Veränderungen der Fettsäurezusammensetzung von Lipidfraktionen aus Kartoffeln während der Lagerung

Alterations in Fatty Acid Composition of Lipid Fractions from Potatoes During Storage Fatty acid composition of total lipids of the lecithin and cephalin fractions were determind by gas chromatography in samples of fresh potatoes and those stored for 8 months in cold. Moreover, a method for isolation of the pure cephalin fraction is reported. In all the three fractions the percentage of linolenic acid increased during storage, whereas the content of linoleic acid decreased. Other fatty acids remained practically unchanged during the storage. An additional experiment in which powdered freeze-dried potatoes were stored under undesirable conditions showed, as expected, that the content of unsaturated fatty acids decreased strongly. The results are discussed.     

Die Gehaltsänderungen der Tocochromanole während der Raffination und Härtung von Soja-, Raps- und Palmöl

Content Changes of Tocochromanoles during Refining and Hardening of Soya, Rape Seed and Palm Oil Content changes of tocochromanoles, found in oils, take place during the refining process. In the submitted work rape seed, soya and palm oil are examined respecting the change of the tocopherole and tocochromanole content during refining and hardening. It was found out that the separate steps of refining and especially of deodorization decrease the tocochromanole content of the examined oils.     

Über die Lipide der Gerstenstärke und ihre Veränderungen während des Wachstums der Gerste

Lipids of Barley Starch and Their Alteration During the Growth of Barley A brief account on the problems involved in the extraction of lipids from cereal starches is given. The composition of lipids in barley starch and its alteration during growth of the grain are reported. Lyso-lecithin constitutes the major portion of the lipids of barley starch. Since lyso-lecithin occurs as adduct with amylose, the content of amylose has been followed as well. The lipid content with respect to dry starch matter increases slightly during the growth. In contrast, the amount of lyso-lecithin in total lipids increases steadily till complete ripening; correspondingly, the amount of less polar lipids decreases to the same extent. The fatty acid composition of lyso-lecithins alter during the process of ripening.     

Untersuchungen zum Abbau von Nickelseifen während der Hydrierung von Rapssamenöl

Investigations of Degradation of Nickel Soaps During Hydrogenation of Rape Seed Oil The presence of free fatty acids in oils that are to be hardened leads generally to Ni-soap formation and has effects on the activity of the Ni-catalyst. In the submitted work first the solubility of the Ni-steatate in vegetable oil was investigated, which increases in a temperature range of 80–200° C of 0.01 to 0.38 mg Ni/g oil. In presence of a Ni-catalyst in the hydrogen reduction milieu Ni-soap is degradated in the first stage to about 80 % on an average. The reaction is reversible and for a Ni-soap content during the limits of solubility the state of equilibrium is adjusted to the average value of 70 %. The hydrogenation is advanced by a small amount of Ni-soap. The dependence of the rate constant on Ni-soap concentration was established.     

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.     

Thermophysikalisches verhalten von epoxidharzpolymeren während und nach der polyadditionsreaktion

The influence of the cross-linking reaction on glass transition T_g, shrinkage, and dielectric loss factor tanδ was studied in the system bisphenol-A-diglycidylether/4,4′-diaminodiphenylmethane at 55 and 70°C. The activation energy E_A and the reaction rate constant k were calculated from the dynamic calorimetric measurements assuming a pseudo-first-order reaction. The storage of the cross-linked epoxy resin polymer at temperatures near the beginning of the glass transition produces an endothermic peak in the DSC-diagram of the specific heat superimposed on the glass transition. The extent of this annealing effect depends on the storage temperature and the storage time. The correlation between the annealing effect, the structure of the polymer segments, and some important material properties is discussed.     

Veränderungen des Gesamtglucosinolatgehaltes von Rapssaat während der Abreife nach Analysen mit Glucose-, HPLC-, H1-(Sulfatase-) und RFA-Methode

Changes in the Total Glucosinolate Content in Rapeseed during Maturation Analyzed by Glucose, HPLC, H-1 (Sulfatase) and X-RF Method The aim of the reported research work was the investigation and quantification of the development of the total glucosinolate content in rapeseed during maturation in order to give a contribution to explain the deviations of results from different analytical methods on identical samples. Results derived by X-RF and H-1 (sulfatase-) method were independent from the stage of maturation. However, the results of HPLC- and glucose release analyses showed continuously increasing values up to harvesting. The supposed reasons for this phenomenon are temporal modifications in the structure of the sidechain and glucose rest of the glucosinolate molecule. The reported results should be observed in intercomparisons of methods of glucosinolate analysis as well as in the certification of seeds and consum batches of oilseed rape. The fact that long before harvest the results derived by X-RF and H-1 method show a constant level offers the opportunity of a prognosis of the probable quality of certain seed batches by means of a pre-harvest analysis.     

Zeitverhalten der isothermen Reaktivdestillation beim thermischen Cracken und Desoxygenieren von Rapsöl

Thermal cracking of rapeseed oil under isothermal reactive distillation conditions allows the production of alternative liquid fuels. Temporal changes of the sump phase and the oil condensate show an increased higher heating value due to deoxygenation. The sump phase also shows an increasing thermal stability, accompanied by polymerization and aromatization. This is derived from a changing iodine value, H/C ratio as well as viscosity. The deoxygenation of the oil condensate is confirmed by a decreasing acid value and the reduction of detected carboxylic acids.     

Veränderungen der Fette unter Fritierbedingungen und deren analytische Erfassung Chemische Veränderungen der Fette beim Fritieren

Alterations of Fats Under Conditions of Deep-Frying and Their Analytical Detection: Artefacts Formation in Frying Fats During Deep-Frying During deep-frying the fats decompose with the formation of volatile, monomeric and polymeric compounds. Their amount and chemical structure depends on the fat blend, the temperature, the frying time, the frying good, and in a high degree on the accessibility of oxygen. As we have shown a quantitative determination of polymeric material in frying fats is possible using gel permeation chromatography. However, gel permeation chromatography determines the size of the molecules only and does not destinguish between various degrees of oxidation. For his purpose we apply liquid chromatography on silica gel which separates various fractions according to their polarity. In combination with a “moving wire” and flame ionisation detector a semi-quantitative evaluation of the amount of polar material in heated fats in possible. Liquid chromatography is applicable for preparative purposes and enables the non-destructive isolation of sufficient material for feeding experiments.     

Biochemische und molekularbiologische Ansätze zur Veränderung der Fettsäurezusammensetzung des Rapsöls

Biochemical and Molecular Biological Approaches for Changing the Fatty Acid Composition of Rape Seed Oil For the technical usability of rape seed oil and uniform esterification of all three positions of the glycerol backbone with erucic acid is desired, which is not found in the varieties examined so far. Our enzymatic investigations revealed that this is especially due to the characteristics of the acyltransferase catalyzing the acylation of the C-2 position of the glycerol backbone. This enzyme is unable to utilize erucic acid as a substrate. The corresponding enzyme activity of Limnanthes douglasii, however, posseses the ability to incorporate erucic acid. To transfer this property to rape seed the corresponding gene has to be isolated. A gene isolation using antibodies or oligonucleotides requires the purification of the protein encoded by the gene, which up to now has failed. In parallel to our further efforts to purify the protein we have started to establish alternative methods of gene isolation based on the functional expression of cDNAs in microorganisms.     

Technologien zur Verarbeitung von Palmöl und dessen Verwendung

Processing and End Uses of Palm Oil In a short introduction, the economic importance of palm oil in the supply of fat for the West European countries, especially, for the Federal Republic of Germany, is emphasized. Furthermore, the properties and composition of oils from various plantations are given. Special conditions of transportation and storage are discussed. Industrial processing of palm oil consists of the following steps:

• Complete refining including degumming, deacidification, thermal bleaching, treatment with bleaching earth, and deodorization
• Hydrogenation
• Interesterification
• Fractionation

Complete refining is essential for the manufacture of all edible products, whereas the last three processes are generally used for the manufacture of special products from palm oil. Thermal bleaching is a characteristic step in the processing of palm oil, by which the carotenoids are destroyed and the oil is decoloured. This operation can be performed at one of the various stages of refining, and by choice, even in conjunction with deodorization or distillative deacidification. The various possibilities are indicated using a block flow diagram and these are critically evaluated with reference to specific processing conditions. The technical equipment required for these processes are described using schematic illustrations. Next to hydrogenation, occasionally carried out as hydrobleaching, the processes, such as interesterification and fractionation, are very significant for the manufacture of finished products and intermediate products from palm oil. Under this aspect the corresponding technologies and their practical applications are discussed. These processes permit wide applications of palm oil and finished as well as intermediate products prepared therefrom in the production of edible oils and fat dressings. A major part of these products are used in shortenings and margarine. Further products are solid fractions from palm oil as substitutes for cocoa butter, liquid fractions as frying oils etc. Typical examples of these applications are given.