Über den Einfluß von Licht auf den oxydativen Verderb von Speiseölen IV: Abhängigkeit der Oxydationsgeschwindigkeit von der Wellenlänge des eingestrahlten Lichts

Influence of Light on Oxidative Deterioration of Edible Oils IV: Dependence of Rate of Oxidation on Wave-Length of Incident Light A distinct decrease in the rate of oxidation with increasing wave-length is observed for soybean, sunflower and peanut oils when these oils are irradiated with various coloured lights having the same quantum-density. While studying the causes of this behaviour, pure absorption curves for the aforesaid oils were determined. Light of short wave was completely absorbed, whereas long-wave light was barely absorbed to any measurable extent. A considerable increase in quantum yield during oxidation occurs with increasing wave-length. Inspite of this, the oxidation of oils is catalysed most strongly by short-wave light, because the influence of pure absorption exceeds the increase in quantum yield. Pure absorption is therefore considered as the decisive factor with regard to the dependence of photooxidation on wave-length. Finally, the rate of oxidation, as determined in darkness, was found to increase with decreasing wave-length of light used for pre-oxidation of the oil.     

Über den Einfluß von Licht auf den oxydativen Verderb von Speiseölen V: Reaktionskinetik

Influence of Light on the Oxidative Deterioration of Edible Oils V: Kinetics of Reaction A time law for the photochemical oxidation without the decomposition of hydroperoxides has been derived from the radical chain mechanism in the oxidation of edible oils. Quantum yield of the photochemical start reaction and of the chain length can be calculated from the experimental results for soybean oil in the first phase. Using these kinetic values as well as from the quantum yield of the brutto reaction it is proven that the first phase in the autoxidation of soybean oil does not proceed by autocatalysis. Autocatalytic oxidations, e. g. soybean oil in the second phase, sunflower oil, and peanut oil, are discussed on the basis of investigations on the oxidation rate as a function of absorbed quantum current. It is found that owing to the presence of antioxidants, the degree of unsaturation of oils alone is not responsible for the readiness with which the oil is oxidized.     

Über den Einfluß von Licht verschiedener Intensität und Wellenlängenbereiche auf den oxydativen Verderb von Speiseölen II: Versuchsergebnisse und Diskussion

Influence of Light of Varying Intensity and Wavelength on the Oxydative Deterioration of Edible Oils II: Experimental Results and Discussion Since the action of light is a major cause for the deterioration of oils and fats, light-catalyzed oxidation of refined soybean oil was carried out under defined conditions of intensity and wavelength and the quantum yields were calculated. Not only was the intensity of light varied at a constant wavelength but also, in contrast to hitherto known work, the quantum density was held constant at various wavelengths. The photochemical action was dependent on the wavelength and the former increased with decreasing wavelength to a much greater extent than as might have been expected from the energy content of the light quantum.     

Über den Einfluß von Licht verschiedener Intensität und Wellenlängenbereiche Auf den oxydativen Verderb von Speiseölen I

Influence of light of Varying Intensity and Wavelengths on the Oxydative Deterioration of Edible Oils I The basic requirements for the experiments on light exposure are reported in this paper. This involves the use of an apparatus which holds the oil under a constant oxygen pressure and is able to measure very sensitively the amount of consumed oxygen. Furthermore, the equipment required, measuring methods and the basis for calculation are given for an exactly defined exposure.     

Über den oxidativen Verderb bei Pflanzenölen

Oxidative Decay of Vegetable Oil The correlations among the parameters: degustation figure, induction period, oxidation velocity and peroxide value of vegetable oils were investigated. The degustation figure, important for the eating quality, could not be predeterminated by the oxidation velocity or the peroxide value. For most of the examined oils, however, the degustation figure could rather safely be predicted after a certain storage period according to the induction time. Vitamine addition of α-tocopherol acetate does not cause any improvement of the stability.     

Über die Entfernung von Schadstoffen bei der Dämpfung von Speiseölen und -fetten

The Removal of Trace Contaminants from Oils and Fats by Deodorization In the introduction to this topic the importance of the pre-treatment of oils and fats in respect of the removal of trace contaminants is discussed. Deodorization conditions used in practice are defined. The role played by deodorization and distillative neutralization in reducing the content of organochlorine pesticides, polycyclic aromatic hydrocarbons, nitrosamines and solvent residues is discussed in detail. Finally, some comments will be made as to the utilization of deodorizer distillates.     

Über die Bildung von Artefakten bei der Dämpfung von Speiseölen und -fetten

The Formation of Artefacts during Deodorization of Fats and Oils Various artefacts are formed during deodorization of fats and oils. Their amount depends on the process parameters, particularly temperature and time of deodorization. The design of the equipment as well as the fatty acid composition of the fats and oils also have some influence. We investigated the formation of trans-isomers as well as of dimeric or oligomeric triglycerides in various fats and oils of different degree of unsaturation by means of IR-spectrometry and capillary GLC on one hand and by gel permeation chromatography on the other hand. The amount of the formation of artefacts is insignificant up to 240°C. At somewhat higher temperatures the amount clearly increases and in the temperature range 260-270°C a steep increase can be observed. Under process conditions as applied in the industrial practice of to-day objectionable concentrations of artefacts are never formed.     

Über den Einfluß der Schichtdicke und der Oberflächenrauhigkeit auf die Glanzzahl von Wachsfilmen

Influence of the Thickness of Film and the Roughness of Surface on the Degree of Gloss of Wax Films With the help of a developed isotopic method film thicknesses of wax layers on different floorings were measured. The surface roughness was found out by a special apparatus. It could be shown that the degree of gloss of a wax film with respect to the substrate is also a function of film thickness and surface roughness of the substrate and each of the applied films.     

Über den Einfluß der Lagerungsdauer auf die Aktivität des Ni-Katalysators

Storage Time Effect on the Activity of Ni-Catalyst The effect of long-time storage on the activity of Ni-catalyst on carrier passivated with fat was investigated. The catalyst was stored under normal conditions in the air for 5 years. Comparing the rate constants the following results were obtained. The activity of the long-term stored catalyst decreased depending on concentration (0.3-0.1% w/w Ni/oil) 6 to 14 fold for sunflower oil and 8 to 9 fold for olive oil (at the same Ni-level). By calculation of the rate constants of subsequent and parallel reactions it was found that the parallel reaction (linoleic acid → stearic acid) takes part on saturation of linoleic acid at a 13-15% level. The largest effect on activity decrease resulted from autoxidation reactions of the fat applied for passivation.     

Über den Einfluß von Sonnenblumen-Krankheiten auf das Samenöl und auf die Veränderungen der freien Fettsäuren

Influence of Sunflower Diseases on the Seed Oil and on Changes in Free Fatty Acids The relationships between the widespread sunflower diseases like peronospora, botrytis disease, etc. on reduction of yield as well as on the deterioration of the quality of oil were investigated. It can be seen from the results obtained that the damage caused by such diseases can be minimized by suitable measures like dressing of the seeds, appropriate nutrition, proper sequence of planting etc. However, the breeding of resistant varieties remains an important task. Promising results were obtained in this respect by the author on the basis of an artificial infection procedure carried out in pathological breeding grounds.     

Über den Einfluß von Chlorkohlenwasserstoffinsecticiden auf Radikalreaktionen von Methyloleat

Effect of Chlorohydrocarbon-Insecticides on Radical-Reactions of Methyl Oleate Chlorinated hydrocarbons having insecticidal action accelerate the autoxidation of methyl oleate by way of shortening the period of induction phase. Measured on the basis of peroxide-formation, the aforesaid effect increases in the order DDT, DDE, heptachlor and heptachloro epoxide. Apart from the accelerating effect which is common to all the active substances studied, the differences with respect to number and nature of peroxides formed and their further conversion products indicate that the individual chlorohydrocarbons favour certain specific mechanisms in the autoxidation of methyl oleate. In this respect, similar behaviour was exhibited by related substances, such as DDT and DDE on one hand, and heptachlor and heptachloro epoxide on the other.     

Über den Einfluß der Hautoberflächenlipide auf Alkalineutralisationsfähigkeit und Alkaliresistenz der Haut

The Influence of Surface Lipids of Skin on Its Ability Towards Alkali Neutralisation and Its Alkali Resistance On 28 experimental persons, the alkali neutralisation time was determined by the method of Tronnier, and the alkali resistance was measured by the method of Burckhardt. Furthermore, the skin surface lipids were extracted with petroleum ether and determined gravimetrically. The composition of skin-surface lipids was determined by thin-layer chromatography. At short alkali neutralisation time, considerably more skin surface lipids were found than for the long periods. Any additional effect of the composition of skin surface lipids on the ability of skin towards alkali neutralisation could not be detected. No evidence on the significance of skin surface lipids towards alkali resistance was found.     

Über den Einfluß der Grenzflächenspannung auf die Haftfestigkeit

The values of adhesion between four diffrent adhesive,and (i) steel substrates whose surface energy had been altered by adsorption, and (ii) several polymer having different surface energies, had been measured. The results show that the adhesion has a maximum value when the surface energy of the hardened adhesive is equals to that of the substrate, i.e. when the interfacial energy adhesive/substrate is a minimum. The adhesion of the adhesives to the polymer was much smaller than to the steel sprcimens and the dependence of the adhesion onm the interfacial energy was sharper in the case of the polymers. The decrease of the adhesion with increasing interfacial energy was fiund to be greater if the liquid adhesive wets the substrate badly than the steel speciman.     

Berechnung der relativen Lösungsviskosität in Abhängigkeit vom Umsatz und der zugesetzten Reglermenge bei der Polymerisation von Laurinlactam

FLORY'S model for calculating solution viscosities of polyamide-6 is applied in a simplified manner to the polymerization of laurinlactam. According to this simpified model it is possible to calculate the relative solution viscosity of polyamide-12 for any given (high) conversion and concentration of chain regulators. Experimental data are in good agreement with the calculated results.     

Einfluß von Licht und Tocopherolgehalt auf die Oxidationsstabilität von Fettsäuremethylestern

Influence of light and contents of tocopherols on the oxidative stability of fatty acid methyl esters The oxidative stability of different plant oil based fatty acid methyl esters can be estimated by determining the induction period with the active oxygen method. Measuring the volatile and oil soluble acids for a long period preceding the induction period shows that the values are approaching a certain limit. Even if the esters do not differ dramatically in the composition of fatty acids it is a fact that the different production processes influence the amount of tocopherols significantly. The exclusion of light is more crucial than the exclusion of air when storing plant oil based fatty acid esters.     

Über den Einfluß der Knäuelung der Makromoleküle auf den Reaktionsverlauf in Lösung

The theory of Flory is extended to include the polycondensation in solution. The rate of the process is shown to be affected by the reactivity of the functional groups and their accessibility, considered to be the probability of interactions resulting in reactions. The accessibility depends strongly on the degree of coiling of the reactants. Calculations were performed to test the concept of the dependence of the polycondensation in solution on the chain length of the polymer and the nature of the solvent. The activation energy was found to increase with the degree of coiling of the reactants. The model reaction of 2, 2-bis-(p-hydroxyphenyl)propane with phenyl chloroformate and the polycondensation of 2,2-bis-(p-hydroxyphenyl)propane with its bis-chloroformate were investigated in the mixed solvents nitrobenzene/decaline and nitrobenzene/p-dichlorobenzene. With the first solvent the polarity and the dissolving quality decrease with increasing content of decaline. In the second mixture only the polarity changes with the content of dichlorobenzene. The rate of the model reaction is hardly affected by the composition of the solvent mixture. In the polymer system the rate is likewise hardly affected if only the polarity of the solvent mixture is changed. Lower dissolving quality caused differences of the kinetic constants ranging over one order. The results seem to support the theoretical considerations.     

Über den Einfluß synthetischer Tenside auf die Zusammensetzung der Hautoberflächenlipide

Influence of Synthetic Surfactants on the Composition of Skin Surface Lipids Twenty male persons were subjected to bath in a surfactant solution for 15 minutes each on 5 consecutive days. Before beginning and 3 days after the end of the experiment percent free fatty acids and triglycerides of the skin surface lipids were determined by thin-layer chromatography. It could be shown that the aforesaid treatment led to significant reduction of free fatty acids and increase of triglycerides. The significance of these findings on the therapy of Acne vulgaris and Seborrhoea oleosa capitis is discussed.