EP2528453A1

EP2528453A1 - Method for reactively crushing jatropha seeds

Info

Publication number: EP2528453A1
Application number: EP11706876A
Authority: EP
Inventors: Jean-Luc Dubois; Julien Magne; Antoine Piccirilli
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2010-01-26
Filing date: 2011-01-26
Publication date: 2012-12-05
Also published as: MX2012008616A; FR2955589A1; CN102802433A; AP3670A; WO2011092430A1; CN107011990A; FR2955589B1; BR112012018633A2; AP2012006452A0; US20130052328A1

Abstract

The present invention relates to a method for reactively crushing jatropha seeds, said method making it possible, starting with specifically conditioned jatropha seeds in the presence of light alcohol and a basic catalyst, to carry out, in a single step, the crushing as well as the reaction for transesterifying the triglycerides present in the jatropha oil, thus causing an oil cake, glycerol, and fatty acid esters to be simultaneously produced. The method for processing the jatropha seeds, according to the invention, makes it possible to inactivate, in a simple, low-cost manner, the phorbol esters in addition to the curcine, thus enabling humans to handle the seeds without risk and moreover use the castor oil cake in animal feed. Characteristically, the seeds are conditioned by a series of operations that include a step of pressing the seeds and a step of drying same.

Description

PROCESS FOR REACTIVE TRITURATION OF JATROPHA SEEDS

The present invention relates to a process for the reactive trituration of Jatropha seeds which makes it possible, starting from specifically conditioned Jatropha seeds and in the presence of light alcohol and basic catalyst, to carry out in a single step the trituration and the transesterification reaction. triglycerides present in the oil Jatropha, to lead to the simultaneous obtaining of a cake, glycerol and fatty acid esters. These are mainly intended for the manufacture of biodiesel. In addition, the process according to the invention makes it possible to obtain a completely detoxified cake. The cakes obtained by the method of treating Jatropha seeds (in particular Jatropha curcas L.) according to the invention retain a nutritional interest and can be directly used in animal feed, without constituting a risk to the health of the people who handle them. .

It is known to prepare fatty acid esters from oleaginous plant seeds in two stages, namely an oil extraction step in the presence of a solvent and a transesterification step of this oil in the presence of alcohol and catalyst, resulting in obtaining an ester phase and a glycerol phase.

The genus Jatropha includes several species known for the irritating properties of their seeds in humans and animals. These are tropical plants grown in Latin America, Asia and Africa and used mainly as hedges. Their potential nutritional and technical applications, including soil erosion control and biodiesel preparation, are now limited by their toxicity.

Jatropha seeds are rich in oil and protein, but they are highly toxic and incompatible with human or animal consumption. The toxic and anti-nutritional compounds of Jatropha include curcine (a lectin), fiavonoids, trypsin inhibitors, saponins, phytates and phorbol esters. Lectin and the activity of trypsin inhibitors can be removed by heat treatment. The high concentrations of phorbol esters, which are thermally stable, remain the main source of toxicity of the oil extracted from Jatropha seeds and cakes. Indeed, this family of compounds is known for its adverse biological effects in humans and animals, particularly in the inflammation and the promotion of tumors. Phorbol esters do not induce tumors by themselves. same, but facilitate the growth of tumors after exposure to doses considered as non-carcinogenic of a carcinogenic compound.

The phorbol ester content varies among the different varieties of Jatropha, as shown by the study by Makkar H. P. S et al. J. Agric. Food Chem. 45: 8, 1997, 3152-3157. The data presented in Table 4 show that these compounds were detected in most varieties tested. There is a variety where phorbol esters are almost absent, Jatropha grown in Mexico, while other varieties are more or less rich in these compounds (especially Jatropha from Kenya or Nicaragua).

The use of Jatropha meal in animal feed can only be ensured if the elimination of toxic and anti-nutritional compounds can be guaranteed. The toxic effects of Jatropha seeds on animals appear to be dose-related, as shown in the publication of S.E.I. Adam, Toxicol. 2: 67-76, 1974. The data presented in Table 1 of Vet. Pathol. 16: 476-482, 1979 show that death of animals fed Jatropha seeds occurs after several days, probably due to a cumulative effect of the toxic compounds.

The publication of W. Haas and M. Mittelbach, Ind. Crops Prod. 12 (2000), 111-118 discloses a method of assaying phorbol esters in Jatropha oil as well as various treatments of the oil. It is shown that conventional treatments for degumming and deodorizing the oil have a small influence on the concentration of these compounds, while deacidification and bleaching can reduce the phorbol ester content by up to 55%. which remains insufficient.

Various methods of detoxification of Jatropha have been tested.

Heating the Jatropha seeds at 160 ° C for 30 minutes does not eliminate the phorbol esters (Aregheore E.M. et al., S. Pac J. Nat Sci 21: 50-56, 2003).

Steam injection into the protein extracts obtained from delipid cake for 10 min at about 92 ° C removed the phorbol esters (Devappa RK and Swamylingappa B., J. Sci., Food Agric., 88: 911). -919, 2008). Nevertheless, this method consumes a great deal of energy and leads to isolating the proteins from the meal which is depleted in constituents of nutritional interest.

Extraction with 90% ethanol followed by treatment of the Jatropha cake with NaHCO 3 at 121 ° C. for 20 minutes made it possible to reduce by almost 98% the level of phorbol esters (Martinez-Herrera J. et al. , Food Chem 96 (2006), 80-89). A basic treatment (aqueous solution of soda or lime at 2%), followed by a heat treatment at 121 ° C. for 30 minutes, carried out on Jatropha cakes, made it possible to reduce their phorbol esters content by 89%. but the detoxification is not complete (Rakshit KD et al., Food Chem Toxicol 46 (2008): 3621-3625).

Other plants contain in their seeds similar toxic compounds, including phorbol esters which are naturally present in many plants of the families Euphorbiaceae and Thymelaeaceae. By way of example, mention may be made of Euphorbia lathyris (mole grass or purge) and Croton tiglium (cathartic croton) of the Euphorbiaceae family, or Bertholletia excelsa (Brazilian walnut), Prunus dulcis (almond tree), Gossypium hirsutum ( cotton), Linum usitatissimum (flax), Ceiba pentandra (kapok), Sapium indicum, S. japonicum, Euphorbia frankiana, E. cocrulescence, E. ticulli, Croton spareiflorus, C. ciliatoglandulifer, Excoecaria agallocha and Homalanthus mutans. The detoxification process of the seeds that are the subject of the invention is generalizable to all these plants.

It is therefore desirable to have a method of treating seeds of Jatropha, and more generally of any seed containing toxic compounds such as phorbol esters and / or curcine or other toxic proteins such as crotin (present in particular in the seeds of Croton tiglium) and abrin (in the seeds A'Abrus precatorius), said method for inactivating, in a simple and inexpensive way these toxic compounds, which would then make possible on the one hand, safe handling by humans and, on the other hand, the use of the meal, especially Jatropha, in animal feed. This is particularly important for the economies of the major producing countries of Jatropha oil (India, Madagascar, Brazil), because if Jatropha oil has multiple industrial uses, Jatropha oilcake can not yet find use on an industrial scale, particularly because of the toxicity problems mentioned above.

The present invention proposes to provide a Jatropha seed treatment method which limits the number of seed processing steps and the handling of the cake, for continuous industrial application to produce fatty acid esters. , and that allows to destroy "at the source" the toxin (curcine) and the phorbols esters present in the Jatropha seeds, if possible by maintaining a nutritional value to the cake. The other advantage of the process versus the conventional processes lies in the small amounts of water used. The refining operations of raw oil for example are very greedy in water. This water saving is a major asset in the development of this technology in developing countries and to a lesser extent in rich countries as water tends to become an increasingly expensive commodity.

For this purpose, the subject of the invention is a process for treating seeds containing toxic components such as curcine, abrin, crotin and / or phorbol esters, in particular Jatropha seeds, said seeds preferably having a level of acidity less than or equal to 3 mg KOH / g, said process comprising the following steps:

i) a step of conditioning the seeds;

ii) a step of contacting the conditioned seeds with an anhydrous light alcohol and an alkaline catalyst under conditions of temperature and duration sufficient to allow the simultaneous extraction and transesterification of the vegetable oil and leading to the production of a mixture comprising esters of fatty acids and glycerol, and a cake.

The method according to the invention makes it possible to react "in planta" the light alcohol with the oil contained in the heart of the seed. In this process, the alcohol plays both the role of solvent and reagent.

Typically, the seeds are conditioned by a sequence of operations including a flattening step and a drying step thereof.

Preferably, said flattening step comprises a triple smooth roll flattening, in particular for the hardest seeds such as Jatropha seeds.

Depending on the conditions employed, the process according to the invention can lead directly to obtaining a detoxified cake. In an alternative embodiment, the cake is subjected to an additional drying step under conditions of temperature and time sufficient to inactivate Curcine and to decompose the phorbol esters.

Advantageously, the cake thus treated loses its harmful character and can be handled safely by humans for use in animal feed.

For the purposes of the present invention, the term "Jatropha seeds" is intended to mean seeds of Jatropha plants, alone or as a mixture with seeds from at least one other oleaginous, oleoprotein or proteinaceous plant, the seeds or the mixture. seeds producing an oil containing at least 40% by weight of oleic acid. It would not go beyond the scope of the invention when the seeds used in the process according to the invention come in whole or in part from genetically modified plants.

Oleaginous plants are grown specifically for their high-fat oil-rich seeds or fruits from which food, energy or industrial oil is extracted. Protein plants belong to the botanical group of legumes whose seeds are rich in proteins. Oil-protein crops are legumes whose seeds also contain oil.

By "detoxified Jatropha cake" according to the invention is meant a Jatropha cake having both:

a detoxification rate of Curcine of at least 90% and preferably at least 95%, in activity, when this level is measured by means of a quantitative test, or of 100% when this rate is measured by means of a qualitative test;

and a decomposition rate of the phorbol esters of at least 95% and preferably at least 99%, in activity, when this level is measured by means of a quantitative test, or by 100% when this rate is measured by means of a qualitative test.

Taking into account the results presented in the publication of Makkar H.P.S. et al, Plant Foods for Human Nutrition 1998, vol. 52, No. 1, pp. 31-36, a phorbol ester content of 0.11 mg / g corresponds to an edible cake (non-toxic). Animal feed specialists generally estimate that for a content of 0.3 mg / g phorbol esters, the meal is detoxified and can be used in animal feed, especially in a mixture with other materials. food.

The detoxified cakes according to the invention therefore have a phorbol ester content of at most 0.3 mg per g, preferably at most 0.11 mg per g of caked meal.

Curcine "detoxification rate" means the mass percentage of inactivated toxin in the meal.

By "decomposition rate" phorbol esters is meant the mass percentage of phorbol esters decomposed in the oil.

Other features and advantages will emerge from the detailed description of the Jatropha seed treatment method according to the invention which follows. The subject of the invention is a process for the treatment of seeds containing toxic components such as curcine, abrin, crotin and / or phorbol esters, in particular Jatropha seeds, alone or in mixtures with seeds derived from at least one other oleaginous, oleo-proteinaceous or proteaginous plant, said seeds preferably having an acidity level of less than or equal to 3 mg OH / g, said process comprising the following steps:

i) a step of conditioning the seeds without prior shelling; ii) a step of contacting the conditioned seeds with an anhydrous light alcohol and an alkaline catalyst under conditions of temperature and duration sufficient to allow the simultaneous extraction and transesterification of the vegetable oil and leading to the production of a mixture comprising esters of fatty acids and glycerol, and a cake, characterized in that the seeds are conditioned by a series of operations comprising a flattening step and a drying step thereof.

Another peculiarity of Jatropha seeds is related to their high toxicity, due in particular to the presence of curcine and phorbol esters. After extracting the oil, curcine concentrates in the cakes and the phorbol esters are concentrated in the oil and / or in the esters, making their manipulation by humans problematic, even dangerous.

The process according to the invention makes it possible to solve simultaneously many problems related to the transesterification of Jatropha oil. This process advantageously makes it possible to pass directly from the seed to the esters of fatty acids, avoiding the steps of trituration, refining, purification and the production of by-products. The fatty acid esters obtained by the process according to the invention are particularly suitable for the preparation of biodiesel, as mentioned above. The process according to the invention makes it possible to obtain a fraction rich in fatty acid esters which is devoid of toxicity and therefore usable without risk, in particular for the manufacture of biodiesel. Moreover, the process leads to the production of detoxified cakes, which can be handled safely by humans and can be used in animal feed without risk of poisoning for animals.

Seed conditioning stage

The first step of the process according to the invention consists in conditioning the Jatropha seeds, used alone or mixed with other plant seeds. oleaginous, oil-protein or protein crops. This conditioning is done on whole seeds. It comprises a first operation of flattening the seeds, followed by a drying operation of the flattened seeds.

The objective of the seed conditioning is to make the oil as accessible as possible to alcohol, without, however, greatly affecting its mechanical strength. This avoids the formation of a paste and fines, respectively detrimental to the implementation of a continuous process and the final purification of the esters produced. Moreover, the conditioned seed must allow easy passage of the reaction fluid (alcohol mixture - basic catalyst) according to a simple phenomenon of percolation.

According to an alternative embodiment, the fresh seeds are flattened on a mechanical flattener with smooth or fluted rollers.

The seeds thus flattened are dried, for example in a thermoregulated ventilated oven or in a continuous belt dryer or rotary hot air. The drying time and the temperature are chosen so as to obtain a decrease in the moisture content of the seeds at values of less than or equal to 2% by weight. Preferably, the drying is carried out rapidly after flattening, in less than one hour, preferably after 5 to 10 minutes, at a temperature sufficient to reduce the moisture content of the seeds to 2% by weight or less.

The residual moisture of the seed is determined by thermogravimetry. The seed is first milled, then the ground material obtained is dried at 105 ° C. in a thermobalance until the weight is stabilized. The water content is expressed as a percentage of the raw material.

In a preferred embodiment, the seed conditioning step i) further comprises a step of preheating the seeds, carried out before the flattening operation. This preheating operation gives the seed a greater plasticity and therefore a more effective crushing during flattening (gain at the contact surface, the rate of percolation of the alcohol and therefore its extractive capacity). It preferably takes place at a temperature of less than or equal to 100 ° C.

Extraction and transesterification step

The seeds packaged as described above are brought into contact with an anhydrous light alcohol and an alkaline catalyst under conditions of temperature and duration sufficient to allow the extraction and transesterification of the vegetable oil. and resulting in a mixture comprising esters of fatty acids and glycerol, and a cake.

The light alcohol used in step ii) is a lower aliphatic alcohol such as methanol, ethanol, isopropanol and n-propanol, and preferably is methanol.

According to an alternative embodiment, an organic solvent (co-solvent) miscible or immiscible with said light alcohol is also added to the reaction medium. As co-solvent, mention may be made of: hexane, heptane, benzene, bicyclohexyl, cyclohexane, decalin, decane, hexane (Texsolve C), gasoline, petroleum ether, kerosene, kerdane , gas oil, kerosene, methylcyclohexane, Texsolve S or S-66, Naphtha (Texsolve V), Skellite, Tetradecane, Texsolve (B, C, H, S, S-2, S-66, S- LO, V), supercritical CO ₂ , propane or butane pressurized, natural solvents such as terpenes (limonene, alpha and beta pinene, etc.), ethers such as dimethyl ether, diethyl ether, ketones such as acetone and mixtures of all these solvents.

The basic catalyst used in the process is chosen from the group: sodium hydroxide, alcoholic sodium hydroxide, solid sodium hydroxide, potassium hydroxide, alcoholic potassium hydroxide, solid potassium hydroxide, sodium or potassium methoxide, sodium or potassium ethylate, sodium propylate and sodium hydroxide. potassium, isopropylate of sodium and potassium.

The reaction takes place in a fixed bed reactor. According to one embodiment, the fixed bed reactor is a thermoregulated percolation column equipped with a grid. A pump makes it possible to supply the column with a basic alcohol-catalyst mixture. The alcohol and catalyst are thus added simultaneously in the reactor, which is maintained at a temperature ranging from 30 to 75 ° C, preferably less than or equal to 50 ° C _T preferably less than 45 ° C, preferably about equal at 40 ° C. The catalyst / alcohol / seed mass ratio is preferably in the range 0.001 to 0.01 / 0.1 to 5/1, preferably in the range of 0.005 to 0.01 / 0.1 to 1/1, even more preferably in the range of 0.005 to 0.01 / 0.1 to 0.5 / 1.

In particular, a catalyst content of less than 0.001, or even less than 0.005, does not make it possible to obtain detoxified cake, and conversely a content greater than 0.01 results in saponification and a poor yield of esters.

The feeding is carried out at the head of bed; the reaction liquid then percolates through the bed and is recovered in a reserve located downstream, under the bed. By pumping, the liquid is returned to the headboard to diffuse back into the bed. The duration of the recirculation cycle of the alcohol / catalyst mixture is from 15 to 60 minutes, preferably from 20 to 40 minutes. At the end of the cycle, the liquid supply is stopped. Part of the liquid still present in the soaked seeds is then recovered by simple dripping.

The extraction and washing of the seeds is then carried out. For this, the column is supplied with anhydrous alcohol which diffuses again by percolation without subsequent recirculation of the alcohol. Preferably, the alcohol extraction is carried out in 3 to 9 stages.

The amount of solvent is injected during a given period (of the order of 4 to 10 minutes), the liquid then being drained for a period of 10 to 20 minutes. The recovered liquid can undergo a neutralization step by addition of acid, then a step of evaporation of the alcohol, to lead to a mixture of phases consisting of a lighter phase rich in esters and a denser phase rich in glycerol . None of these phases contain curcine.

The phase mixture is subjected to a decantation step (consisting, for example, of a static decantation in one or more decanters in parallel or in series, centrifugal decantation, combination of static or centrifugal decantation), making it possible to obtain a higher phase composed predominantly of fatty acid esters of fatty acid

(ester phase) and a lower phase mainly composed of glycerine and water

(glycerin phase).

The ester phase is then subjected to a sequence of chemical reactions and / or separations / purifications aimed at recovering the fatty esters, comprising, in a known manner, a washing step with water followed by a drying step under vacuum.

The fatty acid ester thus obtained is intended in particular for the preparation of biodiesel.

The other product resulting directly from the process according to the invention is the Jatropha cake.

According to an alternative embodiment, the lean meal impregnated with alcohol is dried, for example in a ventilated oven, for 4 hours, at a temperature of less than or equal to 200 ° C., preferably less than or equal to 150 ° C. and even more preferably less than or equal to 120 ° C. This drying step also aims to destroy the curcine remaining in the cake. In parallel, this drying step makes it possible to remove from the cake the solvent (alcohol) used during the extraction.

According to another variant embodiment, the method according to the invention does not include a step of drying the cake at a high temperature (temperature above 120 ° C.); Depending on the conditions used, curcine can be inactivated thanks to physical and / or chemical treatments applied to Jatropha seeds during the conditioning and extraction / transesterification steps described above, so that the operation of drying the cake at high temperatures becomes unnecessary. In this case, the method comprises only a step of drying the cake at temperatures below 120 ° C, intended to remove the solvent (alcohol) used during the extraction, to allow the use of the cake in the feed animal.

The quantitative test for determining the toxicity of oilcakes and liquid phases recovered after the transesterification extraction step is the acute oral toxicity test.

The publication Makkar H.P.S et al. J. Agric. Food Chem. 45: 8, 1997, 3152-3157 discloses a quantitative test of curcine (haemagglutination test) as well as a quantitative assay method for phorbol esters (successive extractions with dichloromethane, followed by HPLC analysis) .

The process according to the invention can easily be carried out continuously on an industrial scale, for example by means of: a continuously operating mobile-strip extractor reactor (De Smet extractor type); a rotary filter or centrifuge. Preferably the reactive trituration with methanol is carried out against the current of the cake, on several consecutive stages. Preferably, the alcohol extraction is carried out in 3 to 9 stages.

The reactive trituration process according to the invention is particularly well suited to seed mixtures, such as soya beans, castor beans, safflower seeds and rapeseed. Advantageously, the Jatropha cake which can not be used pure but mixed with other protein crops, is then directly mixed with other protein sources.

A starting mixture of Jatropha seeds (rich in oil) and soybean seeds (high in protein) in a ratio of 1: 10 leads, by the method according to the invention, to a mixture of methyl esters of fatty acids containing 15 to 40% by weight of oleic acid methyl ester, particularly suitable for use as a biofuel.

The method of reactive seed trituration according to the invention has many advantages.

Thanks to the specific seed conditioning step, it is possible to increase the contact surface for a better percolation of the alcohol-catalyst mixture and thus a better lipid extraction and transformation. consecutive esters. No prior impregnation of the packaged seeds is necessary. The ester fraction obtained from the mixture comprising fatty acid esters and glycerol is particularly suitable for the manufacture of biodiesel.

Starting from whole seeds allows:

on the one hand, to greatly limit the formation of fines, by making the subsequent filtration steps easier, and by limiting the toxic risk since the dry fines tend to dissipate / disperse in the ambient air;

- And secondly, to maintain a good mechanical strength of the seed bed flattened (which will form the cake), very interesting property if it is desired to implement the reaction in a continuous mode.

The cakes are obtained directly from the seeds, according to the process of the invention. These cakes are devoid of toxicity to humans and can therefore be handled safely. In addition, these cakes retain their physical integrity (cohesion, mechanical strength) and have an interesting nutritional value, which allows their use in animal feed.

The invention and its advantages will be better understood on reading the examples hereinafter given purely by way of illustration.

Reactive trituration of Jatropha seeds

Table 1: Characterization of the tested Jatropha seed

Characteristics Jatropha Seed

(Nov 2009)

Humidity,% 7.5

Fat,% MS 35.0

Acidity of fat, mg KOH / g 1.8

Fatty acid distribution (relative%)

Palmitic (C16: 0) 12.8

Palmitoleic (C 16: 1) 0.7

Stearic (Cl 8: 0) 6.4

Oleic (C18: 1) 42.2

Linoleic (Cl 8: 2) 37.2

Linolenic (Cl 8: 3) 0.2

Groundnut (C20: 0) 0.2

Eicosenoic (C20: 1) 0.3

Phorbol ester content, mg / g 3.6 In terms of oil content and fatty acid distribution, Jatropha seed is consistent with the literature (Biodiesel & Jatropha Cultivation, S. Lele, 2006). Its acidity less than 2 mg KOH / g allows implementation in the process according to the invention.

Finally, because of its phorbol ester content, much higher than 0.3 mg / g, the jatropha seed belongs to the toxic varieties.

Reactive trituration test without co-solvent

Reactivation of Jatropha seeds with 3-stage methanol extraction (fixed bed reactor process)

500 g of fresh, unshelled Jatropha seeds were packed on a Henry smooth-roll type flattener with a fixed gap of 0.05 mm. The flattened seeds are in the form of petals 0.2 mm thick and about 0.2 mm in diameter. The flattened seeds were dried at 60 ° C for 16 h. Their final water content is 1.3% by weight.

In a thermoregulated and fixed-bed percolation column, these flattened and dried seeds were brought into contact with a mixture of sodium hydroxide and methanol, containing 0.5% by weight of sodium hydroxide relative to the seed and having a weight ratio alcohol / seed of 1.15. The extraction and transesterification reactions take place at a temperature of 50 ° C. for 30 minutes. The draining of the bed is carried out for 15 minutes. Seed extraction and washing are then carried out with methanol in three stages and countercurrently.

The liquid phase obtained is subjected to decantation to recover firstly a lighter phase rich in esters and a denser phase rich in glycerol. The yield of esters is 77.2%.

The cake obtained is subjected to drying in a ventilated oven at 120 ° C. for 4 hours. It is noted that the lean meal is relatively well exhausted, with a residual fat content of 5.4% (determined according to the NF ISO 659 standard).

Tests carried out to determine the toxicity in the cake show that the meal is detoxified.

Optimization of the reaction in a stirred bed reactor

In order to test the reactivity of the Jatropha seed, tests are carried out in a stirred-bed closed reactor in which the reaction is carried out on a crushed seed. In more detail, the stirred bed reaction is carried out under the following conditions: 1. Dry the entire seed at 100 ° C for 16h.

2. Grinding at room temperature of the seed in the solution in methanolic soda for 5 minutes;

3. Maintaining agitation in a reactor heated at 50 ° C for 30 minutes;

4. Filtration on Buchner filter (simulation of a rotary filter) followed by washing with anhydrous methanol.

Table 2: Mass Balance of Fractionation of Jatropha Seed in Agitated Bed Reactor

** loss of esters = [theoretical ester mass] - [mass of esters produced] - [potential mass of esters in lean cake]

(1): The yield of dry extract is the ratio of the dry extract obtained after evaporation of the miscella on the sum of the theoretical ester and the theoretical glycerine.

- In the first test (LA10-01), the amount of dry extract of the miscella obtained represents only 34% of the theoretical amount expected. In addition, this dry extract is on the one hand not biphasic (absence of glycerin) and on the other hand, has a neutral pH. Therefore, under these conditions, the extractability and reactivity of the lipids are not optimal.

- In the second test (LAI 0-02), carried out with 3 times more engaged catalyst, the dry matter content of the miscella is maximum with probably other extracted products (Yield = 110%>). The yield of esters is 75% while that in glycerol (»400%>) testifies to the formation of soaps. It therefore appears that the amount of catalyst is still too high. The optimum in catalyst is therefore well intermediate between 0.5 and 1.5%, and preferably between 0.5 and 1% by weight, relative to the seed seed engaged.

- In terms of quality, the esters produced have reasonable levels of glycerides (Table 3)

Table 3: Analytical balance of Jatropha esters

* unrealized analysis

** not detected

Implementation of the reaction in a fixed-bed reactor after double flattening In parallel with stirred-bed reactor tests, fixed-bed reactor tests were conducted. As a reminder, the fixed bed reaction is performed under the following conditions:

1. Flaking fresh Jatropha seed on fluted roller flattener. The rolls are first spaced (5.0 mm) to allow a first crushing of the seed. The crushed seed is then ironed in the flattener with rollers tightened to a maximum (0.1 mm).

2. The flakes are then dried for 16 hours at 100 ° C.

3. The flakes are introduced into the brewing column.

4. The methanolic sodium hydroxide solution is then recirculated on the bed for 30 minutes at 50 ° C.

5. The miscella is then withdrawn and the flake bed is then washed with 5 successive washes with methanol at 50 ° C (5 minutes per wash).

At first, the conditioning of the seed was only performed on a fluted roller flattener. Table 4: Mass balance of Jatropha seed fractionation on fixed bed

unrealized

- The 3 tests carried out show low levels of material extracted in the miscellas (36, 49 and 64%), clearly indicating that the conditioning of the flake (morphology, thickness) is not optimal;

In the presence of 0.3% of catalyst, the pH of the miscella obtained is neutral and, moreover, no ester formation is observed.

- Doubling the amount of catalyst, there is well formation of esters (Yield 29%) but the cake remains very rich in lipids and the high yield of glycerin indicates a hyper production of soaps. - By tripling the amount of catalyst, the miscella is very basic (pH> 12) and the medium is again monophasic, the esters being saponified (explosion of the yield in glycerine "600%).

- In terms of quality, the esters produced during test 10-E01 show reasonable levels of glycerides (Table 5).

Table 5: Analytical balance of Jatropha esters

* unrealized analysis

** not detected

Also, it is envisaged to optimize the morphology of the flake by adding a milking step on smooth rollers to obtain a more extractable cake.

Optimization of Jatropha flake preparation after triple flattening

The method of preparation of the flakes is improved in order to reduce the loss of fat in the cake. Flaking is carried out under the following conditions:

1. Flaking fresh Jatropha seed on fluted roller flattener. The rollers are first spaced to allow a first crushing of the seed (0.5 mm). The crushed seed is then ironed in the flattener with the rollers tightened to the maximum (0.1 mm). This flake is then flattened on smooth rollers with a spacing of 0.05mm. The thickness of the flake obtained is approximately 0.2 to 0.3 mm.

2. The flakes are then dried for 16 hours at 100 ° C.

3. The flakes are introduced into the brewing column.

4. The methanolic sodium hydroxide solution is then re-sent to the bed for 30 minutes at 50 ° C.

5. The miscella is then withdrawn and the flake bed is then washed with 5 successive washes with fresh methanol at 50 ° C. (5 minutes by washing) Table 6: Mass balance of Jatropha seed fractionation on fixed bed after triple-flattening

(1): The yield of dry extract is the ratio of the dry extract obtained after evaporation of the miscella on the sum of 1 theoretical ester and the theoretical glycerine.

* impossible

Table 7: Analytical balance of Jatropha esters

Comments:

- The triple flattening provides a plus in terms of lipid extractibility since in the presence of at least 0.8% of catlyseur, the yield of dry extract is greater than 96%.

the maximum ester yield observed is 71% even though the extractability is very important (98%). In addition, the high yield of glycerine does indeed reflect a still important saponification of the lipids;

- In contrast, qualitatively, the ester of the 10-E12 test is low acid and low in monoglycerides and meets these criteria to a biodiesel quality. In general, the final acidity of the esters decreases with the amount of basic catalyst involved;

under the conditions of test 10-E 12, the miscella before evaporation is clear but still strongly basic. Also, we assume that after evaporation of the methanol, the high concentration of the catalyst leads to a parasitic saponification of the esters. Therefore, we will neutralize the miscella before evaporation of methanol in the next test.

Glycerin neutralization test

Operating mode:

1. Flaking fresh Jatropha seed on fluted roller flattener. The rollers are first spaced to allow a first crushing of the seed (0.5 mm). The crushed seed is then ironed in the flattener with the rollers tightened to the maximum (0.1 mm). This flake is then flattened on smooth rollers with a spacing of 0.05mm. The thickness of the flake obtained is approximately 0.20 to 0.30 mm. 2. The flakes are then dried for 16 hours at 100 ° C.

3. The flakes are introduced into the brewing column.

5. The miscella is then withdrawn and the flake bed is then washed with 5 successive washes with fresh methanol at 50 ° C (5 minutes per wash).

6. The miscella are grouped together and sent for distillation (90 ° C, 100mbar).

7. Once the methanol is evaporated, the glycerine and the ester are separated by decantation.

8. The ester is washed to neutrality and then dried under vacuum (90 ° C, 20mbar)

9. The crude glycerin is treated with an aqueous solution of sulfuric acid where the acid represents 5% of the mass of crude glycerin and the water represents 100% of the glycerine mass. The mixture is stirred at 90 ° C for 30min. The mixture is then separated by decantation. The fatty phase (fatty acids) is washed to neutrality and dried under vacuum (90 ° C., 100 mbar).

Table 8: Effect of the reaction temperature

TEST 10-E20

^1st flattening (pre-crushing) on flattener at

Yes

fluted rollers spread

2 ^nd flattened fluted rolls tight Yes

3 ^rd flattening smooth smooth rolls Yes

Drying 100 ° C 16h Yes

Flake thickness 0.2-0.3 mm

Catalyst content (vs flake),% 0.8

Reaction temperature and extraction, ° C 50

Mass ratio Methanol / Seed 2

Yield in dry extract (1),% 100

Ester phase / glycerin yes

Yield of methyl esters,% 67.8

Yield of crude glycerin before neutralization,% 421

Yield of fatty acids resulting from the neutralization of

25.5

crude glycerin,%

Yield of crude glycerin after neutralization,% 143

Loss of methyl esters in cake,% 6.7

Other losses in esters of methyl esters ** (value

0.0

calculated),% (1): The yield of dry extract is the ratio of the dry extract obtained after evaporation of the miscella on the sum of the theoretical ester and the theoretical glycerine.

* impossible

Comments:

- The sulfuric acid treatment of crude glycerin makes it possible to extract glycerine, 25% of free fatty acids (ex-soaps) and reduce the overall yield of glycerine to a more conventional level (143%) . These fatty acids may be recycled in the process in particular by esterification in the presence of an acid catalyst (sulfuric acid) and methanol;

under the conditions of acid treatment of glycerine, it is noted that the esters are not hydrolysed (see Table 9: analysis of the esters resulting from the 10-E20 FF A test) but that they are very acidic (IA = 19 4 or about 10% of free fatty acids) and relatively charged with residual glycerides;

with regard to the methyl ester phase resulting from the E20 test, recovered after removal of the co-produced glycerine, it remains relatively charged with glycerides.

Table 9: Analytical balance of the esters

Reactive trituration test in the presence of ethanol

A reactive trituration process was carried out in the presence of ethanol under the conditions presented in Table 10. Table 10: Conditions and mass balance of the reactive trituration process in the presence of ethanol

* impossible

Comments:

under the conditions of the test, the medium is too saponifying since the reaction medium is in a non-extractable pasty form (soaps);

- with regard to the residual ester potential in the cake, Γ ethanol seems to extract less fat than methanol (12.1% vs. 7.5% in test 10-E12);

despite these observations, the "ethanolic" cake was analyzed in order to determine its content of phorbol esters (Table 17).

Reactive trituration tests in the presence of a co-solvent

Test with a mixture of methanol / hexane (28/72) (m / m)

In the context of these tests, given the high volatility of hexane, the reaction temperature was lowered to 40 ° C. Table 11: Influence of the presence of a co-solvent Methanol / Hexane (28/72) (m / m)

(2) Relative to the 10-E18 test, the ester yield is higher than theoretical and the glycerine yield is abnormally low. However, it turns out that the ester phase is emulsified and therefore seems to retain non-settling glycerin

* impossible

Comments:

- In the presence of the methanol-hexane mixture, the cakes are properly depleted.

- If the ester yield of test 10-E19 seems high, it turns out that they are loaded with glycerides (Table 12) indicating that the reaction medium (depending on the methanol / hexane ratio) is not enough transesterifying . This result is also confirmed regardless of the catalyst content. It is also noted that with a very high catalyst content (0.9%), the medium even becomes saponifying. Table 12: Analytical balance of the esters

Perspectives:

A test with a higher methanol content was therefore carried out:

Reactive trituration tests in the presence of a hexane-alcohol mixture enriched in methanol:

Table 13: Methanol Content Influence

* impossible

** loss of esters = [theoretical ester mass] - [mass of esters produced] - [potential mass of esters in lean cake] Comments:

in the proportions 90/10, the addition of a large quantity of methanol significantly alters the extractability of the lipids (cf potential ester cake) and thus the yield of methyl esters. Under these conditions, the medium is, however, more transesterifying than in the presence of the methanol / hexane mixture = 28/72 (Table 14,% glycerides);

when hexane (50/50 mixture) is increased, the cake is finally properly depleted (2.8% loss of methyl esters in the cake). In fact, the overall yield of methyl esters is significantly improved (88.3%) indicating a resurgence of transesterifying activity under these conditions;

- Qualitatively (Table 14), the methyl esters produced are low acid even though their monoglyceride content is still high (probably due to a retro-conversion of methyl esters to glycerides). .

Table 14: Analytical balance of esters

Evaluation of the detoxifying effect of the process by measuring the evolution of the phorbol ester content

Sample preparation and phorbol ester assays were performed using the Makkar method (Makkar HPS, Becker K, Spore F, Wink M (1997). Agric Food Chem 45: 3152-31 7).

3.1 Preparation of samples

The liquid samples are diluted in methanol and then injected. For solid samples, the phorbol esters are first pounded and mortared in the presence of methanol. The alcoholic extracts obtained are then analyzed by high performance liquid chromatography.

3.2 Operating conditions:

Chromatographic conditions:

- Detector: diode array (integration of peaks at 280nm). Column: Cl 8 reverse phase (LiChrospher 100, 5mm), 250 x 4 mm + pre-column.

- Oven: 22 ° C (T amb).

- Eluents:

B = Acidified water (1.75ml H3PO4 (85%) in 1 liter of demineralized water.

A = Acetonitrile

3.3 Results

Reactive methanol trituration on a triple-flattened flake with glycerine reprocessing (test 10E20

Table 15: Distribution of phorbol esters in fractionation with glycerine reprocessing / 10E20 test

Comments:

losses of phorbol esters (EP) after flaking and drying are approximately 25%. EPs appear relatively sensitive to the rise in temperature. As a whole, the process leads to 40% PE losses;

about 1/3 of the seed EPs are found in the methyl esters and 5% in the dried cake;

in view of the concentrations of PE in the esters directly derived from the process or after acidic reprocessing of the glycerin, the EPs seem to have a relative affinity for the lipophilic compounds (methyl ester phase); - the residual content in the meal is 0.3 mg / g, that is to say very close to the values of the Mexican non-toxic varieties (0.1 mg / g). There is therefore a positive and detoxifying effect of the process according to the invention. Reactive trituration with co-solvent on a triple flattened flake:

Table 16: Distribution of phorbol esters in a co-solvent process

/ Test 10E25

Comments:

in the presence of co-solvent (hexane), the process according to the invention leads to a cake with a low EP content (0.3 mg / g), whereas the methyl esters capture 50% of the

EP of the seed. This result seems to confirm the relatively liposo character of EPs;

- again, in its entirety, the process leads to losses in EP of 40%; Moreover, considering the low levels of PE in the cakes from the process, we can conclude the detoxifying character of the latter. It can also easily be thought that this rate will be further improved at the industrial level comprising drying the flake and cake in a toaster.

Transformation of the Jatropha seed by a conventional method (pressure + semi-refining of the oil + methanolysis, comparative example)

The Jatropha seed is milled by pressure to obtain a raw pressure oil and a fat cake.

For this the seed undergoes the following stages:

> Trituration:

- The seed is crushed on a fluted roller flattener The flakes are then sent to the Taby press, which is heated without a die.

The crude pressure oil obtained is then filtered on cellulose filter 1 Ιμιη

Before being esterified, the crude oil undergoes a semi-refining which comprises the following steps:

degumming

Neutralization Démucilagination:

heating the oil to 65 ° C

when the temperature of 65 ° C. is reached, an addition is made of a mixture composed of 1.5% o phosphoric acid and 6% water (% by weight relative to the dry oil mass). ).

the mixture is then stirred for 10 minutes. The temperature is then raised to 75 ° C. and maintained for 30 minutes. The mixture is then centrifuged for 5 minutes at 4500 rpm

> Neutralization:

The dephosphorized oil is neutralized with an aqueous solution of sodium hydroxide composed of 6% water (relative to the mass of oil) and sodium hydroxide necessary to neutralize all of the free fatty acids with an excess of 5%. The soda solution is added to the dephthalated oil heated to 75 ° C, the mixture is maintained for 10 minutes. The temperature is then increased to 90 ° C for 30 minutes. The mixture is then centrifuged for 5 min at 4500 rpm in order to eliminate the heavy soapy phase. The oil is then washed until neutrality with demineralized water by successive additions of 20% water with stirring for 5 min and centrifugation for 5 min at 4500 rpm. The oil is then dried under vacuum at 90 ° C (20mbar)

The semi-refined oil is then trans-esterified with methanol in the presence of a basic catalyst.

> Transesterilication and purification of esters

in a first step, the semi-refined oil is brought into contact with anhydrous methanol in a mass ratio oil / methanol of 5/1;

the mixture is then stirred with the reflux temperature of methanol (65.degree.

70 ° C); sodium methoxide (25% methanolic solution of catalyst) is then added gradually (in 3 times) in an oil / methanol / catalyst mass ratio of 5 / 1.02 / 0.03;

the mixture is then kept under reflux and with stirring for 2 hours;

After allowing the glycerin (heavy phase) to decant for 1 hour, the latter is removed by withdrawing the reactor;

the ester phase is then washed with deionized water until neutral (each washing is carried out with stirring for 15 min at 90 ° C.).

the esters are finally dried under vacuum at 90 ° C. (20 mbar).

Table 17: Assessment of the classical crushing of the Jatropha sieve

Table 18: Analytical balance of Jatropha oils and esters obtained by the conventional method

Crude oil Semi-oil Ester

Method

refined methyl pressure

Acid number (mg KOH / g) EN14104 2.0 0.20 0.1

Phosphorus content NFT60-227 <5 <5

> 25

Content of MonoGlyceride ARKEMA 1,31

(%)

Content of DiGlyceride (%) ARKEMA - 0,75

-

TriGlyceride content (%) ARKEMA - 0,0

- Table 19: Distribution of phorbol esters in a fractionation with the conventional method 10-E27

Comments:

a large part (61.3%) of the phorbol esters is found in the pressure oil, but these degrade as the semi-refining and transesterification stages progress;

the pressure cake is heavily loaded with EP compared to the cake resulting from the process according to the invention, approximately 12 times more charged. It should be noted in passing that the PE balance for oil cake and pressure oil is slightly in excess (+ 10%);

- semi-refining (neutralization + degumming + drying) results in a loss of 1/3 of the EP of the crude oil;

methanolysis results in a loss of 60% of the EP of the semi-refined oil.

the esters obtained are identical in EP to the esters resulting from the process according to the invention.

in the end, approximately 33% of the phorbol esters were degraded in the conventional process against 40% in the process according to the invention.

Reactive trituration with ethanol Table 20: Distribution of phorbol esters in the products resulting from a reactive trituration process carried out in the presence of ethanol (E10-E26)

(1) T = 100 ° C, 16 hours

(2) T = 100 ° C, 16 hours

* NR = analyzed unrealized

Comments:

- The cake from an ethanol process is 3 times more concentrated in EP than a methanol meal while its residual fat content is only 1.7 times higher. Consequently, the EPs appear less soluble in ethanol than in methanol;

- As previously observed and unexplained, further drying of the cake causes an increase in the EP content in the cake.

Finally, the reactive trituration process according to the invention, in particular with methanol, and preferably in the presence of co-solvent and / or a flake prepared by triple-flattening of the seed, makes it possible to pass directly from seeds of jatropha to fatty acid esters with a yield greater than 70% or even greater than 80% and simultaneously to obtain a detoxified cake containing at most 0.03 mg / g of phorbol esters, a content compatible with the use of the meal in animal feed.

Claims

A method of treating seeds containing toxic components such as curcine, abrin, crotin and / or phorbol esters, in particular Jatropha seeds, said seeds preferably having a level of acidity less than or equal to 3 mg KOH / g, said process comprising the following steps:

i) a step of conditioning the seeds;

ii) a step of contacting the conditioned seeds with an anhydrous light alcohol, and an alkaline catalyst under conditions of temperature and duration sufficient to allow the extraction and transesterification of the vegetable oil and leading to the production of a mixture comprising esters of fatty acids and glycerol, and a cake.

characterized in that step i) comprises operations for flattening and drying the seeds.

2. The method of claim 1 wherein step i) also comprises a preheating of the seeds at a temperature less than or equal to 100 ° C, the preheating operation being performed before flattening.

3. Method according to one of claims 1 and 2 wherein the operation of drying flattened seeds of step i) is carried out rapidly after flattening, in less than one hour, preferably after 5 to 10 minutes, at a sufficient temperature to reduce the moisture content of the seeds to 2% by weight or less.

4. Method according to any one of claims 1 to 3 wherein step ii) comprises a first reaction carried out at a temperature ranging from 30 to 75 ° C, preferably less than or equal to 50 ° C _T preferably less than 45 ° C, preferably about 40 ° C, for 15 to 60 minutes, preferably 20 to 40 minutes, followed by alcohol extraction carried out in 3 to 9 stages and against the current.

5. A method according to any one of claims 1 to 4 wherein the flattening operation is carried out by means of a roller mechanical flattener, and preferably comprises a triple smooth roll flattening.

6. Process according to any one of claims 1 to 5 wherein steps i) and ii) are carried out continuously.

7. Process according to any one of claims 1 to 6 wherein the light alcohol is methanol.

8. Process according to any one of claims 1 to 7 wherein the alkaline catalyst is sodium hydroxide.

9. Process according to any one of claims 1 to 8 wherein the mass ratio catalyst / alcohol / seeds in the range 0.001 to 0.01 / 0.1 to 5/1, preferably in the range of 0.005 to 0 , 01 / 0.1 to 1/1, even more preferably in the range of 0.005 to 0.01 / 0.1 to 0.5 / 1.

10. Process according to any one of claims 1 to 9 wherein in step ii) is also added a co-solvent selected from the group: hexane, heptane, benzene, bicyclohexyl, cyclohexane, decalin, decane, gasoline, ether petroleum, kerosene, kerdane, gas oil, kerosene, Methylcyclo hexane, Naphtha (Texsolve V), Skellite, Tetradecane, Texsolve (B, C, H, S, S-2, S-66, S-LO, V), supercritical CO2, propane or butane pressurized, natural solvents such as terpenes (limonene, alpha and beta pinene)), ethers such as dimethyl ether, diethyl ether, ketones such as acetone and mixtures of all these solvents.

11. A method according to any one of claims 1 to 10 wherein the mixture comprising fatty acid esters and glycerol is subjected to a decantation step to obtain an upper phase predominantly composed of fatty acid esters. fat and a lower phase mainly composed of glycerine and water.

12. The method of claim 11 wherein said upper phase is subjected to a succession of chemical reactions and / or separations / purifications leading to the production of biodiesel.

The method of any one of claims 1 to 12 wherein the seeds of Jatropha are mixed with soybeans in a ratio of 1 to 10.

14. Mixture of methyl esters of fatty acids obtainable by the process according to claim 13 comprising from 15 to 40% by weight of oleic acid methyl esters.

15. Use of the mixture according to claim 14 as a biofuel.

16. A method according to any one of claims 1 to 12 wherein the cake obtained is subjected to a drying step under conditions of temperature and time sufficient to inactivate curcine.

17. The method of claim 16 wherein the drying of the cake is carried out for 4 hours at a temperature less than or equal to 200 ° C, preferably less than or equal to 150 ° C and even more preferably less than or equal to 120 ° C.

18. Detoxified jatropha cake that can be obtained by the method according to one of claims 1 to 12, 16, 17 having:

a curcin detoxification rate of at least 90% and preferably at least 95%, in activity when this level is measured by means of a quantitative test;

a phorbol ester content of less than or equal to 0.3 mg / g.

19. Use of the cake according to claim 18 in animal feed.