FR2760756A1 - Hypo-allergenic vegetable oil production - Google Patents

Abstract

Physical refining of vegetable oils to produce a hypoallergenic product, containing practically no allergenic proteins and a greatly reduce concentration of phospholipids, involves (i) pressing oil-bearing seeds (preferably at ca. 300 bars and 10-40 deg C) in an endless screw press; (ii) allowing the extracted crude oil to settle in a decanter at ambient temperature for 3 to 4 days; (iii) subjecting the supernatant to pre-filtration (preferably through a 20 mu m filter), removing any solids and storing the filtrate in a concentration vessel; and (iv) subjecting the filtrate to microfiltration or ultrafiltration through a porous membrane (preferably of pore size 0.1-0.5 mu m for microfiltration or 0.01-0.1 mu m for ultrafiltration), the permeate being the required product.

Description

Process for producing hvpoallerzenic vegetable oils
The present invention relates to a process for the physical refining of vegetable oils. Said oils are hypoallergenic and have good organoleptic qualities.

 Nowadays, oilseeds are one of the main sources of food, pharmaceutical and cosmetic allergens. Several clinical and scientific studies support the allergenic potential of vegetable oils.

 The work of Yunginger et al (JAMA 1988, 260, 1450-2) in the United States has highlighted the responsibility for peanut oil in the deaths of four adults.

 In France, the work of Moneret-Vautrin et al (Lancet, 1991, 338, lu49; Pediatr.

Allergy Immunol. 1994, 5,184-8) and those of Guy De Montis and ai (Lancet 1993, 341,1411) have highlighted the responsibility of vegetable oils in the appearance of allergic conditions respectively in infants under adapted breastfeeding, containing the oil peanut as a lipid additive and in infants and young children prescribed vitamin
D suspended in vegetable oil.

 Similarly, Brown's work (launch, 1991, 338) reports the same results as those observed by Moneret-Vautrin, he observes an allergy to peanut oil in two infants on suitable milk.

 Porras et al (Int. Archs Allergy appl. Immun. 1985, 78) have demonstrated the existence of allergenic proteins in soy lecithin preparations, margarine and some samples of soybean oil.

 Kanny et al (Allergy, 1994, 49, 561-564) have demonstrated the existence of an allergy to sunflower oil in a 36-year-old woman.

 CHIU et al (J. Allergy Clin. Immunol., 1985, 88, 414-15) have shown that sesame oil is capable of triggering anaphylactic shock in patients with atopic dermatitis.

 Klurfeld et al (Lipids, 1987, 22), isolate and quantify the lectins present in vegetable oils (peanuts, corn, soybeans and sunflowers). They find a protein concentration between 120 and 9379 ngig and a lectinic activity between 24 and 2983 ngig depending on whether the oil is refined or crude.

 Moutete (thesis, Fac NIédNanc 1995) highlighted the presence of allergenic proteins in the different oils analyzed, their concentration is between 100 to 300 ppb. These proteins are characterized by their small size between 14 and 20 kDa, and their pHi between 3.5 and 5.0. A particular property, they have a strong tendency to oligomerization.

 Furthermore, the work of Olszewski et al (Rev. Fr. Allergol. 1995, 35, 3) confirmed the existence of cross-reactions and therefore of common epitopes between the allergenic contaminants of the different oils studied (peanut, sunflower, soybean and olive).

 Finally, the work of Hoffman et al (J. Allergy Clin. Immunol., 1994, 93) made it possible to highlight the importance of oil manufacturers and their different processes on the allergic potential of the oils analyzed.

 From the above description, it is obvious that there is a need to implement a method of extraction and purification of vegetable oils by a physical treatment or process by membrane filtration, making it possible to obtain an oil. containing a zero allergenic charge, having a better shelf life, without affecting the nutritional and biological quality of the vegetable oil.

 Several works Tzen et al (Plant. Physiol. 1993, 101, 267 - 276), Jacks et al (J. Am.

Oil. Chern. Soc., 1990, 67, 353 -361) and Murphy et al (Biochem. And Biophys. Acta, 1991, 1088, 86 - 94) have shown that the lipid vesicles present in oil seeds form in an aqueous environment present in the seed, micellar aggregates of proteins, phospholipids, and free fatty acids, between about 0.65 and 2.0 µm in size.

 Other work based on the study of the behavior of the constituents of oil in the organic phase shows that the dissolution of phospholipids in an apolar solvent such as hexane or another solvent results in the formation of micellar aggregates of such high molecular size. 200,000 daltons.

 On the other hand, the molecular mass of the triglycerides under the same conditions mentioned above is approximately between 900 and 1000 daltons. This difference in size of these two entities has led to the development of ultrafiltration membrane techniques for the separation of two phases, a retentate rich in micellar aggregates and a permeate formed from triglycerides.

 The advantage of the presence of solvents (water / organic solvent) in the oil extraction process by membrane filtration is to lower the viscosity of the oil and therefore increase the filtration rate.

 Several works have been described on the production of oils by physical processes, by simple membrane filtration, but none of them is widely accepted.

 In the methods of the prior art, there is generally a poor flow rate, making the method uneconomical on a large scale, or else they affect the quality of the oil, making the product unacceptable to consumers.

 According to the method of the invention, it has been discovered that microfiltration or ultrafiltration of vegetable oil can be successfully accomplished without having the problems posed by the prior methods. degraded oil quality, premature clogging of the filter and inadequate removal of oil contaminants.

 This method of the invention makes it possible to remove the allergenic proteins by the use of microfiltration or ultrafiltration.

 The pore size of the microfilters is selected to retain the contaminants that are present in the oil, while maintaining an acceptable flow rate through the microfilter. The membranes used are slightly hydrophilic microporous membranes with good flow properties, a narrow particle size distribution and a constant performance in removing contaminants, in particular allergenic proteins.

 These hydrophilic membranes such as cellulose membranes are less adsorbed by allergenic proteins.

 The average diameter of the pores of the membrane must be between 0.1 and 5.0 ssum in microfiltration or better still between 0.01 and 0.1 μm in ultrafiltration. Such microporous membranes are well known and are readily available.

 Most food allergens are proteins, specifically glycoproteins. Their molecular mass is between 10 and 40 kDa. These allergens are relatively resistant to thermal and enzymatic / chemical denaturation. Demonstration of the absence of allergenic compounds can be achieved by immunoassay techniques.

 In a particular embodiment, the detection of allergenic contaminants in oils can be carried out by an ELISA test or a RAST-inhibition in the presence of serum with a high titer of IgE specific to allergenic contaminants.

 Such sera can be marketed by several laboratories, for example the Pharmacia, Boehring laboratories.

 The study of the physicochemical properties of the allergenic proteins of vegetable oils reveals that these proteins are anionic and offer a strong tendency to the formation of micellar aggregates in soluble phase (aqueous / organic environment).

 This aggregation property forms the basis of our invention on the more specific elimination of allergenic proteins.

Process for the production of hypoaliergenic oils
The main object of this invention is to provide a new, efficient and simple process by which the vegetable oils produced contain a reduced load of allergenic proteins.

Said method comprises:
- a trituration (I) of the seeds carefully selected by pressing the oil seeds at 300 bars and at a temperature between about 10 and 400C by means of a mechanical press with a worm screw and an extraction of crude virgin oils;
- decantation (2) for liquid-solid separation
- a degumming, a clarification and a purification by a double filtering of the crude oils: first of all, said crude oils are subjected to a frontal prefiltration (3) through a filter with a pore diameter equal to about 20 clam, the solid residues from this prefiltration are removed, and the filtrate is stored in a concentration tank (4).

 The filtrates are made of oil with a low particle content. Decanting the filtrate makes it possible to recover an oily phase.

 The advantageous characteristic of the invention, the front prefiltration is carried out by means of a filter press, constituted in a known manner of a succession of filtration fabrics, embedding filtration chambers.

 The pore diameter of the filter cloths is a few tens of micrometers.

This prefiltration allows the elimination of traces of humidity, solid waste suspended in oil at the outlet of the presses.

 The oil obtained from the prefiltration after passing through the concentration tank is filtered by microfiltration or ultrafiltration (5) by means of a porous membrane whose porosity must be between 0.01 and 5.0, um approximately, and more precisely between 0.1 and I μm with regard to microfiltration or else between 0.001 and 0.1 μm, preferably between 0.01 and 0.1 μm with regard to ultrafiltration.

 Finally, the filtrate is stored in a conditioning tank (6).

 In the first moments of microfiltration or ultrafiltration, there are aggregates of small allergenic proteins in the permeate. These aggregates disappear from the permeate during filtration.

 To avoid this presence of aggregates at the first moments of filtration, the module operates with retentate recycling (closed loop) to promote the formation of a polarization layer by adsorption, this layer retains small aggregates.

 In other words, the invention consists on the one hand of associating a frontal prefiltration technique with a tangential microfiltration or ultrafiltration process.

 Advantageously, and according to the invention, the permeate obtained at the end of microfiltration or ultrafiltration constitutes an oil free of allergenic contaminants.

 According to the invention, the operating temperature of the process according to the invention is room temperature. In this way, the microfiltration or ultrafiltration membranes can be of organic or mineral nature.

 According to the invention, the speed of circulation of the oils is between 1 and 5 ms - 'Indeed, if this speed exceeds 5 ms ", energy consumption is unnecessarily increased and there is a risk of significant abrasion of the layer membrane.

 On the other hand, if this speed is less than 1 m.s- ', the permeability of the membrane can be affected.

The invention also relates to an installation for the production of pressure oils. It is characterized in that it includes in series:
- a module for crushing seeds,
- a settling tank, for the elimination of solid particles and the reduction of
humidity level,
- a front pre-filtration module, consisting of a filter press,
- a concentration tank for the impurities contained in the filtrate from the prefiltration
frontal,
- a microfiltration or ultrafiltration module, intended to ensure purification by
filtration of the filtrate from the concentration tank;
- and finally, a packaging module for purified oils.

 The manner in which the invention can be implemented and the advantages which result therefrom will emerge more clearly from the example of embodiment which follows, given by way of nonlimiting indication in support of the appended figures. Figure 1 is a representation of the general operating diagram of the method according to the invention. Figures 2 and 3 respectively represent the protein profile of the different oils analyzed by SDS-PAGE electrophoresis and in immunoblotting.

The detection of allergenic proteins in oils was carried out in the presence of sera from patients allergic to allergenic contaminants in oils.

 Crude oils from seed pressure are placed in a settling tank (sedimentation) for 3 to 4 days. The decanted crude oils are then pumped to be conveyed by a mobile piping system to a filter press.

 The principle of the filter press, well known in the field, consists in introducing the product to be filtered under pressure of between 0.1 and 3 bars in microfiltration, in order to compensate for the gradual obstruction of the filtration fabrics by the residues in suspension in oil.

 In fact, when it is desired to obtain a constant flow of filtrate at the outlet of the filter press, the pressure must be upstream of the latter. Is obtained at each of the filtration cloths, and therefore in the filtration chambers, residues in pelletable form, commonly called cakes, which are periodically removed from said filter press according to an operation commonly called deburring.

 The filtrate from the prefiltration is then conveyed to a concentration tank, then sent to the microfiltration or ultrafiltration module, a permeate is obtained which is an oil with a low content of allergenic proteins, phospholipids and other contaminants.

 The advantage of this new process consists in not using a chemical treatment, nor a washing with water, which avoids the problem of aqueous effluent on the one hand and on the other hand, makes it possible to save energy and the production of a hypoallergenic oil having retained its organoleptic qualities and rid of its contaminants.

 Conversely, during conventional refining, more precisely chemical refining, huge quantities of residual liquid occur, this product constitutes a pollutant for the environment and its elimination causes real problems for the oil industry.

 The micellar aggregates are retained during filtration, only the triglycerides pass through the microfiltration or ultrafiltration system. Allergenic proteins in the form of micelle aggregates are retained in the retentate, as well as free fatty acids, waxes, metals, phospholipids are selectively concentrated (adsorbed) and then eliminated. Microfiltration or ultrafiltration also makes it possible to reduce the humidity level to a value less than 1%.

 The present invention relates to a process for producing hypoal lergenic oils, and more particularly, a method for removing allergenic contaminants present in vegetable oils.

 By way of illustration, we recall the traditional process for the refining of virgin howls.

 This process of physical refining by pressure - extraction allows the bursting of the oleiferous cells releasing the oils and the cold extraction of these oils.

 Depending on the operating pressure, the crude oils extracted may contain at least some of the membrane contaminants from cells, including their content, in particular phospholipids, proteins and traces of metals.

 In an advantageous embodiment, the method according to the invention is particularly advantageous, since it makes it possible to remove not only allergenic contaminants, but also phospholipids, free fatty acids, traces of metals, waxes as well as pigments by microfiltration or ultrafiltration.

 The filtration of the oils is carried out cold at a temperature below 40 "C. and more precisely between 15 and 350 C. Advantageously, the filtration is carried out at 17 - 300 C.

Alternatively, with a certain degradation of the flow rate, the oils can be filtered slightly hot, in any case, this temperature must be lower than 400C
The present method can be applied to a wide range of conditions and is not limited to a specific flow rate at which the microfilter must be rinsed. However, a higher flow rate than that used for oil filtration, i.e. 50 IJh / m2 must be used.

 Direct rinsing of the microfilter with water can be accomplished at any desired flow rate and pressure. Likewise, water rinsing can be used over a wide range of temperatures. It is usually preferable to use hot water for rinsing.

 Under certain conditions, reverse flow can be obtained, allowing similar results to be achieved. Normally, however, direct flow of the rinse water is preferred.

 At some point, the membrane will not be capable of sufficient regeneration by the flushing process. When this point is reached, it is necessary that the micofilter is subjected to a chemical cleaning for a period of time sufficient to restore the filtration capacity of the membrane, at least to a predetermined minimum level. Again, the predetermined level at which chemical cleaning of the membrane should be employed will vary depending on the specific apparatus employed and the related operating parameters.

 Consequently, the present method is applicable over a wide range of conditions and is not limited to a specific flow rate at which chemical cleaning of the membrane must be started.

After having finished the chemical cleaning, the membrane is completely rinsed to make it sterile and to rid it of any contaminating agent then it reverts to a use of oil filtration
The agents used for chemical cleaning can vary widely and their purpose is to free the membrane from adsorbed materials, such as fats, proteins, glycoproteins and other organic materials which cause a decrease in the flow through the membrane. From this point of view, treatment with dilute caustic solutions, such as aqueous solutions of sodium hydroxide or potassium hydroxide, is usually preferred.

 Enzymatic formulas, containing proteases and lipases with and without caustic product can also be used to cause chemical degradation of the adsorbed substances. In addition, the use of surfactants can be employed, causing a reduction in the surface attraction between the adsorbed materials and the regions of the external and internal surfaces of the microfilter.

Claims (9)

 1) Process for the physical refining of vegetable hulles in order to produce oils having a zero allergenic protein content and very reduced phospholipid content, characterized in that it comprises the following stages.  filtration by microfiltration or ultrafiltration by means of a porous membrane of the filtrate stored in the concentration tank, the permeate constituting the refined oil.  well submitting said decanted oils to a frontal prefiltration, the solid residues resulting from this prefiltration then being eliminated, and the filtrate being stored in a concentration tank;  subjecting said crude oils to a settling phase for 3 to 4 days in a settling tank at room temperature;  extraction of oils by pressure from the seeds by means of an endless screw press,  2) Method according to claim 1, characterized in that the front prefiltration is carried out by means of a filter press, constituted in a known manner of a succession of filtration fabrics, encasing filtration chambers, the diameter of the pores of the fabrics being of a few tens of micrometer.  3) Method according to one of claims 1 and 2, characterized in that it forms micellar aggregates formed of phospholipids, allergenic proteins, free fatty acids and metals, which are retained at the microfiltration membrane or ultrafiltration in the form of a concentrate or retentate.  4) Method according to any one of claims 1 to 3, characterized in that during filtration by microfiltration or ultrafiltration, the membrane has a pore size between about 0.01 and 5 microns.  5) Method according to claim 1, characterized in that it comprises a rinsing of the microfilter by direct rinsing with water heated to a temperature between 20 "C and about 100" C, to restore microfiltration or ultrafiltration at its initial rate.  6) Method according to one of claim there 5, characterized in that the microfiltration is carried out at a temperature below 40 "C and more precisely between about 15 and 350C.  7) Process for the production of hypoallergenic oils, characterized in that it comprises:  the crushing of the seeds at a pressure of about 300 bars and a temperature between about 10 and 40 "C.  the recovery of filtrates consisting of oils with a low particle content, decantation of the filtrate making it possible to recover an oily phase. This step eliminates the farinettes.  a first coarse filtration through a membrane with a pore diameter equal to about 20 μm; ;  decantation of crude oils,  a second filtration, microfiltration or ultrafiltration through a membrane with a pore diameter of between 0.1 and 5.0 μm in microfiltration or better still between 0.01 and 0.1 m in ultrafiltration.  the recovery of filtrates made of oils with low water content, phospholipids, and allergenic proteins and the elimination of a retentate rich in proteins, phospholipids, metals, waxes, pigments, etc.  8) Method according to any one of claims l to 5, characterized in that it comprises a concentration step capable of generating micellar aggregates of larger size.  9) Method according to any one of claims 1 to 3, characterized in that it comprises two successive stages of filtration implemented at a pressure ranging from 0.4 to 3 bars.