids and is understood to mean a degumming treatment without the use of acid and without neutralization . by way of example , it was observed that in the case of a biomass containing ara , the first press oil was already free of most free fatty acids and phospholipids and , consequently , depending on the desired degree of purity , did not require degumming treatment . on the other hand , in the case of a biomass containing dha for example , such a degumming treatment was necessary in order to reduce , in particular , the phospholipids so as to obtain the desired degree of purity . the oil obtained is suitable for application in foodstuffs , in particular infant formulas or for use as a nutritional supplement . it may also be used in cosmetic or pharmaceutical products . furthermore , the biomass residue obtained is also a product of the process which may be upgraded directly without subsequent treatment , for example as animal feed , in particular for pets . the preparation of such an oil may take place by simply pressing the dried biomass . preferably , the carrier oil is mixed with the residue of the first pressing of the biomass and the oil is subsequently separated from the nonlipid solids by pressing . in order to increase the yield of lc - pufa obtained , it is preferable to reduce the sizes of the particles of dry biomass in order to break the walls of the cells of microorganisms and to thereby release the oil . it is possible , in the preferred embodiment , to reduce the sizes of the particles of the press cake in order to increase the surface area of contact between the carrier oil and the biomass residue . this may be appropriately carried out using various methods , for example : the biomass cake may be ground in the presence of the carrier oil ; the biomass cake may be laminated before mixing it with the carrier oil ; the biomass cake may be treated at high pressure in the presence of the carrier oil , and then the oil obtained may be separated from the biomass cake by pressing and final filtration ; the biomass or cake may be treated with enzymes capable of degrading the walls of the cells . because the carrier is an oil , the oil obtained after contact with the biomass cake has a minimum content of phospholipids , free fatty acids , pigments , polymers and other substances obtained or derived from the biomass which are not triacylglycerols . this means that the process according to the invention constitutes a selective method for preparing a stable purified oil containing lc - pufas . it is not necessary to purify the unsaturated oil containing the lc - pufas by the aggressive and cumbersome methods used prior to the invention such as the stages of degumming , neutralization , dewaxing and decolorization . according to the invention , the pressed oils are subjected , where appropriate , to a refining step using a processing agent , for example a silicate . the treatment with the processing agent may be carried out during contact with the carrier oil or after production of the pressed oil , for example during filtration . finally , the oils are subjected to a stage of deodorization , for example by steam distillation or molecular distillation at a relatively low temperature . the result is that the oil obtained contains a particularly small quantity of trans fatty acids . the process does not use organic solvent and , since the operation is carried out under a nitrogen layer and in the presence of tocopherols or tocotrienols which are naturally present in or which are added to the carrier oil , the lc - pufas are protected from oxidative degradation during the whole process . in addition to the quality of the oil obtained , another advantage of the process consists in the fact that the biomass residue is not contaminated with an organic solvent and may thus be directly upgraded , without subsequent treatment , for example in animal feed , in particular for pets . the detailed description of the process which follows is targeted at the preparation of an oil containing ara , an oil containing dha , and an oil containing ara and dha , taken by way of nonlimiting examples . the working conditions for transferring other lc - pufas to a carrier oil from appropriate biomasses , for example for dhgla or epa , are very similar . in the preferred implementation of the process , the oil is obtained by combining the biomass dry - pressing oil and the oil obtained by mixing the carrier oil with the dry biomass pressing residue and separating the oil from the solid components by pressing . to increase the level of incorporation of lc - pufa , it is desirable to break the microbial cells by high - pressure treatments , by enzymatic processes , or to reduce the sizes of the dry particles of biomass by grinding or laminating . the grinding step used may be one of many techniques known in the prior art . for example , the biomass may be laminated , preferably at low temperature , and then it may be mixed with the carrier oil . as a variant , the biomass may be ground in the presence of the carrier oil . in order to minimize as much as possible damage to the lc - pufas , the grinding conditions should be gentle . in this regard , grinding the biomass in the presence of the carrier oil and under an inert atmosphere , for example under a nitrogen stream , is preferred . next , the oil containing the lc - pufas is separated from the biomass cake by filtration or pressing , preferably at high pressure , and then a final filtration is carried out so as to remove the fine particles of biomass residue . it was observed that the level of incorporation of the lc - pufa increased when the size of the biomass particles decreased ; it was & gt ; 90 % when for example 90 % of the particles had a size & lt ; 250 μm . by way of example , it is possible to use a ball mill or a colloidal mill . the parameters to be considered are the duration of grinding , the size of the biomass particles , the grinding temperature , the ratio between the quantities of biomass and of carrier oil . the duration of grinding has an influence on the size of the particles and the latter is also influenced by the grinding temperature . consequently , in practice , it is preferable to indicate the size of the particles as a crucial parameter of the grinding stage . thus , it is desirable that 90 % of the particles have a size & lt ; 500 μm , preferably that 90 % of the particles have a size & lt ; 300 μm and more preferably still that 90 % of the particles have a size & lt ; 200 μm . the grinding temperature is chosen at a value greater than the melting point of the carrier oil , and is preferably from 20 to 80 ° c . the weight ratio chosen between the biomass and the carrier oil determines the content of lc - pufa of the final oil . thus , for example , 30 parts of biomass are chosen per 70 parts of carrier oil in order to obtain at least 3 . 5 % of lc - pufa in the converted oil . the oil used as carrier may be any oil or mixture of oils which can be consumed as human food . an oil or a mixture entering into the composition of the product which it is desired to enrich with pufa is preferably used . there may be mentioned in particular for an infant formula high oleic acid sunflower oil ( hosfo ), sunflower oil ( sfo ), soya bean oil , palm olein and a medium - chain triacylglycerol ( mct , containing essentially triacylglycerols of saturated c 8 - c 10 fatty acids ). the next stage of the process consists in separating the spent biomass residue by any customary method such as , for example , pressing , filtration or centrifugation . to this end , a press operating at high pressure is preferably used . the oil obtained should be made free of fine insoluble particles by fine filtration . this operation may be carried out , where appropriate , by exposing the oil to a mineral adsorbent as a filter aid , for example dicalite . finally , the filtered oil is deodorized in order to remove the volatile substances . this may be carried out by any known method provided that moderate conditions are used in order to be gentle on the lc - pufas . there may be mentioned , for example , steam distillation , preferably under vacuum , or molecular distillation . the oil obtained may be used in food compositions for human consumption as it is or in the form of a mixture with other oils such as , for example , a fish oil or such as , for example , salad oils or alternatively in the form of an emulsion in salad dressings or mayonnaises . it may be a constituent of a dietetic milk for teenagers or adults , an infant formula for premature babies , full - term unweaned babies or a follow - on milk for small children . it may be incorporated into a nutritive or supplemental composition for oral consumption . it may be incorporated into a pharmaceutical composition for oral , enteral or parenteral ingestion , or for topical , dermatological or ophthalmological application . it may constitute an ingredient for a cosmetic , topical or oral composition . finally , it may constitute an ingredient for a pet food , for example a dry or moist food or a milk . the biomass residue , after separation of the oil , may be advantageously used in animal feed , particularly for pets . the examples below illustrate the invention . therein , the parts and percentages are by weight , unless otherwise stated . to determine the % of free fatty acids ( ffa ), the iupac 2 . 201 method is used , 111 g of the biomass are introduced into a carton cartridge . the cartridge is introduced into the cylinder of the press and the whole is heated in an oven at 70 ° c . for 30 min . the pressing is then carried out by gradually increasing the pressure up to a final pressure of 700 bar . 23 . 2 g of clear pressed oil are thus recovered , which corresponds to 60 . 2 % of oil present in the biomass . the ara , free fatty acid ( ffa ) and phosphorus ( p ) content of the pressed oil is then determined and it is compared with an oil obtained after hexane extraction of the same biomass . the results are summarized in table 1 below . the oil obtained after direct pressing has an ara content similar to the oil extracted with hexane but contains less impurities ( ffa , p ). the pressed oil does not require chemical refining unlike the oil conventionally extracted with hexane . a treatment with an adsorbent ( processing agent ) followed by deodorization make it possible to obtain a stable oil having a neutral odour . 150 kg of biomass were pressed in the komet press under the following conditions : a cloudy oil is collected which is filtered using a 20 micron paper filter . 46 kg of a clear oil are thus obtained , which corresponds to 60 . 7 % of oil present in the biomass . the dha , free fatty acids ( ffa ) and phosphorus ( p ) content of the pressed oil is determined and it is compared with an oil obtained after extracting the same biomass with hexane . the results are summarized in table 2 below . the oil obtained after direct pressing has a dha content similar to the oil extracted with hexane but contains less impurities ( ffa , p ). the losses during refining are lower . treatment with an adsorbent ( processing agent ) followed by deodorization make it possible to obtain a stable oil having a neutral odour . pressed dha biomass of example 2 containing 28 . 2 % of oil containing 39 % of decosahexaenoic acid ( dha ) 1 . 4 kg of the pressed biomass as obtained in example 2 and 2 kg of palm olein are introduced into the container of the mill . the milling is carried out by direct passage through the mill with a slit of 10 microns at a temperature of 40 - 50 ° c . and the mixture is recovered . 2 . 6 kg of this mixture are introduced into the filtration unit and filtration is carried out at 50 ° c ., and then the cake is washed by injecting 0 . 5 kg of palm olein . the cake is then pressed up to a pressure of 15 bar . 2 kg of a slightly cloudy oil are thus recovered , which oil is filtered on the filter press with a 1 micron filter . the p content of the filtered oil , which is up to 66 mg / kg , is determined . the filtered oil is subjected to physical refining . with the aim of reducing the phosphorus content , the oil is stirred at 85 ° c . for 20 min with 2 % trisyl ®, and then dried at 85 ° c . under a 20 mbar vacuum and filtered . finally , the oil is deodorized at 180 ° c ./ 1 mbar for 3 hours . the refined oil is analysed in order to determine its purity ( ffa , p ) and the level of incorporation of the dha . the results are summarized in table 3 below . with the aim of obtaining a refined oil with a dha concentration of about 8 %, 50 g of pressed oil as obtained in example 2 and 500 g of pressed oil as obtained in example 3 before the refining step are mixed in the reactor . the mixture is stirred at 85 ° c . for 20 min with 2 % of trisyl ®, and then dried at 85 ° c . under a 20 mbar vacuum , and finally filtered . 540 g of a clear oil are thus recovered . 300 g of this oil are introduced into the deodorizer and treated with steam for 3 hours at 180 ° c ./ 1 mbar . the refined oil is analysed in order to determine its purity ( ffa , p ) and the dha content . the results are summarized in table 4 below . 0 . 7 kg of the biomass containing dha , 0 . 7 kg of the biomass containing ara and 2 kg of palm olein are introduced into the container of the mill . the milling is carried out by direct passage through the mill with a slit of 10 microns at a temperature of 40 - 50 ° c . and the mixture is recovered . 2 . 5 kg of this mixture are introduced into the filtration unit and filtration is carried out at 50 ° c . the cake is washed by injecting 0 . 92 kg of palm olein . the cake is then pressed up to a pressure of 15 bar . 2 . 5 kg of a slightly cloudy oil are thus recovered , which oil is filtered on the filter press with a 1 micron filter . the p content of the filtered oil , which is up to 26 mg / kg , is determined . the filtered oil is subjected to physical refining . with the aim of reducing the phosphorus content , the oil is stirred at 85 ° c . for 20 min with 1 % trisyl ®, dried at 85 ° c . under a 20 mbar vacuum and then filtered . finally , the oil is deodorized at 180 ° c ./ 1 mbar for 3 hours . the refined oil is analysed in order to determine its purity ( ffa , p ) and the level of incorporation of the dha and of the ara . the results are summarized in table 5 below . 6 . an infant formula for premature babies enriched with ara is prepared from oil prepared by the process of example 1 and a fish oil enriched with dha , containing about 24 % of dha and there are added thereto other oils , for example in the proportions indicated in table 6 below , proteins , where appropriate hydrolysed , carbohydrates , and where appropriate vitamins and trace elements . 7 . an infant formula for full - term unweaned babies enriched with ara and with dha is prepared from the carrier oil prepared by the process of example 5 and there are added thereto other oils , for example in the proportions indicated in table 7 below , proteins , where appropriate hydrolysed , carbohydrates and where appropriate vitamins and trace elements . 8 . a follow - on milk for small children enriched with dha is prepared from the carrier oil prepared by the process of example 4 , and there are added thereto other oils in the proportions indicated in table 8 below , proteins , where appropriate hydrolysed , carbohydrates and where appropriate vitamins and trace elements . a whole milk containing 3 . 92 % of fat and 8 . 58 % of solids - not - fat and a low - fat milk containing 0 . 05 % of fat and 9 % of solids - not - fat are pasteurized separately by treating them at 87 ° c . for 12 s . 34 . 69 kg of whole milk and 160 . 26 kg of low - fat milk , cooled to 15 ° c ., are then mixed , and then a premix of 0 . 77 kg of oil obtained according to example 3 ( palm olein , containing 4 . 9 % of dha ), 1 . 6 kg of soyabean oil and 1 g of vitamin e heated to 50 ° c . is incorporated into this mixture by means of a colloid mill . after heating to 80 ° c . in a plate exchanger , the liquid is uht sterilized at 148 ° c . for 5 s . after cooling at 78 ° c ., it is homogenized in two stages , at 200 bar , and then at 50 bar ; it is cooled to 20 ° c . and it is aseptically packaged in carton - type packaging which has been previously sterilized , the homogenization , cooling and filling stages taking place aseptically . the liquid is heated at 72 ° c . for 15 s in a plate exchanger ; it is homogenized in two stages at 200 bar , and then at 50 bar ; it is cooled to 4 ° c . and it is packaged in carton - type packaging . as a nutritional supplement , an oil prepared according to example 1 containing ara or an oil prepared according to example 2 containing dha is encapsulated in an amount of 500 mg of oil in gelatin capsules . it should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art . such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages . it is therefore intended that such changes and modifications be covered by the appended claims .
a stable oil containing lc - pufas in the form of triacylglycerols , in particular arachidonic acid , dihomogammalinolenic acid , docosahexaenoic acid or eicosapentaenoic acid , may be prepared by direct pressing of one or more biomasses obtained from the culture of a microorganism , especially of a fungus or of a microalga containing the acids ara , dhgla , dha or epa leading to a first press oil and by bringing a carrier oil entering into the composition of a foodstuff , a cosmetic or pharmaceutical product , into contact with the biomass cake , followed by pressing leading to a second press oil , and then by combining the pressed oils and refining the mixture under controlled conditions .