DESC:FIELD OF INVENTION

The present invention relates to an edible oil composition.

BACKGROUND OF INVENTION
Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Vegetable oils are consumed worldwide and are of great importance in human diet. Vegetable oils are a source of energy, essential fatty acids and can carry liposoluble vitamins. In addition to this, they provide, aroma, taste and palatability to the food.
Many studies have proven that it is economical and acceptable that blending of oil provides balanced fatty acid profile and also improved content of bioactive compounds leading to improved health benefits. Reena et al discloses hypolipidemic effect of oils with balanced amounts of fatty acids obtained by blending and interesterification of coconut oil with rice bran oil or sesame oil. Blending of coconut oil with rice bran oil and sesame oil enhanced PUFAs/SAFAs ratio of 0.8-1.0 and also showed a hypolipidemic effect. It is also known that blend of rice bran oil and sunflower oil (80:20) could be beneficial for patients with lipid abnormalities and also for normolipidemic people as a means to maintain normal levels of lipids.
However, due to their composition, especially the presence of high unsaturated molecules, they are prone to oxidation and degradation. Such a degradation can occur during heating or storage of oil thereby affecting the shelf life of oil and in vivo stability of oils. Also, prolonged oxidation and degradation results in nutritional losses and formation of compounds that may be toxic to human health.
Deep oil frying is one of the most popular and oldest cooking techniques in the world, particularly in the Indian subcontinent. In the frying process, the food is immerged in an oil bath at temperatures of 150–190 °C. During the thermal treatment, important changes occur. Frying oil act as a heat transfer medium and contributes to the texture and flavour of fried food. However, hydrolysis, oxidation, and polymerization of oil occurs in frying oil and produce volatile or non-volatile compounds.
Currently, the common method to improve the oxidative stability of the oil is by adding one or more antioxidants that are known to prevent free radical induced damage by preventing the formation of free radicals, scavenging them or by promoting their decomposition. Natural or synthetic antioxidants are generally added to the oil composition to improve the oxidative stability of the oils. Oils with tocopherols added are known for their improved antioxidant capacity. Seppanem CM et al. discloses that addition of 200 ppm of a-tocopherol improves the stability of frying oil, prolonging its useful life. Nadia Manzo et. Al. discloses effects of a-tocopherol and oleic acid content in sunflower oil subjected to discontinuous and prolonged frying process.
Challa Ravi Kiran et. al. discloses that tocopherol mixture, rosemary extract, and SAIB could reduce the total polar compound formation and also secondary oxidation in the oils at about more than 30 % compared to other antioxidants. Similarly, ?-oryzanol and curcumin showed a considerable effect on the frying oil quality.
However, at high temperature, a-tocopherol can be degraded into a wide range of oxidation products. Soon-naam ko et. al teaches changes of vitamin E content in rice bran with different heat treatment. It is disclosed that longer heating with both microwave and electric roaster caused a significant degradation of vitamin E resulting in a decreased content of total vitamin E. It is also known that a-tocopherol at high levels may have a pro-oxidant effect (Teixeira et al ).
In addition to the above, there are several other limitations in the composition particularly in blended oils, their preparation that would be apparent to a person skilled in the art.
Several other methods that are used for improving oxidative stability of oils include partial hydrogenation of triglyceride fatty acids, blending of saturated fats and polyunsaturated vegetable oils with interesterification or partial hydrogenation of fatty acids in these blends.
Thus, there is a need to develop an oil composition with improved oxidative stability and that provides in vivo health benefits to the consumers.

SUMMARY OF THE INVENTION
The present invention provides an edible oil composition with an improved oxidative stability. In an aspect, the present invention provides an edible oil composition consisting of a blend of 68% to 72% rice bran oil and 28% to 32% sunflower oil; 0.01% to 0.02% of tert-butylhydroquinone; 0.005%-0.015% of ascorbyl palmitate; and 0.0005% to 0.0010% of polydimethylsiloxanes. The oil composition has an improved oxidative stability. Preferably, the blend of sunflower oil and rice bran oil is in the ratio of 30:70. In an aspect, the edible oil composition comprises refined sunflower oil and refined rice bran oil blend. The oil composition of the present invention can have an induction time of 19 to 20 hours as determined by the Rancimat Test at 110° C, air flow of 20 L/h and conductivity range of 50 to 200 µS/cm.
The oil composition of the present invention can include a vitamin AD2 premix in an amount of 0.004% to 0.01%. the fat-soluble vitamin premix can be selected from Vitamin A, Vitamin D2 or mixtures thereof.
DETAILED DESCRIPTION OF THE INVENTION
The foregoing objects of the present invention are accomplished, and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention is directed to an edible oil composition with improved oxidative stability. Sunflower oil is a high PUFA oil and is preferred for its high vitamin E content and light clean taste due to the presence of high ratio of polyunsaturated-to-saturated fatty acids. Refined sunflower oil has also being used particularly in Indian cooking due to its high polyunsaturated fatty acid content, bland flavour, and low viscosity. However, the presence of the unsaturated fatty acids makes the sunflower oil susceptible to oxidation or thermal degradation during heating or frying. Rice bran oil is known to be one of the most nutritious and healthful edible oils. Rice bran oil comprises natural ?-oryzanol, tocopherols, tocotrienols. Rice bran oil has about 30% linoleic acid, 44% oleic acid and about 23% saturated fatty acids. It was found that sunflower oil blended with rice bran oil in a ratio of about 30:70 showed improved stability as compared to the single seed oil or unblended oil. In an aspect, the edible oil composition comprises refined sunflower oil and refined rice bran oil blend.
In an aspect, the present invention provides an edible oil composition consisting of a blend of 68% to 72% rice bran oil and 28% to 32% sunflower oil; 0.01% to 0.02% of tert-butylhydroquinone; 0.005%-0.015% of ascorbyl palmitate; and 0.0005% to 0.0010% of polydimethylsiloxane. The oil composition has an improved oxidative stability. Preferably, the blend of sunflower oil and rice bran oil is in the ratio of 30:70. In an aspect, the edible oil composition comprises refined sunflower oil and refined rice bran oil blend in the ratio of 30:70. The oil composition can further include 0.004% to 0.01% of vitamin premix that include fat-soluble vitamins selected from Vitamins A and D. Preferably, the oil composition can include 0.004% to 0.006% of vitamin premix.
The oil composition of the present invention can have an induction time of 19 to 20 hours as determined by the Rancimat Test at 110° C, air flow of 20 L/h and conductivity range of 50 to 200 µS/cm. The oxidative stability is directly proportional to the Rancimat values as provided in Table 8. The edible oil composition of the present invention is about more stable than the single seed oils under frying conditions. The oil composition of the present invention is thus suitable for cooking and frying. In a preferred aspect, the edible oil composition of the present invention is a frying oil.
The edible oil composition of the present invention shows an improved oxidative stability without any additional synthetic or natural tocopherols. The blend of rice bran oil and sunflower oil in the specific ratio of 70:30 provides the improved oxidative stability of the oil. The oryzanol in rice bran oil and natural tocopherols present in sunflower and rice bran oil provides the anti-oxidative property to the blend. It is known that the ascorbyl palmitate added to the oil blend maintains the tocopherol content of the oil blend even after frying and prevents degradation of oil after frying cycles. The ascorbyl palmitate in the range of 0.005% to 0.015% i.e. 50 ppm to 150 ppm enhances the oxidative stability of the composition. The edible oil composition of the present invention uses lesser amount of ascorbyl palmitate than the known compositions and provides an improved oxidative stability to the composition.
The edible oil composition of the present invention is more stable than the single seed oils in generation of secondary and total oxidation products under frying conditions. The p-anisidine values and Totox value shown in Tables 6 and 7 respectively are indicative of such a synergistic property of the oil composition of the present invention.
In another aspect, the present invention provides a method of preparing the edible oil composition. About 28% to 32% of sunflower oil is charged in a vessel. Simultaneously, in another vessel a pre-blend is formed where pre-heated rice bran oil can be mixed with 0.01 to 0.02% of tert-butylhydroquinone, and 0.0005% to 0.0010% of polydimethylsiloxane. The rice bran oil can be preheated to a temperature of about of 55°C. To the pre-blend, 0.005% to 0.015% of ascorbyl palmitate is mixed at a temperature in the range of 70°C to 95°C and stirred to form the oil composition. The pre blend is then mixed with the remaining quantity of the rice bran oil to under stirring.
The fat-soluble vitamin premix can be added to the composition and can be selected from Vitamin A, Vitamin D2 or a combination thereof.
Examples
Example 1: Edible oil composition
Table:1
Sr. No. Ingredients Example 1A Example 1B Example
1C
1 Refined Sunflower Oil 28 32 30
2 Refined Rice Bran Oil 72 68 69.93
3 TBHQ 0.014 0.018 0.017
4 Ascorbyl Palmitate 0.005 0.015 0.01
5 PDMS 0.0005 0.0008 0.0008
6 Vitamin AD2 Premix (Excipients) 0.004 0.006 0.005

A batch of 20gm of oil formulation was prepared by charging about 28% to 32% of sunflower oil in a vessel. Rice bran oil was preheated at a temperature of 45-to-60-degree C. Pre-heated rice bran oil was then mixed with tert-butylhydroquinone, and vitamin AD2 premix. The mixer was operated at 800-1000 rpm for a period of 30 min. Ascorbyl palmitate was then added to the pre-blend at a temperature in the range of 70°C to 95°C. The mixture was stirred to form the homogenous mixture. The pre blend was then mixed with the remaining amount of rice bran oil & sunflower oil under stirring.
Example 2: Edible oil composition – Comparative Example Ascorbyl Palmitate
Table: 2
Sr. No. Ingredients Example 2A Example
2B
1 Refined Sunflower Oil 30.05 30
2 Refined Rice Bran Oil 69.93 69.93
3 TBHQ 0.017 0.017
4 Ascorbyl Palmitate - 0.004
5 PDMS 0.0008 0.0008
6 Vitamin AD2 Premix (Excipients) 0.005 0.005

The above compositions were prepared in a similar manner as mentioned in Example 1, except for the step of addition of ascorbyl palmitate for Example 2A.
Example 3: Edible oil composition – Comparative Example Single Seed Oil (SSO)
Table: 3
Sr. No. Ingredients Example 3A Example 3B
1 Refined Sunflower Oil 99.92 --
2 Refined Rice Bran Oil -- 99.92
3 TBHQ 0.017 0.017
4 Ascorbyl Palmitate 0.01 0.01
5 PDMS 0.0008 0.0008
6 Vitamin AD2 Premix (Excipients) 0.005 0.005

A batch of around 50 gm of oil formulation was prepared by charging sunflower oil in a vessel & preheated at a temperature of 45 to 60 degree C. Pre-heated sunflower oil was then mixed with tert-butylhydroquinone, PDMS, and vitamin AD2 premix. The mixer was operated at 800-1000 rpm for a period of 30 min. Ascorbyl palmitate was then added to the pre-blend at a temperature in the range of 70°C to 95°C. The mixture was stirred to form the homogenous mixture. The pre blend was then mixed with the rest of sunflower oil under stirring.
For example 3B, similar procedure can be adopted.
Example 4
The efficacy studies for the oils of examples 1 to 3 were conducted using the following procedure.
Frying of food is a complex operation with several variable factors, such as temperature of oil, type of food, surface area exposed, composition of food, moisture content of food, draining time etc. As a result it is difficult to obtain standard condition that will reveal the true quality of the oil during frying. Some level of standardization in the protocol was done for making fritters and also the frying conditions like the frying time, the frying temperature and draining time were controlled.
Frying Study Protocol:
I. Preparation of fritters from gram flour:
Table: 4
Ingredients Weight
Gram Flour 300 g
Water 300 ml
Kneading time 10 min
Dough wt 600 g
Salt 4 gm
No. of potato slices per cycle of frying:
(Roughly 85 gm of potato will give 16 slices) 16

Gram flour was purchased fresh from the local market. 300 gm of Gram flour and was weighed in a pan. 300 ml of water and salt was added to it. The dough was kneaded for 10 min. 85 gm of potato is weighed and cut in 16 slices. 16 slices will be fried in per frying cycle. There will be 24 such cycles of frying in an hour. A clean dry frying pan was taken, and its weight noted. 650+0.5 gm of oil was weighed in the frying pan.
I. Procedure for frying:
The oil was heated on full flame up to 120º C. The flame was then lowered and oil heated up to 180º C. 16 slices of potato coated with gram flour dough were added to the heated oil at a time and fried for 1 minute i.e. 1 side of potato fritter and for 1 minute i.e. other side of potato fritter and for ½ minute 1st side of fritter on full flame. Intermittent stirring of the fritters while frying was done. Fritters were then taken in strainer, inclined for 30 sec. above the frying pan at height of 1 foot and parallel to it and at 45° angle so that oil flows drop wise. A jerk was given to the strainer and the fritters were taken in product container. Oil was again heated to 180º C at low flame. Frying was repeated until all the fritters are fried. Frying pan was removed from gas burner. The frying pan was then cooled at room temperature. The oil was then cooled & analyzed for oxidative changes on frying.
The following parameters of the oil were analyzed after frying cycle of fritters:
1. Peroxide Value
Peroxide value is the primary oxidation product which gets generated in oil during frying and is an indication of the extent of oxidation suffered by oil.
Reagents:
i) Acetic acid - chloroform solvent mixture (3: 2). Mix 3 volumes of glacial acetic acid with 2 volumes of chloroform.
ii) Freshly prepared saturated potassium iodide solution.
iii) 0.1 N and 0.01 N sodium thiosulphate solutions. Weigh 25 gm of sodium thiosulphate and dissolve in 1000 mL of distilled water. Boil and cool, filter if necessary. Standardize against standard potassium dichromate solution.
iv) Starch solution - 1% water-soluble starch solution
Procedure:
Weigh 5 gm (±50 mg) sample into a 250 mL stoppered conical flask. Add 30 mL acetic acid chloroform solvent mixture and swirl to dissolve. Add 0.5 mL saturated potassium iodide solution with a Mohrs pipette. Let stand for one minute in dark with occasional shaking, and then add about 30 mL of water. Slowly titrate the liberated iodine with 0.1 N sodium thiosulphate solution with vigorous shaking until yellow colour is almost gone. Add about 0.5 mL starch solution as indicator and continue titration shaking vigorously to release all I2 from chloroform layer until blue colour disappears. If less than 0.5 mL of 0.1 N sodium thiosulphate is used repeat using 0.01 N sodium thiosulphate. Conduct blank determination (must be less than 0.1 ml 0.1 N sodium thiosulphate).
Calculation:
Peroxide value expressed as milliequivalent of peroxide oxygen per kg sample (meq/kg):
Peroxide value = (Titre* N* 1000)/ Weight of the sample
Where, Titre = mL of Sodium Thiosulphate used (blank corrected)
N = Normality of sodium thiosulphate solution.
Fresh oils usually have peroxide values well below 10 meq/kg. A rancid taste often begins to be noticeable when the peroxide value is above 20 meq/kg (between 20 – 40 meq/Kg). In interpreting such figures, however, it is necessary to take into account the particular oil or fat.
(Ref: - AOAC 17th edn, 2000, Official Method 965.33 Peroxide Value in Oils and Fats/ Pearsons Composition and Analysis of Foods 9th edn page 641)
Table: 5

Product Name Peroxide Value (PV) Increase in PV after 1st Frying Cycle from Initial Rise in PV for SSO Vs Example 1C- =
Initial 1st Frying (Rise in PV of SSO/Rise in PV for Example 1C)
Example 1C 2.00
2.00 0.00 -
Example 3A Sunflower Oil 2.19 14.99 12.79 12.79
Example 3B Rice Bran Oil 3.30 8.28 4.97 4.97
It was observed that Example 1C was more stable than the single seed oils (SSO) on generation of primary oxidation products under frying conditions
2. Para-Anisidine Value
Para anisidine value is a secondary oxidation product that is generated in oil during frying. Aldehydes, derived from the secondary oxidation of fat matrix, react with the p-anisidine determining a variation in the absorbance, measured at 350 nm. Anisidine value is expressed as AnV Furthermore, AnV analysis on oil is an indicators of excessive oil deterioration in deep frying process.
Reagents:
a. Isooctane (2,2,4-trimethylpentane) optically clear
b. Glacial acetic acid analytical reagent quality
c. P-Anisidine reagent quality 0.25g/100ml solution in glacial acetic acid
Procedure:
Weigh 0.5-4 gm of sample in 25 ml volumetric flask. Dissolve and dilute to volume with iso-octane. Measure the absorbance (Ab) of solution at 350 nm in a cell with spectrophotometer using reference cell filled with solvent as blank. Pipette exactly 5 ml of fat solution into one test tube and exactly 5 ml of solvent into second test tube. By means of an automatic pipette add exactly 1ml of p-anisidine reagent to each tube and shake. After exactly 10 minutes measure the absorbance (As) of solvent in first test tube in cell at 350 nm using solution from second tube as blank in reference cell.
Calculation:
p.A.V. is given by the formula = (25*( 1.2*As-Ab))/m
where As= absorbance of fat solution after reaction with p-anisidine reagent
Ab= absorbance of solution of fat
m= mass in gm of test portion
Reference: AOCS official method cd 18-90
Table: 6

Product Name p-Anisidine Value (pAnV)) Increase in p-AV after 1 Frying Cycle from Initial Rise in pAnV for SSO Vs Example 1C= (Rise in PV of SSO/Rise in PV for Example 1C)
Initial 1st Frying
Example 1C 42.50
67.64 25.14 -
Example 3A Sunflower Oil 4.40 70.78 66.38 2.64
Example 3B
Rice Bran Oil 49.40 98.96 49.56 1.97

It was observed that Example 1C oil was more stable than the single seed oils (SSO) on generation of secondary oxidation products under frying conditions.
3. Total Oxidation Products by Totox Value
Totox value is the extent of generation of the oxidation product during frying.
Totox Value = 2PV + pAnV
Table: 7

Product Name p-Anisidine Value (pAnV)) Increase in Totox Value after 1 Frying Cycle from Initial Rise in Totox Value for SSO Vs Example 1C=
Rise in Totox Value of SSO/Rise in Totox Value for Example 1C
Initial 1st Frying
Example 1C 46.49
71.64 25.14 -
Example 3A Sunflower Oil 8.79 100.75 91.96 3.66
Example 3B Rice Bran Oil 56.00 115.51 59.51 2.37

It was observed that Example 1C was more stable than the single seed oils (SSO) on generation of secondary oxidation products under frying conditions.
4. Rancimat Studies
Degradation of oil, as assessed on increase in induction hours by Rancimat. Rancimat determines the oxidation stability of natural fats and oils, in their pure form as well as in fat-containing foods, using the established Rancimat method.
It accelerates the aging process of the sample by exposing it to heat and increased volumes of air, and it measures the time that passes until oxidation takes place at a high rate – the induction time
Procedure:
Take 3 gm of oil in rancimat tubes and put it in Rancimat Instrument at 110°C and air flow rate of 20L/h and start the instrument until it reaches end point (Induction hours)
The oils of the present invention showed higher induction time compared to that of the single seed oils.
Table: 8

Product Name Induction time in hours Change in induction hours after 1 Frying Cycles from Initial
Change in induction hours for SSO Vs Ex 1C=
(Change in induction hours of SSO/Change in induction hours for Ex 1C)
Initial 1st Frying

Example 1C 19
16.72 2.28 -
Example 3A Sunflower Oil 12.1 2.91 9.20 4.03
Example 3B Rice Bran Oil 16.4 9.00 7.40 3.25

It was observed that Example 1C was more stable than the single seed oils (SSO) under frying conditions.
The foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.
The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others, skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated.
It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.
,CLAIMS:
1) An edible oil composition consisting of:
A blend of 68% to 72% rice bran oil and 28% to 32% sunflower oil;
0.01% to 0.02% of tert-butylhydroquinone;
0.005% to 0.015% of ascorbyl palmitate;
0.0005% to 0.0010% of polydimethylsiloxanes;
wherein the edible oil composition has an improved oxidative stability.
2) The oil composition as claimed in claim 1, wherein sunflower oil and rice bran oil is in the ratio of 30:70.
3) The oil composition as claimed in claim 1, wherein the sunflower oil and rice bran oil are refined.
4) The oil composition as claimed in claim 1, wherein comprises 0.004% to 0.01% vitamin premix selected from Vitamin A, Vitamin D2 or mixtures thereof.
5) The oil composition as claimed in claim 1, wherein has an induction time of 19 to 20 hours as determined by the Rancimat Test at 110° C, air flow of 20 L/h and conductivity range of 50 to 200 µS/cm.