We reported previously that in oils used for frying by commercial establishments, a high correlation was observed among their Gardner colors, polar compound contents (PC), carbonyl values (CV) and acid values (AV). However, this was not true for frying oils used in hospitals. In the present study, oils that had been used for deep-frying in hospital kitchens were collected and assayed for PC, CV, AV, and Gardner color value to determine the reason for the differences from oil used in commercial establishments. Hospitals were selected so that variation in the number of inpatients, frying oil fatty acid composition, and frying frequency was obtained. As previously observed, we did not find good correlations between the color of the frying oil and the PC, CV or AV, respectively. The extent of oxidation in batches of oil repeatedly used for deep-frying was in the following order: soybean oil > blended oil > canola oil. After use in deep-frying, where the oxygen content goes effectively to zero, allowing the oil to stand at room temperature resulted in the quick and steady absorption of oxygen until it returned to its initial content. In addition to the effect of thermal treatment of oil, standing time between usages is a significantt cause of oxidation.
Two series of lactone-type surfactants with and without a hexyl side chain were prepared by the cyclocondensation of dimethyl alkanedioates with unsaturated diols, such as cis-2-butene-1,4-diol and ricinoleyl alcohol, using a lipase, followed by the addition of hydrophilic 3-mercaptopropionic acid in the presence of triethylamine. The lactone-type surfactants showed clear cmc values and surface tension lowering in aqueous solution irrespective of the hexyl side chain. It was found that the cmc values of lactone-type surfactants were lower than that of typical anionics, e.g., sodium laurate, and the cmc value became lower with increasing size of the lactone ring. The adsorption area at the surface of the aqueous lactone-type surfactant solution was larger when compared to the corresponding non-lactone-type surfactants. Lactone-type surfactants without the hexyl side chain aggregated quickly, forming 3-10 nm micelles; on the other hand, lactone-type surfactants with the hexyl side chain formed significantly larger micelles. This is due to the steric hindrance of the hexyl group on the lactone ring. The solubilization ability of the lactone-type surfactants with a hexyl side chain was superior to those without a hexyl side chain. The lactone-type surfactants showed a high foaming power and low foaming stability. They were also biodegraded by activated sludge.
Petroleum-collecting and dispersing complexes were synthesized on the basis of oleic acid and nitrogen-containing compounds. Surface-active properties (interfacial tension) of the obtained complexes were investigated by stalagmometric method. Petroleum-collecting and dispersing properties of the oleic acid complexes in diluted (5% wt. water or alcoholic solution) and undiluted form have been studied in waters of varying salinity (distilled, fresh and sea waters). Some of physico-chemical indices of the prepared compounds such as solubility, acid and amine numbers as well as electrical conductivity have been determined. The ability of oleic acid complex with ethylenediamine as petro-collecting and dispersing agent towards different types of petroleum has been studied. The influence of thickness and “age” of the petroleum slick on collecting and dispersing capacity of this complex has been clarified. Surface properties studied included critical micelle concentration (CMC), maximum surface excess (Γmax), and minimum surface area (Amin). Free energies of micellization (ΔGomic) and adsorption (ΔGoads) were calculated.
3-hydroxy acids, 3-hydroxy-3,7-dimethyloct-6-enoic acid (1) and 3-hydroxy-2,2,3,7-tetramethyloct-6-enoic acid (2), were prepared from 6-methyl-5-hepten-2-one, and they were subsequently used to prepare (2,6,6-trimethyltetrahydropyran-2-yl)acetic acid (3) and 2-methyl-2-(2,6,6-trimethyltetrahydropyran-2-yl)propanoic acid (4), respectively, via cyclization with an acidic catalyst such as boron trifluoride diethyl etherate or iodine. The reaction of carboxylic acids 3 and 4 with alcohols, including methanol, ethanol, and 1-propanol, produced the corresponding methyl, ethyl, and propyl esters, which all contained a tetrahydropyran ring. Reduction of carboxylic acids 3 and 4 afforded the corresponding alcohols. Subsequent reactions of these alcohols with several acyl chlorides produced novel esters. The alcohols also reacted with methyl iodide and sodium hydride to provide novel ethers. A one-pot cyclization–esterification of 1 to produce esters containing a tetrahydropyran ring, using iodine as a catalyst, was also investigated.
Clove bud essential oil (CEO) and its major individual phenolic constituent eugenol were formulated as nanoparticles in water-based microemulsion systems. The oil titration method was used to incorporate different amounts of the oil and eugenol in the micellar solution of Tween-20. The Antioxidant and antimicrobial activities were evaluated using the DPPH* free radical scavenging assay and the agar disc dilution method, respectively. Results showed that microemulsion improved the evaluated activities of CEO and eugenol compared with the crude counterparts. Individual eugenol microemulsion was more effective than CEO microemulsion which contained only 61.7% eugenol among its constituents. The results of this study could have potential applications in water-based disinfectants, preservation and flavoring of food and in personal hygiene products. It may also have promising applications in the nutraceutical and functional beverage field.
Ordinary fatty acids such as oleic, elaidic and stearic acids exist as their hydrogen-bonded dimers in their liquids and in non-polar solvents. Infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy have revealed that semi-fluorinated (SF) acids containing a perfluorooctyl group (C8F17) as a terminal segment exist also as hydrogen-bonded dimers, which are the units of inter- and intramolecular movements in their liquids and CCl4. The dynamic molecular properties, such as self-diffusion coefficients and intramolecular movements of SF-oleic, SF-elaidic, and SF-stearic acids were compared with those of corresponding ordinary fatty acids (H-acids). From the high equilibrium spreading pressures (ESPs) for SF-acids compared with those for their corresponding H-acids, it was expected that the inter-acyl chain interaction is weaker for the SF-acid than for the H-acid: the SF-fatty acids should have higher molecular mobility than the corresponding ordinary H-acids in the liquid state. However, the self-diffusion coefficients obtained for SF-acids were smaller than those for the corresponding H-acids; the apparent activation energies for the self-diffusion process (translational movement) of SF-acids were larger than those for the corresponding H-acids. Namely, the motion of SF-acid molecules in a liquid phase is rather restricted compared with H-acid in spite of lower inter-acyl chain interaction of SF-acid. This unexpected result suggests that the molecular motion of SF-acid in a liquid phase is not directly governed by inter-acyl interaction, but may be interpreted as a reptation movement of an acid molecule, which is related to intramolecular movement. In fact, low intramolecular movements for SF-acid were confirmed by 13C-NMR T1 measurements.
Cellobiose lipids (CLs) are bolaform glycolipid biosurfactants, which are produced from natural resources by a yeast strain and show fungicidal activity. In this study, the gelation properties of CL in solvents were investigated by several techniques including rheology and atomic force microscopy (AFM). The yeast CL was found to gelate 6 out of 26 solvents. Although it did not provide gels in ethanol or 1, 3-butanediol which are widely used for cosmetic industries, we succeeded in producing gels by mixing ethanol or 1, 3-butanediol with water. AFM observation of the gels on a silicon substrate provided 3D supramolecular structures with an entangled fibrous network. Moreover, it was also found that some of fibrous structures were twisted helical ribbons. This should be due to the cellobiose backbone having several chiral functional groups. The sol-gel phase transition temperatures for gels in mixed ethanol/water and 1, 3-butanediol/water systems were below 100°C, indicating that the gels can be obtained with rather mild preparation conditions. The present CL gels would be useful for novel multifunctional materials applicable to various industries.
Sodium aluminate and its calcinied forms have been evaluated as basic catalysts for the transesterification of waste mutton fat with methanol. The decrease in catalytic activity has been observed with calcinied sodium alumiate. Fat and methanol in 1:29 molar ratio with 1.5 wt.% of sodium aluminate under reflux resulted in 97 % conversion to biodiesel in 1h 20 min. The reaction showed tolerance of additional moisture content of 1 wt.%.