Decolorisation of crude palm oil by acid-activated spent bleaching earth

Regeneration of spent bleaching earth by acid activation and heat treatment has been investigated. Spent bleaching earth was activated by H₂SO₄ of various concentrations (1–40%) and heat treated at 120°C–350°C. The experimental results indicate that treatment of spent bleaching earth with 10% H₂SO₄ at 350°C produced a material which was most effective in removing coloured pigments from crude palm oil. Subsequent experiments were conducted using this particular acid-treated spent bleaching earth. Various parameters which affect the sorption process were studied. They include initial crude palm oil concentration, sorbent dosage and temperature. Applicability of both the Freundlich and Langmuir isotherms to the acid-treated spent bleaching earth–palm oil hexane miscella system indicates that both physiosorption and chemisorption were involved in the sorption process. Measurements of various quality parameters of bleached and crude palm oils were carried out. They include Lovibond Colour index, carotene content, peroxide value, free fatty acid, fatty acid composition and iodine value. The results show that the bleached palm oil retained good oil quality after the decolorisation process using 10% acid-treated spent bleaching earth with a Lovibond Colour of 6·4. © 1998 SCI     

Regeneration of spent earth by wet oxidation

Regeneration of deoiled spent earth by wet oxidation has been investigated. Molecular oxygen was used as an oxidizing agent. Effects of operating parameters such as speed of agitation, temperature, oxygen partial pressure, slurry concentration, and cycle of regeneration have been studied. Kinetics of regeneration was found to be first order with substrate concentration and also with dissolved oxygen concentration. Decolorization capacity of regenerated earth was the same as that of its virgin bleaching earth. Adsorption isotherm data was fitted in Freundlich equation. The values of Freundlich constants of regenerated earth were comparable with the values of virgin bleaching earth.     

Beeinflussung des Bleichprozesses bei Pflanzenölen

Influencing the Bleaching Processes of Vegetable Oils The report describes the influence of the acid-, water- and bleaching earth concentration to the parameters lovibond red, the content of carotene, phosphorus and heavy metals, the peroxid-, the anisidine- and extinction value at 232 nm. As an acid the citric acid has been used in different concentrations. After a bleaching process at 90°C the palm oil was bleached in a heat-bleaching-process at 260°C and a pressure of 1 mbar. The possibility of getting good bleaching with 0.5% bleaching earth by optimizing the bleaching process will be shown.     

Statistical design of experiments of acid activation of smectite clay from Serbia and its bleaching capacity

BACKGROUND: Serbian smectite clay has been activated using a response surface method with central composite design. Because, among the criteria of an edible oil, colour is the most important factor in the commercial value of the oil, and since the colour is due to the presence of pigments such as β‐carotene in the crude oil, acid‐activated clay was used for decolourisation of soybean oil. RESULTS: The effects of five parameters, namely, temperature, time, acid strength, solid/liquid ratio and stirring speed, on the process of acid activation of the clay and its bleaching capacity were determined using a statistical model. The results indicated that all parameters were significant factors in the bleaching capacity of acid‐activated clay, and a quadratic polynomial equation for bleaching capacity was obtained by multiple regression analysis. The optimal bleaching capacity was estimated to be 96.61% for an experimental run under the following conditions: activation temperature 80 °C, HCl concentration 4.78 mol L^?1, stirring speed 450 rpm, solid/liquid ratio 1:4.5 and activation time 2.81 h. CONCLUSIONS: The central composite design, regression analysis and response surface method were effective in identifying the optimal conditions for bleaching capacity of acid‐activated smectite. Copyright © 2008 Society of Chemical Industry     

What to Do with Spent Bleaching Earth? A Review

Animal fats and cold-pressed vegetable oils hardly need bleaching but when vegetable oils started to be produced by solvent extraction, the resulting oils were too dark to sell as such. That also holds for palm oil. Bleaching these oils with bleaching clay solved their color problems but led to the problem of spent earth disposal. Many ways of treating spent earth and ways of disposal have been suggested and/or developed in the past. They will be reviewed in this paper. Given the recent observation that slurrying spent bleaching earth with crude oil inhibits the deterioration of the residual oil in the earth, leads to the conclusion that, for an integrated oil mill-cum-refinery, the best way of spent bleaching earth disposal is the recycling of the earth to the solvent extractor, whereas stand-alone refineries are advised to sell their spent earth to chicken feed manufacturers. In future, a high-temperature hydrolysis process that can treat all kinds of fatty waste may become an attractive means of disposal as well.     

Determination of Raffination of Edible Oils and Fats by Olefinic Degradation Products of Sterols and Squalene,Using Coupled LC-GC

Raffination of edible oils and fats, i.e. bleaching with earth or charcoal as well as deodoration, can be determined by the analysis of dehydroxylation products of sterols and isomerization products of squalene. These olefinic degradation products are isolated from the rest of the oil by LC on silica gel and on-line transfer to GC. Sample preparation consists of preparing a 20% solution of the oil. Nearly half of the “extra virgin” olive oils analyzed contained such products, but concentrations were too low for assuming admixture of regularly refined oils. However, many other oils advertized as non-refined turned out to have been treated beyond declaration.     

Regeneration of spent earth in aqueous medium

A simple method of regeneration of spent earth at a relatively low temperature has been developed. Deoiled spent earth was regenerated in the form of a slurry using water as an aqueous phase, in the temperature range of 170–270°C. The effects of temperature, slurry concentration and cycle of regeneration have been studied. An attempt has been made to discern the controlling mechanism. Regenerated earth from the present method does not impart any malodor to the oil as against theramlly regenerated earth.     

Oil recovery from spent bleaching earth and disposal of the extracted material

Methods for recovering oil from spent bleaching earth are described. Blowing steam and circulating hot water through spent bleaching earth reduce its oil content to only ca. 25% and 20%, respectively. Mixing the cake with milled oilseed may spoil the fresh oil. Hexane extraction of spent earth with hexane is economically feasible for expensive and relatively stable oils only. Because of its simplicity and low cost, extraction with an aqueous solution of soda and salt is economically feasible. The problems with respect to the disposal of the extracted material are discussed.     

Membrane applications and research in the edible oil industry: An assessment

Commercial sources of edible oils and fats include oil-seeds, fruit pulps, animals and fish. Oilseeds processing typically consists of the following steps: i) seed preparation; ii) solvent extraction of flakes and/or extruded collets; iii) desolventization of the meal;iv) recovery of solvent by distillation; and v) degumming, refining, bleaching, and deodorizing of the crude oil. The process consumes large amounts of energy—in the forms of electricity, natural gas and fuel oils—to heat and cool the oil between individual processing steps and to generate high vacuum. Steam requirements for producing edible oil from crude oil range from 2000 to 4000 Btu/lb depending on the type of oil processed. The processing of cottonseed, corn, peanut and soybean oils alone consumes approximately 64.7 trillion Btu/yr of energy in the United States (based on 15.1×10⁹ Ib crude oil processed). Electricity requirements for a typical refinery are between 120,000 kWh and 160,000kWh/yr (based on 1400 to 1800 kWh/22,000 Ib crude oil processed/hr). Current membrane separation research, as applied to miscella distillation; vapor recovery; condensate return; wastewater treatment; degumming, refining, and bleaching; hydrogenation catalyst recovery; oilseed proteins; and nitrogen production, is reviewed in this paper. The greatest potential for energy savings of 15 to 21 trillion Btu/yr exists in replacing or supplementing conventional degumming, refining, and bleaching processes. Decreased oil losses and decreased bleaching earth requirements are other potential advantages of membrane processing. Approximately 2 trillion Btu/yr could be saved using a hybrid membrane system to recover solvents in extraction of crude oils. Although marginal success has been reported to date, the development of hexane-resistant membranes may make this application viable.     

A laboratory study of the bleaching process in stigmasta-3,5-diene concentration in olive oils

The bleaching effect was simulated in pilot plant by measuring the influence of temperature (40, 50, 60, 70, 80, and 90°C), time (5, 10, 15, 20, 25, and 30 min), and concentration of solid adsorbent [1.5 and 8% (w/w) of Tonsil supreme NFF] on stigmasta-3,5-diene (STIG) obtained by dehydration of steroidal compounds. Conditions were chosen to simulate those used in industrial operations. The presence of refined oils in extra virgin olive oil can be detected by these newly formed steroid hydrocarbons. Experimental results indicated that STIG did not exceed an imposed limit of 0.15 mg/kg in extra virgin olive oil, when oils were bleached with 1.5% earth at temperatures ≤80°C for 30 min in admixed to oils sold as virgin. A large proportion of the adulterations were not detectable by the official methods. Color determinations (CIE-1931) chromatic coordinates) were replicated on a refined oil and in admixed extra virgin olive oil. Color of olive oil was not significantly affected by mixing with refined oil (≤20%).     

A spectrophotometric method for the evaluation of vegetable oil colors

Summary A means for evaluating oil color on the basis of an optical density measurement at 500 millimicrons has been proposed. The amount of chlorophyll would be taken into account by present methods or an adaptation of these methods. The advantages of the proposed means of evaluating oil color are that it expresses more exactly the amount of color in the oil, provides a more accurate estimate of color removal during bleaching, and makes possible more exact evaluation of bleaching earth. Data have been presented on the color value (Optical Density × 100) of refined and bleached oils, possible variation in value obtained from different laboratories, estimation of color removed during bleaching, evaluation of bleaching earth, and relationship between color of refined and bleached oils prepared in the laboratory by the Official Method.     

Levels of 15 + 1 EU Priority Polycyclic Aromatic Hydrocarbons in Different Edible Oils Available in the Syrian Market

ABSTRACT

The levels of 15 + 1 EU priority polycyclic aromatic hydrocarbons (15 + 1 EU PAHs) have been determined in different edible oils (extra virgin olive oil, virgin olive oil, sunflower oil, corn oil, and soybean oil) available in the Syrian market. The samples have been prepared by donor–acceptor complex chromatography and subsequently characterized by high-pressure liquid chromatography coupled with fluorescence and ultraviolet detection for quantification purposes. Variable levels of contamination have been found within different kinds of edible oil samples, and only chrysene has been detected in all the studied samples. Moreover, the mean total sum of 15 + 1 EU PAHs has shown variation from 29.8 µg/kg (corn oil) to 63.7 µg/kg (virgin olive oil). A total of 11 samples out of 38 samples (28.9%) have not fulfilled the European Union (EU) food law requirements. Nine samples have exceeded the EU legislation limit of benzo[a]pyrene (BaP) (2 µg/kg) and only two samples have exceeded the EU legislation limit of PAH4 (10 µg/kg) and had acceptable level of BaP. Finally, the mean and maximum dietary exposures of PAHs through consumption of edible oils have been estimated.     

Untersuchungen zur Entölung von Bleicherde mit überkritischem Kohlendioxid

Investigations on De-oiling Bleaching Clay by Supercritical Carbon-Dioxide Refining edible fats and oils, an adsorbent accrues during the bleaching process, which contains oil up to 40% by weight. As disposal of this contaminated material is problematic, it has more and more been taken into consideration to deoil and to recycle the bleaching clay. Up to now, the methods of deposition, extraction with hexane, and scorching have been applied. Our investigations to decontaminate the bleaching clay were carried out by means of high pressure extraction using carbon dioxide as a solvent. For this purpose, bleaching clays from the refinement of rape seed oil and palm oil were investigated. During the CO₂-extraction of the earth, pressure and temperature have been varied and, during the separation process, the number of separation steps in addition. Furthermore the CO₂-mass flow has been altered. Besides of deoiling the bleaching earth as far as possible, the experiments aimed to recover the oil in good quality and to restore an operational bleaching clay. The results of the kinetic investigations revealed that the bleaching clays react differently to variation of the extraction parameters. While it is possible to determine an optimal operating point of the experimental set up for the bleaching clay of palm oil, it is not for the bleaching clay of rape seed oil. The results of the analysis of the extracted oils, palm oil and rape seed oil, are comparably good. The CO₂ extraction delivers a selectively extracted oil. On the contrary, the residual activity of the bleaching clays is a different one, i.e. at most 50% of the activity of fresh bleaching clay.     

Regeneration and Reutilization of Oil-Laden Spent Bleaching Clay via in Situ Transesterification and Calcination

Landfill bound waste from the oil palm industry, spent bleaching clay (SBC) containing significant amounts of adsorbed crude palm oil (CPO) has the potential to be used for biodiesel production. In this study, SBC was subjected to ultrasound-aided in situ transesterification with a co-solvent to convert the oil into methyl esters (biodiesel). Optimized reaction conditions used were 5.4 wt% KOH, methanol to oil mass ratio of 5.9:1 and 1:1 mass ratio of co-solvent (petroleum ether or ethyl methyl ketone) to SBC. The remaining bleaching clay was calcined at 500 °C for 30 min and reutilized for bleaching. Absence of –CH absorption peaks in the FTIR and TGA-FTIR analysis of regenerated clays shows the regeneration efficiency of the method. In situ transesterification and heat regeneration helped to restore pores without adversely affecting the clay structure. The use of ethyl methyl ketone (EMK) as the co-solvent in the in situ transesterification process produced clay with better bleaching qualities.     

Bleaching of Olive Oil by Membrane Filtration

In this study the application of membrane processes for olive oil bleaching is investigated. Olive oil is treated by adding 0.7 wt% of bleaching earth, 0.3 wt% of activated charcoal, and 5% wt% of sodium dodecyl sulfate solution (0.05 m ) and then charged into the membrane cell. Operating conditions including pressure ((2?4) × 10⁵ Pa), temperature (25–45 °C), and stirring rate (100–300 rpm) are optimized. Physico‐chemical properties of membrane bleached oil are evaluated and compared with crude and industrially bleached olive oil. Results show that the filtration conditions for the optimized point are as follows: pressure = 3.7 bar (3.7×10⁵ Pa), temperature = 36.5 °C, and stirring rate = 300 rpm. Under optimum conditions, the amounts of carotenoid and chlorophyll contents are decreased (71.3% and 40.42%, respectively). Acidic and thiobarbituric acid values reduction in membrane‐processed oil (12.42% and 14.46%, respectively) are more than the industrial one. Also, some bioactive compounds such as sterols and phenolic compounds are increased in the membrane‐filtered sample (23.13% and 57.12%, respectively). Practical Applications: Olive oil bleaching is an important step along the refining process. Pigments and minor impurities that reduce olive oil stability are removed in this step. Given the disadvantages of conventional bleaching, alternative methods are introduced. In this study, the effect of membrane filtration on olive oil color is studied. Because of the mild operating conditions, the reduction of clay percentage, as well as the increase of bioactive compounds in optimum conditions, this method has the potential to be a good alternative to conventional bleaching processes.     

Effects of High Temperatures and Duration of Heating on Olive Oil Properties for Food Use and Biodiesel Production

Heating deteriorates the physicochemical properties of a vegetable oil for both edible and biofuel uses. The parameters for edible olive oil are established by European Union regulations and by the International Olive Council. The properties of a vegetable oil to be used as a source for biodiesel production are indicated by the German DIN 51605 for rapeseed oil. Biofuel properties are described by the European EN 14214 and the North American ASTM 6751 standards for biodiesel. It is useful to know how temperature and heating duration influence the physicochemical properties of olive oil. Free acidity, refractive index and myristic acid were not significantly influenced by temperature and heating duration. K232, K266, K270, K274, p-anisidine value, totox index, kinematic viscosity (at 30, 40, 50 °C), estimated higher heating value, relative density, and cetane number increased during olive oil heating. The biological properties: iodine value, oxidative stability index, antiradical (2,2-diphenyl-1-picrylhydrazyl radical, DPPH?) activity, and phenol content, decreased when time and temperature increased. Fatty acid methyl esters were highly influenced by the applied variables. Almost all the fatty acid methyl esters, except myristic, stearic, and arachidic acid esters, were influenced by the combined effect of temperature and time in a very highly significant level. These results show how temperature and duration of heating influence extra virgin olive oil degradation for both edible use and biodiesel production.     

茶油脱色新法研究

在国内茶油的脱色工艺一般为传统的白土脱色,所得油色泽一般为黄色,仅符合一般食用油的要求而难以满足化妆品用油的要求,而且白土脱色工艺中产生的废弃物、废水对环境污染大。本文针对这一情况,采用了一种新型的方法即硅胶柱层析法脱除茶油中的色素,得到了清亮透明无色的茶油并将茶油中油酸的含量提高到了83.63%。     

Recycling and Utilization of Spent Bleaching Earth

Spent bleaching earth was extracted and treated with powerful solvent mixtures. The extracted clays were subsequently conditioned to a moisture content of 10%. The bleaching power of the recovered clays, tested on deacidified soybean oil, was less than 50% of that of the fresh earth. In feeding experiments with chickens it appeared that the fat in spent earth was utilized resonably well.     

Quality of sunflower oil bleached during deodorization

Experiments with sunflower oil show that it is possible under certain conditions to bleach the oil during deodorization. The color of the oil bleached by deodorization is the same as that obtained with bleaching earth. Deodorization at 200 C yielded an oil with transparency at 455 nm of 78~84%. However, to obtain this degree of transparency, processing steps prior to deodorization must be efficient and not yield an oil with high levels of soaps and trace metals. Bleaching during deodorization also has an economic advantage over clay bleaching and deodorization. Data are presented that show the combined process yields an oil with better stability, higher tocopherol content and lower conjugated diene content. Oil processed in this manner has acceptable levels of soap, copper and iron. Sunflower oil with different degrees of oxidation levels has been processed to yield a satisfactory finished product.     

Abtrennung und Extraktion von Bleicherde in geschlossenen Filtern

Separation and Extraction of Bleaching Earth in Closed Filters Application of closed disc filters with centrifugal discharge in filtration and extraction of bleaching earth is described. This type of filter offers advantages, amongst others, those due to exclusion of air and the possibility of extraction of oilcontaining bleaching earth cake “in situ”. Short time interval between starting up and emergence of clear filtrate, and optimum capacities are attained, if pore size of filter membrane is chosen at two to four times the average particle size of solids. Traces of soap contained in the oil have undesirable effect on rate of filtration. It is advantageous to carry out the extraction in two stages, namely, first with dilute miscella, and then with pure solvent. A good quality extracted oil is obtained with hexane as solvent. A combined filtration and extraction plant, attached to an edible fat refinery, consists of 6 filters, each having 20 m² filtration surface. A plant for miscella distillation, and an inert gas plant for generation of protective gas used for compressing, are connected as well. The process is controlled by programmed operation. Filtration capacity of cottonseed oil with 1% bleaching earth with subsequent extraction of filter cake is 340 1/m² · h.