DSC-Thermoanalyse und Kinetik der Kristallisation von Kakaobutter

DSC-Thermal Analysis and Kinetics of Cocoa Butter Crystallization A DSC method for isothermal crystallization of cocoa butter is described. The crystallization curves may be linearized according to the empirical Avrami equation. From the resulting Avrami plots the rate constant of crystallization may be calculated. This method gives valuable results about the specific crystallization tendency of cocoa butters of different origins and about temperature influence on crystallization times. The method seems to be useful for quality control of cocoa butters and for process control during the tempering step of the industrial chocolate production.     

Untersuchungen über die Zusammenhänge zwischen thermodynamischer Stabilität der Kakaobutter und der Lagerbeständigkeit der Schokolade

Investigations on the Relationship between the Thermodynamic Stability of Cocoabutter and Storage Stability of Chocolate In a previous work

1 H. Witzel u. K. Becker, Über die Kristallstruktur der Kakaobutter, Fette · Seifen · Anstrichmittel 71 , 507 [1969].

, the crystalline structures and molecular arrangements of unstable pre-β-form and stable β-form of cocoabutter could be elucidated. In the present work, attempts were made to determine quantitatively the amounts of pre-β-form and β-form of cocoabutter in chocolate by x-ray technique. Furthermore, the influence of the amount of unstable pre-β-form on the rate of formation of fat bloom was investigated. It was found that the quantitative determination of pre-β- and β-forms is not possible. However, from the intensity of some x-ray reflexes conclusions regarding the resistance of chocolate towards the formation of fat bloom can be drawn.     

Die Kinetik des Schmelzens und der Kristallisation von Kakaobutter

The Kinetics of Melting and Crystallization of Cocoa Butter Melting is kinetically the reverse of crystallization. It was shown in a previous publication that the kinetics of fat crystallization is the same as that of precipitation from colloids. It is shown in the present paper that the kinetics of melting of solid fat is the same as that of the dispersion of gels. The kinetics of the melting of cocoa butter was investigated by linearization of experimental data from the literature. The linearization shows that the melting is accompanied by crystal transformations, and that the various crystal forms melt in succession.     

Der Einfluß der chemischen Feinstruktur von Vaselinen auf physikalische und technologische Eigenschaften 12. Mitteilung: Über den Einfluß chemischer und physikalischer Meßdaten auf die Gebrauchseigenschaften von Vaseline

Influence of Chemical Fine Structure of Vaselines on Physical and Technological Properties, 12: Influence of Chemical and Physical Data on the Practical Properties of Vaseline The influence of iso-fractions apart from normal and unsaturated hydrocarbons on the tack property of vaselines was studied. The tack is found to be the sum of tacks contributed by various molecular weight fractions obtained by gel permeation chromatography, which correlate with the observed chemical structures. Furthermore, other expected correlations between chemical structural groups and physical data, such as slip point and viscosity, were confirmed, which enable exact characterization of the vaselines studied. The results show that two different compositions yield vaselines having good practical properties: a) composition consisting of a large amount of long chain branched low melting tacky high molecular weight hydrocarbons (C-30 to C-200) and small proportions of n-paraffins and liquid hydrocarbons; b) compositions consisting of little high molecular weight solid iso-hydrocarbons (C-20 to C-100) together with n-paraffins and a large proportion of viscous tacky oil, which is composed of molecules having many short side chains. Since the vaselines of the type b) liberate the incorporated drugs more easily than those of the type a), to which also the so called natural vaselines belong, the type b) vaselines are considered to be optimum compositions. Practical properties of polymer-free bases could be compared with polymer-containing original vaselines by quantitative separation of the high polymers. Improvement of the practical properties of vaselines containing large proportions of oil can be accomplished by the addition of polyethylenes having molecular weights around 20 000, which can be dissolved in the vaseline base at elevated temperatures, and, on cooling, they improve the gel structure; however, these additives have disadvantages from technological viewpoint, since the processing has to be done at room temperature. Polyisobutylenes, that are frequently used, are unsuitable for improvement of the structure.     

Zusammensetzung,Präparation und Eigenschaften von Rapsphospholipiden

Composition, Preparation and Functionality of Rapeseed Phospholipids It is well known that phospholipids are byproducts of rape seed processing. Nevertheless they have only a small application field because of sensoric problems, undesirable colour and a lack of knowledge on relationship between structure and action. In this study the phospholipid composition of rape seeds of different breeding quality is characterized. The possibilities to prepare the main phospholipid constituents are analyzed. The functionality (interfacial behaviour) of phospholipid classes are tested in two experiments in order to receive more basic information on these compounds.     

Das Verhalten von Glas beim maschinellen Geschirrspülen

The Behaviour of Glass in Mechanical Dish-Washing Under the conditions involved in mechanical dish-washing there is only a slight difference in the behaviour of glasses of different compositions. The higher temperatures attained thereby are mostly responsible for the damages to the glass. Alkaline, especially strongly alkaline solutions, attack more than the acidic ones. The percentage of the complaints lodged for the glass damages is still relatively small. However, the rapidly increasing number of household dish-washing machines makes it necessary that everybody concerned should discuss the problem of cloudiness of glass.     

Toxikologische und dermatologische Bewertung von chemischen Haushaltsprodukten

Toxicological and Dermatological Evaluation of Chemical Household Products In the evaluation of household and other products, possible health risks and the utility value of the product must be weighed carefully. The intended use of household products must not entail a health risk to the consumer. Toxicological and dermatological evaluations of the individual ingredients as well as of the finished products are necessary in order to warrant safe usage. In the following, the most important basic ingredients as well as the extent of experimental testing required for preparations which contain varying concentrations of known ingredients, are discussed. Further, it is pointed out that products, which for technical reasons must contain aggressive chemicals, should be labelled appropriately and should only be sold in childproof packaging.     

Die Zusammensetzung der Triglyceride von Kuhmilch und Humanmilch

Triglyceride Composition of Bovine and Human Milk The triglyceride composition in the fat portion of bovine milk (winter and summer) and mature human milk was calculated from the HPLC partition number and from the carbon number and fatty acid pattern in the HPLC fractions. The triglycerides identified (122 in bovine milk, 94 in human milk) and their contents in the HPLC fractions are tabulated.     

Zusammensetzung und Anwendungen von Isostearinsäure

Composition and Application of Isostearic Acid The clay catalysed oligomerisation of unsaturated fatty acids yields C36 dimer fatty acids, C54 trimer fatty acids and C18 monomer fatty acids. Monomer fatty acids, which consists mainly of straight, branched, saturated and unsaturated fatty acids, can be distilled from the higher molecular weight products and after hydrogenation separated into solid stearic acid are mono- and polybranched C18 fatty acids whose branching points are mainly concentrated in the center of the molecule. Depending on the nature of the used raw materials and the degree of refinery, straight chain fatty acids, cyclic fatty acids, γ-lactones, unsaponifiable and even rosin acids are found as impurities. The low cloudpoint, comparable with oleic acid, as well as the excellent temperature- and oxidation stability gives isostearic acid and their derivatives excellent opportunities in applications as cosmetics, lubricants and plastics.     

Thermisches Verhalten von Mono-, Bis- und Poly-2-oxazolidinonen

In connection with investigations of the thermal stability of isocyanurate and 2-oxazolidinone ring structures in cross-linked molding resins of high dimensional thermal stability, mono-, bis- and poly-2-oxazolidinones, synthesized from isocyanates and purified commercial epoxides of varying structure, have been characterized and their thermal stability in the temperatur range from 230 to 260°C has been studied. Tempering the 2-oxazolidinones under exclusion of air and moisture results in autocatalytic decomposition, increasing with the content of 2-oxazolidinone rings and with tempering time. The gaseous reaction product consisted mainly of carbon dioxide (≥94%). The residual amounts of 2-oxazolidinone and the amounts of carbon dioxide formed supplemented each other to nearly 100%. For the cleavage of the 2-oxazolidinone ring of mono-2-oxazolidinone a first order reaction was found to prevail up to about 15% conversion. The corresponding activation energy was calculated to be 130 kJ/mole. The 2-oxazolidinones investigated showed a dependence of the thermal stability upon the structure of the epoxides used. The reaction products of the 2-oxazolidinone cleavage attack the isocyanurate ring.     

Das Phasenverhalten von Cholesterol-Fettalkohol-Mischungen und Cholesterol-Fettalkohol-Wasser-Mischungen

The Phase Behaviour of Mixtures of Cholesterol-Fatty Alcohol and Cholesterol-Fatty Alcohol-Water Investigations of binary mixtures of cholesterol and fatty alcohol (chain length from 10 to 18 carbon atoms) show that cholesterol and fatty alcohol with at least 12 C-atoms form liquid crystals and a so called α-phase within a limited range of concentration and temperature. The phase diagram of cholesterol and tetradecanol represents the biggest area of the liquid crystalline and the α-phase. The recrystallization temperature of the eutectic mixture decreases because of the formation of the mesophase. The recrystallization is time dependant and incomplete. The addition of water influences the phase behaviour of the mixtures. Both the liquid crystalline and the α-phase are stabilized by water concerning the temperature range. Water penetrates the mesophase and causes a limited swelling.     

Das Zusammenwirken Technischer Regeln und technischer Entwicklungen für die Sicherheit von Chemieanlagen

Interplay of technical specifications and technical developments in the safety of chemical plant. In the planning, construction, and operation of chemical plant requiring close supervision the aims are defined by rules and regulations which refer back to a comprehensive compilation of technical specifications concerning the means by which these aims can be accomplished. These rules were, and are, worked out by business federations in collaboration with occupational and governmental agencies in joint committees. Since both practical experience and fresh knowledge resulting from technical developments are gained in industrial undertakings, the feedback of experience from industry ensuring continuous up-dating of the technical specifications is of immense importance. Starting from the current state of the art, the expert frequently has to work out solutions to specific problems. Once general conclusions which have proved their value in practice can be derived, they are incorporated in the technical specifications. Such a contribution to safety engineering is illustrated for a pressure vessel. The examples described range from the derivation of reliable criteria for assessing the danger of brittle fracture of high-strength steel pressure vessels to the development of preventative techniques of nondestructive testing of components. They also incorporate the development of design data for conservative dimensioning of safety valves for frothing mixtures and their safe release into the atmosphere as well as investigation of the pressures expected on explosion of flammable hydrocarbon/air mixtures.