Bitterkeit und Gelpermeationschromatographie von enzymatischen Proteinhydrolysaten

Bitterness and Gel Permeation Chromatography of Enzymatic Protein Hydrolyzates By enzymatic treatment of different proteins short chain peptides have been obtained. By calculations based on the amino acid composition we can predict the danger of obtaining bitterness. When the ?Q-value”?, calculated from the hydrophobicities of the amino acids of the proteins used as raw material is below 1300, no bitterness will occur. When the Q-value is higher than 1400, there is a danger to obtain bitterness. To avoid bitterness in this case, we must be very cautious with the chain length of the peptides to be obtained and must try, to obtain the chain length as long as possible but compatible with solubility data. For this reason, these trials were controlled by gel permeation chromatography, and it was found, that chain length must be such, that the molecular weight is above 6000 Dalton to avoid bitterness.     

Molgewichtsverteilung und Langkettenverzweigung bei der anionischen Polymerisation von Butadien

The copolymerization of butadien with small amounts of divinyl benzene (DVB) has been investigated. The polymerization has been carried out with a lithiumamide as initiator in n-hexane as solvent under addition of tetrahydrofuran (THF) to govern the content of vinyl groups. By gel permeation chromatography coupled with a viscometer the molecular weight distribution (MWD) and long chain branching as a function of the conversion and of the molecular weight have been determined. Using a differential refractometer and a UV-photometer as detectors the distribution of the branching agent DVB vs. molecular weight has been studied. With our example long chain branching decreases with increasing conversion. The insertion of DVB occurs mainly in the first phase of the reaction. With increasing conversion the MWD becomes broader. At very high degrees of conversion the molecular weight increases considerably by coupling reactions.     

Gelpermeationschromatographie und Kalibrierung an resolischen Phenol-Formaldehyd-Kondensaten

Several resols with a molar ratio of formaldehyde to phenol of 2.5 and 1.7, respectively, and a mass content of sodium hydroxide of 8 or 4 wt.-% were synthesized and were analysed by size exclusion chromatography. Hereby, tetrahydrofuran with 0.4 wt.-% trichloroacetic acid was used as solvent and eluent, which is capable of dissolving even highly alkaline resols. In the lower molar mass range, these resins were separated in up to eight peaks; comparison of the chromatograms of pure substances, which are expected to be found during resol synthesis, allowed detailed interpretation. In the range of higher molar mass, calibration was attempted by polystyrene and poly(ethylene oxide) standards; for the fractions with the highest molar mass, a molar mass of 150 kg mol^-1 was estimated. Comparison of the signals from a refractive index (RI) detector and a u.v. detector showed that the u.v. detector is less disturbed by traces of low molar mass impurities.     

Anwendung der Gelpermeationschromatographie auf die Untersuchung thermisch-oxydativ belasteter Fette

The Application of Gel Permeation Chromatography to the Investigation of Thermal-Oxidatively Treated Oils Principle and apparatus used in gel permeation chromatography (GPC) are given along with methods for the determination of dimeric, trimeric and higher oligomeric triglycerides in frying fats that are subjected to extreme thermal oxidation. Separation of a frying fat into monomeric and oligomeric triglycerides by means of preparative GPC followed by analyses of their products of saponification revealed that dimeric fatty acids occur only in the fraction of oligomeric triglycerides. Accordingly, the dimerization reaction in the presence of atmospheric oxygen consists entirely of an intermolecular reaction. Under various conditions (at 240°C in the presence of air, at 240°C under argon, and under partial exposure to both light and air) all the oligomerization reactions obey the reaction law of the first order, although their rates are different. In the investigation of animal fats by GPC tallow and butter were found to contain none, whereas the fat in cheese, chicken and lard were found to contain upto 1% dimeric triglycerides.     

Photochemische Primärprozesse von Xanthenfarbstoffen. II. Blitzlichtspektroskopische Untersuchungen zum Einfluß von anionischen Mizellen auf die photochemischen Primärprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. II. Investigations of the Influence of Anionic Micelles on the Primary Processes of Selenopyronine by Flash Excitation In aqueous solutions containing anionic micelles, the dye cations of selenopyronine are present at the micellar surface. If the concentration of the dye ions is much lower than the concentration of micelles, only monomolecular triplet decay (k₁^aM = 2 · 10⁻³s⁻¹) is observed. Under these conditions, the half-oxidized and half-reduced form of selenopyronin is not formed. If the concentration of the dye ions is much higher than the concentration of micelles, two or more dye ions are present at every micelle, and a fast bimolecular decay of the triplet state during the flash is observed. The quenching of the triplet state with p-benzoquinone (k₇^aM = 1,9 · 10⁹ l/mol s), DABCO (k₁₀^aM = 1,6 · 10⁷ l/mol s) and EDTA (k₁₁^aM = 1,3 · 10⁵ l/mol s) and the decay processes of the half-reduced and half-oxidized form in the micellar solution are investigated.     

Synthese von anionischen N-acylierten L-Aminosäuren,Oligopeptiden und Proteinhydrolysaten als Eiweißtenside und deren Anwendung in der Wollveredlung

Synthesis of anionic N-acylated L-amino acids, oligopeptides and protein hydrolysates as protein-based surfactants and their application in wool finishing. As model compounds for protein-fatty acid condensation products, ten L-amino acids were N-acylated with fatty acid chlorides by Schotten-Baumann reaction. Structural variation in the non-polar part of the molecule was achieved by using saturated fatty acids of different chain length (C₈–C₁₈). The terminal carboxyl group was modified by reaction with different amino acids. Furthermore, N-octanoyl-, N-dodecanoyl-di, -tripeptides and protein-fatty acid condensation products were synthesized by Schotten-Baumann reaction. A dependence of the surface activity on both molecular weight and amino acid composition of the peptide moiety was found after determination of the surface tension-concentration isotherms: critical micelle concentration (CMC) of the surfactant solutions increase with increasing molecular weight and higher polarity of the peptide part. This coincides with a reduction of surface activity. With increasing alkyl chain length, however, the surface activity increases as can be seen from the decrease in CMC. For the synthesized anionic protein-based surfactants good biodegradabilities (68–78% BOD₅/COD) were determined. The sorption characteristics of protein derivatives on wool were studied in wool finishing processes. An increased bath exhaustion and a more intense coloration of wool were obtained during dyeing of wool by addition of N-acyl-L-amino acids or commercially available protein-fatty acid condensates.     

Über den Kationenaustausch bei anionischen Polyurethan-Dispersionen mit Natriumsulfonat-gruppen

In aqueous dispersions of anionic polyurethanes with SO groups and Na⁺ as counter-ion, Na⁺ was ion exchanged for other cations (H⁺, Ag⁺, Ca⁺⁺, Ba⁺⁺, Ni⁺⁺, Cu⁺⁺, Zn⁺⁺, Pb⁺⁺ and AI⁺⁺⁺). With the exception of AI⁺⁺⁺ the ion exchange took place nearly quantitatively, indicating that site binding of counter-ions did not occur at the particle surface. In addition, the influence of the counter-ion was studied with respect to stability of the dispersion and the mechanical properties of the films.     

Gewinnung molekulareinheitlicher N-Propionyl-oligo-ε-aminocapronsäurepropylamide aus Oligokondensaten durch Gelpermeationschromatographie

N-propionyl-oligo-ε-aminocaproic-acid-propylamides have been prepared by transamidation of caprolactam with propionic acid propylamide. The oligocondensate contains no cyclic compounds, and is nearly free from linear amides with terminal amino or carboxy groups. Variations in the conditions of transamidation change the distribution of chain length. The oligocondensates are separated into individual compounds by gelpermeation chromatography using Sephadex LH-20 and phenol/ethanol/water (1:2.6:1.6 v/v) as eluant. The oligoamides have been isolated up to the pentadecamer. Sufficient amounts of material for physico-chemical measurements are easily obtained by this procedure.     

Flüssigphasenoxydation von Cyclohexen in Gegenwart von Kombinationen von Verbindungen verschiedener Metalle

The Liquid Phase Oxidation of Cyclohexene in Presence of Combinations of Compounds of Different Metals The oxidation of cyclohexene ( 1 ) with molecular oxygen in chlorobenzene solution at 80°C has been studied using cobalt, manganese and copper compounds, respectively in combination with molybdenum complexes. The selectivity has been determined of cyclohex-2-en-1-hydroperoxide ( 2 ), epoxycyclohexane ( 3 ), cyclohex-2-en-1-ol ( 4 ), cyclohex-2-en-1-one ( 5 ), 2,3-epoxy-cyclohexane-1-ol ( 6 ) and cyclohexane-1,2-diol ( 7 ), formed from reacted 1 . Investigation of the consecutive reactions showed that 3 and especially 4 can react in different ways and moreover 4 inhibits the oxidation of 1 . From these results conclusions were drawn on the mechanism of oxidation of 1 .     

Die Herstellung von Kakaoerzeugnissen unter Anwendung von Pflugscharmischern

Manufacture of Cocoa Products Using Plough Share Mixers Various problems arise during mixing and thermal treatment of powdered material in the production and further processing cocoa powder. Means for solving such problems are shown. An effective process of mixing and the plough share mixers used for the same are described; these nearly automatic mixers are widely applicable. A further development of these mixers, the so-called DRUVATHERM-units, enable the combination of several mechnical processes, such as mixing, pulverizing of agglomerates, moistening, coating, tempering, cooling, drying and carrying out reaction processes under pressure or vacuum and at higher temperature. These new type of units can compete with conventional driers and roasters. They open new economical paths in the conventional treatment of products in cocoa industry as well.     

Thermochemische Depolymerisation von Lignin zur Gewinnung von Aromaten

In order to develop a valorization strategy for lignin, commercially available Kraft lignin was converted with sub‐ and supercritical water in a high‐pressure vessel. The effects of reaction temperature and phase state on product formation were investigated by GC‐MS analysis. The basic information of these experiments serves to develop processes for the production of aromatic‐based chemicals from biomass.     

Funktionalisierung von Ultrafiltrationsmembranen zur Integration von spezifischen Adsorbereigenschaften

By integrating a water‐soluble polymer, which has the ability to complex heavy metal ions into ultrafiltration membranes, the separation process could be enhanced to enable also filtration of these species. In this work, a membrane and an adsorber polymer were functionalized with complementary reactive groups so that the adsorber polymer could be immobilized in the porous support layer of the ultrafiltration membrane via click reaction. The separation performances and membrane characteristics of the synthesized membranes are comparable to those of conventional UF membranes.