WO2017164728A1

WO2017164728A1 - Process for producing a heat stable edible oil and/or fat composition

Info

Publication number: WO2017164728A1
Application number: PCT/MY2016/000086
Authority: WO
Inventors: Nur Azwani AB KARIM; Ahmadilfitri MD NOOR; Yin Mee THANG
Original assignee: Sime Darby Plantation Sdn. Bhd.
Priority date: 2016-03-22
Filing date: 2016-12-22
Publication date: 2017-09-28
Also published as: MY194302A

Abstract

The present invention relates to a process for producing a heat stable edible oil and/or fat composition comprising the steps of contacting an oxidized crude glyceride oil with porous adsorbent particles, degumming, bleaching and separating the oil from the porous adsorbent particles and beaching materials, and deodorising the oil to form the heat stable edible oil and/or fat composition.

Description

PROCESS FOR PRODUCING A HEAT STABLE EDIBLE OIL AND/OR FAT

COMPOSITION

FIELD OF THE INVENTION

The present invention relates to a process for producing a heat stable edible oil and/or fat composition. More particularly, the present invention relates to a process for producing a heat stable edible oil and/or fat composition by contacting oxidized crude glyceride oil with porous adsorbent particles.

BACKGROUND OF THE INVENTION

Over the last four decades, there has been a great increase in frying oil and fat consumption, as a wide range of fried and pre-fried foods have been developed. Most oils and fats are used for industrial frying of snack foods such as potato chips, which are one of the popular snack foods throughout the world (Razali, et. al., (1999), "Quality of potato chips fried in palm olein and high oleic sunflower oil during batch frying", Proceeding of the PORIM International Palm Oil Congress, Kuala Lumpur. 99- 103). Frying oil is used as a heat transfer medium. However, some oil maybe absorbed by the fried foods, and hence become a source of flavour and nutrition.

Cooking oil deteriorates upon exposure to heat. The deterioration of oil during deep- frying is caused by the thermal oxidation of fatty acid chains, and varieties of undesirable compounds generated during deep-frying, such as polar compounds, polymerize glycerides, and oxidized fatty acid. When frying oil is used appropriately, these undesirable compounds are generated in only small quantities, and safety is maintained (Billek, et.al, (2000), "Health aspects of thermoxidized oils and fats", EUR. J. LIPID SCI. TECHNOL. 120:587-593). However, under severe conditions, frying oil may develop toxicity owing to the accumulation of these undesirable compounds (Clark & Serbia (1991), "Safety aspects of frying fats and oil", FOOD TECHNOL., 45(2):84-89; Lopez- Varela, et.al., (1995), "Relationships between chemical and physical indexes and column and HPSE chromatography methods for evaluating frying oil", Z. ERNAHRUNGSWISS, 34:308-13). Numerous investigations have been reported on the deterioration and frying performance of general triacylglycerides (TAG) oil (Ahmad Tarmizi & Ismail, (2008), "Comparison of the frying stability of standard palm olein and special quality palm olein", J. AM. OIL CHEM. SOO, 85:245- 251 ; Abdulkarim, et.al., (2007), "Frying quality and stability of high-oleic Moringa oleifera seed oil in comparison with other vegetable oils", FOOD CHEMISTRY, 105:1382-1389; Bansal, et.al, (2010), "Statistical analysis strategies for association studies involving rare variants", NATURE REVIEWS, 11 :773-785; Casal, et.al., (2010), "Olive oil stability under deep-frying conditions", FOOD CHEM. TOXICOL, 48:2972-2979; Farhoosh & Tavassoli-Kafrani, (2010), "Polar compounds distribution of sunflower oil as affected by unsaponifiable matters of Benehull oil (BHO) and tertiary-butylhydroquinone (TBHQ) during deep-frying", FOOD CHEM. 122:381-385; Farhoosh & Tavassoli-Kafrani, (2011), "Simultaneous monitoring of the conventional qualitative indicators during frying of sunflower oil", FOOD CHEM. 125(1):209-213; Romero, et.al., (2006), "Cyclic fatty acid monomer formation in domestic frying of frozen foods in sunflower oil and high oleic acid sunflower oil without oil replenishment", FOOD AND CHEMICAL TOXICOLOGY, 44(10):674-1681 ; Sanchez- Gimeno at.al., (2008), "Some physical changes in Bajo Aragon extra virgin olive oil during the frying process", FOOD CHEMISTRY, 110:654-658).

The oil, for example, soybean oil, rapeseed oil, palm oil and other edible oils and fats, used for cooking deep-fried foods such as french fries and tempura maybe used singly or blended with several other oils. Deep-fry cooking is usually performed by introducing food or ingredients to be cooked into a highly-heated edible oil continuously or repeatedly, in the presence of air. The existence of oxygen, water, heat, components eluted from food stuff, etc., lead to a variety of degradation reactions such as thermal oxidation, thermal decomposition, thermal polymerization, hydrolysis and other reactions. These reactions result in the darkening of the oil, increase in acid value and viscosity of the oil, generation of undesirable odour of the oil, etc. As a consequence, the cooking environment is worsened, and the quality of the deep-fried foods deteriorated. Due to the variety of degradation reactions that occurs, the oils and fats used in deep-frying often cannot be used for a long time.

WO 00/77133 discloses a method of producing a confectionary comprising heating the confectionary in a fat composition comprising diglycerides, L-ascorbic ester and at least one component selected from among catechin, sage extract and turmeric extract. The method uses the additive, such as catechin to prevent oxidation of the oil. Although catechin significantly improves stability of the oil or fat against oxidation, its effect of preventing hydrolysis of the oil or fat is not necessarily satisfactory.

US 8241695 B2 discloses a process for producing a fat and oil composition for deep- frying, which has superior flavour and is suppressed, for a long time, in colour development and unfavourable odour during heating. The process comprises adding at least one type of phosphorus-derived components selected from a crude oil and a partially refined fat and oil to obtain a fat and oil composition that has a phosphorous content of 0.1 to 5.0 ppm. However, this method is not necessarily effective in preventing an increase in acid value of the oil.

US 2012/0301583 A1 discloses an oil and fat composition for deep frying that has excellent heat resistance during heat cooking, and that particularly prevents colouring caused by heating, increase in acid value, and cooked odour. However, this is made possible only by incorporating a phosphorous component, and ascorbic acid and/or an ascorbic acid derivative into the edible oil and fat composition.

As will be clear from the above, the methods described in the above prior publications require the addition of additional compounds to the oil and fat composition in order to achieve the desired results. The effects achieved by the methods disclosed in the above publications are not satisfactory according to industrial standards.

Consequently, there is a need to provide a process for producing a heat stable edible oil and/or fat composition that seeks to address at least some of the problems described hereinabove, or at least to provide an alternative.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention, a process for producing a heat stable edible oil and/or fat composition is provided. The process comprises contacting an oxidized crude glyceride oil with 0.1 wt% to 5.0 wt% of porous adsorbent particles based on the oxidized crude glyceride oil to be treated, at a temperature of 75 to 95°C for 10 to 95 minutes to form an adsorbent treated oil; degumming the adsorbent treated oil to form a degummed oil; contacting the degummed oil with a bleaching material to form a bleached oil; separating the bleached oil from the porous adsorbent particles and the bleaching material; and deodorizing the bleached oil to form a heat stable edible oil and/or fat composition.

In accordance with an embodiment of the invention, the porous adsorbent particles have an average particle size of 10 to 1 ,000 pm.

In accordance with an embodiment of the invention, the porous adsorbent particles have an average pore size of 10 to 150 A. In accordance with an embodiment of the invention, the porous adsorbent particles have a surface area of 90 to 600 m²/g.

In accordance with an embodiment of the invention, the porous adsorbent particles have an average moisture content of 2 to 4%.

In accordance with an embodiment of the invention, the step of contacting the oxidized crude glyceride oil with the porous adsorbent particles comprises mixing the oxidized crude glyceride oil with the porous adsorbent particles. In accordance with another embodiment of the invention, the step of contacting the oxidized crude glyceride oil with the porous adsorbent particles comprises passing the oxidized crude glyceride oil through a bed packed with the porous adsorbent particles.

In accordance with an embodiment of the invention, the porous adsorbent particles are porous silica having a pore size distribution of not more than 10% of the particles.

In accordance with an embodiment of the invention, the step of degumming the adsorbent treated oil comprises reacting the adsorbent treated oil with an acid having a concentration of 80 to 90%, at a temperature between 80 to 90°C for 15 to 30 minutes.

In accordance with an embodiment of the invention, the acid is added to the adsorbent treated oil in an amount ranging from 0.06 to 1.00 %. In accordance with an embodiment of the invention, the step of contacting the degummed oil with the bleaching material comprises contacting the degummed oil with not more than 1.0% bleaching material at 90 to 95°C for 20 to 35 minutes. In accordance with an embodiment of the invention, the step of deodorizing the bleached oil comprises deodorizing the bleached oil at a temperature of not more than 260°C for not more than 90 minutes.

In accordance with an embodiment of the invention, the heat stable edible oil and/or fat composition comprises free fatty acids in an amount ranging from 0.05 wt% to 0.08 wt% based on the total weight of the oil and/or fat composition; a metal content in an amount of 0.5 to 2ppm; partial glycerides in an amount of not more than 3.5 wt% based on the total weight of the oil and/or fat composition; a combined 3-MCPD ester and glycidyl ester content of less than 5 ppm; 50 to 1 ,000 ppm of one or more antioxidant vitamin E components selected from the group consisting of tocopherols and tocotrienols; unsaturated fatty acids in an amount ranging from 47 wt% to 75 wt% based on the total weight of the oil and/or fat composition; and saturated fatty acids in an amount of not more than 55 wt% based on the total weight of the oil and/or fat composition, selected from the group consisting of fatty acid with carbon number 16 and/or less and combinations thereof.

In accordance with an embodiment of the invention, the edible oil and/or fat composition having a reduced total oxidation products of at least 20% lower than that of a corresponding oil obtained by standard purification or refining process.

In accordance with an embodiment of the invention, the heat stable edible oil and/or fat composition has a solid fat content of less than 30% at 20°C.

In accordance with an embodiment of the invention, the heat stable edible oil and/or fat composition has a peroxide value of 5 or less.

In accordance with a second aspect of the invention, a heat stable edible oil and/or fat composition is provided. The heat stable edible oil and/or fat composition comprises free fatty acids in an amount ranging from 0.05 wt% to 0.08 wt% based on the total weight of the oil and/or fat composition; a metal content in an amount of 0.5 to 2ppm; partial glycerides in an amount of not more than 3.5 wt% based on the total weight of the oil and/or fat composition; a combined 3-MCPD ester and glycidyl ester content of less than 5 ppm; 50 to 1 ,000 ppm of one or more antioxidant vitamin E components selected from the group consisting of tocopherols and tocotrienols; unsaturated fatty acids in an amount ranging from 47 wt% to 75 wt% based on the total weight of the oil and/or fat composition; and saturated fatty acids in an amount of not more than 55 wt% based on the total weight of the oil and/or fat composition, selected from the group consisting of fatty acid with carbon number 16 and/or less and combinations thereof.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process for producing an edible oil and/or fat composition having reduced concentration of pro-oxidation and oxidation products, and which is stable against thermal oxidation or hydrolysis. The oil and/or fat composition can be used in conventional frying operations using standard frying temperatures. The oil and/or fat composition provides excellent flavour and appearance to fried foods when the oil and/or fat composition is used to fry food products. More particularly, the inventors of the present invention have developed an edible oil and/or fat composition that reduces the darkening of the oil, reduces decomposition/deterioration of antioxidants present in the oil, reduces the increase of acid value in the oil and prevents generation of undesirable odour when the oil and/or fat composition is used. The process of the present invention comprises contacting an oxidized crude glyceride oil with 0.1 to 5.0 wt% of porous adsorbent particles based on the oxidized crude glyceride oil to be treated.

The term "oxidized crude glyceride oil" as used herein refers to crude oil having a total oxidation value of more than 0.1.

In one embodiment of this invention, the oxidized crude glyceride oil contacts with the porous adsorbent particles at a temperature of 75 to 95°C, preferably 90 to 95°C. The oxidized crude glyceride oil is first heated to the predetermined temperature before the oxidized crude glyceride oil comes into contact with the porous adsorbent particles. The oxidized crude glyceride oil is heated to sufficiently melt and destroy all crystal structure in the crude glyceride oil to provide a homogenous solution. The temperature employed in this step will influence the efficiency of the adsorbent treatment process. High temperature can deteriorate the oil while low temperature may reduce the efficiency of the adsorbent.

The oxidized crude glyceride oil contacts with the porous adsorbent particles for a predetermined period of time, sufficient for optimum reaction between the adsorbent particles and the oxidized crude glyceride oil to take place. Preferably, the oxidized crude glyceride oil contacts with the porous adsorbent particles for 10 to 95 minutes, more preferably 80 to 95 minutes to form an adsorbent treated oil.

The term "porous adsorbent particles" as used herein means that each adsorbent particle contains pores, cavities or channels for receiving the oxidized crude glyceride oil when the oil comes into contact with the adsorbent particles. In one embodiment of this invention, the average pore size of the porous adsorbent particles is in the range of 10 to 150 A. Preferably, the average pore size is 90 to 110 A, more preferably, 50 to 70 A. The adsorbent particles may be of any suitable shapes and forms. Each particle may be of a regular or irregular shape and form. In all configurations, the porous adsorbent particles have an average particle size of 10 to 1 ,000 pm. In a preferred embodiment, the porous adsorbent particles have an average particle size of 60 to 150 μιη. In a more preferred embodiment, the porous adsorbent particles have an average particle size of 200 to 600 pm.

In one embodiment of this invention, the porous adsorbent particles have a surface area of 90 to 600 m²/g. The average water moisture content of the porous adsorbent particles is preferably in the range of 2 to 4%.

Any commercially available porous adsorbent particles may be used for the process of the present invention including, but not limited to, porous zeolite, carbon, aluminophosphate, precipitated silica, pyrogenic silica, silica gel and the like. In a preferred embodiment, the porous adsorbent particles are porous silica material, preferably porous silica manufactured by the wet route (that is, precipitated silica or silica gel). Preferably, the porous silica has a pore size distribution of not more than 10% of the particles.

In one embodiment, the step of contacting the oxidized crude glyceride oil with the porous adsorbent particles comprising mixing the oxidized crude glyceride oil with the porous adsorbent particles. In another embodiment, the step of contacting comprises passing the oxidized crude glyceride oil through a bed packed with porous adsorbent particles. In this embodiment, the bed packed with the porous adsorbent particles is typically a fixed bed column. The packed column may be any conventional packed column known in the art. The packed column has dimensions that enable a desired flow rate of oxidized crude glyceride oil through the packed column. The packed column may be constructed to be of any length and cross-sectional area. The bed may be constructed in a horizontal or vertical direction. The step of contacting the oxidized crude glyceride oil with the porous adsorbent particles produces an unpurified treated oil composition. The unpurified treated oil comprises (i) at least 20% lower in metal content than the oxidized crude glyceride oil. The metal content mainly consists of iron, phosphorus and copper; (ii) at least 15% lower in partial glycerides than the oxidized crude glyceride oil. The partial glycerides are selected from the group consisting of monoglyceride and diglycerides; (iii) at least 25% lower in the total oxidation products than the oxidized crude glyceride oil; and (iv) at least 23% higher in the deterioration of bleachability index (DOBI) than the oxidized crude glyceride oil. Contacting the oxidized crude glyceride oil with the porous adsorbent particles causes the adsorbent particles to adsorb the metal components, the partial glycerides and the prooxidants (i.e. components that contribute to the oxidation process) which in turn, results in higher DOBI. All these characteristics increase the heat stability of the purified oil and/or fat composition obtained by the process of the present invention. After treatment with the porous adsorbent particles, the adsorbent treated oil is further processed to purify the oil to improve the quality of the oil.

In the process of the present invention, the adsorbent treated oil is subjected to a degumming process to form a degummed oil. Degumming generally refers to the removal of gums, phospholipids, proteins and other similar compounds from the crude oil. In one embodiment of this invention, the step of degumming comprises introducing an acid into the adsorbent treated oil to allow the acid to react with the adsorbent treated oil. Suitable acid for use in this step include, but not limited to, inorganic and organic acids, having a pH of at least 0.5 as measured at 20°C in a one molar aqueous solution. Examples of these acids include, but not limited to, phosphoric acid, acetic acid, citric acid, tartaric acid, succinic acid, lactic acid or the like, or a combination thereof. The use of aggressive, corrosive and/or toxic acids is preferably avoided. Preferably, edible acid such as acetic acid, citric acid, tartaric acid, lactic acid or the like is used. More preferably, phosphoric acid is used. Preferably, the phosphoric acid has a concentration of 80 to 90%.

In one embodiment of this invention, the acid is allowed to react with the adsorbent treated oil at a temperature of 60°C to 100°C, more preferably 80°C to 90°C for 1 to 30 minutes, more preferably 20 to 25 minutes. This is carried out by adding the acid to the adsorbent treated oil while the oil is at a temperature of 60°C to 100°C, preferably 80°C to 90°C. A temperature between 20°C and 60°C may be employed, however, longer time will be required to allow the acid to mix homogeneously with the adsorbent treated oil. In a preferred embodiment, the acid reacts with the adsorbent treated oil at 85°C for 25 minutes. The amount of acid added to the adsorbent treated oil depends on the amount of phosphatides, and preferably is 0.06 to 1.00%, and more preferably 0.08%.

After the oil is degummed, the oil undergoes a bleaching process to form a bleached oil. Bleaching is a process of removing pigments from the oil. In one embodiment, the bleaching process comprises heating the degummed oil to a temperature of 90 to 100°C, preferably 90 to 95°C, followed by adding a bleaching material to the degummed oil. The amount of bleaching material added to the degummed oil depends on the amount of coloured materials in the oil. In one embodiment, the amount of bleaching material added to the degummed oil is not more than 1.0 %. The bleaching material and the degummed oil are allowed to mix for a predetermined period of time, preferably for 20 to 35 minutes, more preferably about 30 minutes.

Any suitable bleaching material may be used in this invention including, but not limited to, natural bleaching earths, acid-activated bleaching earths, activated carbon, synthetic amorphous silica compounds and the like. In one embodiment, the bleaching material is acid-activated bleaching earth.

After the oil is bleached, the bleached oil undergoes a separation process to separate the bleached oil from the porous adsorbent particles and the bleaching material. Any suitable physical separation methods may be employed without departing from the scope of the invention. In one embodiment, the bleached oil is separated by filtration. Any type of standard or existing filter can be used in this step without departing from the scope of the invention.

The separated bleached oil is then subject to means for deodorizing the oil to remove any undesired odour and flavour from the oil to obtain the resultant edible oil and/or fat composition. The step of deodorizing comprises introducing the separated bleached oil into a deodorization apparatus and heating the bleached oil to a temperature of 200 to 280°C, preferably 240 to 260°C for 20 to 120 minutes, preferably 60 to 90 minutes to deodorize the bleached oil. Any suitable types of deodorization apparatus may be used without departing from the scope of the invention. Apart from removing undesired odour and flavour from the oil, the deodorizing step may also remove other minor undesired components such as free fatty acids, volatile impurities and coloured bodies from the oil. After the bleached oil is deodorized, the oil and/or fat composition obtained thereto is cooled and may be stored for use. One of the advantages of the process of the present invention is that the process uses only a relatively small amount of porous adsorbent particles for the treatment of the oxidized crude glyceride oil. The adsorbent treated oil when further purified to the resultant oil and/or fat composition has improved quality and frying performance. The purified treated oil and/or fat composition of the present invention essentially comprises the following components:

• Free fatty acids, preferably in an amount of 2.0% or less, more preferably 1.0% or less, still more preferably 0.5% or less, especially 0.1 % or less, most preferably 0.05% to 0.08% or still most preferably 0.05% or less, to avoid off- putting or unpleasant odour and/or taste;

Reduced metal content of at least 2% lower. The metal content mainly consists of iron, phosphorus and copper. The term "reduced" refers to a metal content which is lower than that of corresponding oil obtained by standard purification/refining process without the additional step of treating the oxidized crude glyceride oil with porous adsorbent particles. Preferably, the metal content in the purified treated oil and/or fat composition is in an amount ranging from 0.5 to 2 ppm;

Not more than 3.5 wt% of partial glycerides selected from the group consisting of monoglyceride and diglycerides. This provides the purified treated oil with better stability against hydrolysis;

Reduced total oxidation products of at least 20% lower than that of corresponding oil obtained by standard purification/refining process without the additional step of treating the oxidized crude glyceride oil with porous adsorbent particles;

The levels of 3-MCPD ester and glycidyl ester precursors differ from corresponding oil obtained by standard purification/refining method. The purified oil composition of the present invention has a reduced 3-MCPD ester and/or glycidyl ester content. More preferably, the combined 3-MCPD ester and glycidyl ester content is at least 30% lower, more preferably at least 40% lower, even more preferably at least 50% lower, most preferably at least 60% lower than corresponding oil obtained by standard purification/refining method. Taking palm oil by way of example, when refined by standard physical refining (degumming, bleaching, deodorization), it has a combined 3-MCPD ester and glycidyl ester content of 2.0 to 20 ppm. By comparison, a refined oil obtained by the process of the present invention has a combined 3-MCPD ester and glycidyl ester content of less than 5 ppm, preferably less than 3 ppm, more preferably less than 2 ppm, especially less than 1 ppm, most preferably less than 0.5 ppm. Unless specified otherwise, the combined 3-MCPD esters and glycidyl ester content is determined using DGF Standard Methods C-lll 18(09); • 50 to 1 ,000 ppm of one or more antioxidant vitamin E components selected from the group consisting of tocopherols and tocotrienols;

• At least 400 ppm of one or more antioxidant vitamin E components selected from the group consisting of tocopherols and tocotrienols in the fresh oil/fat composition;

• At least 100 ppm of one or more antioxidant vitamin E components selected from the group consisting of tocopherols and tocotrienols after the oil composition was continuously exposed to elevated temperature, water and oxygen for more than 10 hours;

• Preferably 70 to 100%, more preferably 80 to 100%, most preferably 90 to 100% of the fatty acid constituents of a triglyceride is a fatty acid having 10 to 24, preferably 14 to 22, more preferably 16 to 22 carbon atoms;

• Unsaturated fatty acids in an amount ranging from 47 wt% to 75 wt% based on the total weight of the oil and/or fat composition; and · Saturated fatty acids in an amount of not more than 55 wt% based on the total weight of the oil and/or fat composition. The saturated fatty acids is selected from the group consisting of fatty acid with carbon number 16 and/or less and combinations thereof. The oil and/or fat composition of the present invention has a solid fat content of less than 30% at 20°C, more preferably less than 15% at 20°C.

The oil and/or fat composition has a peroxide value (POV) of 5 or less, preferably 2.5 or less, more preferably 1.5 or less, especially 0.5 or less, most preferably 0.1 or less. The colour (1 R + Y) as measured by the Lovibond method using 5¼ inch glass cell is 3.5 or less, preferably 3.0 or less, more preferably 2.5 or less, especially 1.5 or less. It is preferred that the smoke point of the oil and/or fat composition of the present invention is at least 180°C, more preferably at least 200°C, even more preferably at least 220°C, most preferably at least 240°C.

The oil and/or fat composition of the present invention has a reduced concentration of pro-oxidant and reduced oxidation products and impurities. The oil and/or fat composition is stable against thermal oxidation or hydrolysis. The naturally occurring antioxidant in the oil remains high even after the oil is subject to a long thermal exposure. The naturally occurring antioxidant is less likely to decompose during thermal exposure and thus, it is stable for long term use. The oil and/or fat composition can prevent colouring caused by heating as well as cooked odour produces during heat cooking. The oil and/or fat composition can also prevent an increase in acid value of the oil.

The oil and/or fat composition of the present invention is suitable for use as oil for frying or deep-frying a variety of food ingredients. The fried or deep-fried .food cooked through the use of the oil and/or fat composition has favourable appearance and flavour. The oil and/or fat composition of the present invention is suitable for preparing, but not limited to, snacks such as potato chips, fabricated potato, tortilla chips, and fried beans; french fried potatoes; fried chicken; chicken nuggets; doughnuts; instant noodles; fried breads; fried cakes; fried cookies; everyday dishes such as spring roll, cutlets, fried fish fillets, fried shrimps, fried squid fillets, fried oysters, fritters and tempura; and frozen food of similar types. The frying temperature can be at least 140°C, preferably 150 to 200°C, more preferably 160 to 190°C. The following examples are provided to further illustrate and describe particular embodiments of the present invention, and are in no way to be construed to limit the invention to the specific procedures, conditions or compositions described therein.

EXAMPLES

Quality Measurement of Oil/Fat

Stability of Oil/Fat against Oxidation: The induction period was measured using a 743 Rancimat Apparatus (Metrohm, Switzerland). 3g of oil with desired concentration of antioxidants was heated to 120°C under an air flow rate of 20L/h.

Glyceride Composition: Fat samples (0.05g) were dissolved in n-hexane (5ml) and then analyzed for triacylglycerides composition using gas chromatography (Model: Clarus 500, Perkin Elmer, USA). The triacylglycerides was separated using SP2380 (Supelco, Bellefonte, PA) capillary column (0.25cm i.d x 30cm x 0.2pm). The temperatures of the samples were maintained in the analysis in a column oven: at 180°C, injection block: 100°C and detector temperature: 370°C. The carrier gas used was nitrogen at 45mL/min. The injection volume was 1 μί.. Vitamin E Content: Tocopherols and tocotrienols were determined in normal phase HPLC using hexane/iso-propyl alcohol (99.5:0.5 %v/v) as the mobile phase. The specifications for the HPLC are: column - GENESIS SILICA 120A 4pm, 4.6 x 250mm (Jones Chromatography), G 1321A FLD detector (Agilent). The measurement conditions are set at: absorbance 290 nm, column temperature 30°C, flow 1.4 ml/min, analysis time 22 min, and injection volume 20 μΙ.

Free Fatty Acid, Peroxide and Anisidine Value: Free fatty acid, peroxide value and anisidine value were measured according to method AOCS 1997, Ca 5a-40, AOCS 1997, Cd 8-53 and AOCS 1997, Cd 18-90, respectively.

Colour Tone: The colour of the samples was measured with a Lovibond tintometer (Brand F, produced by The Tintometer Ltd.) using a 1-inch cell.

Smoke Point: Determination of smoke point was carried out using the AOCS 1997 Official Method Cc 9a-48.

Glvcidyl ester & 3-MCPD: The content of 3-MCPD esters and glycidyl esters was determined using DGF Standard Methods C-lll 18(09). Flavour of Oils

A denotes: Completely free from any unfavourable taste such as acidity and astringency; remarkably excellent. B denotes: Almost no unfavourable taste; excellent.

C denotes: Slight presence of unfavourable taste such as acidity and astringency.

D denotes: Clear presence of unfavourable taste and disagreeable flavour. Flavour of Fried Food

A denotes: Completely free of any unfavourable taste such as acidity and astringency; remarkably excellent.

B denotes: Almost no unfavourable taste; excellent.

C denotes: Slight presence of unfavourable taste such as acidity and astringency. D denotes: Clear presence of unfavourable taste and disagreeable flavour. EXAMPLE 1

The oil compositions shown in Table 1 were prepared using the following oils:

Comparative Oil I : Crude palm oil (free fatty acid: 3.38%).

Invention Oil J : Oil I was contacted with silica gel particles (ZEOprep 60,

ZeochemAG, particle size of 200-500 pm, 3.33 wt/wt% ) in a reactor (internal diameter: 6cm; length: 66cm) at a temperature of 70-75°C and pressure of 800-850 mbar for 8 hours to obtain Invention Oil J.

Comparative Oil K : Crude palm oil (free fatty acid: 3.88%).

Invention Oil L : Oil K was contacted with silica gel particles (ZEOprep 60,

ZeochemAG, particle size of 200-500 pm, 1.67 wt/wt% of oil) in a reactor (internal diameter: 6cm; length: 66cm) at a temperature of 70-75°C and pressure of 800-850 mbar for 8 hours to obtain Invention Oil L.

Comparative Oil M : Crude palm oil (free fatty acid: 3.35%).

Invention Oil N Oil M was contacted with silica gel particles (ZEOprep 60,

ZeochemAG, particle size of 200-500 pm, 0.67 wt/wt% of oil) in a reactor (internal diameter: 6cm; length: 66cm) at a temperature of 70-75°C and pressure of 800-850 mbar for 8 hours to obtain Invention Oil N.

TABLE 1

Comparative Invention Comparative Invention Comparative Invention

Parameters

oil I oil J oil K oil L oil M oil N

FFA (%) 3.38 3.19 3.88 3.47 3.35 3.15

DOBI 2.50 3.07 2.52 3.23 2.39 2.85

Total oxidation

12.64 8.42 22.95 11.59 10.25 5.92 products

Partial glycerides

4.08 3.64 3.26 3.16 3.21 2.34 (%)

Metal content

- - 12.85 10.35 15.61 11.12 (ppm)

EXAMPLE 2

The oil compositions shown in Table 2a were prepared using the following oils:

Comparative Oil A : Crude palm oil (free fatty acid: 1.20%) was degummed, bleached and deodorized. The oil was degummed with 0.05- 0.1 wt/wt% phosphoric acid (85% concentration) at 85°C for 20 minutes. This was followed by bleaching with 1 % Taiko Supreme for 30 min at 95°C. Deodorization of the oil was carried out for 90 min at 260°C and 2-5 mmHg using 2% spurge steam.

Comparative Oil B

and Invention Oil C : Crude palm oil (free fatty acid: 3.88%) was treated in a similar manner as the preparation of Comparative Oil A. The same crude palm oil was contacted with silica gel particles (ZEOprep 60, ZeochemAG, particle size of 200-500 μιη, 1.67 wt/wt% of oil) in a reactor (internal diameter: 6cm; length: 66cm) at a temperature of 70-75°C and pressure of 800-850 mbar for 15 hours. The eluate was collected and subjected to degumming, bleaching and deodorization to obtain Invention Oil C. The oil was degummed with 0.06% phosphoric acid (85% concentration) at 85°C for 20 minutes. This was followed by bleaching with 1 wt/wt% Taiko Supreme for 30 min at 95°C. Deodorization of the oil was carried out for 90 min at 260°C and 2-5 mmHg using 2% spurge steam.

Invention Oil D Similar to the procedure used for preparation of Invention Oil

C, Oil B was subjected to silica (ZEOprep 60, ZeochemAG, particle size of 200-500 μηι, 0.033 wt/wt% of oil) adsorption treatment and refining, to thereby obtain Invention Oil D.

Comparative Oil E

and Invention Oil F Crude palm oil (free fatty acid: 3.40%) was treated in a similar manner as the preparation of Comparative Oil B to obtain Comparative Oil E. The same crude palm oil was mixed with silica gel particles (ZEOprep 60, ZeochemAG, particle size of 200-500 μη^η, 3.3 wt/wt% of oil) at 85°C for 80 minutes, followed by addition of 0.06% phosphoric acid (85% concentration) and 1 wt/wt% Taiko Supreme to produce Invention Oil F. The oil was degummed at 85°C for 20 minutes whereas bleaching was conducted at 95°C for 30 minutes. Deodorization was carried out for 90 min at 260°C and 2-5 mmHg using 2% spurge steam.

Table 2a

Analysis Comparative Comparative Invention Invention Comparative Invention parameter oil A oil B oil C oil D oil E oil F

PG (%) 3.10 3.22 2.66 0.01 2.76 2.56

TG (%) 97.32 96.68 97.34 99.99 97.24 97.44

Total

Oxidation 2.2 7.28 2.60 2.35 2.80 2.04 Product Smoke

210 201 210 240 230 225 point (°C)

3- CPD

0.71 2.61 0.96 - 1.83 1.17 (ppm)

GE (ppm) 1.3 1.38 0.73 - 1.45 0.57

Oil A, B, C, E, and F (Table 2b) were prepared in 100g oil with 1% water (w/w) added in to accelerate the oxidation process. The oil samples were stored in an oven at 90°C and heated continuously for 120 hours. At intervals of 24 hours, the oil samples were taken out and measurements such as free fatty acid content (AAOCS 1997, Ca 5a-40), peroxide value (AOCS 1997, Cd 8-53), anisidine value and colour analysis (PORIM 1995, p4.1) were taken.

Total oxidation products were calculated according to equation 2PV + AnV. Each oil and fried oils were evaluated for flavour by 10 panellists in accordance with the above mentioned criteria. The results obtained are shown in Table 2b.

TABLE 2b

Oils A, B, C, and D (7.0 kg) were each introduced into separate 10L deep fryer (Model FG7-05, FAGOR, Sydney). The oils were heated to a temperature of 180°C and maintained at this temperature for the first 20 min before frying. A batch of 490 g pre- fried french fries was fried for 2 minutes. The same operation was repeated 15 times every 22 minutes. Thus, the entire test was performed for 330 minutes. The same procedure was repeated for 2 days. The colour tone, glyceride content, induction period, total tocopherol, and free fatty acid value of the samples after 220, 440, and 660 minutes from the start of frying were measured. Results obtained are as shown in Table 2c.

TABLE 2c

Comparative Oil Invention Oil Analysis Parameter Time (min)

A B C D

0 0.02 0.08 0.02 0.02

Free fatty acid (given as % 220 0.05 0.24 0.15 0.05 palmatic) 440 0.15 0.35 0.18 0.08

660 0.24 0.37 0.27 0.14

0 15.53 15.42 12.56 12.42

220 7.24 9.57 11.34 12.18

Induction period (hr)

440 2.15 1.90 10.52 11.54

660 1.10 1.09 9.71 10.30

0 1.0 2.2 1.8 1.0

220 3.1 5.5 2.1 1.7

Colour (Red)

440 4.7 6.8 2.8 2.0

660 5.4 8.2 4.8 3.3

0 614.00 648.00 533.00 541.00

220 209.00 293.00 468.00 468.00

Total tocopherol (ppm)

440 25.00 37.00 375.00 384.00

660 8.00 0.00 317.00 322.00

0 97.32 96.68 98.19 100.00

220 96.94 96.56 97.86 99.90

Triglyceride (%)

440 96.53 96.12 97.57 99.89

660 96.03 95.82 97.35 99.76

0 3.10 3.22 1.31 0.00

220 3.28 3.43 1.57 0.09

Diglyceride (%)

440 3.56 3.92 1.83 0.11

660 4.08 4.23 2.10 0.24

0 A A A A

Oil flavor

660 B C B B

Fries flavor 660 A C B B EXAMPLE 3 Comparative Oil G : Crude palm oil (free fatty acid: 1.01 %) was degummed, bleached and deodorized. The oil was degummed with 0.05- 0.1 % phosphoric acid (85% concentration) at 85°C for 20 minutes. This was followed by bleaching of the oil with 1 % Taiko Supreme for 30 min at 95°C. Deodorization of the oil was carried out for 90 min at 260°C and 2-5 mmHg using 2% spurge steam.

: Crude palm oil (free fatty acid: 3.10%) was contacted with silica gel particles (ZEOprep 60, ZeochemAG, particle size of 200-500 pm, 3.3 wt% of oil) in a reactor (internal diameter: 6cm; length: 66cm) at a temperature of 70-75°C and pressure of 800-850 mbar for 15 hours. The eluate was collected and subjected to degumming, bleaching and deodorization to obtain Invention Oil H. The oil was degummed with 0.06% phosphoric acid (85% concentration) at 85°°C for 20 minutes. This was followed by bleaching the oil with 1 % Taiko Supreme for 30 min at 95°C. Deodorization of the oil was carried out for 90 min at 260°C and 2-5 mmHg using 2% spurge steam.

Oils G and H (7.0 kg) were each introduced into a 10L deep fryer (Model FG7-05, FAGOR, Sydney). The oils were each heated to a temperature of 180°C and this temperature was maintained for the first 20 min before frying took place. A batch of 490g pre-fried french fries was fried for 2 minutes. The same operation was repeated 15 times every 22 minutes. Thus, the entire test was performed for 330 minutes. The same procedure was repeated for 4 days. The colour tone, glyceride content, induction period, total tocopherol, and free fatty acid value of the samples after 440, 880 and 1 ,320 minutes from the start of frying were measured. The results obtained are as shown in Table 3. TABLE 3

Comparative Oil Invention Oil

Analysis Parameter Time (min)

G H

0 0.01 0.01

Free fatty acid 440 0.19 0.12

(given as %

palmatic) 880 0.43 0.36

1320 0.72 0.70

0 12.91 12.34

440 1.76 10.10

Induction period (hr)

880 0.69 9.26

1320 0.56 7.39

0 1.9 1.9

440 3.4 2.9

Colour (Red)

880 7.9 7.5

1320 11.5 11.0

0 535 540

Total tocopherol 440 24 371

(ppm) 880 13 280

1320 4 163

0 97.34 98.05

440 96.68 97.66

Triglyceride (%)

880 95.22 96.91

1320 93.89 95.84

0 2.66 1.95

440 3.32 2.34

Diglyceride (%)

880 4.78 3.09

1320 6.11 4.16

Oil flavor 0 A A

1320 B B

Fries flavor 1320 A A

The results in Table 3 show that Invention Oil H has a comparable free fatty acid value (of 0.70) as the Comparative Oil G (with a value of 0.72) after 1320 minutes of frying at 180°C. This shows that the process of the present invention can produce a frying oil with comparable or better frying stability as compared to premium frying oil (Oil G) by using standard quality crude palm oil. The premium frying oil currently available on the market is produced using premium quality crude palm oil (PQCPO) and this premium quality crude palm oil is very limited in supply. The present invention provides an alternative for producing premium frying oil using only standard quality crude palm oil, without the need to use premium quality crude palm oil.

The above is a description of the subject matter the inventors regard as the invention and is believed that others can and will design alternative systems that include this invention based on the above disclosure.

Claims

1. A process for producing a heat stable edible oil and/or fat composition, the process comprising:

contacting an oxidized crude giyceride oil with 0.1 wt% to 5.0 wt% of porous adsorbent particles based on the oxidized crude giyceride oil to be treated, at a temperature between 75 to 95°C for 10 to 95 minutes to form an adsorbent treated oil; degumming the adsorbent treated oil to form a degummed oil;

contacting the degummed oil with a bleaching material to form a bleached oil; separating the bleached oil from the porous adsorbent particles and the bleaching material; and

deodorizing the bleached oil to form a heat stable edible oil and/or fat composition.

2. The process according to claim 1 , wherein the porous adsorbent particles having an average particle size of 10 to 1 ,000 pm.

3. The process according to claim 1 , wherein the porous adsorbent particles having an average pore size of 10 to 150 A.

4. The process according to any one of claims 1 to 3, wherein the porous adsorbent particles having a surface area of 90 to 600 m²/g.

5. The process according to claim 1 , wherein the porous adsorbent particles having an average moisture content of 2 to 4%.

6. The process according to claim 1 , wherein the porous adsorbent particles is selected from the group consisting of porous zeolite, carbon aluminophosphate, precipitated silica, pyrogenic silica and silica gel.

7. The process according to claim 1 , wherein the oxidized crude giyceride oil is contacted with the porous adsorbent particles at a temperature between 90 to 95°C.

8. The process according to claim 1 , wherein the oxidized crude giyceride oil is contacted with the porous adsorbent particles for 80 to 95 minutes.

9. The process according to claim 2, wherein the average particle size of the porous adsorbent particles is 200 to 600 μιη.

10. The process according to claim 3, wherein the average pore size of the porous adsorbent particles is 50 to 70 A.

11. The process according to claim 1 , wherein the step of contacting the oxidized crude glyceride oil with the porous adsorbent particles comprises:

mixing the oxidized crude glyceride oil with the porous adsorbent particles.

12. The process according to claim 1 , wherein the step of contacting the oxidized crude glyceride oil with the porous adsorbent particles comprises:

passing the oxidized crude glyceride oil through a bed packed with the porous adsorbent particles.

13. The process according to claim 12, wherein the bed is a fixed bed column.

14. The process according to claim 1 , wherein the porous adsorbent particles are porous silica having a pore size distribution of not more than 10% of the particles.

15. The process according to claim 1 , wherein the step of degumming the adsorbent treated oil comprises:

reacting the adsorbent treated oil with an acid at a temperature between 80 to 90°C for 1 to 30 minutes.

16. The process according to claim 15, wherein the acid is in an amount ranging from 0.06 to 1.00 %.

17. The process according to claim 15, wherein the acid is selected from the group consisting of phosphoric acid, acetic acid, citric acid, tartaric acid, succinic acid, lactic acid and a combination thereof.

18. The process according to claim 17, wherein the acid is phosphoric acid.

19. The process according to claim 18, wherein the phosphoric acid having a concentration of 80 to 90%.

20. The process according to claim 1 , wherein the step of contacting the degummed oil with the bleaching material comprises:

contacting the degummed oil with not more than 1.0% bleaching material at 90 to 95°C for 20 to 35 minutes.

21. The process according to claim 16, wherein the bleaching material is an acid- activated bleaching earth.

22. The process according to claim 1 , wherein the step of deodorizing the bleached oil comprises:

heating the bleached oil to a temperature of 200 to 280°C, preferably 240 to 260°C for 20 to 120 minutes, preferably 60 to 90 minutes to deodorize the bleached oil.

23. The process according to claim 1 , wherein the heat stable edible oil and/or fat composition comprises:

free fatty acids in an amount ranging from 0.05 wt% to 0.08 wt% based on the total weight of the oil and/or fat composition;

a metal content in an amount of 0.5 to 2ppm;

partial glycerides in an amount of not more than 3.5 wt% based on the total weight of the oil and/or fat composition;

a combined 3- CPD ester and glycidyl ester content of less than 5 ppm;

50 to 1 ,000 ppm of one or more antioxidant vitamin E components selected from the group consisting of tocopherols and tocotrienols;

unsaturated fatty acids in an amount ranging from 47 wt% to 75 wt% based on the total weight of the oil and/or fat composition; and

saturated fatty acids in an amount of not more than 55 wt% based on the total weight of the oil and/or fat composition, selected from the group consisting of fatty acid with carbon number 16 and/or less and combinations thereof.

24. The process according to claim 23, wherein the edible oil and/or fat composition having a reduced total oxidation products of at least 20% lower than that of a corresponding oil obtained by standard purification or refining process.

25. The process according to claim 1 or 23, wherein the heat stable edible oil and/or fat composition has a solid fat content of less than 30% at 20°C.

26. The process according to claim 1 or 23, wherein the heat stable edible oil and/or fat composition has a peroxide value of 5 or less.

27. A heat stable edible oil and/or fat composition comprising:

a metal content in an amount of 0.5 to 2ppm;

a combined 3-MCPD ester and glycidyl ester content of less than 5 ppm;

28. The heat stable edible oil and/or fat composition according to claim 27, wherein the edible oil and/or fat composition having a reduced total oxidation products of at least 20% lower than that of a corresponding oil obtained by standard purification or refining process.

29. The heat stable edible oil and/or fat composition according to claim 27, wherein the heat stable edible oil and/or fat composition has a solid fat content of less than 30% at 20°C.

30. The heat stable edible oil and/or fat composition according to claim 27, wherein the heat stable edible oil and/or fat composition has a peroxide value of 5 or less.