Title of Invention

"A COMPOSITION FOR PURIFICATION OF HEATED EDIBLE OILS"

Abstract

The present invention relates to a composition for the purification of heated edible oils. The prior art reports the purification of raw/crude oil and not heated or finished oil. However, the present invention for the first time discloses the purification of heated oils which have been repeatedly used for frying. The said purpose is achieved by providing a composition comprising of pre-activated magnesium carbonate, magnesium oxide, bentonite powder, refoil activated optimum grade bleaching earth and celite, all in equal proportions along with 1% calcium sulphate.

Full Text

The present invention relates to a composition for the purification of heated edible oils. Deep frying is a process where food items are fried in a vegetable oil at an elevated temperature (175-180°C). Frying process is such where a progressive degradation of physical and chemical qualities of the frying oils take place. Normally during frying free fatty acids, and peroxide value increases along with polymerization consequently oils start foaming, and darkening in colour. These changes not only cause inconvenience in frying but also effect the quality of final product, bringing about adverse changes in its color, appearance, texture and flavour. Since degradation in oil quality is unavoidable, normally in commercial catering and even in house hold, either the oil is discarded or reused again and again by adding fresh batch of oil to minimise the concentration of deleterious components developed. Use of antioxidants have also been found not of much use as they decompose during repeated heating. The deterioration of oils during frying forced industries to modify their fryer by remote heating / indirect heating or controlled heating of oils with a filtration unit attached with the system to prevent the oil for exposure to air and heat. However the domestic method of frying remained unchanged and classical. In domestic frying same oil is used for repeated frying and whenever the quantity drops down a fresh batch of oil is added and frying continued without noticing the damage done to the oil. Keeping the above problem In mind it became necessary to develop a filter aid which can purify repeatedly heated (heat abused) frying oil at domestic level. This is for the first time a filter aid in the form of a sack is developed which can remove free fatty acids, peroxides and polymerized components produced, all at a time from the heat abused oil. The oil thus purified can be reused with much less of deleterious substances. References may be made to Tanahashi S, Nagano K, Kasai M, Tsubone P., Iwana A, Kazuse Y, Tasaka K and Isooka Y. Process for purification of crude glyceride oil, United States patent, USA 787 981 (US4787981) 1988 where in a process for purification of crude glyceride oil (e.g. Soyabean, rapeseed, cottonseed, safflower, corn germ, sunflower and rice bran oils) which involves diluting the crude oil with an organic solvent, passing the diluted crude oil with a semipermiable polyinnide membrane, and bleaching and deodprization. This process is a different process where memberane is used for purification of raw oil by removing free fatty acids and unsaponifiable matter. The oil thus obtained is subsequently refined in a conventional manner. Reference may be made to Chajuss-D and Chajuss-EM purification of vegetable oils, Israeli patent, IL 58842 (IL 58842) 1983, where in crude vegetable oil is converted to a finished oilhaving good flavour, odour and colour, which is .suitable for human consumption. The hydrocarbon solvent and oil miscella is mixed or washed with aqueous alcohol. Later the solvent oil miscella phase is separated from the aqueous alcohol phase which is removed from the miscella phase. The hydrocarbon is recovered from the miscella and oil is treated with bleaching earth, carbon etc and filtered to get purified oil. Basically it is a refining process where aqueous alcohol washing step has been added. Rest of the process is similar to refining process. It is not related to purification of repeatedly heated oils. References may be made to Mgebrishvill TV, Artyuskov VN, Martorsochuk VI and Dekhtesman DA, method for purification of vegetable oil, USSR patent, 594 163 (594163), 1978, where in the vegetable oil is hydrated, heated at 210-230°C and citric acid is added along with sodium acetate, the mixture is allowed to stand for 3-5 min and then is neutralised with alkali. The non triglyceride matter coagulate out. The process of heating and acid treatement are carried out under vaccum preferably at 40-70 mm Hg. The citric acid and sodium acetate mixute is preferable in a 1:1 ratio. This is a modified process of purification of vegetable oil, where again raw oil is taken and purified to make it edible. It is not directly related to present work. Refenece may be made to Arutyunyan N.S, Kopeikovskii VM, Arisheva EA Gusev.VN, Sheredeko VM, Bantser GV, Krisanov SD, Kozinnyi AM, Ivashchenko W, Mezin VK, Tarabaric heva LA and svechni K AN, method of purifying vegetable oil, USSR patent, 348 598 (348598) 1972, where in the suspended particles which are generated during heating are removed by filtration at the hot condition and later the oil is allowed to cool. It is a simple process of filtration to remove the unwanted particles from the oil and not directly related to the present work. Reference may be made to S.N.Sulthana, studies on frying of foods in oils, Ph.D., thesis CFTRI Mysore, University of Mysore, 1982 Page 217, where in stress on the quality control of frying oils have been given by estimating color, smoke point, viscosity, foaming height, free fatty acids, oxidised fatty acids after treating the heat damaged raw ground nut oil with adsorbents like bleaching earth (unknown brand) activated carbon (plant or animal not known) magnesium carbonate, slide acid, aluminium oxide and calcium oxide separately at elevated temperature (150°C) and stirring. It has been concluded that none of the adsorbent had any beneficial effect except aluminium oxide that too a little extent. Experiments have also been conducted at mixture of magnesium oxide and bleaching eath (unknown brand) at the ratio of 4:2 and 5:3. However decrease in free fatty acids was found to be nominal after treatment (5.3 to 4.6 and 4.3) which is still more than the permissible limit of 3% for raw groundnut oil under prevention of F:ood Adulteration Act. In this report although a mixture of two adsorbent is used by author, but experiment conditions are different and purification effect is much less compared to the present invention as given in the specification. Moreover an important aspect like peroxide value is not reported and left out with only groundnut oil selected for total study, which is a serious draw back. Most of the reference which are cited above have described the purification of raw/crude oil and not the refined/finished oil. They are dealing with the purification of raw oil using various non-classical methods like membrane filtration, ordinary filtration, solvent and aqueous solvent partitioning methods in conjunction with the conventional refining steps like bleaching and deodorization. But in the present invention it is the oil which has already been used repeatedly for frying and left out as a residual oil in the domestic kitchen, may be intended to be thrown is being purified. Here heat abused oil is allowed to pass from a purification pad by gravity filtration and purified oil is collected. The main object of the present invention is to provide a composition of filter aid for purification of heated edible oils which obviates the draw backs as detailed above. Another object of the present invention is to develop a purification pad which can reduce free fatty acids in the purified oil. Still another object of the present invention is to device a filter aid which can reduce peroxides in the purified oil. Yet another object of the present invention is to device a filter aid which can enhance smoke point of purified oil. Yet another object of the present invention is to develop a purification pad through which heat abused oil can pass and get purified. Yet another object of the present invention is to purify repeatedly heated -heat abused vegetable oils (left over in the kitchen and normally discarded) and use it as it is or as a diluent after removing all the deleterious matter namely peroxides, epoxides, hydroxy, keto, acids and polymers. Novelty of the technique is that all these matters are removed in one step purification in a totally inert atmosphere. Accordingly, the present invention provides a composition for the purification of heated edible oils comprising pre-activated magnesium carbonate, magnesium oxide, bentonite powder, refoil activated optimum grade bleaching earth and celite in equal proportions along with 1% calcium sulphate. In an embodiment of the present invention, the composition is seamed in a circular pad. In an embodiment of the present invention, the said composition is useful for the purification of fried oils selected from groundnut, soybean, sunflower and safflower. A circular purification filter aid pad [diameter 8.0 cm] is prepared using unbleached cloth, circles of diameter 9 cms was cut from the unbleached cloth. Two circles are taken and placed one above the other and stitched at the seam to make a circular bag with an opening. The bag is filled with 15 gms of purification matter and sealed completely. The pads need to be kept in an anhydrous condition separately, preferable a pouch of silica gel anhydrous for drying may be kept along with pads in a sealed containers. As the purification matter is already activated before filling the bags it need not be activated again. However any trace of moisture present in the pad may be rendered inactivated while pouring the semi-hot oil. To prepare the purification filter aid-pad various adsorbants, binding agent, filter aid and purification agent like bleaching earth, activated carbon, magnesium oxide, calcium oxide, magnesium carbonate, silicic acid, aluminium oxide, bentonite powder and celite were selected and activated at 110°C for 4 hours, before they were filled up in the pad, separately. The heat abused oil was passed through these pads separately, but they did not give satisfactory results with respect to free fatty acids, peroxide value, smoke point and color. However when mixture of optimum bleacing earth + bentonite powder (5:1 w/w), magnesium oxide and silicic acid mixed in equal proportion were tried keeping other parameters as above, results were encouraging i.e., free fatty acid, peroxide value and color has come down. In search for a better mixture for purification pad another mixture containing pre-activated optimum + bentonite powder 5:1 w/w, magnesium oxide, silicic acid, activated charcoal and keiselgel G was mixed in equal ratio before putting in to the pad. The oil purified through this pad did lower free fatty acids and peroxide compare to the heat abused oil but carried carbon fine particles along with the purified oil giving a black tinge to the oil, which is undesirable. In continuation of the search for a better mixture for purification pad, mixture of bentonite powder, magnesium oxide light, silicic acid, magnesium carbonate and mixture of magnesium carbonate, magnesium oxide, bentonite powder, optimum grade bleacing earth and celite in equal proportions were also tried. Among these two sets, the later mixture found most effective with respect to decrease in free fatty acids percent, peroxide value, color and increase in smoke point. Hence, purification pad containing preactivated magnesim carbonate, maganesium oxide, bentonite powder, optimum grade bleaching earth and celite in equal proportion (15gm/pad) is recommended for the best results. In our country even today deep frying is done in liquid oils of higher unsaturation (Iodine value 85 to 145). Frying oils during frying are exposed to elevated temperature in the presence of moisture. Under these conditions number of changes take place in the frying oils like hydrolysis, oxidation, themolysis and polymerization (Scheme 1). As these reactions proceed, they triger formation of volatile and non-volatile decomposition products, which have bad effect on flavour, color and texture of fried foods as well as life of frying oils. The decomposition products and rate of their formation vary with the nature of fat used, the surface volume ratio, the excess of air, the nature of fried foods and interval of heating. Experiments have shown that these products are carcenogenic in nature and also produce irretation to mucosa membrane with other associated problems. Hence, it is better to discard such a heat abused oil rather than reuse it an such or as a diluant. The present day practice is to dilute such a used frying oil with fresh batch of oil and continue the frying, which results in reducing these deleterious moities up to certain extent only. (Scheme Removed) Scheme-1: Products generated during deep frying To remove the variety of products generated during deep frying as shown in scheme-1 by one step cleaning using an individual agent is rather impossible as they belong to different class of compounds having different properties, but they have attraction towards alkaline earth metal oxides and carbonate along with fuller earth, bentonite and other adsobents. Removal of deleterious matter like free fatty acids, peroxides, oxycompounds and color pigments from the impure oil is taking place by the simple process of adsorption, which can be better understood as follows; the normal adsobents used are predominantly natural and acid activated clays hydrated aluminium silicates, activated carbon, alkali earth metal salts and other complexes. They posses the power to adsorb on their surface not only the color compounds, but also in oil when colloidally suspended substances such as gums resins and certain degradation products are present. At the surface of the adsorbent some of the valences, which hold the atoms together, are free for which longmuir has suggested formula for adsorption based on the attraction forces. On the similar lines adsorption based on pseudo-chemical reaction called chemisorption also take place between a metal salt and the degradation products and held together in the same fashion as surface adsorption. They form salts between the color compounds, natural or degraded portion and the reactive hydrogen of the metal salts etc. This phenomenon is represented by the equation called VAN BEMMELEN-FREUDLICH equation. (Equation Removed) In this equation x is the amount of solute adsorbed by m grammes of adsorbent, C is concentration of solute in the solution, a and 1/n are the adsorption constant of which a represents the adsorption value of the adsorbent material or the adsorption at unit concentration; 1/n is the adsorption exponent indicating the quality or efficiency of the adsorption at frying concentration of the solute. The higher a and smaller 1/n the more effective is adsorbent. But the present invention do not follow this equation in the same manner as we are creating a situation where adsorption and chemi sorption are taking place at the same time in the mixed environment. Most of the adsorptive purification are done by a single adsorbent. But this purification filter aid-pad consists of a series of material efficient in removing the unwanted matter by adsorption and chemisorption working simultaneously. Hence efficacy of purification has increased to many fold. A fresh purification filter aid-pad which is stored in a box along with anhydrous silica gel separately is taken out and loaded on which the repeatedly heated frying oil left in the frying pan in a domestic kitchen after last frying (allowed to cool down, 100-150 ml) can be poured. The oil should be poured slowly at the center of the pad and allowed to spread around, and left overnight to facilitate gravity filtration. After oil is completely passed through, the purification pad is discarded. The purified oil collected can be used as such for frying or used as a diluent. Only one pad should be used at a time and 100-150 ml of heat abused oil can be purified at one time. The following example are given by way of illustration and therefore should not be construed to limit the scope of the present invention. Example 1 15 gms each of the adsorbent and chemisorbent namely bleaching earth, activated, carbon, magnesium oxide, calcium oxide, magnesium carbonate, silicic acid and aluminium oxide were taken in a glass funnel plugged with cotton separately. 50ml of repeatedly heated frying oil (sunflower oil which was used for preparation of khara bundi and khara sev, 5 times) was poured into the glass funnel and collected in conical flask (250 ml capacity) separately. The rate of filtration was found to be very slow and there was no noticeable difference in the colour of the oil indicating not a good retention of pigments and breakdown products by the agent. Therefore use of a single agent for purification is given up. Example 2 Another set of adsorbents namely optimum grade bleaching earth + bentonite powder 5:1 w/w, magnesium oxide light and silicic acid, activated separately at 110°C for 2 hours mixed together in equal proportions was used for the purification purpose. 15gms of the above activated mixture was loaded on the glass funnel pludged with cotton. 100 ml of the repeatedly heated frying oil (groundnut oil which was used for preparation of sweet bundi and khara sev, 4 times) was poured into the glass funnel and allowed to filter off in a conical flask. The purified filtered oil was subjected for free fatty acids and peroxide estimations. % FFA of repeatedly heated frying oil = 1.87 % FFA of purified oil = 0.25 Peroxide value of repeatedly heated frying oil = 93.8 Peroxide value of purified oil = 38.1 The above values indicate that FFA and PV has come down after purification. Example 3 15gm of the adsorbant mixture, consisting of optimum grade bleaching earth + bentonite powder 5:1 w/w magnesium oxide light and silicic acid, activated independently at 110°C for 2 hours and mixed together in equal proportion, was placed over the filter paper and covered by another filter paper of same dimention. 100 gms of oxidised oil (safflower oil which was used for papad and bajji frying) was passed through this filter aid. After complete oil was passed through another 25 gm of oil was passed and purified oil was collected in a big beaker. To check the efficacy of filter aid-pad free fatty acids and peroxide value were determined as given in Table -1 Table1 (Table Removed) The above purified oil was once again passed through the filter aid-pad but with a freshbatch of purification matter. The free fatty acids and PV of resultant oil was 0.44 and 54.4 respectively. Example 4 Another batch of physically refined and old sample of soybean oil was taken for purification. This oil was passed through the purification filter aid-pad which was already used for example-3. The oil allowed overnight to pass through gravity filtration. The purified oil collected from the chamber B was subjected for free fatty acids and peroxide value estimations and results are given in Table-2. Table 2 (Table Removed) Example-5 To increase the efficacy of purification filter aid-pad, the filter papers have been replaced by unbleached cloth circles. Two circles joined together and stitched to give a circular bag, which can be filled with purification matter and sealed later. This type of pad has an advantage not to allow any oil to pass without treatment. Further more the purification matter was also changed by changing the mixture composition. 10gms each of bentonite powder, magnesium oxide light, silicic acid and magnesium carbonate was taken and mixed together thoroughly. This purification matter was activated at 110°C for 2 hours before use. 15gms of this purification matter was filled up in the purification filter aid-pad. 150 gms of heat abused oil (sunflower oil repeatedly, 6 times, heated while preparation of chips, frying of papads, preparation of bajji and bundi) was allowed to pass through by gravity filtration overnight. The purified oil was collected and subjected for estimation. Table 3 (Table Removed) Along with the assessment of quality of purified oil another phenomenon has been studied in this batch was to estimate the quantity of impure oil retained in the purification pad. Weight of the impure oil passed through the purification filter aid-pad =150 gm Weight of purified oil collected = 101.6 gm Weight of the impure oil retained with the purification filter aid-pad = 48.4 gm % impure oil retained with the purification filter aid-pad = 32.2 Replication of the experiment showed the impure oil trapped in the purification filter aid-pad ranged between 27.3 to 32.2% For the purpose of quantification of impure oil (values given above) trapped in the purification pad, acetone was (found better solvent among others) used to extract the oil out of the purification pad. The solvent from the extract was removed using vacuum rotatory flash evaporator and oil preserved for quantitation and other estimations. As replication was done to verify the quantity trapped in the pad, all these samples collected were subjected for thin layer chromatography. One % chloroform solution of the above samples along with corresponding heat abused oils and purified samples were spotted on thin layer chromatographic plates 20X20 cms, 0.5 mm thickness, coated with slurny of silica gel and containing calcium sulphate as binder, air dried and activated at 110°C for 1 hour. The plate after spotting were developed in solvent system petroleum ether: diethyl ether: acetic acid 40:60:2 v/v. After development the plate was air dried and visualized under iodine vapors. TLC revealed that degradation products and oxidized portion which were present in the heat abused oil were removed up to a very large extent from the purified oil. Consequently these degradation products and oxidized portion were present in the impure oil trapped in the pad as also shown by TLC. The experiments were also conducted to carry out complexation. TLC where one percent chloroform solution of the fresh sunflower oil, repeatedly heated (heat abused) sunflower oil and purified oil (oil passed through the purification filter aid-pad) were spotted on thin-layer chromotographic plate 10X20 cms, 0.5 mm thickness, coated with silica gel-G and preactivated. The spotted plate was developed in solvent system petroleum etherdiethyl ether 60:40 v/v. After development the plate was air-dried and sprayed with 21% alcohol solution of 2,4-dinitrophenyl hydrazine. The heated oil developed three dark-yellow spots on an orange background immediately after spray between Rf 0.1 to 0.35 confirming the presence of carbonyl compounds. However these spots were absent in fresh and purified sunflower oil samples. This further indicates the removal of carbonyl / oxycompounds from heated oil when passed through the purification filter aid-pad. Example 6 Another batch of purification matter consisting of 15 gms each of magnesium carbonate, magnesium oxide, bentonite powder, refoil activated optimum grade bleaching earth and celite along with calcium sulphate 1% as binder was mixed together thoroughly, activated at 110°C for 4 hours and filled up in purification pads (15 gms/pad). A fresh batch of Godrej refined sunflower oil marketed by Godrej Foods Ltd, Wadala Mumbai, batch No.P168, May 2000, containing permitted antioxidants was procured from the market. About 2L of this oil was used for deep frying purpose. Bunddis were prepared in this oil for making laddos, which is an Indian traditional sweetmeats. Four batches of bunddis were prepared at different interval of times. Subsequently papads were deep-fried and bengal gram dhal was deep fried in to this oil. This dark color oil was used for purification purpose. Two vegetable oil purification filter aid-pads were loaded with 150 gms of above heat abused vegetable oil separately and allowed to pass through by gravity filtration overnight. The purified oil collected, the impure oil retained in purification pad and subsequently extracted with acetone, the heat abused oil as such and the corresponding fresh market sample were subjected for estimations. Results are given in Table 4. Table 4 (Table Removed) Refined sunflower oil, which is one of the frying oils, is the oil of choice as a frying medium at present due to economic consideration as it is cheaper than groundnut and mustard oils. The market sample of Godrej brand refined sunflower oil used for frying was found to be of very good quality as its, PV, FFA and smoke point were found to be 3.6, 0.15 and 190°C respectively well within the required limits. However this oil when used for frying at regular intervals, after six consecutive fryings went very bad. This is mainly because of the high degree of unsaturation, at it is evident by its PV, FFA and smoke point which were found to be 17.9, 0.35 and 165°C respectively. This directly indicates that a great extent of thermal and oxidative changes has taken place during deep frying. This resultant heat abused frying oil was passed through the purification filter aid-pad which is fabricated for the first time for this purpose. So far we do not have a device invented which can be used for the purification of heat abused vegetable oils at the domestic level. Purification pad, consists of purification matter like adsorbent, chemisorbent, filter aid and binder acting simultaneously. At every purification, fresh pad has to be used, which can be supplied separately in anhydrous condition. The above oil passed through two different purification pads (i) and (ii) to clean up oil and also achieve repeatability. Peroxide value, free fatty acids and smoke point of purified oils (I) 7.9, 0.18, 178; (II) 8.5, 0.19 and 177 indicated that purification has taken place up to a great extent and oil purification filter aid-pad is working satisfactorily. The main advantage of the present invention are: 1. A purification filter aid-pad is provided to the house hold which can be used for purification of resultant heat abused frying oils. 2. The resultant heat abused frying oil ready to be discarded, normally 100-200 ml left over in the domestic kitchen, is purified and made reusable as such or as a diluent. This is a total benefit to the consumer. Free fatty acids, peroxides, polymers have drastically been reduced from the heat abused frying oils. Hence, even if the purified oil used as such without dilution, it will not contribute these toxic components to the product up to the extent if it would have been diluted without purification with fresh oil and used. 3. It can be used by house hold with no energy consumption and training. 4. It works on purely physical phenomenon and no chemical reaction takes place at any stage. Therefore there is no chance of any artifect or unwanted product forming and travelling to the purified oil. 5. The adsorbents in the mixed form when used as purification filter aid-pad found to be very effective in removing the unwanted oxycompounds and polymers as shown in Table-4, than in their individual form Table-5. Table - 5 Efficacy Estimation of Individual Adsorbents for Purification of Heat Abused Sunflower Oil (Table Removed) This efficacy in the mixed form could be achieved due to the synergistic effect of chemisorbents and adsorbents made to work together in the purification filter aid -pad. We Claim: 1. A composition for the purification of heated edible oils comprising pre-activated magnesium carbonate, magnesium oxide, bentonite powder, refoil activated optimum grade bleaching earth and celite in equal proportions along with 1% calcium sulphate. 2. A composition as claimed in claim 1, wherein the composition is preferably seamed in an unbleached cloth bag. 3. A composition as claimed in claim 1, wherein the edible oils are preferably selected from groundnut oil, soybean oil, sunflower oil and safflower oil. 4. A composition for the purification of heated edible oils substantially as herein described with reference to the foregoing examples.

Documents:

384-del-2001-abstract.pdf

384-del-2001-claims.pdf

384-del-2001-correspondence-others.pdf

384-del-2001-correspondence-po.pdf

384-del-2001-description (complete).pdf

384-del-2001-form-1.pdf

384-del-2001-form-18.pdf

384-del-2001-form-2.pdf

384-del-2001-form-3.pdf