A simplified process for the elimination of the halphen-test response in cottonseed oils

Since certain biological effects have been ascribed to the cyclopropenoids that give a positive response to the Halphen test, processes were explored to eliminate this response from cottonseed oils. Heating alkali-refined, Halphen-positive cottonseed oils in a modified laboratory deodorizer in the presence of cottonseed oil fatty acids, capric acid, citric acid, or phosphoric acid was found to be an effective method of eliminating this response. These treated, Halphen-negative cottonseed oils, the untreated Halphen-positive cottonseed oil, and a corn oil control were incorporated into rations fed to different groups of laying hens. Hens that ingested either the Halphen-negative cottonseed oil or the corn control produced normal eggs, whereas hens fed the Halphen-positive cottonseed oil produced eggs with pink whites, decreased pH of whites, and increased pH of yolks on storage, and lower ratios of oleic acid to stearic acid in the yolk lipids. The simple processes presented—particularly the use of cottonseed oil fatty acids—appear to offer a practical means of inactivating the cyclo-propenoids in cottonseed oil and thus eliminating the biological effects attributed to them. Presented at AOCS Meeting in Houston, 1965. Honorable Mention, Bond Award Competition. So. Utiliz. Res. Dev. Div., ARS, USDA.     

Optimization of Deodorization Design for Four Different Kinds of Vegetable Oil in Industrial Trial to Reduce Thermal Deterioration of Product

Trans fatty acids (TFA) have been shown to be associated with various health disorders. Due to thermal stress, one major source of dietary TFA is high-temperature deodorization of vegetable oils. In this study, precision minimal deodorization was proposed to obtain healthier “zero-TFA” vegetable oils (TFA ≤0.3%). By optimizing temperatures for different deodorizers, dual columns with dual temperatures (DCDT) deodorizers were proposed, transformed, and industrially implemented among dozens of plants. The deodorization temperatures were optimized and customized, respectively, for four kinds of vegetable oil (soybean oil and rapeseed oil: tray column 205 °C and packed column 225 °C, maize oil and sunflower seed oil: tray column 210 °C and packed column 230 °C). Industrial trials showed that all four kinds of oils can achieve “zero-TFA” by DCDT deodorization at the customized mild temperatures, and meanwhile oil physicochemical qualities and shelf-life stabilities were compared with corresponding conventional refining oils. The initial free fatty acid and color were a little higher than that of conventional refining oils, but no significant differences were shown in change trends of these physicochemical indexes during the shelf life, which indicated a good and stable oil quality of “zero-TFA” oils for future industrial productions and sales.     

Laboratory continuous deodorizer for vegetable oils

A laboratory-scale continuous deodorizer, based on a modified Snyder distillation column, was constructed and tested for the deodorization of alkali-refined and bleached vegetable oils. Soybean oil extracted with supercritical carbon dioxide and without further processing also was deodorized to a finished edible oil. Results of taste panel evaluations of the finished oils show that the quality of oils deodorized over a temperature range of 194–260 C is equivalent to commercial salad oils. Oil flow rates are 1 to 2 ml/min, and contact time is about 5 min; a vacuum of 0.5 to 1.0 mm Hg is maintained with countercurrent steam flow of 1 to 5% of the oil weight. Small samples of oil (250–1000 ml) are readily accommodated in this equipment, and the deodorization conditions more nearly simulate commercial practice than do traditional small-scale batch deodorizers. Presented at the AOCS meeting in Philadelphia, PA in May 1985.     

A New Process for the Selective Hydrogenation of Cyclopropenoids in Cottonseed Oil

A new process has been developed, in which the cyclopropenoid groups in cottonseed oil can be selectively and continuously hydrogenated under mild conditions. This process utilizes nickel in a fixed-bed reactor, thereby eliminating the ex-pensive filtration commonly associated with slurry reactors. In pilot-plant runs at essentially atmospheric pressure and at temperatures from 150 to 315P (66-157C), Halphen-negative oils were produced in as short a contact time as 2 min. Little or no hydrogenation or isomerization of normal fatty acids occurred during the process. Reaction rate data indicate that cyclopropenoid removal follows first-order behavior.     

Biological studies with cyclopropenoids inactivated with fatty acids

Cyclopropenoids inactivated by reactingSterculia foetida oil with cottonseed oil fatty acids were fed at three dietary levels to growing rats and laying hens for 4 weeks. At the termination of the experiments, all animals were autopsied and examined microscopically for pathological lesions, but no pathology that could be related to dietary treatment was observed. Hemoglobin, packed cell volume and plasma cholesterol were similar in animals fed all of the diets. Growth rate of rats and egg production of hens fed the experimental diets were similar to those of animals fed the control diet. After 3 and 6 months of storage, eggs from hens fed the inactivated cyclopropenoids were normal and showed no evidence of the unusual characteristics of cyclopropenoid feeding. Lipids of heart, liver and adipose tissues of all the rats and hens varied little from the normal fatty acid composition. Small amounts of three unidentified fatty acids were found in the adipose tissues of rats fed the higher levels of inactivated cyclopropenoids. The results of these feeding studies suggest that inactivation of cyclopropenoids with fatty acids eliminates the unusual biological effects attributable to cyclopropenoids. Presented at the AOCS Meeting, New Orleans, April 1970.     

Deodorizing system modification for heat recovery and steam refining of palm oil

With continuous deodorizers of the double shell type most of the steam normally used to preheat the feedstock in the deaerating section can be saved by a modification-the essential feature of which is the addition of a heat recovery section location between the final deodorizing section and the cooling section, by means of which heat is transferred from the hot deodorized oil to the feedstock. Consistent with the principles of the original design, no pumping or piping of hot oil outside the deodorizer is required. Continuous deodorizers of the stripping tray type can be modified for “steam refining” or “stripping” of high free fatty acid palm oil to reduce the free fatty acid palm oil to reduce the free fatty acids to 0.03% max. This is accomplished by means of additional trays in the stripping sections of the deodorizer. The capacity, sparge steam temperature, vacuum and retention time remain the same as with normal deodorization. Presented at the JOCS-AOCS Joint Meeting, New Orleans, April 1973     

Chemical and physical changes in cottonseed oil during deodorization

The effects of deodorization time and temperature on the physical and chemical properties of cottonseed oil were investigated. Higher temperatures and longer times lead to increases in free fatty acids, peroxide value, viscosity and refractive index while iodine value, unsaponifiable matter and induction period decreased.     

Edible oil deodorization

Deodorization of fats and oils is necessary to remove the disagreeable flavor and odors that are naturally present or created durign processing. Steam stripping of the oils is used to remove these volatile flavor and odor components. This paper discusses the process specifications for deodorization and the mechanical design of edible oil deodorizers.     

Detection of adulteration of cottonseed oil by gas chromatography

To detect adulterant vegetable oils in cottonseed oil, soybean, rapeseed, and ricebran oils were mixed into cottonseed oil extracted experimentally from seeds. These adulterated oils and the component oils were analyzed for sterols, fatty acids, and triglycerides by gas chromatography. In sterol analysis, stigmasterol was determined for adulteration with soybean and ricebran oils. Brassicasterol content seemed to be reliable as the indicator of adulteration for rapeseed oil. In fatty acid analysis, erucic acid for rapeseed oil and linolenic acid for soybean and ricebran oils were proof of adulteration. Triglyceride analysis was not so reliable as sterol analysis for detecting contamination, except that triglycerides with carbon-58, 60, and 62 indicate adulteration with rapeseed oil. Rapeseed oil (5%) and soybean and ricebran oils (10%) were the limits of detection for adulteration in cottonseed oil. Analysis of cottonseed oil from six refineries did not show positive indications of adulteration.     

Deodorization and finished oil handling

Deodorization is the final processing step in the production of edible oil products. Chemical/physical aspects of deodorization and mechanical design of deodorizers are explained, including chemical analysis of feedstock, finished product and by-products. This includes normal operating standards and means of correcting off specification operation. Operating procedures, labor requirements and maintenance are reviewed. Finished oil handling includes use of antioxidants, inert gas addition, pipelines and storage facilities. Emphasis is on the practical operations of deodorization and finished soybean oil handling.     

<Emphasis Type="Italic">Camelina sativa</Emphasis> Oil Deodorization: Balance Between Free Fatty Acids and Color Reduction and Isomerized Byproducts Formation

Camelina sativa oil is characterized by its high content (up to 40 wt%) of α-linolenic acid and its unique flavor. It is considered to have beneficial health properties and is suitable for food and cosmetic uses. In the present study, response surface methodology was used to optimize processing parameters for bench-scale deodorization of camelina oil. The mathematical models generated described the effects of process parameters (temperature, steam flow, time) on several deodorization quality indicators: free fatty acids (FFA), trans fatty acids (TFA), color, and polymerized triglycerides (PTG). These newly established models can be used as a tool to identify optimum deodorization process conditions within chosen constraints. Based on the optimization of minimum retained FFA with the constraint of a maximum allowable TFA, deodorization parameters can be defined. At a constant steam flow rate of 42 ml/h, a temperature range of 210–220 °C, and deodorization time of 70–120 min were defined. 220 °C appears to be a critical upper temperature limit; above this temperature, isomerization rates significantly increase.     

Refining high-free fatty acid wheat germ oil

Wheat germ oil was refined using conventional degumming, neutralization, bleaching, and continuous tray deodorization, and the effects of processing conditions on oil quality were determined. The crude wheat germ oil contained 1,428 ppm phosphorus, 15.7% free fatty acid (FFA), and 2,682 ppm total tocopherol, and had a peroxide value (PV) of 20 meq/kg. Degumming did not appreciably reduce the phosphorus content, whereas neutralization was effective in removing phospholipid. Total tocopherol content did not significantly change during degumming, neutralization, and bleaching. A factorial experimental design of three deodorization tempeatures and three residence times (oil flow rates) was used to determine quality changes during deodorization. High temperatures and long residence times in deodorization produced oils with less FFA, PV, and red color. Deodorization at temperatures up to 250°C for up to 9 min did not significantly reduce tocopherol content, but, at 290°C for 30-min residence time, the tocopherol content was significantly reduced. Good-quality wheat germ oil was produced after modifying standard oil refining procedures.     

Gas-liquid chromatographic analysis of cyclopropenoid fatty acids

A method is described for the analysis of cyclopropenoid fatty acids in oils. The method consists of reacting the methyl esters of the cyclopropenoid fatty acids with silver nitrate in methanol to form ether and ketone derivatives. The derivatives formed from the cyclopropenoid fatty acids are separated from the methyl esters of the normal fatty acids by gas-liquid chromatography on a 15% diethylene glycol succinate column. The method is applicable to oils containing from 0.01% to 100% of cyclopropenoid fatty acids. The derivatives of oils containing lew levels of cyclopropenoids are separated from the normal methyl esters by alumina chromatography prior to gas-liquid chromatography. Studies on the quantitative aspects of the derivative formation, alumina chromatography, and gas-liquid chromatography are reported. Analyses for total cyclopropenoid fatty acid content of cottonseed oil andSterculia foetida oil by the gas-liquid chromatographic and hydrobromic acid titration procedures showed good agreement. Replicate analyses of a sample ofSterculia foetida oil for malvalic and sterculic acid gave coefficients of variation of 6.04% and 1.17%, respectively.     

Purification and deodorization of structured lipids by short path distillation

Purification of structured lipids (SL), produced from lipase‐catalyzed acidolysis of rapeseed oil and capric acid, and deodorization of randomized SL, produced from chemical randomization of fish oil and tricaprin, were studied in a bench‐scale short path distillation (SPD). SL obtained from enzymatic acidolysis usually contain a large proportion of medium‐chain and long‐chain free fatty acids. Two SPD steps have been applied for the removal of free fatty acids. Parameters such as evaporator temperature, feeding flow rate, stirring roller speed, and the content of free fatty acids (FFA) added to the starting materials were optimized with respect to FFA left in the product residuals and to tocopherol loss from the starting oil. Evaporator temperature and flow rate were optimized using response surface methodology and two models were obtained for the FFA content left and loss of tocopherols. An applicable parameter zone was created to obtain a certain FFA (0.5% for example) content. In general, conditions that result in a lower FFA content will lead to a higher loss of tocopherols. In most parts of the parameter zone, 50% loss of tocopherols will be expected. The deodorization study of randomized SL from fish oils and tricaprin indicated that SPD in comparison with batch deodorization gave a product of a poorer sensoric quality.     

Stripping medium requirement in continuous countercurrent deodorization

A mathematical formula was derived that allows the stripping steam requirement of the countercurrent deodorization process to be calculated as a function of system pressure, vapor pressure of the pure volatile compound, initial and final volatiles contents, and the number of transfer units (an equipment parameter) of the countercurrent deodorizer. Just as in batch or cross-flow deodorization systems, the steam requirement in countercurrent systems is proportional to the system pressure and inversely proportional to the vapor pressure of the pure volatile compound. Increasing the number of transfer units (for instance, by increasing column height) to more than two makes the countercurrent system require less steam than cross-flow systems with a vaporization efficiency of 0.6. In addition, the short residence time in a countercurrent deodorization column minimizes side reactions and allows the deodorization temperature to be raised without generating unwanted by-products such as trans-isomers and/or oligomers of unsaturated fatty acids. The increased deodorization temperature increases the vapor pressure of the pure volatiles and leads to further savings in stripping medium and motive steam. Countercurrent deodorization systems therefore require less energy than cross-flow deodorization systems and/or produce oil with fewer unwanted by-products.     

Industrial thin-film deodorization of seed oils with SoftColumnTM technology

Development of thin-film deodorizers started in the 1970ies, and they have been in industrial use since the middle of the 1980ies. The latest type is the SoftColumn^TM, a deodorizer specially developed for mild, low cost processing of seed oils. This deodorizer consists of a structured packing section and a flexible holding section. Regenerative oil heating/cooling and final heating is carried out in external, sparged vacuum heat exchangers, and the design of the heat exchangers leads to superior heat recovery and savings in fuel consumption. This set-up provides major advantages with regard to oil quality, economy, and flexibility. The extremely effective stripping of free fatty acids (FFAs) leads to shorter overall holding times of the oil at elevated temperatures, and steam consumption is cut to a third of the amount required in conventional deodorizers. The product oil has not only low acidity, low colour, good taste and stability, but also low trans fatty acid (TFA) concentrations. By adjusting the stripping steam flow the plant can be optimized both for tocopherol retention or removal. Flexible holding times allow optimization of heat bleaching/TFA formation without compromising on capacity. In this paper product analysis data on tocopherol and trans fatty acids from thin-film deodorizers in industrial operation are shown.     

Effects of physical refining on contents of waxes and fatty alcohols of refined olive oil

Changes in the contents of waxes and fatty alcohols during deodorization/physical refining of bleached olive oil were studied. Experiments were carried out with 1.85% acidity oil, which was physically refined in a discontinuous deodorizer of 250-kg maximum capacity using nitrogen as stripping gas instead of steam. The variables studied were load and temperature of oil in the deodorizer as well as N₂ flow. Analyses of waxes and alcohols were carried out at different operation times. The maximum content of wax was always observed when the oil reached the deodorization temperature. The variation in the wax content depended on temperature and N₂ flow. Wax decomposition started and continued during the operating time, and a progressive decrease, which was pronounced between 3 and 4 h, was observed. Small changes in waxes were observed between 4 and 5 h. Total content of fatty alcohols diminished throughout the operating time, and changes did not depend on the variables studied.     

Degradation products formed from long‐chain PUFA during deodorization of fish oil

Omega‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA) are sensitive to heat and may be destroyed by thermal processes such as deodorization. For example, deodorization of fish oil may induce polymerization, geometrical isomerization and cyclization of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. In this paper, we review our main findings on the effects of deodorization at three different temperatures on semi‐refined fish oil LC‐PUFA. Cyclic structures have been elucidated and mechanisms responsible for ring formation have been discussed. Polymers were found to be the most abundant degradation products formed during fish oil deodorization. A method for quantitative measurement of geometrical isomers of EPA and DHA by gas‐liquid chromatography (GLC) has been developed and validated. Overall assessment of the results obtained with this method suggests that deodorization at temperatures above 180°C affects the quality and the content of LC‐PUFA in fish oil.     

Analysis of cyclopropenoid and cyclopropanoid acids in fats and oils

The analysis of cyclopropenoid acids may be considered, from a historical standpoint, to have started with the discovery of the Halphen test. Although this test as orginally conceived was utilized as a means of detecting adulteration of premium edible oils with cottonseed oil, it has since been shown to be a characteristic test for cyclopropenoid fatty acids and has been adapted with various modifications as a quantitative colorimetric test for these substances. More recently, spectrophotometric methods particularly in the IR region have been applied to the analysis of these substances. The 9.8 μ band, characteristic of the cyclopropane, and the 9.91 μ band, characteristic of the cyclopropene group, as well as the 11.0 μ band, characteristic of some of the noncyclic degradation derivatives, have been utilized. Gasliquid chromatography (GLC) has been applied to the methyl esters of cyclopropanoid and hydrogenated cyclopropenoid acids. The reactivity of the cyclopropene ring toward hydrohalogens has been the basis of several analytical methods developed for use with cyclopropene acid-containing oils. Both aqueous and nonaqueous solutions of hydrohalogens have been employed. The hydrohalogenation methods are the most precise methods currently available for these analyses but only GLC has the inherent potential of identifying the specific cyclopropenoid or cyclopropenoids involved. So. Utiliz. Res. Dev. Div., ARS, USDA.     

Thermal degradation of long‐chain polyunsaturated fatty acids during deodorization of fish oil

Long‐chain polyunsaturated fatty acids (LC‐PUFA) of the n‐3 series, particularly eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid, have specific activities especially in the functionality of the central nervous system. Due to the occurrence of numerous methylene‐interrupted ethylenic double bonds, these fatty acids are very sensitive to air (oxygen) and temperature. Non‐volatile degradation products, which include polymers, cyclic fatty acid monomers (CFAM) and geometrical isomers of EPA and DHA, were evaluated in fish oil samples obtained by deodorization under vacuum of semi‐refined fish oil at 180, 220 and 250 °C. Polymers are the major degradation products generated at high deodorization temperatures, with 19.5% oligomers being formed in oil deodorized at 250 °C. A significant amount of CFAM was produced during deodorization at temperatures above or equal to 220 °C. In fact, 23.9 and 66.3 mg/g of C20 and C22 CFAM were found in samples deodorized at 220 and 250 °C, respectively. Only minor changes were observed in the EPA and DHA trans isomer content and composition after deodorization at 180 °C. At this temperature, the formation of polar compounds and CFAM was also low. However, the oil deodorized at 220 and 250 °C contained 4.2% and 7.6% geometrical isomers, respectively. Even after a deodorization at 250 °C, the majority of geometrical isomers were mono‐ and di‐trans. These results indicate that deodorization of fish oils should be conducted at a maximal temperature of 180 °C. This temperature seems to be lower than the activation energy required for polymerization (intra and inter) and geometrical isomerization.