Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; MAKING THEREOF
  • A23C15/00—Butter; Butter preparations; Making thereof
  • A23C15/12—Butter preparations
  • A23C15/14—Butter powder; Butter oil, i.e. melted butter, e.g. ghee ; Anhydrous butter
  • A23C15/145—Removal of steroids, e.g. cholesterol or free acids; Fractionation of anhydrous milkfat by extraction with solvents other than solvent crystallisation or with supercritical gases or by distillation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/12—Molecular distillation
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11B—PRODUCING, e.g. BY PRESSING RAW MATERIALS OR BY EXTRACTION FROM WASTE MATERIALS, REFINING OR PRESERVING FATS, FATTY SUBSTANCES, e.g. LANOLIN, FATTY OILS OR WAXES; ESSENTIAL OILS; PERFUMES
  • C11B3/00—Refining fats or fatty oils
  • C11B3/12—Refining fats or fatty oils by distillation

Definitions

• the present invention relates to a process for removing cholesterol from a fatty material of animal origin and in particular lactic fat, by molecular distillation.
• Molecular distillation has been a technique known for a long time, in particular for separating, purifying, discolor or deodorize liquid or liquefiable products.
• FR 2 0338 describes the elimination of most of the cholesterol from a lactic fat while avoiding the separation of the triglycerides by molecular distillation.
• a conventional molecular distillation apparatus comprises means for establishing a thin film, with a thickness of the order of 0.1 to 1 mm, of the liquid to be distilled on a wall heated to an appropriate temperature.
• the film is conventionally formed by mechanical means involving, for example, centrifugal force, while the surface is conventionally heated by radiant electrical resistors.
• these resistors are arranged in a spiral on the side of the cone opposite to the film of liquid which forms thereon. by the effect of centrifugal force, and reflectors are provided to focus the infrared radiation emitted by the resistors in a direction opposite to the cone.
• the temperature to which the distillation cone can be brought is limited by the very fact of the limitation of the density of calorific power transmissible by radiant resistors. In practice, one cannot exceed with electrical resistances a temperature of the order of 230 ° C. on the surface of the cone. As a corollary, we can only work with very limited flow rates, for example of the order of 15 kg / hour for a 38 cm diameter cone corresponding to an active heating surface of 0.1 m 2 , which limits the economic advantage of such devices. In this respect, the solution consisting in increasing the size of the cone in order to be able to increase the flow rate is not always desirable, since it leads to excessively long residence times in the still. In addition, the cost of the material increases very quickly with the dimensions.
• the resistors radiate heat energy not only to the cone, but also to other constituent parts of the device.
• the thermal efficiency is poor, and on the other hand it is necessary to specially design the parts of the device close to the resistors.
• the products of interest consist of the distillate (light fraction).
• the product of interest consists of the heavy glyceride fraction.
• This non-volatile fraction is fragile and undergoes the negative effects of temperature. That is why it is necessary to improve the conditions of its treatment.
• the present invention aims to overcome these drawbacks of the prior art and to propose a process for molecular distillation of fatty matter of animal origin, in particular of lactic origin to extract cholesterol which is improved from the point of view of ease and operating performance and the quality of the products obtained.
• the subject of the present invention is a process for extracting cholesterol from a fatty material of animal origin by molecular distillation using a conventional molecular distillation apparatus comprising means for obtaining a thin film with a thickness of 0.1 to 1 mm, of a liquid fatty substance to be distilled on a wall heated under vacuum to cause the evaporation of cholesterol, process consisting in recovering the light heavy fraction in cholesterol, characterized in that said surface is heated by an induction heater.
• This process is suitable for the elimination of cholesterol from animal fat used in human food and more particularly for the extraction of cholesterol from milk fat, and in particular dehydrated butter as well as from tallow and lard. .
• Lactic fat can be separated from whole milk by centrifugation or by vacuum evaporation of the cream.
• the fat obtained is preferably essentially anhydrous, that is to say that it contains less than 0.1% of water.
• the molecular distillation of the anhydrous lactic fat is preferably carried out.
• the process according to the invention is characterized in that the molecular distillation is carried out under vacuum from 1 to 20 ⁇ m and more particularly from 3 to 10 ⁇ m of Hg, at a temperature of 160 to 220 ° C.
• the unsaponifiable fraction containing the eliminated cholesterol represents 2 to 6% by weight of the initial fat.
• the process according to the invention makes it possible to preserve to a greater degree than the usual process the organoleptic qualities of the fat. .
• the use of induction heating also makes it possible to obtain a significantly higher flow rate of treated raw material compared to the prior process with resistance heating while retaining the qualities mentioned above.
• purer products are generally obtained with an increased yield, in particular by the fact that no pyrolysis takes place on the heating surfaces and that the calorific power is practically transmitted in a substantially uniform manner.
• the process according to the invention is characterized in that the distillation is carried out at a temperature of the order of 165 ° C to 185 ° C and at an initial fat flow rate of 15 to 0 kg / hour for a cone 38 cm in diameter, that is to say an active heating surface of 0.1 m 2 and preferably from 20 to 30 kg / hour.
• the surface is an interior surface of a conical rotor driven in rotation, supplied with fluid to be evaporated in its center and disposed in a chamber vacuum
• the induction heating device comprises at least one inductor constituted (s) by one (or more) conductor (s) wound in a spiral on the side of the cone opposite to the film of liquid and supplied by an alternating current generator.
• the induction heating device comprises one or more inductors wound in a spiral as close as possible to the cone without however being in contact (less than 5 mm, preferably from 1 to 3 mm) with it and distributed substantially over its entire extent .
• the or each conductor comprises a hollow metal tube in which a coolant is circulated.
• a tube rather than a wire as in Japanese patent n ° 62237003 allows easy cooling and therefore the tube supports higher intensities and brings more power to the rotor.
• the cone is made of stainless steel or any suitable magnetic material known in the technique of induction heating, and the generator delivers an alternating current at a frequency of the order of 1 kHz to 30 kHz and more particularly from 1 to 25 kHz.
• the generator includes several regularly distributed inductors, in which case the generator can include several modules to supply the inductors individually.
• Two opposite ends of the hollow conductor pass through a rear wall of the vacuum chamber parallel or concentric to one another and through a sealed connector, for their connection with the generator and with a device for circulating the coolant.
• this induction heating device can be further improved because it has drawbacks during its practical use, especially when working with large cones, for example 90 cm in diameter.
• the liquid to be distilled arrives at the center of the cone in a cold state or only slightly warmed, and the supply of heat energy is insufficient to bring it quickly to the distillation temperature. Then, the thickness of the film of liquid on the cone decreases appreciably from the center towards the edges of the cone.
• a new induction heating device is advantageously used for large heating surfaces allowing large flow rates, which makes it possible, using simple and economical means, to apply a density of different calorific power to the cone. center of the rotor and at its edges.
• a molecular distillation apparatus is therefore used, of the type comprising a conical metal rotor driven in rotation and fed in its center by a liquid to be distilled, a vacuum bell defining a chamber housing the cone and means induction heating of the rotor located below and close to it, characterized in that the heating means comprise at least two concentric inductors providing regions homologous to the rotor with different heat power densities.
• At least two concentric inductors are used, preferably 3 inductors each produced by conical spiral winding of a metal tube.
• Figure 1 is a side view in partial section of part of a molecular distillation apparatus useful in the process according to the present invention.
• Figure 2 is a view taken along the arrows II of Figure 1.
• Figure 3 is a view similar to Figure 2 showing a variant of the arrangement of the heating means.
• the figure is an axial sectional view of a part of the apparatus with several concentric inductors.
• Figure 5 combines an axial section view and a graph showing a heating characteristic of the apparatus of Figure 4.
• FIG. 1 Illustrated in Figure 1 is a part of a molecular distillation apparatus which firstly comprises a sealed enclosure 10 or vacuum bell, in which a high vacuum, of the order of 1 to 10 ⁇ m Hg, can be established.
• This enclosure has a condensing dome 1 1 consisting of a cold wall.
• a rotor 20 capable of rotating around an axis A while being driven by a motor M via a shaft 22 passing through a device schematically indicated at 24, forming both a bearing and a sealed passage through the rear wall 13 of the enclosure 10.
• the axis A is conventionally inclined relative to the horizontal, by an angle denoted alpha which can take a wide range of values depending on the construction and the application of the distiller.
• the rotor 20 is preferably made of stainless steel, magnetic or non-magnetic. It has the shape of a cone, the hollow surface S of which faces the condensation dome 11. In the center of this surface S there opens an outlet orifice 32 of a conduit 30, shown only partially, which conveys a liquid in front of be subjected to molecular distillation.
• the rotor 20 can also be used in any other material suitable for induction heating and suitable for the treated product, such as a metal alloy, a composite material, a coated metal, etc.
• the distillation is carried out by heating the rotor 20 using suitable heating means to bring its conical surface S to an appropriate temperature, as regular as possible.
• the liquid brought to the center of said surface due to the rotation of the rotor, develops into a thin film of substantially uniform thickness on this surface under the effect of centrifugal force.
• the most volatile part of the liquid evaporates and then condenses on the condensing dome 1 1, possibly cooled by tubes (not shown) in which a cold liquid circulates, then is collected in an appropriate chute 12 fixed inside the enclosure 10 in its lower part.
• the conical surface S is heated by induction heating means comprising in the present example a single inductor I constituted by a hollow copper tube 50 developed in a spiral below (approximately 2 mm ) of the conical rotor 20, extending at a substantially constant distance from said surface.
• induction heating means comprising in the present example a single inductor I constituted by a hollow copper tube 50 developed in a spiral below (approximately 2 mm ) of the conical rotor 20, extending at a substantially constant distance from said surface.
• the choice of stainless steel to make the rotor is advantageous in that the efficiency, expressed by the ratio of the heat energy generated in the rotor to the electrical energy applied to the inductor, can reach 75 to 90%.
• the tube 50 can be chromed or plasticized, in order to avoid any degradation by contact with the treated products, or else embedded in an epoxy resin reinforced to ensure this protection while strengthening the structure of the inductor.
• a coating compatible with the temperatures generated in the tube is chosen.
• the two ends 52, 54 of the tube pass through the wall of the vacuum enclosure 10, with removable sealing devices. Said ends are connected to a current generator at a determined frequency, for example of the order of 1 to 30 kHz, diagrammatically indicated in 56.
• a static converter operating with reverse conduction thyristors such as described for example in the article "Thyristors with reverse conduction for medium frequency converters of great power", 3. Vitins and H. Renggli, Revue Brown Boveri 1 -86, pages 50-55.
• the current, flowing in the tube 50, will cause in a partially instantaneous and essentially uniform manner heating of the rotor 20, by induction.
• a temperature essentially Uni term of 300 ° C can be reached approximately 30 seconds after the inductor is put into service.
• the power that the generator will have to provide will be of the order of a few kilowatts and sized according to the characteristics of the rotor and the desired operating parameters.
• the tube 50 In order to avoid excessive heating of the tube 50 itself, it is also traversed by a flow at an appropriate flow rate of a cooling liquid, for example water, using a circuit of appropriate circulation schematically indicated in 58.
• a cooling liquid for example water
• FIG 3 illustrates an alternative embodiment of the induction heating means; in this case, the single induction winding I of the embodiment of FIGS. 1 and 2 is replaced here by three inductors in the form of "pancakes", respectively II, 12, 13, ... each consisting of a winding of a hollow copper tube and regularly distributed below the cone 20.
• these inductors can be supplied with electric current individually so as to more flexibly modulate the supply of heat energy to the distillation cone.
• the apparatus included the same distillation cone 38 cm in diameter and an active heating surface of 0.1 m 2 .
• the distillation was carried out under vacuum of 10 ⁇ m of Hg.
• the apparatus was heated by a resistance and for Examples 2-2 and 2-3 by induction.
• a single inductor was supplied under an alternating voltage of the order of 90 V, with a variable frequency between 1 and 10 kHz and a variable power.
• a thermocouple kept the cone at a determined temperature.
• the device used for this example is the CVC PILOT-15.
• EXAMPLE 2-2 Apparatus similar to that of Example 1 but heated by induction as described above and in FIG. 1, set at a flow rate close to that of Example 1
• the recovered product is less degraded by this new process, which is confirmed by organoleptic examinations.
• EXAMPLE 3 Apparatus with several concentric inductors (FIGS. 4 and 5) The dimensioning of the still resulted in the separation of the cone into three heating zones each having their inductor.
• the object of such an arrangement of inductors is in particular to apply to the cone 20 a calorific power density which is higher in the region of the center and which is lower in the region of the edges, compared to a value medium, in order to overcome the drawbacks of the single inductor device discussed above. It was found that this result could be obtained by supplying the two inductors (or more) in parallel by the same generator.
• the device with several concentric inductors of the invention by a judicious choice of the position and dimensions of the crown in which each inductor is inscribed, and the number of turns of each inductor, makes it possible to obtain a density profile. of appropriate power along a radius of the rotor.
• the conical rotor 20 and three concentric inductors, namely an internal inductor 100a, an intermediate inductor 100b and an external inductor 100c.
• the intermediate inductor ensures a regular decrease and a slight slope of the power density between the region near the center of the rotor and the region of its edges.
• the rotor 20 is preferably made either of stainless steel or else of a composite material composed of an upper layer of food-grade stainless steel (liquid side), for example of type 316, of a layer intermediate aluminum and a lower layer of magnetic stainless steel. Such a composite is known in particular under the commercial designation "Duranell" (registered trademark).
• the rotor preferably has a thickness of the order of 5 mm.
• Each inductor is arranged below the conical surface of the rotor 20, with a sufficiently small spacing, typically 2 mm or less, to obtain good heating efficiency.
• each inductor is produced with a copper tube with an outside diameter of 10 mm and a wall thickness of 1 mm.
• the turns of each inductor have in this case a constant pitch of the order of 14 mm.
• C oncrticment was used an induction heater to a stainless steel rotor food grade 5 mm thick and with a diameter of 90 cm.
• the area in which heating was to be applied was a crown with an inner radius of 66 mm and an outer radius of 417 mm.
• the total power to be applied to the cone was approximately 50 kW.
• the ratio between the power densities in the inner region of the crown and in its outer region should be of the order of 5 to
• Dl internal radius of the crown containing the inductor in millimeters
• Y supply voltage in volts
• I current in the inductor in amperes
• P total power delivered by the inductor in kilowatts
• FIG. 5 shows the power density profile obtained concretely along a radius of the cone. More precisely, six thermocouples were placed at regular spacings along the radius, and each time, from the instant of the induction heating start-up, the rate of temperature rise of the inner surface of the cone (in ° C per second), this speed being directly proportional to the power density actually applied; the curve 200 represents diagrammatically the evolution of the power density as a function of the radius r at which one places oneself on the cone (abscissa).
• the ratio between the maximum power density (at the break in slope between the parts of the curve 201 and 202) and the minimum power density (at the outer limit of the external inductor 100c) is of the order of 6.3. This profile has proven in practice to be quite suitable for the molecular distillation of cholesterol in milk fat.
• step 1 distillation of MGLA + RD2: duration: 19 hours
• stage 2 distillation of Dl: duration: 2 hours Quantity of D l: 285 Kg Flow rate: 150 Kg / h Distillation rate: 35%
• step 3 shutdown, cleaning, restart duration: 3 hours
• stage 1 will relate to the distillation of MGLA without addition of RD2, the conditions and results being substantially the same; the purpose of this recycling operation is to reduce the loss of fat for a given level of cholesterol removed.
• step 1 distillation of 15% (D l) of the fat giving a residue depleted in cholesterol at 919-6 (RD I)
• step 2 distillation of 4096 of the distillate (Dl) in such a way that the corresponding residue (RD2) has a cholesterol level identical to that of step No. 1.
• the second step was carried out on the small 38 cm rotor apparatus also heated by induction of Example 2, this for reasons of available volume to be treated.
• the preceding distillate is taken up in an induction heating apparatus 38 cm in diameter.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Microbiology (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Food Science & Technology (AREA)
• Polymers & Plastics (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
• Fats And Perfumes (AREA)

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• 1989
  • 1989-11-22 FR FR8915317A patent/FR2654583B1/fr not_active Expired - Fee Related
• 1990
  • 1990-11-22 JP JP50017691A patent/JPH05501580A/ja not_active Withdrawn
  • 1990-11-22 EP EP19900917668 patent/EP0502066A1/de not_active Ceased
  • 1990-11-22 CA CA002069408A patent/CA2069408A1/fr not_active Abandoned
  • 1990-11-22 WO PCT/FR1990/000838 patent/WO1991007877A2/fr not_active Application Discontinuation

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