Removal of waxes from sunflower seed oil by miscella refining and winterization

Miscella refining and winterization produced a sunflower seed salad oil that did not cloud on refrigeration for 7 days. Refining reduced phospholipid content, and this facilitated wax removal during winterization.     

The processing and storage characteristics of glandless cottonseed

Two consecutive storage tests of seven and six-months' duration were conducted to determine the relative effects of adverse storage conditions on glandless and glanded cottonseed and the products derived from each. The moisture conditions during storage resulted in extreme quality deterioration in both glandless and glanded seed. The damage sustained by glandless seed was not substantially different from damage occurring to glanded seed. Neither did glandless seed appear to deteriorate at a faster rate. Normal direct solvent extraction processing methods were followed to process seed for products quality evaluations as measured by nitrogen solubility, epsilon amino free lysine, and gossypol content for meals and FFA, cup refining loss, refined color, bleach color and gossypol content for oils. Oil from glandless seed refined and bleached to lower AOCS colors than corresponding glanded seed oils. Refining losses for oils from damaged seed were slightly higher for glandless seed oils. The meal quality from glandless seed was superior in all categories measured. A laboratory of the Cotton Research Committee of Texas operated by the Texas Engineering Experiment Station.     

Miscella refining

Miscella refining can be practiced as a batch process or, preferably, as a continuous process with oil concentrations through the range of 30–70% by wt of oil. Miscella refining is preferably practiced at the oilseed solvent extraction plant for the economic reason of single solvent recovery system. Three immediate benefits are lower refining loss, lighter colored refined oil, and elimination of water washing. Various types of chemical conditioning, mechanical conditioning, and combinations of both are discussed for miscella refining certain oils. Blends of compatible crude oils can be advantageously miscella refined and, if desired, winterized or hydrogenated to produce oils with unique properties.     

Current practices in continuous cottonseed miscella refining

Miscella refining of crude cottonseed oil has become a generally accepted commercial process for the past 20 years. The simple and efficient continuous process for removal of undesirable impurities is described, having changed little in its basic form since discovery 40 years ago. The individual unit processes, control systems, process flow charts, chemical reactions and oil-to-hexane ratios used in miscella refining are described. The several advantages to miscella refining vs conventional oil refining are noted.     

Color stability of glandless cottonseed oil

The color stability of oil extracted from glandless cottonseed contaminated with various levels of glanded cottonseed was studied. The rate of darkening in bleached color of cottonseed oil during storage was proportional to the original glanded cottonseed or gossypol content in the oil and to time and temperature of storage. Glandless cottonseed with 0–10% glanded seed contamination, as might be expected in commercial production of glandless cotton, yielded oil with equivalent or better color when conventionally refined and bleached after 30 days storage at 25 to 40 C than miscella refined oil from glanded cottonseed. This indicates that new oil mills for extracting glandless cottonseed need not invest in miscella-refining units in order to produce high quality oil.     

Studies on the pigments of some citrus,prune and cucurbit seed oils when processed with or without cottonseed oil

Pigments of citrus, prune and cucurbit fruit seed oils were studied spectrophotometrically. The citrus fruits used were: orange (O), mandarin (M), bitter orange (BO) and lemon (L). The prunes used were apricot (A), peach (P) and plum (PL); while melon (M), watermelon (WM) and Winter squash (S) were the cucurbits. Absorption spectra and Lovibond color were studied for crude, refined and bleached oils. Cottonseed oil (CSO) was mixed with some of the previous oils in the crude state, then refined and bleached. Absorption spectra of the crude fruit seed oils revealed carotenoid pigments at 400, 425, 455 and 480 nm, chlorophyll at 610 and 670 nm and unknown pigments at 525, 570 and 595 nm. Refining did not remove these pigments, whereas bleaching eliminated them completely. In oil mixtures of CSO+A, CSO+M and CSO+S, interference occurred between gossypol ‘360 nm’ from CSO and the pigments of A, M and S seed oils. Refining the oil mixtures removed gossypol, but its effect on carotenoids, chlorophyll and unknown pigments was limited. Bleaching completely removed all these residual pigments. Lovibond color for all bleached oils was very low (0.2–2 yellow). The refined oils, except those containing Winter squash seed oil, were found to have an acceptable color (0.8–15 yellow). Results of the proposed process reveals the possibility of mixing crude edible oil with crude fruit seed oils, then processing the oil mixture by the conventional methods of refining and bleaching.     

Miscella refining test method for the determination of cottonseed oil color

Most of the cottonseed oil mills in the United States have already converted to expander solvent extraction and miscella refining. This practice permits mills to produce and market a consistently light-colored, prime bleachable summer yellow cottonseed oil at reduced cost and refining loss. A laboratory-scale miscella refining test was developed to asses the oil quality in terms of its color. The test involves the addition of 3 parts oleic acid per 100 parts of crude oil in the miscella followed by refining with 2.5 parts NaOH when crude oil contains less than 4.5% free fatty acid (FFA). When crude oil contains FFA between 4.5 and 7.5%, no oleic acid is added prior to refining with 2.5 parts NaOH. When crude oil contains FFA higher than 7.5%, no oleic acid is added and the caustic addition table in American Oil Chemists' Society Method Ca 9a-52 is followed. The test was conducted at room temperature and gave reproducible colors comparable to commercially refined oils.     

Continuous refining of crude cottonseed miscella

A simple, easily controlled process for continuous caustic refining of crude cottonseed miscella in a two-stage system is described. The effect of crude oil quality, oil: hexane ratios, temp, mixing conditions and chemical treatment are noted. The chemical reactions in the process are followed microscopically. The process yields a refined oil of less than: 1.0 bleach oil color, 0.03% free fatty acid and 15 ppm soap, and with 30~40% oil savings over Official Cup Loss. The by-product soap may be used advantageously in the meal from the extractor unit. Presented at the AOCS Meeting in Minneapolis, 1963.     

Characterization and processing of cottonseed oil obtained by extraction with supercritical carbon dioxide

Extraction of flaked cottonseed with supercritical carbon dioxide at temperatures of 50–80 C and pressures of 8,000–15,000 psi yields an improved crude cottonseed oil compared to those obtained by conventional solvent or expeller processes. Improvements include lighter initial color, less refining loss and lighter refined bleached colors. Crude cottonseed oils obtained by supercritical fluid extraction require less refining lye and show less tendency to undergo color fixation while in storage. Presented at the AOCS annual meeting, Chicago, May 1983.     

Refining crude cottonseed oil dissolved in hexane

Measurements were made of the surface tensions of mixtures of cottonseed oil and hexane and of their interfacial tensions against water and caustic soda solutions. Attempts were made to study the reaction rate between the two phases. The results show that in caustic refining of hexane miscellas the caustic is readily dispersed into the oil-hexane phase. Refining losses were found to be lower for miscellas containing less than 70% oil. Concentrations as low as 40% were refined successfully. The losses were inversely related to the viscosity of the solution. Sponsored by the Texas Engineering Experiment Station and the Cotton Research Committee of Texas, College Station, Texas.     

A comparative study of batch and continuous refining of cottonseed oil in the Sudan

This study is concerned with a comparison of some technical aspects regarding batch vs continuous refining (centrifugal alkali refining) of crude cottonseed oil. Implication of processing modes of operation were examined in light of their effect on the following performance criteria: (a) percentage of refining loss as a function of the initial crude-oil free fatty acid (FFA) content: (b) refined oil color as a function of initial crude-oil FFA: (c) caustic soda consumption as a function of initial crude-oil FFA: (d) bleachability characteristics of refined oil. The study shows, in quantitative terms, that continuous refining of cottonseed oil is more efficient in each of these performance criteria, particularly the percentage of refining loss.     

Refining cottonseed oil at high rates of shear

Summary Ten crude cottonseed oils obtained from different areas in the South and Southwest were refined with and without the use of high-shear agitation in the step involving the initial mixing of the crude oil and caustic soda solution. In each instance the use of high shear produced a lower color in the refined oil. The improvement with some oils was not marked because they either refined very well by the ordinary method or failed for some unexplained reason to respond readily to high-shear mixing. However a good proportion of the oils which were quite dark after refining by the ordinary method refined to a much lighter oil when high shear was used. It was established that in high shear refining the color of the refined oil decreased as the temperature at which high shear was used decreased, the time at high shear increased, and the rate at which shear was applied increased. However an increase in the latter above a certain value had no effect. Also it was found that the color of the refined oil decreased as the amount and strength of the caustic soda solution increased. Absorption spectra of some of the processed oils indicated that high shear was more effective than ordinary mixing in removing from an oil the gossypol-like and carotenoid color bodies. Presented at the 28th fall meeting of The American Oil Chemists’ Society, Minneapolis, Minn., Oct. 11–13, 1954. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

A rapid alkali-wash method of refining cottonseed oil for refined color determination

Summary A very simple, rapid, reproducible method of refining crude cottonseed oils, for refined color measurement, has been developed. The results can be used to predict the colors of these oils when refined by the American Oil Chemists' Society Cup Method. The method has the advantages of rapidity and use of simple equipment and techniques and requires only small quantities of oil. Furthermore variations in results because of the amount and strength of lye and of “break” are not encountered since uniform conditions are employed. Because the method is used when it is desired to measure refined color without determining refining loss, it is not a substitute for the official cup refining method. The oil color research described in this paper was conducted as a cooperative project of the Texas Engineering Experiment Station and the Cotton Research Committee of Texas.     

The purification of edible oils and fats

Originally, oils were not refined but with the introduction of solvent extraction, refining became necessary. Crude cottonseed oil was refined by treating the oil with caustic soda and the same process was used for all other oils that needed refining. The subsequent introduction of centrifugal separators converted the original batch process into a continuous process. Degumming was introduced to obtain lecithin but limited to soya bean oil. Physical refining was introduced for high acidity oils like palm oil after the oil had been degummed to low residual phosphorus levels in the dry degumming process, in which the oil is first of all treated with an acid and then with bleaching earth. In Europe, further degumming processes were developed that allowed seed oil to be physically refined and later phospholipase enzymes were introduced to reduce oil retention by the gums and improve oil yield. Given these various oil purification processes, the refiner must decide which process to use for which oil in which circumstances. The paper provides a survey of what to do and when. It also discusses several topics that require further investigation and development.     

Digestibility and nutritional value of crude oil from three amaranth species

Oils from a selection ofAmaranthus caudatus, A. hypochondriacus andA. cruentus were extracted with hexane. The crude oils were analyzed for acid value, saponification and iodine number, and were included in basal casein diets for rat studies at 5 and 10% levels to replace equal amounts of refined cottonseed oil. The oils fromA. cruentus andA. hypochondriacus were similar in the oil properties studied and different fromA. caudatus. At either 5 or 10% food intake levels, weight gain and PER were not statistically different from values reported for cottonseed oil. True digestibility of amaranth oil was lower than that of cottonseed oil.A. cruentus oil gave the lowest digestibility. Oil levels induced statistical differences in food intake and digestibility. Oils fromA. caudatus, A. hypochondriacus and cottonseed induced similar serum cholesterol levels, while oil fromA. cruentus gave statistically higher values. Hemoglobin, hematocrit and serum proteins were similar among all groups. Microscopic analysis of the organs of the rats revealed some changes that were also found in cottonseed oil-fed rats. It was concluded that crude amaranth oil has lower digestibility than cottonseed oil, but that it is not responsible for growth-depressing effects when the seed is fed raw as compared to processed materials.     

Gaseous ammonia as a refining agent for cottonseed oils

In this investigation the application of gaseous ammonia to cottonseed oil refining was explored. The ammonia reacted quantitatively with the free fatty acids in the oil; its solubility in coftonseed oil was determined as a function of pressure. In “degumming” it was more efficient in removing phosphatides than other agents. A reduction in refining loss resulted for oils refined with gaseous ammonia as outlined and compared with the standard AOCS cup loss analysis. However, the oil colors were substantially higher even though the ammonia treated oils were re-refined with caustic solution. Results using cottonseed oil-hexane “miscellas” containing less than 70% oil showed low refining losses, but the colors were estremely high. Above 70% oil content the losses were higher, but the colors were lower. The colors never equalled “standard cup” results. This study was sponsored by the Texas Engineering Experiment Station and the Cotton Research Committee of Texas.     

Chemistry of refining

Processing practices are reviewed, discussing the chemistry involved. Refining is a process of purification. Both the individual unit operations and the whole integrated process are considered. Efficiency of the physical and the alkaline refining procedures as practiced in Malaysia are compared. Palm oil is unique in being a fruit flesh oil and not a seed oil. The crude oil is produced at the oil mill by cooking, pressing and clarification. Quality of the crude affects the efficiency of refining and thus the quality of the fully processed product. Moreover, after fractionation problems can arise in refining of crude stearin. Recent research into the nature of the minor and trace constituents of crude palm oil is described. Their partition during fractionation and removal during the purification process of refining are important. Some chemical artifacts that can be formed during processing are discussed. Certain findings of the research laboratory are confirmed by actual commercial operations. Unique product specifications mean that both feedstock quality and refinery operation need to be controlled. Efficient optimization of processing requires a better understanding of the chemistry involved. Alternative purification procedures specifically relevant to palm oil are being investigated in the laboratory.     

Alternative hydrocarbon solvents for cottonseed extraction: Plant trials

Hexane has been used for decades to extract oil from cottonseed and is still the solvent of choice for the edible-oil industry. Due to increased regulations as a result of the 1990 Clean Air Act and potential health risks, the edible-oil extraction industry urgently needs an alternate hydrocarbon solvent to replace hexane. Based on laboratory-scale extraction tests, two hydrocarbon solvents, heptane and isohexane, were recommended as potential replacements for hexane. A cottonseed processing mill with a 270 MT/day (300 tons/day) capacity agreed to test both solvents with their expander-solvent process. Extraction efficiencies of isohexane and heptane, judged by extraction time and residual oil in meal, refined and bleached color of miscella refined oil, and solvent loss, were comparable to that of hexane. However, fewer problems were encountered with the lower-boiling isohexane than with the higher-boiling heptane. With isohexane, the daily throughput increased more than 20%, and natural gas consumption decreased more than 40% as compared to hexane.     

Effect of different methods of disintegration of cottonseed on some properties of the crude oil with special reference to high moisture seed

Summary Both the expeller and hydraulic types of mills are used for crushing high moisture seed in the northeastern section of North Carolina. The quality of crude oil from the hydraulic mill is decidedly better than crude oil from the expeller mill, when the seed are comparable and as the moisture content of the seed increases the difference in quality of crude oil from the two types of mill is progressively greater in favor of the hydraulic mill. The disintegration of cottonseed meats in the food chopper, used for the free fatty acid determination in cottonseed, and the expeller mill have a very similar effect on the color of the oil. Apparently the effect of expelling also causes an increase in free fatty acids and refining loss, especially when working high moisture seed. A Paper Presented at the 26th Annual Meeting of the American Oil Chemists’ Society at Memphis, Tenn, May 23–24, 1935     

Variation in the F. F. A. content of cottonseed within a sample

Collaborators on F.F.A. in cottonseed vary more than they do on F.F.A. in cottonseed oil. It was suspected that this variance was due to the variance in F.F.A. in the seed in a sample. This work reports on the variance in the seed in two cottonseed oil samples as determined by Edeler's micro-method. It is concluded that the collaborators' discrepancies are not all explainable on the basis of variance in seed.