Classifications

• • 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
  • C11B7/00—Separation of mixtures of fats or fatty oils into their constituents, e.g. saturated oils from unsaturated oils
  • C11B7/0075—Separation of mixtures of fats or fatty oils into their constituents, e.g. saturated oils from unsaturated oils by differences of melting or solidifying points
• • 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
  • C11B7/00—Separation of mixtures of fats or fatty oils into their constituents, e.g. saturated oils from unsaturated oils
  • C11B7/0083—Separation of mixtures of fats or fatty oils into their constituents, e.g. saturated oils from unsaturated oils with addition of auxiliary substances, e.g. cristallisation promotors, filter aids, melting point depressors

Definitions

• Natural glyceride oils and fats comprise many different triglycerides, the physical properties of which to a large extent are determined by chain lengths and degree of unsaturation of the fatty acid moieties. To make natural glyceride oils and fats more suitable for particular applications it is often required to separate them into fractions which are more homogenous with respect to melting behaviour.
• a method for filtering a suspension comprising fat crystals of a paste-like consistency comprises introducing the fatty material in a fluid state into a filter chamber of a filter apparatus having pressing means, maintaining the fatty material therein at crystallization conditions to crystallize the higher melting compounds and actuating the pressing means to squeeze out the liquid oil.
• the filter chamber is initially coated with a fat layer, solidified by cooling this layer to far below its melting point, to prevent the liquid oil to be dry fractionated to percolate through the filter cloth before the crystallisation stage is completed.
• EP-A 399 597 Another method to increase the efficiency and yield of the dry fractionation is disclosed in EP-A 399 597. According to this method the olein fraction obtained after dry fractionation of the starting fatty material and separation by membrane filter pressing is subjected to a similar dry fractionation at a lower crystallization temperature and the stearin fraction obtained is recycled to the fatty material to be dry fractioned in the first dry fractionation treatment. This method allows an effective separation between the higher melting point components and the lower melting point components, but it requires more time and effort to achieve the fractionation.
• the amount of oil or fat added to the oil being dry fractionated and its rate of addition may be determined experimentally. They depend strongly upon the oil or fat being fractionated but we have also found that they can be varied between rather wide limits without seriously affecting the filtration characteristics and olein properties. In general, it has been found advantageous to add the triglyceride oil or fat having a composition other than the oil or fat being dry fractionated gradually and over an extended period of time. It has been found that adding more during the early part of the crystal growth stage hardly diminishes the amount that has to be added during later parts of the crystallisation stage.
• the start of the addition of oil or fat of a composition other than the oil or fat being dry fractionated is preferably postponed as much as possible.
• the process according to the invention can effectively overcome this drawback if the oil being added during the crystal growth stage is the olein fraction resulting from the ongoing fractionation process.
• the fat or oil to be fractionated is allowed to crystallize to such an extent that it can still be agitated, at which point in time filtration is started and stearin and olein are collected, whereby the olein is recycled to the crystallizer as to dilute the crystal slurry. Crystallization is allowed to continue until the olein has the properties aimed for, at which point in time the olein resulting from the separation stage is collected and no longer recirculated.
• the addition of a fat containing higher melting triglycerides and recycling of the olein isolated from the ongoing fractionation are combined. If then the rate of stearin removal is about the same as the rate of addition of the fat containing the higher melting triglycerides, the volume of the batch being processed hardly changes, leading to maximum crystallizer utilisation. In addition, a single step process achieves what otherwise requires several steps.
• a 7 l laboratory crystallizer was used. It consisted of a cylindrical glass vessel provided with a water jacket connected to a thermostat that can heat as well as cool, and with a helical agitator. An amount of 3075 g palm olein was introduced into the vessel, heated to a temperature of 60°C, kept at this temperature for 1 hour and then cooled to a temperature of 16°C. When crystallisation was observed to start, a mixture of 1300 g of the same palm olein and 625 g palm oil, that was maintained at a temperature of 25-30°C and therefore remained liquid was added to the crystallizer by means of a peristaltic pump at a rate of addition of on average 76 g/hour.
• the palm oil content in the crystallizer was 12.5 wt%.
• a sample was taken when the solid fat content as measured by pulse-NMR had reached 23.0 % and this sample was separated in an olein and a stearin fraction using a filter press.
• a further amount of the mixture of palm olein and palm oil was added to the crystallizer to raise its palm oil content to 13.4 % and the solids content of the crystallizer was allowed to increase to 24.4 wt% when again a sample was subjected to pressure filtration.
• the solids content of the filter cake was found to be 65.5 wt% as measured by pulse-NMR.
• the difference in solids content of the filter cake is also reflected in their content of mono-unsaturated triglycerides (MUT) as determined by high pressure liquid chromatography.
• MUT mono-unsaturated triglycerides
• butter fat was dry fractionated and the oil added during the crystal growth phase was the olein fraction resulting from the ongoing fractionation.
• the same laboratory crystallizer was used as in example 1.
• About 5.6 kg of butter fat was heated to 60°C, kept at this temperature for about one hour and then slowly cooled to about 25°C.
• a portion of the crystallized fat was subjected to filtration over a laboratory basket centrifuge, the stearin fraction was collected and the olein fraction was recycled into the crystallizer.
• the fat mixture in the crystallizer was then progressively cooled to 20°C, 19°C, 15°C and 13°C, and the same procedure was repeated at each of these temperatures.
• the operation conditions are illustrated in the following table 1.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Fats And Perfumes (AREA)

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Cited By (5)

Citations (6)

• 1994
  • 1994-10-27 EP EP94116973A patent/EP0651046A1/de not_active Withdrawn

Patent Citations (6)

Non-Patent Citations (2)

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