APPLICATION OF RSM IN OPTIMIZING THE REMOVAL OF FFA AT THE DEGUMMING STAGE IN THE REFINING OF PALM OIL

Transcription

1 1014 APPLICATION OF RSM IN OPTIMIZING THE REMOVAL OF FFA AT THE DEGUMMING STAGE IN THE REFINING OF PALM OIL EGBUNA S.O Department of chemical engineering, Enugu State University of Science and Technology, Enugu. ABSTRACT: This work investigated the effects of degumming parameters of the degumming stage on the stability of refined palm oil. The raw palm oil used in the investigation was obtained from Adah palm mill, Imo State, in the South Eastern province of Nigeria. The oil was characterized before and after refining and used in the investigation. Central Composite Design,(CCD), a type of Response Surface Methodology (RSM), was used to optimize the process conditions of degumming acid, contact time and process temperature. The result showed that quality of final product of palm oil refining depends on the conditions of degumming, and on the nature of the degumming chemicals used. The degumming was done at a temperature range of 40 to 120 o C, and the optimum temperature was found to be 80 o C, at the contact time of 40 minutes, and acid concentration of 1%. It was established that colour fixation during deodorization is mainly due to the decomposition of the oxidation products of aldehydes and ketones at the deodorization temperature of 200 o C and above. The stability standard of the degummed at the optimal conditions was however, measured in terms of colour, 2.5 Red units, Free Fatty Acid(FFA), predicted and actual values of 3.67% and 3.8% respectively, Peroxide Value(PV) 5.8m.eq/kg, Anisidine Value(AV) 7.5m.eq/kg, Iodine Value(IV) 50.6, Iron (Fe) 350 (Ppb), and Phosphorous content 0.03(mg/l), all of which were compared with those of the American Chemist Society (AOCS),[1]. KEY WORDS: Optimization, Degumming, Characterization, RSM, FFA, Stability. 1.0 INTRODUCTION In the past few years demand for refined vegetable oils has increased worldwide, Wordbook Encyclopedia, 2001, Gunstone,2002, and Rauken, This might be due to increase in world population, rising standard of living, consumer preference, and technological advancement. Vegetable oils find applications as cooking and frying oils, as well as in the manufacture of margarine, shortening, Vanaspati, baker s fat, soap, grease, lubricants, creams, as well as bio diesel, and transformer oil, Pahl, 2005, Udeh 2015, and hence the need to stabilize its quality for these purposes. Palm fruit, is a monocotyledonous fruit obtained from oil palm (Elaeis Guinensis) found in abundance in the Eastern part of Nigeria, It is 0.5 to 5mm long, and oval in shape and weighs about 6-8g on the average. The oil content of the fruit is about 50%, Mahatta, 1985, Nkpa et al 1989, and Eze et al, (2012). Human beings have known how to extract oils from their natural sources since ancient time, and make them fit for their use. The oils were normally consumed crude, since very little treatment was done order than filtration or decantation. In Nigeria, palm oil is still consumed crude Two methods are used in the extraction of the oil in the recent times, namely mechanical expression and solvent extraction Dawodu, 2009, and Egbuna and Aneke, The former is pressure dependent, while the latter works with diffusion principles, making use of hexane as solvent, Egbuna et al, 2013(a). The oil contains considerable amount of impurities like Free Fatty acid, a precursor of rancidity, (Ref) carotene and chlorophyll pigments, phosphotides, odour, and oxidation products, which are usually removed by refining, because they impart unpleasant odour and flavour to the finished product Egbuna, Two refining methods are available, Egbuna et al, 2013(b), and Belaw and Tribe, 1972; the chemical process, which makes use of caustic lye to neutralize the FFA content, and the physical process, which came into use by the 20 th century,[7]. The latter was so much improved upon at the deodorization stage, with the effect of reduction in overall processing cost.[12]. Practical experience has distinguished the two process routes, ALFA LAVAL, There is a substantial colour reduction at the neutralization stage, and fuel savings on steam distillation of the chemical process, due to the

2 1015 moderate temperature applied to preserve the anti oxidants, sterol and tocopherol present in the oil, Anderson, Capacity is also improved, and quality is assured. The physical process offers advantages of improved deodorizer efficiency, low water consumption, reduced oil loss, savings on chemical, manpower reduction, less corrosion and pollution tendencies, and equally high quality and stability of the finished product, and hence its choice of the process method, [12]. Hoffman, 1989, had shown that bleaching stage of the refining of palm oil and the nature of the bleaching clay used play a vital role in the stability of the finished product. Hymore and Ajayi, (1996), have also demonstrated that Local activated Clay can effectively remove caroteniod from palm oil, and reduce FFA content. Many factors influence the stability of refined palm oils, and have been the subject of much study, Olaofe et al, Among the factors are; type of raw oil, its colour, Phosphotides, Free fatty acid content, taste, and other physical and chemical properties. To be refined, the raw oil has to be degummed, Egbuna et al, 2007, Mbah, and Njoku, 2007, and Ige, et al, 1984, bleached and deodorized in order to remove its objectionable properties,[3]. The degumming process is a well-established operation in the processing of edible oils, and is one of the major stages for the stabilization of the refined oils. All the colloidal and suspended particles, and soluble phosphotides would have been removed at this stage. Anderson,1997, Danh et al,2009, and Ruddy, 2011, had, in one time or the other used design expert, statistical method or applied RSM in their work to optimize the process conditions during extraction or refining of vegetable oils. NIST/ SEMATECH, 2012, and Ejikeme et al 2013, had also used RSM to optimize the bleaching of using a locally activated clay. In this work, we have tried to; show how the stability of the refined palm oil is affected by the conditions under which the degumming is carried out. show why degumming stage of palm oil refining remains a vital part of palm oil refining demonstrate how an effective degumming stage can lead to good oil quality, optimize the degumming process parameters of time, Temperature and acid concentration, with a view to obtaining the optimal values for palm oil. 2.0 EXPERIMENTAL 2.1 Materials/Equipment: The materials and equipment used in the investigation include; raw (crude) palm oil received from Adah palm Industry, South Easter province of Nigeria[10], bleaching earth (Activated Enugu clay), Egbuna, 2015, test chemicals, titration apparati, a set of sieves, Lovibond Tintometer, Steam/vacuum apparatus, Distillation apparatus, conical flasks, beakers, and test tubes, magnetic stirrer, and steam bath. Table 1 shows the physio-chemical properties of the palm oil used in the investigation. (a) Properties : The properties of the oil that were determined include, the, FFA(%),PO 4 (Ppm), PV(m.eq/kg), AV(m.eq/kg), Colour, Fe(Ppb), etcetera, of the degummed, bleached and deodorized palm oil. This was done by using the American Chemists Society (AOCS) standard test methods, [1]. Their values are presented in Table 3. (b) Sample : The crude and refined oil samples used for the stability tests were stored in full, glass bottles at 313K for 28 days. Colour, phosphorous, FFA, PV, and AV, were measured at intervals. The activated bleaching clay used was sieved to 70-5 microns and the same sample was used throughout the experiment. 2.2 Experimental procedure: (a) Degumming Process : Degumming of crude Palm oil was done to reduce the phosphotide and FFA, so as to minimize the foaming tendency of the finished product observed during frying, and reduce rancidity of the oil on storage. The experiment was done using Citric acid, and phosphoric acid, and results compared with international values. One per cent (1%) by weight each of citric acid and phosphoric acid was added to 100g of the crude oil sample in a conical flask. The mixture was heated to a constant temperature of 353K, and stirring done with the magnetic stirrer for 40 minutes. The whole mass was poured into a separating funnel and allowed to settle for 30 minutes. The lower layer (the lecithin), was run off through a valve. Temperature was subsequently varied.

3 1016 Table I Physico -Chemical properties of the palm oil used in the investigation AOAC,[1], Bockish, 1998 Characteristics Crude palm oil Physical Colour Deep orange red Odour Slight palm oil odour Taste Palm fruit taste Sp. Gravity Slip/Melting point 35 o C Moisture 1.3% Refractive index Free fatty acid (FFA) 3.8% Colour in 1 inch cell 23Red units Anisidine value m.eq/kg 8.2 Peroxide value m.eq/kg 5.8 Acid value 9.8 Phosphorous (Ppm) 9.0 Iodine value 48.0 Iron (Ppb) Characterization of degummed, bleached and deodorized oils, [1], Betiku et al., The degummed, bleached and deodorized oil samples were subjected to analyses to determine their physical and chemical properties. Among the properties determined, which will be reported here include; colour, FFA, PV,AV, PO 4 and Fe contents (a) Phosphorous: The phosphorous in the oil sample was determined by ashing. The phosphate obtained was transferred into phosphomolybdate which was reduced to a blue- coloured compound. The concentration of the blue compound was determined by comparison with blue colored glass disks. Procedure: 5g oil sample was weighed into a platinum dish, and 0.5g calcium oxide added and both ashed. The ash was dissolved in cc of 2N hot dilute hydrochloric acid, and filtered into a 100cc volumetric flask. The dish was washed into the volumetric flask and filtered, and, made up to 100cc. A blank experiment was similarly prepared, but with no oil sample present. 5cc of the filtrate was taken in a tube and 2cc and 1cc of molybdate and hydroquinone solution added in that order. The mixture was allowed to stand for 5 minute for the green phosphate colour to develop. 2cc of carbonate/sulphate solution was quickly added and stirred, ( CO 2 evolved). Both the test experiment and its blank were placed in the comparator against a uniform light for comparison. The result was reported as ; Phosphorous (Ppm) = AxVx5 x0.326 Gxvx10000 Where A - comparator scale reading of PO 4 (Ppm), V - Volume of ash solution, v - volume of ash solution taken for the colour development, G - weight of oil sample. (b) Colour pigments: Colour pigments present in Palm oil include; carotenoids, chlorophyll, and gossypol. The carotene has been found to be an excellent indicator of crude oil quality. Procedure: Lovibond Tintometer with 1-inch cell was used for the analysis of colour, and the latter read in terms of red colour band that matched the colour of the refined oils. (c) Free Fatty acid: Free fatty acid results from chemical or enzymatic hydrolysis of the fatty acid glycerides. Its presence in oil sample is a measure of the quality of the crude and refined oils. Procedure: 2.8ml of oil of known FFA, was measured into a conical flask and diluted with 25ml of ethanol. A drop of phenolphthalein was added. This was titrated against 0.1N sodium hydroxide until a permanent pink colour was registered, and the results recorded. 1

4 1017 FFA(%) = VxMxN 10W Where, N - Normality of NaOH; V - Volume of NaOH; W - Weight of oil sample, M- Molecular weight of oil sample used. (d) Oxidation products: When an unsaturated fatty acid chain reacts with air at room temperature, (a process known as autoxidation), hydroperoxides are formed. At high temperature, these peroxides break down to hydrocarbons, aldehydes and ketones. These cleavage products impart odour and flavour to oil and must be removed. (i) Peroxide Value; This is a measure of primary oxidation whose product is hydrocarbons. These hydrocarbons are further oxidized to water, which causes rancidity of the oil on storage. Procedure: 30ml of chloroform - glacial ethanoic acid mixture in the volume ratio of 1:2 was transferred to a conical flask connected to a reflux condenser. The mixture was then heated to boiling and the vapour condensed in the lower part of a jacketed tube. When the reflux became steady, about 1.6 ml of potassium iodide was added from the top of the condenser. The precipitate of KI was dissolved by adding 5 drops of water. The mixture was heated for 5 minutes and 2ml of the oil was pipetted into the mixture through the top of the condenser also. The pipette was rinsed with 2ml of chloroform into the boiling mixture, and boiling continued for 5 minutes. 50ml of distilled water was added, and 2ml of the sample was then titrated with 0.02N thiosulphate solution, using starch solution as indicator. The result is reported as; PV = VxNx1000 G Where V - vol. of thiosulphate used (ml), N - normality of thiosulphate solution, and G - vol. of sample (ml) (ii) Anisidine value; This measures the amount of secondary oxidation in a sample of oil. Its products are aldehydes and ketones, whose oxidation induces higher rancidity effect to the oil. Procedure; The procedure for analysis for AV is the same as in the PV, except that the temperature at which these cleavage products are formed is higher. (e) Iron (Fe): This is a metal element which, with copper, induces oxidation of the unsaturated fats and oils at the double bond. Removal of iron will reduce the rate of oxidation reaction at the high temperature of deodorization. Procedure: 0.2mg Fe stock solution was pipetted into 100ml conical flask. 10ml of 10% hydroxylamine hydrochloride was added. The solution was diluted with water and mixed. 10ml of 0.25% phenolphthalein was added and allowed to stand for 15 minutes and diluted to the mark. Using about 5ml test tube, the transmittance was read in spectrophotometer 20 at 510 UV light. The results of characterization experiments are presented in table II. Table II Laboratory experimental results compared with the international standard. (Test temperature is 80 o C, and bleaching earth dosage is 1%), [7]. Parameters Laboratory experiment International standard Degummed Bleached Deodorized Degummed Bleached Deodorized Colourin1inch 19.5 Red 11.5Red 3.2Red units 20.0 Red 10.5Red 2.5 Red cell unit units unit units units FFA% PV m.eq/kg AV m.eq/kg IV (Ppb) Phosphorous Iron

5 Optimization of FFA removal using with CCD Optimization of the factors for the degumming of palm oil using phosphoric acid was carried out using Central Composite Design, a type of Response Surface methodology, RSM. The CCD had two factorial level with 3 numeric factors, which also has 6 axial points and 6 centre points, Betiku, et al The factors and levels used for the CCD are shown in Table III, while the design matrix with the responses is shown in table IV. Table III, Factors and levels for the RSM (CCD) Variable Units Acid Conc. w/v(%) Temperature o C Contact time Min Table IV, Design matrix with responses for FFA removal, (%) Std. Run Acid conc Time Temp. Response Order Order (%) (mins) ( o C) (%) DISCUSSION 3.1 Optimization Numerical optimization was used to search the design space using the model created to find the factor setting that met the desired goal of maximal removal efficiency. With 20 solutions founds (table IV), the optimal conditions were selected based on the highest desirability. The optimum conditions are: Acid concentration of 1%, Contact time of 40 min. and Process temperature of 80 o C. The optimum conditions were validated by repeating the degumming at the predicted optimum conditions. 3.2 Analysis of Variance (ANOVA) Analysis of variance is a method of dividing the variation observed in experimental data into different parts, each attributable to a known source. It shows if the factor or models in the experiments are significant or not. The result is shown in table V.

6 1019 Table V ANOVA TABLE Sum of Mean F- value p-value Source Squares df Square Value Prob>F Model < significant A-Acid conc. (%) B-Contact time(mins) C-Temperature(oC) < Residual Lack of Fit not significant Pure Error Cor Total The Model F-value of 19.39, implies the model is significant. There is only a 0.01% chance that a "Model F- Value" this large could occur due to noise. Values of "Prob > F" less than indicate model terms are significant. In this case A and C, are significant model terms. Values greater than indicate the model terms are not significant. The "Lack of Fit F-value" of 1.09, implies there is a 49.43% chance that a "lack of Fit F- value" this large could occur due to noise. R-Squared Adj R-Squared Pred R-Squared Adeq Precision The "Pred R-Squared" of is in reasonable agreement with the "Adj R-Squared" of "Adeq Precision" measures the signal to noise ratio. A ratio greater than 4 is desirable. The ratio of indicates an adequate signal. This model can be used to navigate the design space. 3.3 Model Equations Final Equation in Terms of Coded Factors: FFA (%) = * A- 0.13* B * C 4 Final Equation in Terms of Actual Factors: FFA (%) = *Acid conc. (%) * Contact time(mins) *Temperature( o C) Model Validation To validate the model equations obtained for adequacy in predicting response, residual plots were used. ANOVA assumed that residuals were independent of each other and are distributed according to a normal distribution with constant variance. This is shown in table VI, where the predicted, actual and residual values were given according the standard order. Table VI, Validation Standard Order Actual Value Predicted Value Residual

7 In te rn a lly S tu d e n tiz e d R e s id u a ls N o rm a l % P ro b a b ility International Journal of Scientific Research Engineering & Technology (IJSRET), ISSN Normal Plots Normal Plot of Residuals; this is shown in Fig. 3 Color points by value of : Normal Plot of Residuals Internally Studentized Residuals Fig. 3 Normal Plot of Residuals The normal probability plot indicates whether the residuals follow a normal distribution, in which case the points will follow a straight line. Some moderate scatter, even with normal data were observed. Definite patterns like an "S-shaped" curve, which indicates a transformation of the response may provide a better analysis as shown in Fig Residuals vs Predicted Plot; the plot is shown in Fig. 4 Color points by value of : Residuals vs. Predicted Predicted Fig. 4 Residuals vs Predicted Plot

8 P re d ic te d In te rn a lly S tu d e n tiz e d R e s id u a ls International Journal of Scientific Research Engineering & Technology (IJSRET), ISSN This is a plot of the residuals versus the ascending predicted response values. It tests the assumption of constant variance. The plot should be a random scatter (constant range of residuals across the graph.) Expanding variance ("megaphone pattern <"). This plot indicates the need for a transformation Residuals vs Run; this is also shown in Fig.5 Color points by value of : Residuals vs. Run Run Number Fig. 5 Residuals vs Run order This is a plot of the residual versus the experimental run order. It allows for a check to be made for lurking variables that may have influenced the response during the experiment. The plot showed a random scatter. Trends indicate a time related variable lurking in the background. Blocking the randomization provides insurance against trends ruining the analysis Predicted vs Actual; this plot is shown in Fig. 6. Color points by value of : Predicted vs. Actual Fig. 6 Predicted vs Actual Figure 6, is the graph of the actual response values versus the predicted response values. It helps to detect a value, or group of values, that are not easily predicted by the model. The data points should be split evenly by the 45 degree line Actual

9 P h o s p h o ru s P K O (m g /l) P h o s p h o ru s P K O (m g /l) P h o s p h o ru s (m g /l) International Journal of Scientific Research Engineering & Technology (IJSRET), ISSN Model Graphs One Factor Plots The One Factor Plots of Acid concentration, Contact Time and Process temperature, are shown in Fig.7(a c) Factor Coding: Actual Phosphorus (mg/l) CI Bands Design Points X1 = A: Acid concentr 0.2 One Factor Warning! Factor involved in AC interaction. Actual Factors B: Contact time = C: Temperature = A: Acid concentr Factor Coding: Actual One Factor CI Bands Design Points 0.05 X1 = B: Contact time(mins) Actual Factors A: Acid conc. (%) = 1.50 C: Temperature(oC) = B: Contact time(mins) Factor Coding: Actual One Factor CI Bands Design Points 0.05 X1 = C: Temperature(oC) Actual Factors A: Acid conc. (%) = 1.50 B: Contact time(mins) = C: Temperature(oC) Fig. 7 Model plots of Acid concentration, Contact Time and Process temperature

10 1023 The figures show the effects of the process variables on the degumming efficiency of the Phosphoric acid. It can be seen that the three factors of acid concentration, time and temperature had serious effects on the degumming efficiency of the acid. It therefore means that as the values of the factors increased, the removal efficiency is affected. Fig.7(a), shows that the removal efficiency of FFA continues to increase as the acid concentration is increased. This could be attribited to the hydrophobic nature of the acid. There tend to be no limit to acid concentration but sound judgement is to stop concentration increase at the optimum point when any additional increase did not result to a corresponding removal of FFA. In Fig 7 (b), FFA removal also increased with time, as noted by Egbuna et al This is because, according to [14], FFA removal is affected marginally by the resident time. The effect of temperaturee on removal efficiency of FFA is shown in Fig.7(c). As shown, the removal efficiency reduces with increase in temperature. It follows then that the higher the process temperature, the lower the removal efficiency. 4.0 CONCLUSION The optimal process parameters for the removal of FFA during degumming of palm, with Phosphoric acid has been investigated. Response Surface Methodology, a type of Central Composite Design, (CCD), was successfully applied in the experimental design in order to study the effect of the key parameters of Time, Temperature and Acid Concentration on the degumming efficiency, and the conditions for the optimal removal of FFA were found to be, time, temperature and Acid concentration of, 40min. 80 o C and 1% by weight of acid concentration, respectively, with FFA of % in the degummed oil. The predicted percentage of 3.8% has a good correlation with the actual value. Validation was done by repeating the experiments at the predicted optimum conditions as shown in table VIII. The results obtained from the optimization of the degummed Palm oil parameters showed that the degumming efficiency is linearly affected by Concentration of degumming acid, and contact time, and degumming temperature, as these can be interpreted from graph and chart shown above. Concentration, and Temperature, invariably increase the degree of FFA removal from Palm. The good correlation between the predicted and experimental values shows that the method adopted is good enough for the process and that the process variables of acid concentration, and temperature were significant. The results obtained, have demonstrated that the quality and stability of finished palm oil product can be greatly influenced by the degumming stage. Variation of the degumming conditions has shown how temperature, degumming chemicals and time conditions can affect the stability of the final product. REFERENCES [1] Official Methods and Recommended Practices of AOCS, Edited by David Firestone, 2013, 6 th edition; ISBN [2] The Worldbook Encyclopedia, 2001, Vol.14 Pp707, Worldbook Inc. Chikago [3] Gunstone, F. D., 2002, Vegetable s in food Technology Composition, Properties and Uses, Pp , Blackwell Publishing Ltd. U.K. [4] Rauken, M.D., Kill, R.C., 1993, Fats and Fatty foods; Food Industries manual, 3 rd ed. Pp ; Longman Inc.London. [5] Pahl G., 2005, Biodiesel growing a new energy economy, White River Junction VT; Chelsea Green Publishing Co. [6] Ude O.C., 2015, Siutability of oils extracted from Soya beans and Castor seed as transformer ooils, M.Eng. Thesis, Dept. of Chemical Engineering, Enugu State,University of Sc. and Technology, Enugu, Nigeria. [7] [8] Mahatta T. L. (1985), Technology of refining of oils and fats, Small business publications, (SBP), building, 4/45 Roop Nagar, Delhi. [9] Nkpa N.N; Akpan H.Y; Arowolo T.A; 1989, Quality of Nigerian Palm after bleaching with Local treated clays; J. AOCS, [10] Eze K. A., Nwadiogbu J. O., Nwamkwere E. T., (2012). Effect of acid treatment on the physicochemical properties of kaolin clay. Archives of Appl. Sci. Research, 4 (2), [11] _value [12] Dawodu, F.A., 2009, Physico-chemical studies of oil Extraction Processes from some Nigerian grown plantseeds., Electronic Journal of Environmental, Agricultural and Food Chemistry *(2) Pp [13] Egbuna S.O; Aneke N. A. G. 2005, Evaluation of the Quality Stability in a Physically Refined Palm, Proceedings of the 35 th Annual Conference and AGM of the NSChE, Kaduna,

11 1024 [14] Egbuna S.O, Ujam A.J, Ejikeme M. E; 2013, Comparative Analysis Of Diffusion Rates In Palm Extraction Using Different Extraction Solvents, ARPN journal of science and technology, Vol 3 no 10, [15] Egbuna, S.O., 2010, Design of an oil Extractor and optimization of of Process conditions for Vegetable oil Refining,Unpublished Ph.D Thesis, Dept. Of Chemical Engineering, Enugu State,University of Sc. and Technology, Enugu, Nigeria [16] Egbuna S.O; Ozonoh M; Aniokete T.C; 2013, Diffusion Rate Analysis In Palm Kernel Extraction Using Different Extraction Solvents. International Journal of Research in Engineering and Technology, V0l 2 issue 11, [17] Belaw D. B., Tribe G. K., 1972,Activated Clay In Palm Refining, And Its Effects On Trace Metal Contaminants, Laporte, Malaysia, SON.BHD.. [18]ALFA LAVAL, 1978, Analysis of Fats and s Laboratory manual, Sweden [19] Anderson A.J.C. (1962), Refining of oil for edible purposes, 2nd ed. Pergamon Press London. [20] Hoffman G. (1989), The Chemistry and Technology of edible oils and fats and their high far products, Academic Press, New York. [21] Hymore F.K; Ajayi A.F. (1989), Use of Local Clay in the Refining of Palm, J. NSChE, Vol. 8, No 2 [22] Olaofe, O., Adeyemi, F.O., and Adediran, G.O., 1994,Amino Acid, Mineral Composition and Functional Properties of some oilseeds., J.Agric. Food Chemistry., 42, [23] Egbuna S.O; Aneke N.A.G; Chime T. O; 2007, Evaluation Of The Effects Of Degumming On The Quality And Stability Of Physically Refined Palm ; Journal of Engineering and Applied Science, Vol 3 P [24] Mbah, G.O. and njoku C.C.,2007, Effects of process conditions on the yield of oil from African Bean Seed, (Pentaclethra Macrophylia), Proceedings of the 37 th Annual conference of the Nigeria Society of Chemical Engineers, Enugu, Pp [25] Ige, M.N., Ogunsua, A.O., and Okon, O.L., 1984, Functional properties of some Nigera Seeds; Casophor Seeds and Three Varieties of some Nigeria seeds; Food Chemistry 33: [26] Andeson, M., 1997, Design of Experiment; American Institute of Physics. The Industrial Physicist Pp 24 [27] Danh, L.T., Mammucari, R., Truong, P. and Toster, N., 2009, RSM Applies to Supercritical Carbondioxide Extraction of Vetiveria Zizaniodes Essential oil; Chemical Engineering Journal, 155: [28] Ruddy, K.2011, Ckecking Assumptions about Residuals in Regression Analysis, The Minitab Blog. [29] NIST/SEMATECH e Handbook of Statistical method,2012. [30 Ejikeme E..M, Egbuna S.O., and Ejikeme P.C.N (2013), optimal Performance of Acid Activated Ngwulangwu clay, International journal of Engineering and innovative technology, pp [31]. Bockish, M., 1998, Fats and s Handbook Pp95 96, Champaign, IL: AOCS Press. [32] Betiku, E., Adepoju, T.F., and Aluko, S.E., 2012, Optimization of oil extraction from Beni Seed (Sesamum Indicum L), Seed using Response Surface methodology, (RSM) and Quality Characterization; Abstract Submitted to 5 th Workshop on Fats and s as Renewable Feedstock for the Industry. [33] Egbuna S. O; Aneke N.A.G; Chime T. O; 2009, Investigation Of The Effects Of Bleaching Clay Particles On The Quality And Stability Of Physically Refined Palm ; Journal of Engineering and Applied Science, Vol 5 P 8 14.