WO2018156013A1

WO2018156013A1 - Process for producing refined palm fruit oil

Info

Publication number: WO2018156013A1
Application number: PCT/MY2018/000009
Authority: WO
Inventors: Noor Hidayu OTHMAN; Ahmadilfitri MD NOOR; Mohd Suria Affandi Yusoff
Original assignee: Sime Darby Plantation Bhd
Current assignee: Sime Darby Plantation Bhd
Priority date: 2017-02-21
Filing date: 2018-02-21
Publication date: 2018-08-30
Anticipated expiration: 2019-08-21

Abstract

Provided is a process for producing refined palm fruit oil with reduced 3- monochloropropane-1,2-diol (3-MCPD) and reduced chlorine content. The present process comprises the steps of: a) heating a crude palm fruit oil to completely melt the palm fruit oil; b) passing the molten crude palm fruit oil through an ultrafiltration membrane to produce a degummed palm fruit oil; c) bleaching the degummed palm fruit oil by contacting the degummed palm fruit oil with a bleaching adsorbent; and d) deodorizing the bleached palm fruit oil at temperatures between 200°C to 245°C for a time period of 90 minutes to 200 minutes to produce a refined palm fruit oil.

Description

PROCESS FOR PRODUCING REFINED PALM FRUIT OIL

FIELD OF THE INVENTION

The present invention relates to a process for refining crude palm fruit oil, such as crude palm oil or crude palm kernel oil,

BACKGROUND OF THE INVENTION

Free 3-monochioropropane-l,2-diOl (3-MCPD) has been identified as a contaminant in various foods like liquid seasoning (e.g. soy sauce) and bakery products that have been heated to high temperatures. This substance is formed when fat- and chloride salt- containing foods are processed at high temperatures.

Studies have identified 3-MCPD fatty acid esters in refined oils, such as refined palm oil. 3-MCPD fatty acid esters are believed to be formed at high temperatures following a reaction between fats and chloride ions. In the refining of palm fruit oil and fractions of palm fruit oils, 3-MCPD fatty acid esters are believed to be formed predominantly during deodorisation, the last stage in refining wherein undesirable odorous and taste-bearing substances are removed. Besides 3-MCPD fatty acid esters, 2-MCPD fatty acid esters and giycidyl fatty acid esters have also been identified in these refined palm fruit oils.

Processing techniques that minimise formation of the 3-MCPD fatty acid esters during the refining of crude palm fruit oil products have been suggested in the prior art.

WO 2010/063450 describes a method for reducing the 3-MCPD content of refined vegetable oil by using a refining method wherein a crude oil is degummed, the degummed oil is admixed with a bleaching earth and bleached, the bleaching earth is separated off from the bleached oil, and so a filter oil is obtained and the filter oil is deodorised, characterised in that water is added to the crude oil for the degumming, and the degumming is carried out without addition of acid at a temperature of below 70°C, the degummed oil is heated to a temperature in the range from 80 to 100°C and the bleaching earth is added to the heated degummed oil in an amount of greater than 1.5% by weight, and the bleaching is carried out at a temperature in the range from 80 to 100°C

WO 2011/069028 describes a method of removing glycidyl esters from oil, the method comprising: contacting the oil with an adsorbent; and, subsequently steam refining the oil. Examples of adsorbents mentioned include magnesium silicate, silica gel, and bleaching clay. Example 1 E of WO 2011/069028 describes an experiment in which deodorised palm oil was contacted with adsorbents and redeodorised. Deodorised palm oil was incubated with the adsorbents at 70°C for 30 min under 125 mm Hg vacuum. Adsorbents included magnesium silicate (Magnesol R60™, Dallas Group, Whitehouse, HI), silica gel (Fisher Scientific No. S736-1), acidic alumina (Fisher Scientific No. A948- 500), and acid washed activated carbon (ADP(TM) carbon, Calgon Corp., Pittsburg, PA).

WO 2013/093093 describes a method of removing glycidyl esters from a vegetable oil comprising contacting the oil with at least 0.5 % by weight of the oil of an acid-activated bleaching earth and deodorising the oil at a temperature of less than 200°C for at least 30 minutes.

WO 2015/174820 Al relates to a process of refined palm fruit oil products that yieids a refined oil product having an exceptional low content of 3-MCPD fatty acid esters. The process of refining a crude palm fruit oil products comprised of (a) removing phospholipids and/or free fatty acids from a crude palm fruit oil product by subjecting the oil product to a pretreatment, thereby producing a pretreated palm fruit oil product with a reduced phospholipid content and/or a reduced free fatty acid content; (b) simultaneously or sequentially contacting the pretreated palm fruit oil product with a bleaching earth and a porous silica material to produce a bleached palm fruit oil product, said porous silica material having a surface area of at feast 10 m /g and being selected from the group consisting of silica, amorphous silicate, zeolite and combinations thereof; and (c) deodorizing the bleached palm fruit oil product to produce a refined palm fruit oil product; wherein the pretreated palm fruit oil product is contacted with the porous silica material at a temperature of at least 95 °C and wherein the bleached palm fruit oil product is deodorized at a temperature of not more than 240°C.

WO 2014/081279 Al relates to a process of refining palm oil in order to produce low level of 3-MCPD fatty esters in refined palm oil. Accordingly, the process comprises the steps of water degumming of crude palm oil, removal of aqueous phase by centrifugation, followed by acid degumming at lower temperature. Subsequently, bleaching is conducted with an activated bleaching earth and silicate adsorbent (for example magnesium silicate, calcium silicate and aluminum silicate) as filter aid and final adsorption of the 3-MCPD fatty esters precursors prior to deodorization step. WO 2012/165397 Al describes a method for producing crude palm oil from which free chlorine has been removed. The invention further provides for a crude palm oil in which a free chloride content is reduced to 2 ppm or less, and refined palm oil in which a content of 3-monochloropropane- 1,2-diol fatty acid esters is 1 mg/kg or less by refining the crude palm oil.

WO 2014/058294 Al relates to a process for degumming of crude paim oil using polyvinyltdene fluoride (PVDF) ultrafiltration membrane. The process comprises the steps of providing a feed oil comprises a crude paim oil containing phosphorus, heating the feed oil and feeding into a membrane processing module comprising PVDF ultrafiltration membrane and passing the feed oil through the PVDF ultrafiltration membrane at pressure in a range of 2 x 10^Λ5 to 5 x 10^Λ5 Pa to obtain a permeate fraction having a phosphorus content which is less than the phosphorus content of the feed oil.

WO 2015/053609 Al relates to a system and process for producing refined oils and fats using a membrane system. The process involves pre-treating a crude oil or and fat using a series of membrane units to remove undesirable constituents with the view of improving the quality and stability of the refined oil and fat. Each series of the membrane units comprises a plurality of membrane modules, with each membrane module containing 1,000 to 3,000 fibers, and wherein the plurality of membrane modules in at least one of the series of the membrane units are polyvinylidene ftuoride (PVDF) ultrafiltration membrane modules. The membrane- treated oils and fats are further refined by subjecting the oils and fats to bleaching and deodorization processes to produce the desired refined oils and fats. Zulkurnain et a/. (The effects of physical refining on the formation of 3- monochtoroprop&ner 1,2-diol esters in relation to palm oil minor components, Food Chemistry 135 (2012) 799-805) describe the outcome of a study in which D-optimal design was used to study the effects of the degumming and bleaching processes on the reduction in 3-MCPD fatty ester formation in refined palm oil from poor-quality crude palm oil relative to the palm oil minor components that are likely to be their precursors. Water degumming remarkably reduced the formation of 3-MCPD fatty esters by up to 84%, from 9.79 mg/kg to 1.55 mg/kg. Bleaching with synthetic magnesium silicate caused a further 10% reduction, to 0.487 mg/kg. The authors conclude that the reduction in 3-MCPD fatty ester formation could be due to the removal of related precursors prior to the deodorisation step and that the phosphorus content of bleached palm oil showed a significant correlation with the formation of 3-MCPD fatty esters.

The phosphoric acid dosage had a greater effect on the development of chloroesters than did the different types of bleaching adsorbents. The increase in acid dosage had no significant effect on the 3- MCPD fatty ester level (p > 0.05), with the exceptions of the activated carbon and magnesium silicate conditions (Musfirah et a/. (20X2); The effects of physical refining on the formation of 3-monochtoropropane-l,2-diol esters in relation to palm oil minor components", Food Chem., 135:799-805),

There was a significant reduction of 3-MCPD fatty esters in bleached oil when lower dosage of phosphoric acid is used for degumming. However, deodortzation effect is more significant than bleaching, as seen in the relatively higher content of 3-MCPD fatty esters. Further reduction of the esters was also observed when water was used for degumming. In this case, the 3-MCPD fatty esters were significantly lower for both bleached and refined, bleached and deodorized oil, indicating that acidity of the phosphoric acid had an effect on their formation (Ramii et al._f (2011), "Effects of degumming and bleaching on 3-MCPD fatty esters formation during physical refining", J Am Oil Chem Soc,„ 88: 1839-1844).

Ramli et at., (2011) ("Effects of degumming and bleaching on 3-MCPD fatty esters formation during physical refining", J Am Oil Chem Soc, 88: 1839-1844) studied the effect of bleaching earths (natural type vs. acid) upon the formation of 3-MCPD fatty esters. Bleaching earth with higher acidity (lower pH values) resulted in a higher formation of 3-MCPD fatty esters, irrespective of type of degumming used - whether acid degumming or water degumming. Most of the higher acidity earths have been activated with acid. Bleaching clays are acid activated by either sulphuric acid or hydrochloric acid to increase their surface area (150-350 m2/g) to provide a larger surface area for adsorption.

Several claims were made on the critical effects of deodortzation step in the formation of the 3-MCPD fatty esters. High deodorization temperatures were found to facilitate the formation of the esters. The deodorisation step could be observed to be the most critical step for the formation of 3-MCPD fatty esters in refined oils. High deodorisation temperature exceeding 200"C are considered to be the main reason for high contents of 3MCPD-esters observed m refined oils (Franke et al., (2009), "Influence of chemical refining process and oil type on bound 3-chhro-l, 2-propanediol contents in palm oil and rapeseed oil", LWT-Food Sci and Technol, 42:1751-1754). Studied by Hrncirik and van Duijn (2011) (^vAn initial study on the formation of 3-MCPD fatty esters during oil refining", Eur. J. Lipid Sci. Technol., 113: 374-379) indicated that 3-MCPD fatty esters and the related compounds (glycidyl esters) are formed during deodorization, but that it is independent of bleaching versus neutralization/bleaching and deodorization conditions. Besides, no decrease of chloride levels during deodorization was observed and all samples still contained substantial amount of chlorides after the deodorization (palm oil 2.7-5.2 rng/kg).

There remains a need in the art to provide a refined palm fruit oil with reduced 3-MCPD fatty acid esters and low chlorine content to address the above problems, or at least to provide an alternative.

SUMMARY OF THE INVENTION The present invention provides a process of refining crude palm fruit oil that yields a refined palm fruit oil having a low content of 3-monochloropropane-l,2-diol (3-MCPD) and a low chlorine content.

The process for producing a refined palm fruit oil according to the present invention includes the steps of:

a) heating a crude palm fruit oil to completely melt the palm fruit oil;

b) passing the molten crude palm fruit oil through an ultrafiltration membrane to produce a degummed palm fruit oil;

c) bleaching the degummed palm fruit oil by contacting the degummed palm fruit oil with a bleaching adsorbent; and

d) deodorizing the bleached palm fruit oil at temperatures between 200°C to 245°C for a time period of 90 minutes to 200 minutes to produce a refined palm fruit oil.

Although the inventors do not wish to be bound by theory, it is believed that ultrafiltration step used to degum the crude paim fruit oil by removing phospholipids, also removes organochlorine substances that give rise to the formation of 3-MCPD esters during deodorisation. The degummed palm fruit oil is subsequently refined by bleaching and deodorisation. The deodorisation of the bleached palm fruit oil is carried out under conditions that minimize formation of 3-MCPD esters.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process for producing refined palm fruit oil according to the present invention includes the steps of:

a) healing a crude palm fruit oil to completely melt the palm fruit oil;

b) passing the molten crude palm fruit oil through an ultrafiltration (UF) membrane to produce a degummed palm fruit oil;

The term "oil" whenever used herein encompasses oils that are liquid, semi-solid or solid at 20°C. The crude palm fruit oil employed in the present process usually contains solid fat. However, the present invention also encompasses the use of fractions of palm fruit oil that are completely liquid at ambient conditions and that are passed through the UF membrane without prior heating.

A suitable analytical method for determining 3-MCPD fatty esters content of oils is described in AOCS Official Method Cd 29a- 13. Glycidyl esters are converted to 3- monobromopropanediol (3-M8PD) monoesters in an acid solution containing a bromide salt. 3-MBPD esters, together with 2- and 3-MCPD fatty esters, are then converted into the free (non-esterified) form in acid methanolic solution. The fatty acid methyl esters generated during the reaction are extracted from the sample; 3-MCPD and 3-MBPD, are then derivatized with phenylboronic acid prior to GC-MS analysis.

The total chlorine content of oils can be suitably determined by Mitsubishi NSX-2100 H, Trace Elemental Analyzer in accordance to standard ASTM D4929. The trace elemental analyzer is a furnace system with a micro-coulometric detector that was used for measuring and detecting total chlorine whether in organic or inorganic form.

The crude palm fruit oil used in the present process typically contains at least 80 wt% triglycerides, more preferably at least 90 wt. % of triglycerides. Examples of crude palm fruit oils that may be refined by the present process include crude palm oil, crude palm oil fraction, crude palm kernel oil, crude palm oil fraction, crude coconut oil, crude coconut oil fraction and combinations thereof. Examples of fractions of palm oils that may be refined by the present process are palm olein with iodine value of 56-60, palm super olein with iodine value above 60, palm stearin with iodine value between 30-37, hard palm stearin with iodine value between 22-29, palm super stearin with iodine value less than 14, palm mid fraction with iodine value between 37-48 and combinations thereof.

The process for producing refined palm fruit oil according to the invention includes the step of passing a molten crude palm fruit oil through an UF membrane to produce a degummed palm fruit oil. The oil should be completely liquid when it is passed through the UF membrane, meaning that usually the crude palm fruit oil needs to be heated to completely melt the oil before it is passed through the ultrafiltration membrane.

Heating of the crude palm fruit oil reduces the oil viscosity and this in turn helps to improve the oil flux rate of the membrane, in a preferred embodiment, the crude palm oil is heated to a temperature between 38°C to 90°C, more preferably 45°C to 85°C, even more preferably 50°C to 70°C.

The UF membrane degumming can be conducted with or without the use of phosphoric acid or citric acid. Preferably, the UF membrane degumming is conducted without the use of phosphoric acid or citric acid.

Preferably, the ultrafiltration membrane used in the process according to the invention is selected from ceramic membrane such as polyvinylidene fluoride (PVDF) membrane, polymeric membrane such as multi-channel tubular Zirconia/a-Alumina ceramic membrane or any combination thereof. More preferably, the ultrafiltration membrane used herein is PVDF membrane. The degumming of the crude palm fruit oil is preferably conducted as described in WO 2014/058294 Al (A Process for Degumming or Crude Palm Oil) and WO 2015/053609 Al (A Membrane Pre -treatment System and Process for Producing Refined Oils & Fats). After UF membrane degumming, the degummed palm fruit oil has a low phospholipids content, which can be measured in the form of phosphorus content. Preferably, the phosphorus content is between 0 to S ppm, more preferably between 0 to 3 ppm, and even more preferably between 0 to 2 ppm.

In the bleaching step of the present process a bleaching adsorbent is used in order to further remove contaminants, such as colour pigments, metal tons, oxidation products and chlorinated compounds to produce a bleached oil.

Typically, an amount of bleaching adsorbent between 0.75% to 3%, preferably 1% to 2.5%, more preferably 1.2% to 2.0%, by weight of degummed palm fruit oil is used in the bleaching step.

The bleaching adsorbent used in the present process preferably selected from bentonite clay, palygorskite clay, montmorillonite clay, smectite clay or any combination thereof. Preferably, the bleaching adsorbent is in the form of naturally active clay or thermal activated clay, and even more preferably, thermal activated clay.

Preferably, the degummed palm fruit oil is contacted with the bleaching adsorbent at temperatures between 85°C to 130°C, preferably 90°C to 125°C, more preferably 95°C to 120°C, for 20 minutes to 90 minutes, preferably 30 minutes to 50 minutes.

In a preferred embodiment, the degummed bleached oil contains between 0.2 ppm to 3 ppm total chlorine content, preferably 0.35 ppm to 2.5 ppm, more preferably 0.5 ppm to 2.0 ppm, prior to the deodorization step. The bleached palm fruit oil obtained using naturally active clay typically has a chlorine content that is 50% to 90% reduced compared to the original crude palm fruit oil.

The bleached palm fruit oil obtained using acid activated clay typically has a chlorine content that is 15% to 65% reduced compared to the original crude palm fruit oil.

The bleached palm fruit oil obtained using thermally activated clay typically has a chlorine content that is 55% to 90% reduced compared to the original crude palm fruit oil. In the present process the bleached palm fruit oil is deodorised at temperatures between 200°C to 245°C for a time period of between 90 minutes to 200 minutes to produce a refined palm fruit oil. Qeodorization of the bleached palm fruit oil is preferably carried out at a temperature between 210°C and 245°C, more preferably between 220°C and 245 °C

Typically, deodorisation according to the invention is carried out at a pressure in the range of between 0 mbar to 5 mbar.

Advantageously, the present process produces a refined palm fruit oil having a 3-MCPD ester content between 0.1 to 1.5 ppm, preferably 0.1 to 1 ppm, more preferably at most 0.5 ppm. The invention is further illustrated by the following non-limiting examples.

EXAMPLES Example 1:

Crude palm oil (CPO) having 1.12% free fatty acid (FFA), 15.56 meq 0_?/kg peroxide value (PV), 2.86 of degree of bleachability index (DOBI) and 4.26ppm Total Chlorine (TC) were refined using the degummlng, bleaching and deodorization conditions shown in Table 1.

Table 1

It can be observed that BPO-1C had produced the lowest TC (1.16 ppm) after membrane degumming and bleaching processes as well as the lowest total chlorine (0.86 ppm) and 3-MCPD Fatty acid esters (0.54 ppm) in refined palm oil (RBDPO-1C).

After the refining process, all refined palm oil (RBDPO) were subjected to heat stability study for 5 days. 1% distilled water was added into 250g oil sample and stored in an oven set at 90°C. The results obtained are shown in Table 2.

Aside from having the lowest 3-MCPD level, a combination of membrane degumming and superior bleaching adsorbent produced RBDPO 1C with better FFA and colour stability after 5 days storage.

Example 2:

Crude palm oil (CPO) having 1.5% free fatty acid (FFA), 0 meq 02/kg peroxide value (PV), 3.63 of degree of bleachability index (DOB1) and 3.80 ppm Total Chlorine (TC) were refined using the degumming, bleaching and deodorization conditions shown in Table 3. Table 3

Table 4 shows the results of heat stability study of RBDPO conducted according to Example 1. RBDPO-2C produced from a combination of membrane degumming and thermal clay bleaching adsorbent had the most stable oil performance especially for FFA and colour after 5 days storage.

Example 3

Crude palm oil (CPO) having 1.8% free fatty add (FFA), 0 meq 02/kg peroxide value (PV), 2.98 of degree of bleachability index (DOBI) and 3.46 ppm Total Chlorine (TC) were refined using the degumming, bleaching and deodorization conditions shown in Table 3.

Table 5

Table 6 shows the results of heat stability study of RBDPO conducted according to Example 1. RBDPO-3C produced from a combination of membrane degumming and thermal clay bleaching adsorbent had the most stable oil performance especially for FFA and colour after 5 days storage.

Table 6

Example 4

Experiment 1 was repeated to examine the refining performance using a combination of membrane degumming and acid clay bleaching adsorbent as compared to conventional degumming process as shown in Table 7. Two batches refining process were conducted using different quality of CPO. Experiment 4A-1 and 4B-1 used feed CPO comprised of 2.57%FFA, 2.79 DOBI, 6.28 meq 0²/kg PV and 3.58ppm TC. Meanwhile, experiment 4A- 2 and 4B-2 used feed CPO comprised of 3.84%FFA, 2.75 DOBI, 5.25 meq 0²/kg PV and 3.27ppm TC.

Table 7

It can be observed that both RBDPO 4B-1 and RBDPO 4B-2 had lower TC and 3-MCPD as compared to conventional refining process (refer to Table 7) with better oil stability performance especially on FFA and colour after 5 days storage at 90°C (refer to Table 8). Although the 3-MCPD level obtained from a combination of membrane degumming and acid clay adsorbent not as good as RBDPO- 1C, RBDPO-2C and RBDPO-3C; most likely it demonstrated that the quality of feed CPO and less/no acidic refining condition are very important in producing low-3MCPD palm oil.

Table 8

Example 5

Experiment 1 was repeated to examine the refining performance between a combinations of membrane degumming with natural clay and membrane degumming with thermal clay bleaching adsorbents as shown in Table 9. The feed CPO used had 3%FFA, 2.79 DOBI, 6.28 meq 0²/kg pv and 3.58ppm TC.

Table 9

0.88 0.87 0.84

It can be observed that the combination of membrane degumming and thermal clay bleaching adsorbent produced lower total chlorine as well as 3-MCPD fatty acid esters in refined oil as compared to bleaching with natural clay. However, all refined oil samples are stable towards 5 days storage period as shown in Table 10 although RBDPO-5B and RBDPO-5D have better oil quality after refining process.

Table 10

Example 6

Experiments were conducted for deodorization temperature of 220 °C with retention time of 180 minutes. Initial feed CPO used had 3.31% FFA, 2.56 DOBI, 9.36 meq 02/kg PV and 4.45 ppm TC. Results as per Table 11 shows that membrane degumming is able to reduce TC content regardless of any types of bleaching earth used and membrane degumming together with lower deodorization temperature provides further reduction to the 3-MCPD content. Thermal clay (Rafinol 900FF) is found to be able to meet all the refined oil specification at low deodorization temperature.

Table 11

Claims

1. A process for producing refined palm fruit oil, the process including the steps of:

a) heating a crude palm fruit oil to completely melt the palm fruit oil;

2. The process according to claim 1, wherein the ultrafiltration membrane used in step (b) is a ceramic membrane, polymeric membrane or any combination thereof.

3. The process according to claim 2, wherein the ultrafiltration membrane used in step (b) is PVDF membrane.

4. The process according to claim 1, wherein the crude palm fruit oil is heated to a temperature between 50 °C to 70 °C.

5. The process according to claim 1, wherein the degummed palm fruit oil has phosphorus content between 0 to 5 ppm.

6. The process according to claim 1, wherein an amount of bleaching adsorbent between 0.75% to 3% by weight of the degummed palm fruit oil is used for step (c).

7. The process according to claim 1, wherein the bleaching adsorbent of step (c) is selected from bentonite clay, palygorskite clay, montmorillonite clay, smectite clay or any combination thereof.

8. The process according to claim 7, wherein the bleaching adsorbent is in the form of naturally active clay, acid activated bleaching clay, thermal activated bieaching clay or any combination thereof.

9, The process according to claim 1, wherein the degummed palm fruit oil is contacted with the bleaching adsorbent at temperatures between 90°C to 130°C for 20 minutes to 90 minutes.

10. The process according to claim 1, wherein the bleached palm fruit oil has between 0.5 ppm to 3 ppm total chlorine content.

11. The process according to claim 1, wherein the bleached palm fruit oil is deodorised at a temperature of between 220°C to 245°C.

12. The process according to claim 1, wherein the bleached palm fruit oil is deodorised at a pressure of between 0 mbar to 5 mbar.

13. The process according to claim 1, wherein the refined palm fruit oil has a 3-MCPD ester content between 0.1 ppm to 1.5 ppm.

14. The process according to claim 1, wherein the crude palm fruit oil is selected from crude palm oil, crude palm oil fraction, crude palm kernel oil, crude palm oil fraction, crude coconut oil, crude coconut oil fraction and combinations thereof.