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.     

Zur reaktionstechnischen und fluiddynamischen stabilität von multirohrreaktoren für die massepolymerisation

Due to the very strong variation of the viscosity of the reaction mass with increasing monomer conversion, three stationary states for the tubes of a multitubular system with cooling vessel can be found. As a consequence, a maldistribution of the fluid arises, so that the reactor stability and the polymer quality are negatively influenced. The recycling of the reaction mass is a helpful method to increase the reactor stability. In this paper some fundamental aspects of the use of multitubular reactors for the polymerization of styrene are studied.     

Partikelform und Porosität von biogenen Pyrolysekoksen

Char particles from pyrolyzed biomass vary in particle size and shape. On average, the particles are more elongated the larger their size. The average size‐specific elongation is almost alike for all investigated samples, i.e. independent from their source material and process. The particle collectives cannot be characterized accurately with classical particle size distributions, which assume spherical particle shape. Accounting for their shape, they can be described more accurately with particle size distributions that are based on an ellipsoid model. The high bulk porosity is mainly attributed to the spaces between particles.     

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.     

Einfluß von zusatzstoffen auf die wärmestabilität von auf PVC basierenden systemen

The instability of systems on PVC basis may be attributed to physical and chemical phenomena. The stability of the system is basically influenced by the oxidation stability of the plasticizers. The volatility loss in plasticizer is only partially due to physical processes. During ageing, oxidation and degradation processes take place to a minor or major degree, or exclusively, depending on the structure of the plasticizer. These processes may be affected in their order of magnitude by the stabilizers and fillers present in the system.     

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.     

Prinzipien der Herstellung und Stabilität von Emulsionen

Principles of formation and stability of emulsions. The present state of knowledge concerning the principles of emulsion formation and stability are summarised and new theoretical and experimental results are presented. Also described are the characteristic features of the most common types of machines used for emulsification and the mechanics of droplet disruption in laminar and turbulent flow as well as cavitation. In laminar flow, the minimum droplet size is theoretically determined by the shear stress and regulated by a critical Weber number, provided that the particular emulsifier can rapidly occupy sites on the newly formed interface. If this occupation is inhibited, than only larger droplets can be formed. The upper size limit can be calculated from kinetic considerations. The second part of the paper addresses the fundamentals of emulsion stability and the emulsifier's influence on interactions between dispersed droplets. A way of describing the state of the droplets in an emulsion at rest using a population balance theory is also discussed.     

Einfluß der chemischen Struktur auf das Luftabscheidevermögen und die hydrolytische Stabilität von Estern

Influence of the Chemical Structure in Regard to the Air Release Properties and the Hydrolytic Stability of Esters Esters, based on fatty chemical basis, are of great importance for the lubricant industry as efficient, biodegradable basestocks and additives. The structure possibilities and synthetic variations of ester oils are described. Basic datas are presented inclusive application areas. Parameters like air release properties and hydrolytic stability possess a central function in special applications like hydraulic fluids or compressor lubes. Oil dispersed air bubbles influence the compressibility and can cause disturbances in oil containing systems. Esterhydrolysis by water are followed by precipitation, decompositions and increased corrosivity. The determination of the air release according DIN 51 381 and the hydrolytic stability leanded against ASTM D-2619 are explained. A great number of esters based on primary and polyhydric alcohols in combination with branched and unbranched, saturated and unsaturated mono- and dicarboxylic acids were tested. Structure-effects rules were fixed in dependence of viscosity, iodine value, branching degree and carbon chain length in order to improve the choice of esters for synthetic oils.