GB2470571A

GB2470571A - Fatty material purification method

Info

Publication number: GB2470571A
Application number: GB0909070A
Authority: GB
Inventors: Marc Kellens; Wim De Greyt
Original assignee: Desmet Ballestra Engineering NV SA
Current assignee: Desmet Ballestra Engineering NV SA
Priority date: 2009-05-27
Filing date: 2009-05-27
Publication date: 2010-12-01
Also published as: GB0909070D0

Abstract

A process for adjusting the moisture content and acidity of fatty material, the fatty material acidity being characterized by a pH determined using a pH water extract method, the process comprising the steps of providing a fatty material that may already have undergone some purification treatment, adding an aqueous suspension of liquid adsorbent to the fatty material and causing it to form a mixture with the fatty material, optionally adding some water or aqueous alkali to the mixture, and forming an aqueous phase separate from the fatty material and removing the aqueous phase from the fatty material resulting in a fatty matter characterized by a pH determined using a pH water extract method of preferably 6 to 9 and a moisture content preferably of 0.01 to 0.1 % (w/w).

Description

FATTY MATERIAL PURIFICATION METHOD TO IMPROVE ENZYMATIC

ACTIVITY IN ENZYMATIC FATTY MATERIAL PROCESS

FIELD OF THE INVENTION

The invention relates to purification of fatty materials by treatment with a liquid adsorbent prior to enzyme-catalyzed process, in particular prior enzymatically cata lysed interesterification.

BACKGROUND OF THE INVENTION

Interesterification is a process used to modify the physical properties of fatty materials (oils or fats) by rearranging the fatty acids groups within and between the different triglycerides. In particular, a fatty material (oil or fat) characterized by a desired melting behaviour can be obtained by interesterification from adequately chosen starting materials. The interesterification reaction can be either chemically or enzymatically catalysed.

If the interesterification is chemically catalysed, the fatty acids groups are rearranged randomly along the 3 positions of the glycerol backbone according to the law of probability. If the interesterification is enzymatically catalysed, selectivity in the rearrangement of the fatty acids groups along the 3 positions of the glycerol backbone can be observed. For example, certain enzymes will specifically catalyse the exchange of the fatty acids in 1-and 3-positions of the glycerol backbone. This selectivity is highly desirable to obtain oils and fats with a specific melting profile and a higher nutritional value. Indeed, a recent study (Sundram K., Karupaiah 1., Hayes K. in "Stearic acid-rich interesterified fat and *. 25 trans-rich fat raise the LDL/HDL ratio and plasma glucose relative to palm olein in humans.", Nutrition and Metabolism 2007, 4:3) has showed that stearic acid * S..

(saturated) is less efficiently metabolised by humans when occurring on the 2- * position than when occurring in the 1-or 3-positions of the glycerol backbone.

Compared to chemically catalysed interesterification, the enzymatically catalysed interesterification is also the preferred process to reduce the amount of waste effluent and the use of chemicals.

However, the drawback of the enzymatically catalysed interesterification is the relatively low activity and low stability of the enzymes used as catalyst. Indeed, enzymes show optimal activity when precise conditions are met. In particular it is important to operate at precise temperature, acidity, water activity and concentration in absence of contaminants. When one or more of these precise conditions are not met, a denaturation, or inactivation, of the enzyme can take place inducing loss of its structure and activity. This denaturation is the mechanism behind the progressive loss of activity of the enzyme catalyst during the interesterification of fatty materials (oils and fats). The denaturation of the enzyme is observed even if refined fatty materials are the feedstock of enzymatically catalysed interesterification. In fact, very minute amount of impurities present in the fatty materials to be interesterified may lead to the progressive denaturation and loss of activity of the enzyme selected as catalyst.

Therefore methods have been proposed to purify further fatty materials used as feedstock for the enzyme catalysed interesterification even if these fatty materials have already been previously refined by conventional processes.

One of the established companies developing enzymes has marketed Lipozyme TL IM (Novozymes, Bagsvaerd, Denmark), that can be used in applications such as the interesterification of oils and fats. This company made available to its customers the specifications that oils and fats have to meet in order to maintain the optimal activity of its enzymes. One of the specifications of interest is the "pH water extract" determined using the "pH water extract method". The pH water extract value is defined as the pH of de-ionized water that has been used to : wash a sample of fatty material provided that the pH of the de-ionized starting water has been adjusted to a value of 7. More precisely, pH water extract should ideally range from 6 to 9. If the pH water extract is below 6, it may indicate the presence of excess acid species such as, but not limited to, citric acid or phosphoric acid. The specifications also recommends the presence of a minimum .. : moisture content of 0.02% in the fatty material intended to be interesterified by *:*. enzymatic catalyst such as for example Lipozyme TL IM.

WO 2008/069804A1 describes a method and system where, prior to enzymatic interesterification, the oil or fat is forced to percolate through (a series of) packed column(s) loaded with moisture-free silica, preferably chromatographic silica. While this procedure will certainly efficiently remove impurities contained in the oils or fats, this method induces automatically a progressive pressure drop caused by the fouling of the packed column. Furthermore, this system is not designed to provide control of the acidity or moisture content of the treated fatty materials (oils or fats).

US 2008/0057552A1 describes the pie-treatment of oils or fats to be modified with enzyme catalyst, with granular clay, protein, granular carbon or combination of those materials. This pre-treatment has demonstrated positive activity benefits, but raised other issues such as the separation of the granular clay, protein or granular carbon and their disposal. Furthermore this process does not allow any control of the acidity or moisture content of the treated fatty material (oil or fat).

US 2005/0014237A1 describes a process to improve the productivity of an enzymatic method for making esterified, transesterified or interesterified products where deodorisation, eventually augmented by additional purification, performed just before the enzymatic transformation can extend the useful life of the enzyme catalyst. This process will require higher capital investment before being put into practice and hence will result in higher operating costs. Finally this process does not provide for the precise control of the acidity of the treated fatty materials (oils or fats).

US 4,416,991A describes a transesterification method where the oils and fats to be transformed are previously dried to reduce the water concentration below a set value. However, this invention does not describe how to purify further or *..

.. : control the acidity of the fatty materials (oils or fats) that will be further transesterified by enzymatic catalysis.

US 4,861,716A describes a continuous enzyme catalysed interesterification * process in which the enzyme preparation includes the adequate amount of water *** to obtain proper catalytic activity. In addition an operating temperature between 0 S... . . . . . : and 60°C is claimed. However, this invention does not describe how to purify or control the acidity of the fatty materials (oils or fats) that will be further transformed by enzymatically catalysed interesterification.

None of the above-described purification processes can control the acidity or the moisture of the fatty materials (oils or fats). In the fatty materials (oils and fats) field, acidity is associated with the presence of free fatty acids (FFA), and therefore a deodorisation treatment, such as described in US 2005/0014237A1, would be expected to reduce the concentration of these FFA. However, other acids, used during various steps of the refining process of fatty material such as, but not limited to, citric acid or phosphoric acids remain at trace level in the final refined fatty material (oil). Other acids, such as for example HCI or H2S04, are used as bleaching earth activators and could still be present at trace level after the completion of the bleaching process. Such acid species as for example citric acids or phosphoric acid, HCI or H2S04 may have a substantial impact on the enzyme activity even if present at very low concentration.

ASPECTS OF THE INVENTION

Accordingly, it is an aspect of the invention to overcome the limitation of the existing pre-treatment processes of fatty materials intended for the enzymatic catalysed interesterification and in particular to provide a method to adjust the pH of the water extract within the range of pH 6 to 9 in order to maximize the enzyme activity and productivity.

It is a further aspect of the invention to adjust and optimize the moisture content of the fatty materials used in enzymatically catalysed interesterification in order to maximize the enzyme activity and productivity.

It is a further aspect of the invention to purify the fatty materials used in enzymatically catalysed interesterification in order to maximize the enzyme activity and productivity. * . * ** * * ***

0**** SUMMARY OF THE INVENTION

It has surprisingly been found that particular liquid adsorbents are capable of * adjusting the moisture content and/or the acidity of fatty materials, the acidity *** being characterized by a pH determined using a pH water extract method, the *:::: process comprising the steps of: a) providing a fatty material that may already have undergone some purification treatment; b) adding an aqueous suspension of liquid adsorbent to the fatty material and causing it to form a mixture with the fatty material; c) optionally adding some water or aqueous alkali to the mixture; d) forming an aqueous phase that is separated from the fatty material and removing the aqueous phase from the fatty material.

It has been found that aspects of the present invention have been realized by a process comprising the steps of: a) providing a fatty material that may already have undergone some purification treatment; b) adding an aqueous suspension of liquid adsorbent to said fatty material and causing it to form a mixture with said fatty material; C) optionally adding some water or aqueous alkali to said mixture; d) forming an aqueous phase separate from the fatty material and removing the aqueous phase from the fatty material.

thereby adjusting both the moisture content and the acidity of said fatty material, said fatty material acidity being characterized by a pH determined using a pH water extract method.

It has also been found that aspects of the present invention are realized by a method for interesterifying a fatty material produced by the above-described process, wherein said method is enzymatically catalysed.

Consequently, the process of the invention may be advantageously used in various processes that precede and involve the enzymatically catalysed interesterification of oils and fats.

DETAILED DESCRIPTION OF THE INVENTION * * * * S * ***

Definitions * S. The "pH water extract method" is a method in which 75 ml of deionised water *** with a pH of 7 and 75 ml of fatty material (oil) are both heated up separately to *: 85°C and then mixed using an Ultra-Turrax high shear-mixing device at 24000 rpm *:*. for 90 sec after which the phases are separated by centrifugation for 15 minutes at 2000G and the pH of the water phase measured using a standard pH-meter. The pH thus measured is the "pH water extract value".

Acidity In the context of our invention, fatty material (oil) acidity is characterized by a pH determined using a pH water extract method. The principle of the pH water extract method used is to mix heated water of pH 7 with the same quantity of heated fatty material (oil or fat) for 90 sec using a high shear-mixing device. The phases are then separated by centrifugation and the pH of the water phase is measured using a standard pH-meter. This value is called the "pH water extract value". In this method, the acidity contained in the fatty material (oil or fat) is substantially extracted by the water and is qualitatively measurable using a standard pH-meter. Indeed, as is demonstrated in the Br�nsted acid-base model, pH by definition refers to an aqueous solution and cannot therefore be directly measured in fatty materials.

Method According to an embodiment of the method, according to the present invention, the activity of the enzyme used as catalyst is enhanced.

According to an embodiment of the method, according to the present invention, the activity of the enzyme used as catalyst is prolonged.

According to an embodiment of the method, according to the present invention, the enzyme used as catalyst is Lipozyme TL IM.

Table 1 lists the specifications, that the oils or fats intended to be * *** s.... enzymatically interesterified have to meet in order to ensure optimal and prolonged enzyme activity. Table 1 is specifically valid for the Lipozyme TM IM, * (Novozymes, Bagsvaerd, Denmark), which is mostly used on industrial scale as catalyst for the enzymatic interesterification of oils and fats. 5... * . * S. *

Table 1: Specifications of oils or fats intended for enzymatic interesterification (for Lipozyme TL IM from Novozymes)

Chemical Specifications

FFA 0.1%max Moisture and impurities 0.1 % max Moisture content 0.02% mm Soaps I ppm max Fe 0.1 ppm max Ni 0.2 ppm max Cu 0.01 ppm max P 3ppmmax AnV: 5 max PV I meqOIkg max pH water extract 6-9

Physical Specifications

Oil temperature 70°C As mentioned in Table 1, the pH water extract value of fatty materials (oils or fats) intended to be enzymatically interesterified should be between 6 and 9. Fatty materials (oil or fats) characterized by a marked acidity or marked alkalinity have a detrimental impact on the catalytic activity of enzymes such as Lipozyme TL IM, reducing its average production rate and its activity period V1/2. Influence of fatty material (oil or fat) acidity on enzyme performance would be of general character, i.e. a pH effect, rather than the result of specific binding of a particular acid onto the enzyme active site.

A minimum fatty material (oil or fat) moisture content of 0.02% is indicated in Table 1. Such minimum moisture content of the oils or fats intended for interesterification is necessary in order to avoid enzyme dehydration. Indeed, a too dry fatty material (oil or fat) will have a dehydrating effect on the enzyme leading to decreased average production rate and reduced activity period V1/2. On the other :. 15 hand, the moisture content is to be maintained below 0.1% in order to avoid hydrolysis and resulting FFA increase to take place. e

Other specifications listed in table I concern the maximum concentrations of metals such as for example Cu, Fe, Ni or other contaminants such as P and soaps.

Some of the specifications listed in Table I may not be consistently met by the classical refining processes. Indeed, the pH water extract value is typically not measured after refining stages such as bleaching or deodorisation. On the other hand, some refining methods, such the one described in W020081069804 Al in which the oils or fats must percolate through packed column(s) loaded with moisture-free silica is certainly efficient to remove most of the contamination but could have adverse effect on the moisture content of the treated oil by removing too much water. The resulting purified oil or fat could be too dry.

Process According to an embodiment of the process, according to the present invention, at least a part of said fatty material is a crude triglyceride oil that has already been subjected to one or more refining processes such as physical refining, degumming, neutralisation, bleaching, winterising ordeodorisation.

According to a further embodiment of the process, according to the present invention, at least a part of said fatty material has been subjected to a fractionation process.

According to another embodiment of the process, according to the present invention, at least a part of said fatty material has been subjected to full or partial hydrogenation.

According to another embodiment of the process, according to the present invention, the amount of liquid adsorbent falls within the range of 0.025 to 10.0 % by weight of said fatty material.

According to another embodiment of the process, according to the present .. : invention, the water added in step c) is less than 5 % by weight of said fatty * ,*.

material.

According to another embodiment of the process, according to the present S... invention, the removal of the aqueous phase from the fatty material in step d) employs a centrifugal separator or a filter.

According to another embodiment of the process, according to the present invention, the process is operated at 70°C.

According to another embodiment of the process, according to the present invention, a period of from about 1 to about 3 days elapses between steps c) and d).

According to another embodiment of the process, according to the present invention, the process is operated at a temperature lower than 70°C.

According to another embodiment of the process, according to the present invention, the separation step d) is operated at a lower temperature than the preceding steps a), b) and c).

The present invention is a method using liquid adsorbent such as, but not limited to, aqueous colloidal silica Ludox � PW-50 (Grace Davison, Grace GmbH & Co KG, Worms, Germany). The fatty materials treated by the process according to the invention may have already been refined by conventional process and/or fractionated by any fractionation processes and/or fully or partially hydrogenated.

The process according to the invention can be operated batch-wise or continuously. In the process according to the invention, the fatty material is blended with liquid adsorbent and the resulting blend is mixed during a set period.

After the mixing, the aqueous phase is separated from the treated fatty material.

Optionally some water or aqueous alkali can be added to the mixture at any stage of the treatment. The amount of liquid adsorbent and the amount of the optional water can be adjusted to the required level of purification, acidity measured by pH water extract and moisture content that the treated oil or fat has to reach, Good results have been obtained with a Ludox PW-50 concentration ranging from 0.025% to 0.2% (v/w) but our invention is not limited to this particular concentration range or this particular liquid adsorbent. The amount of additional water can be for example 3% (v/w) but again the invention is not limited to this particular concentration. Good results have been obtained for oils or fats heated at 70°C and mechanically agitated at 150 rpm for 30 minutes but our invention is not limited to those specific conditions. After the mixing, the aqueous phase containing the liquid adsorbent can be separated by decantation or centrifugation. The L:.25 separation can be operated directly after the mixing step or a rest period can be imposed between the mixing step and the phase separation. The temperature of the rest period and/or the phase separation can be adjusted and does not * .. : necessarily correspond to the temperature of the mixing step.

Therefore a remarkable feature of the treatment according our invention consists in the simultaneous reduction of the acidity measured by pH water extract value and adjustment of the moisture content of the treated fatty material (oil or fat).

The reduction of the acidity measured by pH water extract value and the adjustment of moisture content of the treated fatty material according to our invention lead therefore to better and prolonged activity of enzyme used as catalyst for the interesterification of the treated fatty material. Lipozyme TL IM (Novozymes, DK) is particularly suitable for use in the present invention, but our invention is not limited to this particular type of enzyme.

Various liquid adsorbents may be utilized in the present invention, such as, sols or colloids of metal oxides, etc., and derivatives or mixtures thereof.

Preferably, the liquid adsorbents include sols or colloids of metal oxides, such as for example, colloidal silica, colloidal alumina, colloidal zirconia, colloidal titania, etc. or mixtures thereof. Such materials may have a variety of particle sizes, shapes, distributions, porosity, solid content, surface coating, counter-ions, etc. They exist in a number of different commercially available grades and the particles may have a negative charge and a positive counter ion such as a sodium or ammonium cation or may have a positive charge when the stabilising counter ion is a negative anion such as for example a chloride anion.

Liquid adsorbent may be in the form of a suspension in water and the solids content of such suspensions generally varies between 25 % and 50 % by weight, but our invention is not limited to this particular solids content concentration. Liquid adsorbent may be prepared by any method well known from the person skilled in the art. For cost reasons, the amount of liquid adsorbent to be mixed with the fatty material in step b) of the process of the invention is preferably kept as low as **: possible. In practice, the amounts of liquid adsorbent used falls within the range of about 0.025 to about 10.0% byweight, preferably from about 0.05 to about 0.5% L:25 by weight, based on the total weight of the fatty material.

For the effective treatment, a minimum contact time between the liquid adsorbent and the fatty material is preferred. This time is not critical and may range from about 1 minute to about 300 minutes, preferably from about 5 minutes e to about 60 minutes, and more preferably from about 10 to about 30 minutes.

The water optionally added in accordance with step C) of the process of the present invention serves the purpose of diluting the liquid adsorbent and the adjustment of the moisture content of the treated fatty material. Typically, an adequate amount of water may be less than about 5 % by weight, preferably less than about 0.5 % by weight, and more preferably less than about 0.05 % by weight of the fatty material being treated. The water optionally added in accordance with step c) of the process of the present invention may have an alkaline pH. Its pH preferably does not exceed 13, more preferably does not exceed 12 and even more preferably does not exceed 11. Such alkalinity can be obtained by adding to water appropriate quantity of various alkaline substances such as for example carbonates, hydroxides and oxides. *S. * * S ** * **** * S S. * .* * * * *.. . * S.

S *S*' * * S ** . S. * * S * * .*

Claims

Claims: 1. A process comprising the steps of: a) providing a fatty material that may already have undergone some purification treatment; b) adding an aqueous suspension of liquid adsorbent to said fatty material and causing it to form a mixture with said fatty material; c) optionally adding some water or aqueous alkali to said mixture; d) forming an aqueous phase separate from the fatty material and removing the aqueous phase from the fatty material.thereby adjusting both the moisture content and the acidity of said fatty material, said fatty material acidity being characterized by a pH determined using a pH water extract method.
2. The process according to claim 1, wherein at least a part of said fatty material is a crude triglyceride oil that has already been subjected to one or more refining processes such as physical refining, degumming, neutralisation, bleaching, winterising or deodorisation.
3. The process according to any one of the preceding claims, wherein at least a part of said fatty material has been subjected to a fractionation process.
4. The process according to any one of the preceding claims, wherein at least a part of said fatty material has been subjected to full or partial hydrogenation.L:' 25
5. The process according to any one of the preceding claims, wherein the amount of liquid adsorbent falls within the range of 0.025 to 10.0 % by weight of said fatty material. * * * I. S

SS S
6. The process according to any one of the preceding claims, wherein the water added in step c) is less than 5 % by weight of said fatty material.
7. The process according to any one of the preceding claims, wherein the removal of the aqueous phase from the fatty material in step d) employs a centrifugal separator or a filter.
8. The process according to any one of the preceding claims, wherein said process is operated at 70°C.
9. The process according to any one of the preceding claims, wherein a period of from about I to about 3 days elapses between steps c) and d).
10. The process according to claim 9, wherein said process is operated at a temperature lower than 70°C.
11. The process according to any one of the preceding claims, wherein the separation step d) is operated at a lower temperature than the preceding steps a), b) and c).
12. The process according to any one of the preceding claims, wherein said fatty material resulting from said process has a moisture content between 0.01 and 0.1 % (w/w).:.
13. The process according to any one of the preceding claims, wherein said acidity of said fatty material is characterized by a pH value between 6 and 9 **4S measured using the pH water extract method. -.. * .25 *.. S.
14. A method for interesterifying a fatty material produced by a process according to any one of the preceding claims, wherein said method is enzymatically :::,;
15. The method according to claim 14, wherein the activity of the enzyme used as catalyst is enhanced.
16. The method according to claim 14, wherein the activity of the enzyme used as catalyst is prolonged.
17. The method according to claim 14, wherein the enzyme used as catalyst is Lipozyme TL IM. * * ** * *
I S.' * I. * *.* S * ** * *1** A * * S* I * SS I.