GB2410201A

GB2410201A - A demulsifying process using an ionic emulsifier

Info

Publication number: GB2410201A
Application number: GB0329043A
Authority: GB
Inventors: Miroslav Buchmet
Original assignee: Danisco AS
Current assignee: International N&H Denmark ApS
Priority date: 2003-12-15
Filing date: 2003-12-15
Publication date: 2005-07-27
Also published as: GB0329043D0

Abstract

A process for separating an emulsion into its component phases comprising the step of contacting the emulsion with an ionic emulsifier. Suitable emulsifiers are the reaction product of a carboxylic acid, preferably a hydroxyl carboxylic acid, and a carboxylic acid or alcohol, or a salt thereof. Preferred hydroxyl carboxylic acids are glycolic acid, lactic acid, tartronic acid, malic acid, tartaric acid or citric acid. Preferred carboxylic acids are C6-C26 acids, particularly stearic acid, and a preferred alcohol is glycerol. Particularly preferred ionic emulsifiers are citric acid glycerides and calcium or sodium stearoyl lactylate. The emulsion to be separated may be a water-in-oil emulsion, such as in a low - fat edible spread. The emulsion may also comprise an existing emulsifier such as polyglycerol polyricinoleate.

Description

PROCESS

The present invention relates to a process for separating an emulsion into its component phases and the use of an ionic emulsifier for separating an emulsion into its component s phases.

An emulsion is a colloid consisting of a stable mixture of two immiscible phases, typically liquid phases in which small droplets of one phase are dispersed uniformly throughout the other. A typical emulsion is an oil and water emulsion, such as a water-in-oil lo emulsion. Emulsions may, for example, be industrial emulsions such as water- containng crude oils emulsified by addition of surface active substances, or edible emulsions such as mayonnaise, salad cream or margarine.

Emulsions are typically stabilized by the addition of an emulsifier and many effective emulsifiers are known. However, the use of these effective emulsifiers may become problematic if the separation of the emulsion into its component phases is desired. For example, many oil and water emulsions having industrial applications may need to be disposed of at the end of their useful life. This could be done by incineration, but the presence of water makes the cost of incineration high and thus breaking the emulsion and separating the water phase would be desirable. In the food industry, separating the oil/fat phase from the water phase of an emulsion foodstuff may be desirable in order to rework or analyse the foodstuff. The recovery of the oil/fat phase may also have cost benefits since it is a valuable component of the emulsion.

2s Polyglycerol polyricinoleate (PGPR) is a particularly effective emulsifier. Emulsions, in particular water-in-oil emulsions, prepared with PGPR are typically very stable and therefore separation of such emulsions into their component phases is know to be problematic.

Some methods for breaking oil and water emulsions are known in the prior art.

US 4,115,598 relates to water-in-oil type emulsions of a fat content of 35 to 65 percent which destabilise at body temperature. The emulsions contain a fat blend having a solids content of 10-35 percent at all temperatures from 10 -20 C, a difference in solids content at 10 and 20 C of no more than 10 percent and a solids content at 30 C of less than 5 percent. Monoglycerides, preferably of an iodine value of 20 to 100 are present and preferably oil-in water emulsion promoting emulsifiers as well.

US 6,310,106 discloses a process for breaking an emulsion into a water phase and an oil s phase having particular application in crude oil emulsions. The process involves contacting the emulsion with a demulsifying effective amount of an alkoxylated C'024 carboxylic acid ester derived by the addition of ethylene oxide and/or propylene oxide onto a ring opened epoxidised C,0 24 carboxylic acid triglyceride which is ring opened with a C6,6 carboxylic acid.

STATEMENT OF INVENTION

The present invention alleviates the problems of the prior art.

In one aspect the present invention provides a process for separating an emulsion into its component phases comprising the step of contacting the emulsion with an ionic emulsifier.

In a further aspect the present invention provides use of an ionic emulsifier for separating an emulsion into its component phases.

The term "emulsion" is well known in the art. It typically taken to mean a stable mixture of two immiscible phases, typically liquid phases in which small droplets of one phase are dispersed uniformly throughout the other. 2s

The term "separating an emulsion into its component phases" is well known in the art and means creating a phase boundary between each of the different phases Preferably it means complete separation of the phases such that each phase is distinct and does not contain droplets or does not substantially contain droplets of any other phase within it.

The term "ionic emulsifier" as used herein means an emulsifier molecule comprising a hydrophilic portion and a hydrophobic portion wherein the hydrophilic portion comprises an ionic group. The hydrophobic portion typically comprises a non-polar aliphatic and/or aromatic hydrocarbon group.

The present applicants have surprisingly found that an emulsion may advantageously be separated into its component phases by addition of an ionic emulsifier. Separating an emulsion into its component phases may find application in many different fields and in particular in the food industry. The process of the present invention may be used in one aspect to separate oil and water emulsions, such as water in oil emulsions, for example edible spreads. The oil phase thus separated may be reused in the production of further edible spreads. The water phase thus separated may be reliably analysed to provide information on the composition, in particular the salt content, of the initial spread.

PROCESS

As previously mentioned, in one aspect the present invention provides a process for separating an emulsion into its component phases comprising the step of contacting the emulsion with an ionic emulsifier.

ionic Emulsifier In a preferred aspect, the ionic emulsifier is the reaction product of a hydroxy carboxylic acid and a second reactant, or a salt thereof.

Hydroxy Carboxylic Acid The term "hydroxy carboxylic acid" as used herein means a molecule comprising at least one carboxylic acid group (COOH) and at least one hydroxy group (OH).

Preferably the hydroxy carboxylic acid is an alpha-hydroxy carboxylic acid or a beta- hydroxy carboxylic acid. More preferably, the hydroxy carboxylic acid is an alpha- hydroxy carboxylic acid.

The term "alpha-hydroxy carboxylic acid" means a molecule comprising a hydroxy group attached to a carbon alpha to a carboxylic acid carbon.

The term "beta-hydroxy carboxylic acid" means a molecule comprising a hydroxy group attached to a carbon beta to a carboxylic acid carbon.

In a preferred aspect the hydroxy carboxylic acid is selected from the group consisting of glycolic acid, lactic acid, tartronic acid, malic acid, tartaric acid and citric acid.

HO O HO O O O

OH / OH HO OH

OH

Glycolic acid Lactic acid Tartronic acid

O OH O O OH O

HO HO OH HO OH

O OH O OH O OH

Malic acid Tartaric acid Citric acid As previously mentioned, the hydroxy carboxylic acid comprises at least one hydroxy group and at least one carboxylic acid group. In a preferred aspect the hydroxy carboxylic acid comprises only one alcohol hydroxy group. In one preferred aspect the hydroxy carboxylic acid comprises at least two carboxylic acid groups.

In a highly preferred aspect, the hydroxy carboxylic acid is lactic acid or citric acid.

Second Reactant As previously mentioned, in a preferred aspect, the ionic emulsifier is the reaction product of a hydroxy carboxylic acid and a second reactant, or a salt thereof.

Preferably the second reactant is a carboxylic acid or an alcohol.

In one preferred aspect, the second reactant is a carboxylic acid.

Preferably the carboxylic acid is a C6-C26 carboxylic acid, more preferably a C,2-C20 carboxylic acid, more preferably a C,2, C,4, C,6, C, 8, or C20 carboxylic acid. In a highly preferred aspect the carboxylic acid is a C, carboxylic acid.

Preferably the carboxylic acid is aliphatic. Preferably the carboxylic acid Is saturated.

Preferably the carboxylic acid is straight-chained.

In a highly preferred aspect the carboxylic acid is stearic acid.

In one aspect the present invention provides a process for separating an emulsion Into its component phases comprising the step of contacting the emulsion with an ionic emulsifier, wherein the ionic emulsifier is a salt of the reaction product of lactic acid and stearic acid.

In one aspect the present invention provides a process for separating an emulsion into its component phases comprising the step of contacting the emulsion with an Ionic emulsifier, wherein the ionic emulsifier is sodium stearoyl lactylate. In another preferred aspect, the ionic emulsifier is calcium stearoyl lactylate In one preferred aspect, the second reactant is an alcohol.

Preferably the alcohol comprises more than one hydroxy group. More preferably the alcohol is a diol or a trial. In a highly preferred aspect, the alcohol is glycerol.

Preferably the alcohol is partially esterified. In one aspect preferably the alcohol is a monoglyceride. In another aspect preferably the alcohol is a diglyceride. In a further aspect, preferably the alcohol is a combination of monoglycerides or a combination of diglycendes or a combination of monoglycerides and diglycerides.

in this aspect preferably the ester moiety of the monoglyceride and/or each ester moiety of the diglyceride has a chain length of from 4 to 24 carbon atoms.

The ester moiety of the monoglyceride/diglyceride is preferably derived from a fatty acid.

Preferred fatty acids are selected from the group of fatty acids having a chain length of between 4 and 24 carbon atoms. More preferably these are selected from the group of fatty acids having a chain length of between 12 and 22 carbon atoms. These correspond to the fatty acids found in most well known triglyceride oils Examples of suitable fatty acids are fatty acids derived from a vegetable fat such as soy bean oil, rapeseed oil, olive oil, palm oil, sunflower oil, corn oil, safflower oil, cotton seed oil, palmkernel oil, coconut oil, linseed oil, butter oil or fractions thereof, or other lauric acid oils.

In a preferred aspect the present invention provides a process for separating an emulsion into its component phases comprising the step of contacting the emulsion with an ionic emulsifier, wherein the ionic emulsifier is the reaction product of citric acid and a monoglycende, a diglyceride or a combination thereof.

Citric acid (2-hydroxypropane-1,2,3-tricarboxylic acid) and mono- and diglycerides of fatty acids, can form an ester under certain reaction conditions. The resulting reaction product mainly comprises citric acid, wherein one carboxylic group of the citric acid is esterified with one of the free hydroxyl groups of the glycerol backbone of the mono- or diglyceride. Some di- or even tri-esterified citric acid may be present in the reaction mixture, depending on the specific reaction conditions used such as temperature and reaction time. One monoglyceride molecule can also be esterified with two citric acid molecules. Thus in the present specification the term "reaction product of citric acid and a monoglyceride, a diglyceride or a combination thereof " encompasses monoesters, diesters, triesters of citric acid and mixtures thereof. This term also Includes esters wherein one monoglyceride is esterified with two citric acid molecules. In the present specification the ester or mixture of esters is also referred to as "ester of citric acid" or "citric acid ester".

The esters are for example prepared in a reaction of citric acid with monoglycerides or a mixture of mono- and diglycerides. Examples of a suitable starting mixture comprises more than 20 wt%, preferably greater than 40 wt%, more preferably from 80 to 99 wt%, more preferably 90 to 95 wt% of monoglyceride.

The mono- and dglycerides of fatty acids which are esterified with citric acid may be produced according to state of the art.

The citric acid esters suitable for use in the present invention may be selected from the following commercial citric acid esters: GRINDSTEDO CITREM SP 70, GRINDSTED CITREM LR 10, GRINDSTED6) CITREM BC-FS, GRINDSTED CITREM N 12 and combinations thereof.

Emulsion s As previously mentioned, in one aspect the present invention provides a process for separating an emulsion into its component phases comprising the step of contacting the emulsion with an ionic emulsifier.

lo According to the invention, the emulsion comprises at least two phases. In one aspect, preferably the emulsion comprises only two phases.

Preferably the emulsion is an oil and water emulsion, more preferably a water-in-oil emulsion.

Preferably the emulsion is a foodstuff, more preferably an edible spread.

In this aspect preferably the emulsion comprises an aqueous phase and a fat phase.

The aqueous phase is a liquid at room temperature. The fat phase may or may not be a liquid at room temperature.

The edible spread may optionally comprise a protein or a combination of proteins.

Suitable amounts of protein are from 0.1 to 2 wt% on total product weight. Examples of suitable proteins are soy protein, dairy proteins such as whey protein, whey powder, skim milk powder, butter milk powder, Na- caseinate or combinations thereof.

An emulsion according to the invention preferably comprises a wt% of 30 to 98 of a triglyceride fat or a mixture of triglyceride fats (fat blend).

A suitable fat blend for margarine or spreads in tubs or wrappers consists of a mixture of an oil and one or more fats. The ratio of liquid oil and fat is chosen so that after processing together with an aqueous phase, a product with suitable consistency and spreadability is obtained.

Any edible, liquid oil and fat can be used, e.g. soybean oil, rapeseed oil, palm oil, sunflower oil, corn oil, safflower oil, olive oil, cottonseed oil, palm kernel oil, coconut oil and other lauric acid oils, butter oil and partially or fully hydrogenated fractions or interesterifications thereof.

In a preferred aspect the emulsion is a low fat edible spread.

The term "low fat" means that the emulsion has a fat content of 40 wt% or less.

to In addition to the above mentioned ingredients, emulsions which are foodstuffs according to the invention may optionally contain further ingredients suitable for use in these products. Examples of these ingredients are sweetener materials, EDTA, spices, vitamins, bulking agents, stabilising agents, flavouring materials, colouring materials, acids, preserving agents, flavour compositions, vegetable particles etc. Traditionally, margarines and like products, and also butter comprise salt Known margarines and spreads comprise varying amounts of salt, which are tuned to the consumers desires. Preferably the amount of salt is between 0.2 to 3, preferably 0.8 to 3 wt% of salt.

In one aspect preferably the emulsion comprises an existing emulsifier. Preferably the existing emulsifier comprises a polyglycerol fatty acid ester. Preferably the polyglycerol fatty acid ester is polyglycerol polyricinoleate, such as GRINDSTED) PGPR 90 available from Danisco.

In a preferred aspect, the amount of ionic emulsifier contacted with the emulsion is from 0.1 to 5% by weight of the emulsion, preferably 0.1 to 3% by weight, preferably 0.1 to 1.5% by weight, preferably 0.3 to 1.5% by weight, more preferably 0.5 to 1.5% by weight.

In one aspect, the emulsion Is a water-in-oil emulsion. In a preferred aspect, the emulsion is a water-in-oil emulsion and the extent of separation is such that at least 80% of the oil phase is recoverable, preferably at least 85%, more preferably at least 90%, more preferably at least 95%.

As previously mentioned, preferably there is complete separation of the phases such that each phase is distinct and does not contain droplets of any other phase within it. This has a number of advantages such as increased accuracy of the analysis of the phases.

USE s

As previously mentioned, in one aspect the present invention provides use of an ionic emulsifier for separating an emulsion into its component phases.

In this aspect preferably the ionic emulsifier is as described herein. In this aspect preferably the emulsion is as herein described.

Aspects of the invention are defined In the appended claims.

The present invention will now be described in further detail by way of example only with reference to the accompanying figure in which: Figure 1 shows the extent of emulsion separation using three different ionic emulsifiers as compared with the control.

The present invention will now be described in further detail in the following examples.

EXAMPLES

Polyglycerol Polyricnoleate (GRINDSTED PGPR 90) is a very efficient emulsifier which 2s creates an extremely stable very low fat water In oil emulsion. The drawback is that producers have difficulty in separating the fat phase from the water phase when the spread has to be reworked or analysed.

Our studies show that adding an ionic emulsifier to melted low-fat and very low-fat spreads containing GRINDSTED<g) PGPR 90 and DIMODAN@) S-T (Distilled Monoglyceride) efficiently separates the emulsions into their component phases.

The ionic emulsifiers used in these studies were: Citric Acid Ester of mono-diglycerde (GRINDSTED) CITREM SP 70) 3s Calcium Stearoyl Lactylate (GRINDSTED() CSL P 80) Sodium Stearoyl Lactylate (GRINDSTED SSL P 70)

EMULSION SEPARATION

Method For these experiments protein-free 40% fat spreads containing 0.3% DIMODAN S-T and 0.4% GRINDSTED() PGPR 90 were utilised.

100g of the spread was placed in a beaker. 1 wt% of an ionic emulsifier selected from GRINDSTED0) CITREM SP 70, GRINDSTED@) CSL P 80 and GRINDSTED SSL P 70 was added. Control samples to which no ionic emulsifier was added were also used.

The spread and ionic emulsifier mixtures and the controls were warmed to 70 C and kept at this temperature overnight.

Results The results are shown in Figure 1. As expected, the control samples did not separate.

The samples containing an ionic emulsifier did separate. Lower quantities of ionic emulsifier showed reduced ability to separate emulsions.

USE OF SEPARATED FAT PHASE

This experiment was designed to test whether the separated fat phase obtained from the emulsion could successfully be re-used to produce lowfat spread or full-fat margarine.

_

TRIAL NO. 1 2 3 Water Phase: Water 17 17 17 9 Salt 1 1 1 1 Potassium sorbate 0.1 D. 1 0.1 3.1 EDTA 0 015 0.015 0.015].015 = Fat Phase:

_

Sunflower oil 63 32 32 12 5 Soya 41 20 11 11 38 5 Palm oil 17 17 17 Separated fat 1 40 to Separated fat 2 0 FAT total 81 5 81.5 81.5 39.7 TRIAL NO. 1 2 3 4 GRINDSTED PS 301 0.4 0.4 0.4 DIMODAN S-T 0.2 B-carotene (ppm) 6 6 6 7 The products obtained using separated fat 1 (trial no. 2 and 4) and separated fat 2 (trial no. 3) did not differ from the control (trial no. 1).

s SALT ANALYSIS (WATER PHASE) It is sometimes desirable to perform a salt analysis of a salt-containing emulsion, however the presence of an existing emulsifier may affect the results of such analysis.

lo In this experiment a low-fat spread containing GRINDSTED PGPR 90 was used. As a consequence of its extremely good water-binding properties, GRINDSTED PGPR 90 can affect the results of the analysis of the water phase. This occurs because it is usually impossible to break the emulsion and liberate the ingredients included in the discontinuous water phase. Use of an ionic emulsifier helps to avoid this, thus making it possible to get reliable analysis data.

Method As an example, we carried out a salt analysis of the spread containing 40% fat, 1% salt, 0.4% GRINDSTED(D PGPR and 0.3% DIMODAN<g) S-T.

Standard salt analysis procedure: Heat 1 Og spread sample with 1 cog water to 1 00 C Add 2ml 5% potassium chromate.

2s Titrate with 0.1 N solution of silver nitrate.

To investigate the influence of the ionic emulsifier on the analysis results, 19 of an ionic emulsifier selected from GRINDSTED() CITREM SP 70 and GRINDSTED6) CSL P 80 was added to the 10Og water. The rest of the procedure was according to the standard procedure. The results of our analysis are shown in the following table: Sample Salt content by titration Mean value of salt content Control 0 50 0 53 Sample destabilized with 1.10 1. 08 GRINDSTED@CITREM SP 70 1 06 Sample destablised with 1.08 1.09 GRINDSTED CSL P 80 1 10 The conclusion is that adding an ionic emulsifier gives reliable salt content analysis results.

All publications mentioned in the above specification are herein incorporated by lo reference. Various modifications and variations of the described methods and system of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in chemistry or related fields are intended to be within the scope of the following claims

Claims

1. A process for separating an emulsion into its component phases comprising the step of contacting the emulsion with an ionic emulsifier.

2. A process according to claim 1 wherein the ionic emulsifier is the reaction product of a hydroxy carboxylic acid and a second reactant, or a salt thereof.

3. A process according to claim 2 wherein the hydroxy carboxylic acid is an alpha o hydroxy carboxylic acid or a beta-hydroxy carboxylic acid.

4. A process according to claim 2 or 3 wherein the hydroxy carboxylic acid is selected from the group consisting of glycolic acid, lactic acid, tartronic acid, malic acid, tartaric acid and citric acid.

5. A process according to any one of claims 2 to 4 wherein the hydroxy carboxylic acid is lactic acid or citric acid.

6. A process according to any one of claims 2 to 5 wherein the second reactant is a carboxylic acid or an alcohol.

7. A process according to claim 6 wherein the carboxylic acid is a C6-C26 carboxylic acid.

2s

8. A process according to claim 6 or 7 wherein the carboxylic acid is a C,2-C20 carboxylic acid.

9. A process according to any one of claims 6 to 8 wherein the carboxylic acid is a C,8 carboxylic acid.

10. A process according to any one of claims 6 to 9 wherein the carboxylic acid is steanc acid.

11. A process according to any one of the preceding claims wherein the ionic 3s emulsifier is sodium stearoyl lactylate or calcium stearoyl lactylate.

12. A process according to claim 6 wherein the alcohol comprises more than one hydroxy group.

s

13. A process according to claim 12 wherein the alcohol is glycerol.

14. A process according to claim 12 or 13 wherein the alcohol is partially esterified.

15. A process according to any one of claims 12 to 14 wherein the alcohol is a lo monoglyceride, a diglyceride or a combination thereof.

16. A process according to claim 15 wherein the ester moiety of the monoglyceride and/or each ester moiety of the diglyceride has a chain length of from 4 to 24 carbon atoms.

17. A process according to any one of claims 12 to 16 wherein the ionic emulsifier is the reaction product of citric acid and a monoglyceride, a diglyceride or a combination thereof.

18. A process according to any one of the preceding claims wherein the emulsion is an oil and water emulsion.

19. A process according to any one of the preceding claims wherein the emulsion is a water-in-oil emulsion.

20. A process according to any one of the preceding claims wherein the emulsion is a foodstuff.

21. A process according to any one of the preceding claims wherein the emulsion is an edible spread.

22. A process according to any one of the preceding claims wherein the emulsion comprises an existing emulsifier.

23. A process according to claim 22 wherein the existing emulsifier comprises a polyglycerol fatty acid ester.

24. A process according to claim 23 wherein the polyglycerol fatty acid ester is polyglycerol polyricinoleate.

25. A process according to any one of the preceding claims wherein the amount of ionic emulsifier contacted with the emulsion is from 0.5 to 1. 5% by weight of the emulsion.

26. A process according to any one of the preceding claims wherein the emulsion is a water-in-oil emulsion and the extent of separation is such that at least 80% of the oil phase is recoverable.

27. Use of an ionic emulsifier for separating an emulsion into its component phases.

28. Use according to claim 27 characterized by the features of any one of claims 2 to 26.