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.     

Zum Einfluß von Antioxidantien natürlichen Ursprungs auf die Stabilität von Linolsäuremethylester in Modellsystemen

The Effect of Natural Antioxidants on the Stability of Methyl Linoleate in Model Systems This paper presents a model system based on linoleic acid methylester on potato starch which allows to estimate the antioxidative effects of certain additives in oxygen-sensitive foods of low lipid content. It is shown that a tocopherol mixture from natural sources (Covi-Ox T70) and an extract from rosemary (RM) were much more effective than the conventional ascorbyl palmitate (AP). So concentrations of 2 ppm Covi-Ox T70 or 20 ppm RM, respectively, were more effective than 200 ppm AP. Reducing intermediates of the Maillard reaction (Amadori compounds) do not show antioxidative effects in all cases; in our investigations only fructose-γ-aminobutyric acid and fructosearginine were able to retard linoleic acid oxidation to some extent; however, in the latter case, the free amino acid showed a similar effect. The antioxidative effect of the different additives tested is due to their radical scavenging character; only AP was able to reduce the hydroperoxides arising from autoxidation processes to the corresponding hydroxy compounds which cannot be decomposed to rancid products anymore.     

Einfluß von Futterfetten auf die Qualität tierischer Veredlungsprodukte

Effects of Feed Fats on Quality of Animal Product At the same level of energy supply intake of fats/oils do not lead to a higher fat deposition in the carcass. Additionally, fats are carrier of fat soluble vitamins A, D, E, K and improve their absorption from the intestinal tract. The fatty acid profile of fat deposited in the organism, as for example in egg yolk is influenced by the intake of fatty acids provided by feed. This especially concerns linoleic- and linolenic acid as well as lauric- and myristic acid, High contents of polyunsaturated fatty acids negatively influence oxidative stability as well as consistency of body fat and therefore quality of animal products. An improved oxidation protection can be carried out by supplementation of antioxidants. Medium-chain, saturated fatty acids reveal positive effects on both criteria.     

Zusammenfassung von Versuchen über die Wirkung bestimmter Futterkomponenten auf die Stabilität der Milch und des Schweinespecks

Summary of Investigations Concerning the Effect of Certain Feed Components on Stability of Milk and Bacon Even if lipidoxidations in metabolism are necessary, on spontaneously running autoxidations in the body must be kept a close watch. In animal products oxidative damages can occur as a consequence and simultaneously sensoric changes. Finally men will have advantages and disadvantages of the stability or instability of food. The effect of feed on milk and bacon quality has been investigated in a series of feeding trials. Oxidation of milk leads to a taste of oxidation or metallic savour. Oxidation of bacon causes because of getting rancid a shorter stability, which can be tested by an acceleration of the oxidative progress in laboratory. An extrapolation of the results in milk and bacon should be carefully transferred to the oxidation of the cell membrane. Investigations of cows and pigs have demonstrated that the unsaturated fat of the feed diminishes the stability of the animal products. Antioxidants, having been taken up, and vitamin E improve them facing the oxidations in milk and bacon. Hardened fish oil, added to the feed, had a favourable effect on milk and bacon stability as on the savour. Mineral substances, fed to animals, had no significantly oxidative effect. Additions of copper showed that the fat in the porc liver was of greater stability against oxidation. An addition of molybdenum did not change the activity of xanthineoxidase in milk either. This enzyme had an activity which correlated with the antioxidative properties of milk.     

Verwendung von Futterfetten in der Tierernährung sowie ihr Einfluß auf die Qualität der Schlachtkörper

Use of Feed Fats for Animal Nutrition and their Influence on the Quality of the Slaughtered Bodies For about 40 years fats have become an important feed component in rations of agricultural working animals. An increase of fat use in compound feed up to forty times was noted in the period from 1955 to 1984. But still today there are signs of uncertainty concerning quality assessment and selection of fats for feeding the various working animals. Today the quality of feed fats can be determined by analysis methods which enable a relatively quick assessment. Unfortunately there is no official control so that at last the compound feed factories have to fulfil this task. As fats have in comparison to carbohydrates an energy value which is 2.3 times higher, the energy amount of the compound feed increases by their addition. Thus the improved genetic ability of putting on weight of the working animals can completely be made use of. A greater fattiness of slaughtered bodies is not caused by fat addition in balanced rations. Because of their variety of different fatty acids and above all by their differences in the consistency and oxidation stability fats are of great influence on the performance of the animals and their slaughtered body quality. Depending on the content of polyenic acids and their oxidation degree lower increases of weight and damages in the organism are possible. High amounts of multiple unsaturated fatty acids cause a worse fat consistency in the slaughtered body and the from that produced products. Furthermore the suitability for storage declines by the lacking stability of the polymeres. Higher additions of vitamin E, Selenium or also of technical antioxidants show positive effects.     

Analyse von Ablagerungen auf Werkzeugoberflächen (Plate-out) bei der Extrusion von PVC

An analytical method to determine the composition of the plate out on different tool parts during PVC extrusion is described. The method was developed by the initial compound of a formulation causing plate out. The single components were separated by solvent extraction of the materials with tetrahydrofurane (THF). The parts insoluble in THF (TiO₂, CaCO₃, etc.) were determined gravimetrically and the single components were identified by chemical and spectroscopic methods (atomicabsorption spectroscopy, X-ray fluorescence, mass spectroscopy). The soluble parts (PVC, plasticizer, lubricant, etc.) were identified by gel permeation chromatography and determined quantitatively by NMR-spectroscopy.     

Über den katalytischen Einfluß von Hämin und Hämoproteiden auf die Oxydation von Polyensäuren

Catalytic Influence of Haemin and Haemoproteids in the Oxidation of Polyenoic Acids In alkaline solution, the oxidation of linoleic acid catalysed by haemin proceeds as a first order reaction. Deviations from ideal form of equation for the reaction occur due to colloidal state of linoleic acid. Also in neutral region, the catalytic reaction proceeds as a first-order reaction with reference to surface-concentration of linoleic acid. Thereby, an inhibition is caused by the product of reaction. The catalysis is not specific for cis- or trans double bonds. On the other hand, haemin is catalytically ineffective in the oxidation of conjugated acids. Hence it is assumed that catalytic oxidation does not proceed as a chain reaction. Instead of this, by an electromeric effect absorbed haemin displaces the double bonds of linoleic acid towards conjugation and thus enables addition of oxygen.     

Wäßrige Stoffsysteme zur Absorption von SO2

Aqueous absorbents for absorption of SO₂. The removal of SO₂ from flue gases is dominated by processes of absorption with aqueous absorbents. Aqueous systems are favourable in contrast to organic absorbents because the water vapour contained in the flue gas does not interfere with the separation. The transport of gaseous SO₂ into the liquid phase and the subsequent transformation into sulfite/bisulfite or sulfate after oxidation is typical for the aqueous processes of absorption. Starting from water as absorbent the addition of various basic agents makes an increase in the absorption capacity of the washing solution possible by several orders. Different solubilities of the agents or the resulting compounds, the dependence of the vapour pressure on the concentration and desired and undesired reactions determine the thermodynamics of the processes. The regenerative sodium salt processes as the Wellman-Lord (sodium sulfite) process, the Flakt-Boliden (sodium citrate) process and the sodium phosphate process, the regenerative ammonium sulfite process, the processes producing gypsum and the absorption with oxidation to sulfuric acid are noted. The advantages and limitations of the particular processes are pointed out by means of the vapour liquid equilibria, the solubilities of the salts and the oxidation reactions.     

Die Bedeutung von Antioxidantien in der Ernährung

Significance of Antioxidants in Nutrition Optimal nutrition of livestock and profitable animal production are not possible without approved additives of antioxidants established in feedstuffs regulation for a long time. A deficiency of vitamin E and selenium furthermore lead to suboptimal performances and also to diseases. A frequently supplementation of vegetable oil in pig and poultry feed with high contents of linoleic and linolenic acid will lead to high accumulation of these fatty acids in body fat. Consequently the oxidation stability decreases which can be improved decisively by tocopherols. Supplementation of vitamin E and selenium with a maximum level of 500 μg/kg feed combined with an accumulation in animal foodstuffs is important to human requirements of these essential agents. Compared to animal nutrition the recommendations for human requirements (DGE) of both antioxidants are to low. 12 mg tocopherol and 20 to 100 μg selenium are deficient to react on different processes of oxidation in human organism. A considerably improved vitamin E and selenium supply can not be covered by normal food intake. Therefore the use of concentrates is more efficient like in animal nutrition. This type of prophylaxe should be more applicated in health providence. Not only a high life expectancy should be achieved but also a good health condition within this life time.     

Zur antioxidativen Wirkung ausgewählter Tocochromanole auf die Stabilität von Sonnenblumenöl

Antioxidative Efficiency of Selected Tocochromanols on Oxidation-Stability of Sunflower Oil The tocopherols (T) α-T, γ-T, δ-T as well as ascorbylpalmitate (AP) were added in varied combinations to a sunflower-oil of which the natural tocopherol-content was known. In order to study the effect of the added tocopherols on the oxidation-stability of the oil, the different induction times have been measured under standard conditions. The investigation was planned along the “Response Surface Method”. The raw data of induction time measurement were treated by the SAS-program for multiple regression analysis. The optimized regression function first was examined by variance analysis for sufficient degree of adaption and then used to plot a 3-D response surface of the experimental results. The “Two-factor Response Surface Designs” are convenient to find the best combination of the 4 given factors for optimizing the oxidation stability of the edible oil.     

Hochselektive pH-Festkontakt-Sensoren auf der Basis von Protonen-Carrier-PVC-Membranen mit polymeren Weichmachern

Highly Selective pH-Solid-State-Sensors Based on Proton-Carrier-PVC-Membranes with Polymeric Plasticizers Basing on membrane chemical experiments, the systematic development of a highly selective proton carrier PVC membrance for solid state contact sensors with trioctylamine as ligand and a phthalic acid polyester as polymeric plasticizer is described. Its resistance to saponification leads, compared to monomeric plasticizers, to higher stability of measured values of alkaline solutions. The incorporation of lipophilic anions is indispensable for the repulsion of elements of negative charge. The membrane systems' selectivity is strongly influenced by the ligand's exolipophilic periphery. Several membrane systems attractive for analysis are specified.     

Stabilität von Dispersionen

Stability of Dispersions The importance of production and application of disperse systems in the industry is steadily growing. On the other site colloidale systems surround us every day (for example foodstuffs, pharmaceutica, and so on). With the knowledge about the mechanism of interaction forces we are able to develope new materials and improve available systems. The stability of such systems is one of the central point of research. One of the well known physical models of colloid stability is given by DLVO‐Theory. With this theory we have a tool to influence the stability of such dispersion systems. In this paper electrokinetic methods are used to investigate interaction forces in disperse systems. The influence of pH‐value, electrolyte concentration, and valency is shown. But, not in all cases the DLVO‐model works satisfactoryly. Some reasons of this behavior will be discussed.     

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.     

Struktur-Aktivitäts/Selektivitäts-Beziehungen von Oxidationskatalysatoren

Structure-Activity/Selectivity Correlation of Oxidation Catalysts Various reactive forms of oxygen are active in the selective oxygen functionalization of olefins and aromatic compounds. These forms are different on different crystal faces of transition metal oxides as shown by their different cation-oxygen bond lengths. Therefore, face specifity of transition metal oxides as catalysts can be expected for the selective oxidation of hydrocarbons. Furthermore, the reactivity of the framework oxygen in the transition metal oxides for selective oxygen functionalization of hydrocarbons is dependent on the nature of the catalytic cycle (one- or two-electron-processes). Therefore, structure sensitivity of oxidation catalysts on the selectivity of transition metal oxides as oxidation catalysts is possible. Starting from this concept the following phenomena of the activity/selectivity relations are discussed for the most important industrial oxidation catalysts:

• —ensemble effects on the selectivity of supported Ag catalysts for the oxidation of ethylene to ethylenoxide.
• —face specifity of multicomponent Bi/Mo-oxide catalysts in the selective oxidation of propylene to acrolein and in the ammoxidation of propylene.
• —structure sensitivity of V₂O₅-containing catalysts in the oxidation of aromatic compounds.

     

Qualitätsaspekte von Palmöl

Quality Aspects of Palm Oil The quality of crude palm oil of different origins is surveyed. The influence of transport and storage conditions on the hydrolytic and oxidative deterioration is discussed. The effect of the crude oil quality on the quality parameters of the refined oil is demonstrated on the basis of colour, stability towards oxidation and keepability in general. Some of this correlations are shown graphically.     

Zur optimierung der Polymerfraktionierung auf der Grundlage von Lösungsgleichgewichten in Lösungsmittel-Fällungsmittel-Systemen

The phase separation behavior of dilute polydisperse polymer solutions primarily depends on the partial concentration of each polymer component. So the equilibrium data obtained by turbidimetric titration with “calibration” fractions and their mixtures can be used for the construction of a solubility diagram (Claesson-diagram) which generally allows to describe fractionation processes. It can be shown that the characteristic features of precipitation fractionations can well be derived from the solubility diagram. This diagram then offers the possibility for a complete discussion of parameter variation (concentration, step of γ-variation, process-scheme, temperature, solvent/nonsolvent-system) on the efficiency of a fractionation step. On one hand these results correspond – as for the concentration variation – to well known experimentell experiences. On the other hand it is possible for the first time to give definite predictions for the influence of temperature and the solvent/nonsolvent system. The temperature selection can be shown to be inconsiderable for the separation effect. The usual characterization of solvents and nonsolvents as “good” or “poor” is absolutely insufficient, if not misleading, for there is no connection between these properties and the shape of the solubility diagram. Based on the analysis of the single parameters the optimum conditions for the preparation of narrow preparation of narrow precipitation fractions can be derived.     

Einfluß von gleitmitteln auf die rheologischen eigenschaften von PVC-mischungen

The significance of lubricants is emphasized by the growing number of publications on this field. However, most of the authors compare the effect of the different lubricant types at the same concentration. But the rightness of this kind of comparison is questionable because the rheological characteristics of PVC compounds change sharply at the compatibility. Relatively little attention is paid to the processes taking place before the forming of the melt phase (powder blending) during PVC processing as well. From the results of the measurements made on a capillary viscosimeter and on a Brabender-plastograph the conclusion can be drawn that the comparison of lubricants is better in the same state (at the compatibility) than at the same concentration. The processes taking place in the mixing head of a Brabender-plastograph can be divided into three stages (powderblending, fusion, melt flow) and these are influenced differently by lubricants. The results of the measurements made on the capillary viscosimeter and the plastograph show a very good agreement in the melt flow state in view of lubricant effectivity.     

Einfluß von Bestandteilen der Raffinationsfettsäuren für Geflügel auf die Mastleistung von Broilern

Influence of Acid Oil Components on Broiler Performance The German feedingstuffs regulations (FMV) only feature limited quality criteria for acid oils to be used in poultry, i.e. inorganic acids, impurities insoluble in petrol ether and unsaponifiable matter. Producers of these products and the trade have generally tended to include further quality criteria into their specifications, such as oxidation characteristics, the content of linoleic and linolenic acid and a guaranteed absence of castor oil, dark cotton seed oil and crude marine oils. To avoid the use of products which do not correspond to the definition of the FMV for acid oils and which might have dilaterious effects on poultry, more attention should be paid especially to the content of polymers arising e. g. from distillation residues and used fried fats. The influence of unsaponifiable matter and polymerized fatty acids in acid oils on the growth performance of broilers, as determined in trials with male birds and accompanying analytical investigations, is described. Footing on these results, proposals are made to extend the specifications for feeding oils to be used in poultry compounds.     

Über den Druckeinfluß auf die Katalysierte Flüssigphasenoxidation von cis- und trans-Oct-4-en

About the Influence of Pressure on the Catalyzed Liquid-Phase Oxidation of cis- and trans-Oct-4-ene The investigation of the influence of pressure on the liquid-phase oxidation of cis- and trans-oct-4-ene shows that the reaction rate increases up to 491 kPa in the non-catalyzed oxidation reaction, but up to 981 kPa in the MoO₂(acac)₂-catalyzed reaction n-oct-1-ene reacts more slowly than cis- and trans-oct-4-ene as well in the pressure-less reaction as in the oxidation under pressure. In the non-catalyzed oxidation reaction the cis/trans- ratios don't depend on the pressure, but in the MoO₂(acac)₂-catalyzed oxidation reaction the cis/trans-epoxide ratios increase with increasing pressure. The optimum of the reaction temperature lies between 110 and 130°C.     

Auswirkung von Korrosion und veränderlicher mechanischer Spannung auf das Schwingungsrißverhalten von Bauteilen

Effect of corrosion and fluctuating mechanical stress on the fatigue properties of construction units . Considerable damage is still being caused by fatigue corrosion resulting from fluctuating stresses in construction units, even though such a source of damage has been known for more than half a century. More than 10% of the total corrosion damage encountered in chemical engineering stems from this type of transcrystalline crack. The particular difficulties met with in attempts to guard against such material damage rest, on the one hand, in the multiplicity of factors influencing the loss of strength and, on the other, in the problems associated with the applicability of laboratory results to the behaviour of constructional units. In this paper the influence of corrosion medium, limiting value of stress cycle endured, thickness of construction unit, frequency, mean stress and crack-propagation characterization on stability towards vibration corrosion is dealt with and shows the design engineer how the relevant data concerning component behaviour are to be handled.