In our previous study on the gas chromatography-mass spectrometry (GC-MS) analysis of thirty diacid triglycerides (triglycerides containing two different acyl groups in the molecule), we showed the ratio of intensities for two fragment ions possessing either of two constitutive acyl moieties of the triglycerides. Calculation of this ratio was carried out on four kinds of specific fragment ions i.e., RCO+, [RCO+74] +, [RCO+115] +, and [RCO+128] +. In this paper, we described the application of these ratios to the correction of fatty acid composition. Such a correction was found to make specific fragment ions of greater use in determining fatty acid composition. In particular, the correction of the fragment ion RCO+ was most effective, for this purpose. The correction of fragments ion [RCO+115] + and [RCO+128] + was less so since they were influenced to a greater degree by complex obstructive fragment ions. The reproducibity of results for the fragment ion [RCO+74] + was not completely sufficient owing to the weakness of the ion intensity.
Glycerol poly (oxyethylene) ether (GPEE) was found to effectively stabilize Candida cylindracea lipase in an aqueous solution (100U/ml) at 50°C. That is, this lipase became thermally stable in the presence of GPEE. Polyoxyethyleneglycol (PEG) and polypropyleneglycol (PPG) were also tested as stabilizing agents of this lipase in an aqueous solution and found to be effective. The relationship between the amount of additives in the lipase solution and their stabilizing extent was complicated. GPEE stabilized the lipase in proportion to its concentration and PEG brought about maximum stabilization at a concentration of 2.5mmol/20ml of solution. But stabilization became progressively less with increasing amount of PEG. Consequently, each additive is considered to have indivisual mechanism for imparting stability to a lipase solution.
The effect of the addition of surface active agents was studied for the direct flame atomic absorption spectrophotometric determination of metals such as cadmium, chromium, copper, lead, and nickel in waste water containing fatty oil. Absorbances of the elements were increased by the addition of oleyl-12, hexadecyltrimethylammonium bromide, Tween-20, sodium dodecylbenzenesulfonate and Brij-35 for emulsifying fatty oil in aqueous solution. The enhancing of absorbance was independent of the type of surface active agents used, but was dependent on the stability of emulsion. It was found that the effective amount of surface active agents was about 0.21.0% region for a sample solution containing less than 10% of fatty oil, but in the case of large content of fatty oil (More than 20%), this method is carried out after diluted with water to a suitable concentration.
The possibility of using polyols as cosurfactants to increase oil solubilization in nonionic surfactant aqueous solutions was investigated. Diols were found to decrease the solubilization of liquid paraffin, but increase that of benzyl acetate, a perfume having a benzene ring. The effects of glycerol, D-sorbitol, and poly (ethylene glycerol), however, were found to be opposite to those shown by diols. Measurement of cloud point, critical micellization concentration (cmc), and interlayer spacing of the lamellar liquid crystalline phase suggested that, while diols form mixed micelles with nonionic surfactants and make the hydrophile-lipophile balance (HLB) inclined to be more hydrophilic, glycerol, D-sorbitol, and poly (ethylene glycol) decrease the affinity between nonionic surfactants and water and caused HLB to take on a more hydrophobic nature. The cmc of docecyl hexa (oxyethylene) ether increased by the addition of diols and poly (ethylene glycol), but decreased on adding D-sorbitol. Glycerol had no significant effect on cmc. The primary soluble position of polyols in micellar aqueous solutions was suggested; i.e. diols dissolve between hydrophilic and lipophilic groups of surfactants, poly (ethylene glycol) in the oxyethylene chain part of micelles, glycerol and D-sorbitol in the water phase.
To establish a standard method for determing solid fat content, the NMR method was tested at six laboratories and the results were examined for collaboration. Two types of instruments, pulse NMR and wide-line NMR were used. Standard deviation in results at six laboratories was less than 1.5 for the step wise method, but more than 1.5 for the rapid method. The standard deviation in results at a single laboratory was much less than either of these cases. No significant difference could be observed in the values obtained using both instruments. Solid fat content values measured for a mixture of fully hydrogenated rapeseed and rapeseed oil agreed well with the percentage of solid by weight.
To establish a method for the detection of sesame oil, three color reactions, Villavecchia, Baudouim and Soltsien method, responsible for the coloration of sesamol were collaboratively examined. These three reactions have long been used as methods for the detection of sesame oil, but the sensitivity and color stability of each of these reactions are studied for the first time in the present research. The Villavecchia method, using hydrochloric acid and furfural as color reagents, was found to be the best among three methods with respect to the sensitivity and stability of coloration.The detection limits for refined and unrefined sesame oil were 1% and 0.5% respectively.