1,3-specific intraesterification

Abstract

The present invention relates to a method for increasing the SUS content in an oil or in an olein fraction, comprising performing 1,3-selective enzymatic intraesterification on a natural starting oil or olein fraction prepared therefrom wherein the ratio between SUS and SUU is at least 1:1.5 and the SSS content is low, in particular close to 0%. Further, the present invention relates to 1,3-Selective intraesterified oil or olein, obtainable by performing the present method.

Claims

1. A method for increasing the SUS content in an oil, comprising performing 1,3-selective enzymatic intraesterification on a natural starting oil wherein the ratio between SUS and SUU is at least 1:1.5 and the SSS content is low.

2. The method as claimed in claim 1, wherein the natural starting oil is a single oil extracted from an oil source and not blended with other oils.

3. The method as claimed in claim 1, wherein the ratio between SUS and SUU is in order of increased preference at least 1:1.5, 1:2, 1:3.5, 1:5, 1:7.5, 1:10, 1:15.

4. The method as claimed in claim 2, wherein the oil source is sunflower seed, soybean, cottonseed, shea fruits, or rapeseed.

5. The method as claimed in claim 1, wherein the starting oil is high stearic high oleic (HSHO) sunflower oil.

6. The method as claimed in claim 1, wherein the starting oil is selected from high stearic high oleic soybean oil, high stearic high oleic cottonseed oil and high stearic high oleic rapeseed (canola) oil.

7. The method as claimed in claim 1, wherein the starting oil is a tropical oil selected from shea olein and palm olein.

8. A method for increasing the stearin yield from a starting oil, comprising the steps of: a) performing the method as claimed in claim 1 on the starting oil to obtain 1,3-selective intraesterified oil having a higher SUS content than the starting oil; and b) fractionating the 1,3-selective intraesterified oil thus obtained to obtain a stearin fraction and an olein fraction.

9. The method as claimed in claim 1, wherein the unsaturated U in SUS and/or SUU is oleic acid.

10. The method as claimed in claim 1, wherein the reaction time of the 1,3-selective enzymatic intraesterification is at least about 30 minutes.

11. The method as claimed in claim 1, wherein the 1,3-selective enzymatic intraesterification is performed by using lipase enzymes.

12. A composition comprising a 1,3-selective intraesterified oil, obtainable by performing a method as claimed in claim 1, wherein the 1,3-selective intraesterified oil is enriched in SUS as compared to the oil it was produced from.

13. A composition consisting of a stearin fraction, obtainable by performing the method as claimed in claim 8.

14. The composition of claim 13, wherein the composition is selected from the group consisting of a margarine, spreads, coatings, fillings, frying oils and cooking oils.

15. The method as claimed in claim 11, wherein the lipase enzyme comprises a lipase from Rhizomucor miehei (RMIM).

16. The method as claimed in claim 11, wherein the lipase enzyme comprises a lipase from Thermomyces lanuginosis (TLIM).

17. A method for increasing the SUS content in an olein fraction, comprising performing 1,3-selective enzymatic intraesterification on an olein fraction prepared from a natural starting oil wherein the ratio between SUS and SUU is at least 1:1.5 and the SSS content is low.

18. The method as claimed in claim 17, wherein the natural starting oil is a single oil extracted from an oil source and not blended with other oils.

19. The method as claimed in claim 17, wherein the ratio between SUS and SUU is in order of increased preference at least 1:1.5, 1:2, 1:3.5, 1:5, 1:7.5, 1:10, 1:15.

20. The method as claimed in claim 18, wherein the oil source is sunflower seed, soybean, cottonseed, shea fruits, or rapeseed.

21. The method as claimed in claim 17, wherein the olein fraction is from high stearic high oleic (HSHO) sunflower oil.

22. The method as claimed in claim 17, wherein the olein fraction is from an oil selected from high stearic high oleic soybean oil, high stearic high oleic cottonseed oil and high stearic high oleic rapeseed (canola) oil.

23. The method as claimed in claim 17, wherein the olein fraction is from a tropical oil selected from shea olein and palm olein.

24. A method for increasing the stearin yield from a starting olein fraction upon fractionation of a starting oil, comprising the steps of: a) fractionating a starting oil having a ratio between SUS and SUU of at least 1:1.5 and a low SSS content, to obtain a stearin fraction and a starting olein fraction; b) performing the method as claimed in claim 1 on the starting olein fraction to obtain 1,3-selective intraesterified olein having a higher SUS content than the starting olein fraction; and c) fractionating the 1,3-selective intraesterified olein thus obtained to obtain a stearin fraction and an olein fraction.

25. The method as claimed in claim 24, wherein the total stearin yield from steps a) and c) together is higher than the stearin yield after fractionating the starting oil.

26. The method as claimed in claim 17, wherein the unsaturated U in SUS and/or SUU is oleic acid.

27. The method as claimed in claim 17, wherein the reaction time of the 1,3-selective enzymatic intraesterification is at least about 30 minutes.

28. The method as claimed in claim 17, wherein the 1,3-selective enzymatic intraesterification is performed by using lipase enzymes.

29. A composition comprising a 1,3-selective intraesterified olein, obtainable by performing a method as claimed in claim 17, wherein the 1,3-selective intraesterified olein is enriched in SUS as compared to the oil it was produced from.

30. A composition consisting of a stearin fraction, obtainable by performing the method as claimed in claim 24.

31. The composition of claim 30, wherein the composition is selected from the group consisting of a margarine, spreads, coatings, fillings, frying oils and cooking oils.

32. The method as claimed in claim 28, wherein the lipase enzyme comprises a lipase from Rhizomucor miehei (RMIM).

33. The method as claimed in claim 28, wherein the lipase enzyme comprises a lipase from Thermomyces lanuginosis (TLIM).

Description

FIGURES

(1) FIG. 1 shows a schematic overview of the method for increasing the stearin yield.

(2) FIG. 2 shows the predictive equation obtained for 1,3-selective intraesterification. The equations are developed for a more general interesterification process (selective 1,3 acidolysis). Selective 1,3 intraesterification happens when So=0. All computations are based on moles. For simplification we will assume that the acid in the interesterefication is stearic S. Let T.sub.0 the initial total mole concentration of the oil, [XYZ].sub.0 be the initial total mole concentration of a particular TAG XYZ, where X, Y, Z could be P, S, O, L, A or B, let S.sub.o be the initial total numbers of Stearic moles. The expected final mole concentration [XYZ].sub.F is given by the expression in FIG. 2. 1.sub.{W=S} is an indicator function that takes the value “1” if W=S, and “0” otherwise. There are several assumptions for these calculations to be true, among them, the enzyme has 1,3-positional specificity and has no fatty acid specificity, there are no losses of enzyme activity during the course of the reaction, steady state is achieve after some time, there is no formation of diglycerides, no trans-insteresterification and the total moles of the oil at any time, [T].sub.t=T.sub.0, similarly, [P].sub.t+[S].sub.t+[O].sub.t+[L].sub.t+[A].sub.t+[B].sub.t=S.sub.0.

(3) FIG. 3 shows the results of the optimization of the reaction time when using the RMIM enzyme.

(4) FIG. 4 shows the solid fat content of the starting oil and starting olein fraction, and their 1,3-selective intraesterified products.

(5) FIG. 5 shows the melting point of the starting oil and starting olein fraction, and their 1,3-selective intraesterified products.

EXAMPLES

Example 1

1,3-Selective Intraesterification of HSHO Sunflower Oil and Olein Fraction

(6) Trials were performed with HSHO oil and a HSHO olein fraction using two different enzymes, RMIM and TLIM (obtained from Novozymes), which are selective for sn-1 and sn-3 positions of the triglycerides. In these trials 100 g of the oil or olein was treated with 10 g of either of the two enzymes at a temperature of 60° C. The reaction time was 4 hours.

(7) Results are shown in Table 1 that shows the TAG composition of the starting oil and the starting olein fraction, and their 1,3-selective intraesterified products. Results are given for two different enzymes.

(8) The SUS content in the intraesterified products of both the HSHO oil and the HSHO olein fraction is significantly increased, while the SUU content is significantly decreased.

(9) TABLE-US-00001 TABLE 1 SSS SUS SUU UUU StOSt StOO HSHO (Before ER) 0.0 9.4 51.8 38.8 4.1 30.7 ER HSHO oil (enzyme 0.0 11.3 43.0 45.7 5.0 25.3 RMIM) ER HSHO oil (enzyme TLIM) 0.8 11.9 40.5 46.7 5.2 23.4 HSHO olein (Before ER) 0.0 7.1 51.8 41.1 2.1 31.1 ER HSHO olein (enzyme 0.3 11.1 42.6 46.0 4.2 23.6 RMIM) ER HSHO olein (enzyme 0.7 11.5 40.3 47.5 4.3 22.1 TLIM) ER (Enzymatic 1,3 Rearranged)

(10) The SSS content is higher for the TLIM enzyme than for the RMIM enzyme, which means that the RMIM enzyme is more selective than the TLIM enzyme as expected. When using the TLIM enzyme it may be beneficial to further decrease the reaction time in order to minimize the SSS content in the intraesterified product.

Example 2

Method for Increasing the Stearin Yield Upon Fractionating a HSHO Sunflower Oil or Olein Fraction

(11) In a first preliminary trial, an HSHO sunflower oil having a SUS content of 9.4 was selected and subjected to a first fractionation step to yield 12.0% stearin and 88.0% olein. In short, the oil was melted and heated up to 60° C. Then, the temperature was decreased gradually until 17/20° C. The oil was then held at this fractionation temperature during 16 hrs. Stearin was separated through a membrane press filter with squeezing pressures up to 6 bars. The resulting stearin fraction had a SUS content of 38.8% which defines the quality of the final product.

(12) The remaining SUS concentration in the olein fraction was 5.5. This SUS concentration was subsequently increased to 9.0 by 1,3-selective intraesterification. This value was determined by using the predictive equation shown in FIG. 2. The resulting 1,3-selective intraesterified olein was then used in a second fractionation step to again obtain a stearin and olein fraction. According with the level of exhaustion of SUS in the olein in the fractionation steps, yields of stearin in the second fractionation step could range from 12.0% to 20%. Then yields for olein would be 88% and 80%, respectively. This means that the total stearin yield could range from 24 to 32.0%, which is an increase of about 12% to 20% when compared to not performing the 1,3-selective intraesterification step. One can envisage that repeating the 1,3-selective intraesterification and second fractionation steps may even further increase the stearin yield. A schematic overview of this process is shown in FIG. 1.

Example 3

Determination of Reaction Conditions

(13) 1,3-Selective intraesterification is accomplished by means of enzymes (lipases). One issue that arises during this process is that with an increase in reaction time, selectivity of the enzyme for the sn-1 and sn-3 positions of the triglycerides may decrease. As a result, the SSS content in the resulting intraesterified oil or olein fraction may be higher than is desired. Therefore, a preliminary trial was performed to determine the optimum reaction time at which the amount of SUS is maximized without significantly increasing the amount of SSS.

(14) High stearic high oleic (HSHO) olein was intraesterified with 10% (w/w) of the Lipozyme RMIM enzyme (obtained from Novozymes). Samples were taken at 2, 4, 6 and 8 hours and analyzed after the separation of the enzyme. The results are shown in FIG. 3.

(15) The reaction time of 4 hours was chosen as the tentative optimum time for further trials.

Example 4

Determination of Solid Fat Content

(16) The solid fat content (SFC) of the HSHO oil, HSHO olein fraction and the 1,3-selective intraesterified products were determined using DSC.

(17) FIG. 4 shows that the solid fat content of the 1,3-selective intraesterified products is higher than the solid fat content of the original HSHO oil and HSHO olein fraction at temperatures above 0° C.

Example 5

Determination of Melting Point

(18) The melting point of the HSHO oil, HSHO olein fraction and 1,3-selective intraesterified products was determined using standard techniques.

(19) FIG. 5 shows that the melting point of the 1,3-selective intraesterified HSHO oil and HSHO olein fraction are significantly increased when compared to the original HSHO oil and HSHO olein fraction.