Deacidification of olive oils by supercritical carbon dioxide

An investigation of the application of supercritical carbon dioxide (SC-CO₂) extraction to the deacidification of olive oils has been made to verify that the nutritional properties of the oil remain unchanged when this technique is applied. Preliminary runs at 20 and 30 MPa in the temperature range of 35–60°C were performed on fatty acids and triglycerides as pure compounds or mixtures, to determine their solubility in SC-CO₂. The solubility data obtained show that CO₂ extracts fatty acids more selectively than triglycerides under specific conditions of temperature and pressure (60°C and 20 MPa). It has been noted that the physical state of the solutes plays an important role in determining the solubility trends as a function of temperature and pressure. Extraction of free fatty acids from olive oil was performed on samples with different free fatty acid (FFA) contents at 20 and 30 MPa and at 40 and 60°C. Experimental data suggest that the selectivity factor for fatty acids is higher than 5 and increases significantly as the fatty acid concentration of the oil decreases. For a FFA content of 2.62%, the selectivity reaches a value of 16. In order to evaluate any variations in the composition, several SC-CO₂ extractions of husk oil with high FFA content (29.3%) were made. The results show that selectivity is still significant (≈5) and the composition in the minor component of the deacidified oil has not changed. On the basis of the experimental results and preliminary process evaluations, the authors conclude that SC-CO₂ extraction could be a suitable technique for the deacidification of olive oils, especially for oils with relatively high FFA (<10%).     

Solubilities of Soybean Oil,Jojoba Oil and Cuticular Wax in Dense Carbon Dioxide

The solubility of jojoba oil in dense carbon dioxide has been investigated by a dynamic method between 100 and 2600 bar and at temperatures within the range 20 to 80° C. The solubility isotherms and isobars of jojoba oil are compared with those of soybean oil. The appearance of solubility maxima was demonstrated for both cases in the high pressure region. The results are discussed and their implications for preparative extraction pointed out. In order to optimize the precipitation conditions a study was made of the solubility of cuticular wax in the low pressure region as a function of temperature and this was compared with the behaviour of typical essential oil components. The available differences can be utilized for an effective preprecipitation of wax from essential oils.     

A comparison between determinations of the solubility of oxygen in oils by exponential dilution and chemical methods

The exponential dilution method has been tested as a rapid means for estimation of the solubility coefficient of oxygen in liquids. The relative standard deviation of the method was 5.7%. The method is not influenced by the presence of peroxides, which interfere with chemical oxygen determinations by ferrous-ferric ion titration. Values ranging from 0.07 to 0.17 were obtained for the coefficient of solubility of oxygen in raw and refined sunflower and soybean oils of different state of oxidation at room temperature.     

The effect of oxygen concentration on oxidative deterioration in heated high-oleic safflower oil

High-oleic safflower oil was heated at 180°C in atmospheres with four levels of oxygen concentration (2, 4, 10, and 20%) modified with nitrogen gas, to assess the effects of atmospheric oxygen concentration on the oxidative deterioration of deep-frying oils. Acid value, carbonyl value, polar materials, linoleic acid, tocopherol contents, and oxidative stability were measured to evaluate the quality of heated oils. These values were found to be correlated with both heating time and oxygen concentration. Acid and carbonyl values and polar material content of oils heated at oxygen concentrations of 2 and 4% were lower than those at 10 or 20%. On the other hand, linoleic acid and tocopherols were hardly reduced in oils after heating for 30 h at 2% O₂, whereas they were decomposed according to the oxygen concentration and heating time. Oxidative stability was well maintained in oils heated at 2 and 4% O₂. These results suggest that the oxidative deterioration of heated higholeic safflower oil depends on oxygen concentration.     

A rapid method for concentrating highly unsaturated fatty acid methyl esters in marine lipids as an aid in their identification by GLC

The selective solubility of unsaturated fatty acid methyl esters in nitromethane at temperatures down to −20C can be used to concentrate highly unsaturated methyl esters. With a typical sample of marine oils methyl esters having an iodine value of 110–190, a concentrate can be ready for GLC analysis in an hour or less and the nitromethane layer can be injected directly for analysis in GLC apparatus with ionization detectors. Examples of the use of the method in the identification of component fatty acids in herring oil are given.     

Effects of Process Variables on the Denaturation of Whey Proteins during Spray Drying

The effects of varying feed concentration (20–40% w/v) and outlet temperature (60 to 120°C) on whey protein denaturation (determined by DSC) and solubility (at pH 4.6) have been investigated in a pilot-scale co-current spray dryer. The study confirms that low outlet gas temperatures (60 and 80°C) produce the lowest amount of denaturation and solubility loss, with almost complete denaturation observed at 120°C along with a less dramatic reduction in solubility. Slightly more denaturation and loss of solubility was found with a 40% feed concentration. It is hypothesized that crust formation, resulting in high particle temperatures while still maintaining a wet core, is likely to lead to high levels of denaturation.     

Effects of Process Variables on the Denaturation of Whey Proteins during Spray Drying

The effects of varying feed concentration (20-40% w/v) and outlet temperature (60 to 120°C) on whey protein denaturation (determined by DSC) and solubility (at pH 4.6) have been investigated in a pilot-scale co-current spray dryer. The study confirms that low outlet gas temperatures (60 and 80°C) produce the lowest amount of denaturation and solubility loss, with almost complete denaturation observed at 120°C along with a less dramatic reduction in solubility. Slightly more denaturation and loss of solubility was found with a 40% feed concentration. It is hypothesized that crust formation, resulting in high particle temperatures while still maintaining a wet core, is likely to lead to high levels of denaturation.     

基于聚丙烯无纺布与耗氧传感器的泄漏乳化油的监测

利用聚丙烯无纺布（polypropylene non-woven fabric,PP NWF）和耗氧传感器结合来构建一个乳化油监测探头。PP NWF是一种超疏水吸油材料,可以快速吸附乳化油污,利用该性能,本监测探头先用PP NWF富集乳化油污,再用探头对材料中的氧含量进行监测,从而达到乳化油监测的目的。本文通过监测不同种类的乳化油（表面活性剂为吐温80的正己烷乳化油、石油醚乳化油、甲苯乳化油及表面活性剂为司班80的正己烷乳化油、石油醚乳化油、甲苯乳化油）来验证其可行性。结果表明：该监测探头可以监测到不同乳化条件下的乳化油,并且能监测到不同种类的乳化油。其中监测甲苯乳化油时响应时间最短,可以在6s内监测到该油污。固定PP NWF时的耗氧传感器探头的最低检测限为1.27g/L,监测效率较未固定PP NWF时提高了近8倍。综上,固定PP NWF的耗氧传感器探头可以作为海洋乳化油监测重要的一个系统,对海洋乳化油泄漏事故进行在线实时监测,可以快速准确提供早期溢油预警。     

Studies on the oxygen uptake of fat emulsions used in intravenous alimentation

The rate of oxidation of various emulsions designed for intravenous use was studied manometrically. Soybean phosphatide dispersions rapidly absorbed oxygen at 38°C. whereas when used in emulsions containing fat with or without additional stabilizing agents, little oxygen was absorbed even when such unsaturated oils as linseed were used. On the other hand, emulsions of oils stabilized with gelatin took up oxygen rapidly, and the finer the size of the fat particles, the more rapidly was oxygen taken up. At 60°C. all rates of oxidation were increased, but the differences between preparations remained. The results are discussed.     

Löslichkeitsverhalten von fetten Ölen in komprimiertem Kohlendioxid im Druckbereich bis 2600 bar

Solubility Behaviour of Fatty Oils in Dense Carbon Dioxide in the Pressure Range up to 2600 bar Different possibilities to determine the phase equilibrium are shown. A dynamic procedure is developed which allows to evaluate solubility data of fatty oils in dense gases. Construction, functioning and handling of the apparatus are described with which the solubility of soybean oil in dense carbon dioxide is examined in the pressure range up to 2600 bar and in a temperature intervall between 25°C and 80°C. The formation of solubility maxima at a interval between 25°C and 80°C. The formation of solubility maxima at a gas density of 1.06 g/cm³ is found out. The facts which influence the solubility behaviour are discussed and the importance of the results for the extraction of oil seeds is given thought.     

Estimation of supercritical fluid-liquid solubility parameter differences for vegetable oils and other liquids from data taken with a stirred autoclave

Fujishiro and Hildebrand developed a procedure for determining the solubility parameter difference between the components of a partially miscible binary mixture, knowing the molar volumes of the components and the composition of each phase. Using this procedure, the solubility parameter differences between supercritical carbon dioxide (SCCO2) and each of three vegetable oils and four hydrogen bonding liquids have been determined. For the vegetable oils the solubility parameter differences at 72 C over the pressure range 5,000–10,000 psi were low, of the order of 2.0, and decreased only slightly with increasing pressure. For the hydrogen-bonding liquids at 52 C, over the same pressure range, the solubility parameter differences were much larger, of the order of 4 to 7 units, and independent of pressure except for ethylene glycol for which the difference increased from 5.7 to 6.7 from 5,000 to 10,000 psi.     

Transport of oxygen and carbon dioxide through polycarbonate membrane

Sorption equilibria and permeation rates for oxygen and carbon dioxide in polycarbonate membrane were measured at different temperature between 30 and 60°C and at pressures up to 2.5 MPa. The pressure dependence of mean permeability coefficient to oxygen obeyed the conventional dual-mode mobility model, whereas that to carbon dioxide followed a modified dual-mode mobility model with concentration-dependent diffusivities, as that of polystyrene to the same gas did.     

Comparison of oxygen bomb method to other methods for measuring oxidative stability of peanuts and peanut products

The active oxygen method of the American Oil Chemists' Society has been used extensively to evaluate the oxidative stability of fats and oils. The AOM lacks versatility, however, in that it can be used for only a few products such as lard and vegetable oils. Experience in our laboratory has shown that results also can differ widely, even on the same sample. Recent work with the oxygen bomb at the National Peanut Research Laboratory has shown that it is both reliable and accurate when compared to other methods for measuring the oxidative stability of peanuts and peanut products. Results with the oxygen bomb were compared to the active oxygen method and iodine value of the peants.     

Reaction conditions for measuring oxidative stability of oils by thermogravimetric analysis

A method for evaluating the oxidative stability of oils based on heating the sample in an oven and periodically testing for weight gain has been known for over 100 years. Thermogravimetric analysis (TGA) with its highly sensitive recording electrobalance turns this simple method into a powerful technique for studying the relative thermooxidative stabilities of oils. This paper explores the potential of an isothermal TGA via evaluation of several freshly processed, unhydrogenated soybean oils. The objective was to define the parameters of the TGA experiment for fast routine measurement and to compare isothermal and dynamic experiments. The consideration of influence of temperature, specific surface area, air flow rate, sample volatilization and nature of the sample pan on the induction period (IP), which is a measure of the oil’s resistance to oxidation, revealed that the temperature and specific surface area are the major parameters that affect the oxidation process. The Arrhenius plot in the range of 80–150 C has shown that the overall activation energy of the oxidation process for three freshly processed oils lies within the range of 21–22 kcal/mole. The rate of oxidation at 150 C is directly proportional to the specific surface area of an oil, suggesting that the rate of oxygen diffusion determines reaction rates at this temperature. A coefficient of variation of the IP better than 2% was found in a routine experiment (10 mg sample, 150 C, 60 ml/min air flow rate, aluminum pan) for typical oils which had an IP range of 25–31 min.     

Impact of oxygen transport properties on the kinetic modeling of polypropylene thermal oxidation. II. Effect of oxygen diffusivity

The kinetic model, established in a previous article (François‐Heude et al., J. Appl. Polym. Sci., in press) to predict the homogeneous oxidation in iPP films typically thinner than 100 µm, is now extended to simulate the oxidation profiles in thicker plates by coupling the oxygen diffusion and its consumption by the chemical reactions. In this perspective, oxygen transport properties (namely oxygen solubility, diffusivity, and permeability) are measured by permeametry on a reference iPP. These values are compared with an exhaustive compilation of literature data to evaluate their variability among the whole iPP family, which one has been reasonably ascribed to initial differences in polymer morphology, but also to evaluate their consistency, especially their temperature dependence between 20 and 140°C. Failing to simulate oxidation profiles, the kinetic model is then used as an inverse resolution method for estimating more satisfactory values of oxygen transport properties. It is thus evidenced that the crystallinity changes induced by thermal oxidation largely explains the dramatic decrease in oxygen penetration toward the sample core just after the induction period. A strategy aimed for introducing the relationship between the polymer crystalline morphology and oxygen transport properties into the kinetic model is given in the graphical abstract, although the effect of polymer polarity remains to be established prior to this implementation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41562.     

The solubilities of seven gases in olive oil with references to theories of transport through the cell membrane

The solubilities of He, Ne, Ar, N₂, O₂, CO and CO₂ in olive oil have been determined in the temperature range 24–56 C. The gas solubility apparatus was a considerably improved version of the one reported by Morrison and Billett and gave a precision, depending on the gas solvent system of ±0.2% to ±1.0%. Plots of log L, the Ostwald coefficient, and log α, the Bunsen coefficient, against 1/TK were linear and showed a small temperature dependence for CO₂. The enthalpy and entropy changes corresponding to the solution process were calculated. The partition coefficients of the gases between olive oil and water were calculated using reported values for the solubility of the gases in water. These results have been used to test and extend the Meyer-Overton theory of transport through the cell membrane. Presented in part at the American Chemical Society Meeting, Miami Beach, April, 1967.     

Untersuchungen zum Abbau von Nickelseifen während der Hydrierung von Rapssamenöl

Investigations of Degradation of Nickel Soaps During Hydrogenation of Rape Seed Oil The presence of free fatty acids in oils that are to be hardened leads generally to Ni-soap formation and has effects on the activity of the Ni-catalyst. In the submitted work first the solubility of the Ni-steatate in vegetable oil was investigated, which increases in a temperature range of 80–200° C of 0.01 to 0.38 mg Ni/g oil. In presence of a Ni-catalyst in the hydrogen reduction milieu Ni-soap is degradated in the first stage to about 80 % on an average. The reaction is reversible and for a Ni-soap content during the limits of solubility the state of equilibrium is adjusted to the average value of 70 %. The hydrogenation is advanced by a small amount of Ni-soap. The dependence of the rate constant on Ni-soap concentration was established.     

Effects of cold stress on rats fed different levels of docosenoic acids

Male Sprague-Dawley rats, 4 weeks old, were subjected to an ambient temperature of 4 C for periods up to 24 days and fed a synthetic diet containing one of the following oils: peanut oil (PO), rapeseed oil (RO), low erucic acid rapeseed oil (LO), and partially hydrogenated marine oil (HO), each at 20% w/w. A parallel experiment using the same oils was performed at room temperature (23 C). During cold stress, animals on the RO diet showed higher mortality than all other groups; all 20 animals in this group died within 5 days. At room temperature, however, all animals survived. The lipid accumulation in the heart reached its peak in all groups after 3 days and then gradually declined. The accumulation was most pronounced in the RO animals and coincided with the high mortality at 4 C. The fatty acid composition of the cardiac triglycerides reflected that of the diet, while the composition of the cardiac lecithin was only marginally modified.     

Low-temperature pyrolysis of sewage sludge and putrescible garbage for fuel oil production

Low-temperature pyrolysis of putrescible garbage (PG) and mixtures of PG with sewage sludge (SS) was investigated with the aim to study the mechanisms and product distribution and to identify optimum process conditions for maximising the fuel oil yield. Experiments were performed in two rotary kiln type reactors in series, where the reaction temperature between 400 and 550 °C and solid retention time of 20 and 60 min were employed. Maximum oil yields were obtained at the highest temperature and lowest time (ca. 550 °C and 20 min) for all the different types of feedstock studied. High temperature and short solid retention time favoured the production of oil while high temperatures and longer retention times reduced the viscosity of the oil. Oils produced from pyrolysis of PG were found to have relatively higher viscosity compared to that from the sewage sludge. The compositions of the different oils were analysed with a GC-MS and ¹³C NMR, enabling the different types of bonds and organic functional groups in the fuel oils to be identified. The species detected in oils from both PG and SS were found to be rich in oxygenated aromatics, however, the arrangement and type of oxygen in the structures were different between the oils. Ash resulting from the combustion of the sewage sludge was also blended into the mixtures of PG and SS to determine the effect of ash on the viscosity of oil and was found to have a significant promoting effect on the oil viscosity.     

The solubility of water in edible oils and fats above 100 C

The solubilities of water in rapeseed and coconut oils have been determined at temperatures between 90 and 160 C. Oil samples were equilibrated with water vapor under conditions of constant temperature and humidity. The equilibrium water content was determined by means of the Karl Fischer titration method. Solubility was found to be independent of the type of oil when expressed in terms of the mole fraction, in agreement with previous work at temperatures below 100 C. An equation is given relating solubility and temperature between 0–250 C.