Inactivation of peroxidase, polyphenoloxidase, and lipoxygenase in paprika and chili powder after immediate thermal treatment of the plant material

Residual activities of lipoxygenase (LOX), peroxidase (POD), and polyphenoloxidase (PPO) were determined in paprika and chili powder after immediate thermal treatment of the fresh plant material. Heat treatments comprised water and steam blanching of the integral fruits and pasteurization of the comminuted tissues, respectively. PPO showed the lowest heat stability and was completely inactivated by heating at 80 °C for 10 min. Inactivation of LOX was also largely accomplished by heating at 90 °C for 5 min and at 100 °C for 5 min, whereas up to 3.5% (paprika) and 3.3% (chili) of the initial POD activities were retained even when applying rigorous time–temperature regimes. The results demonstrate that substantial inactivation of deteriorative enzymes was ensured by the recently suggested process, thus facilitating the production of high quality spice powders.     

Analysis of hurricane wind loads on low-rise structures

Time series of pressure coefficients collected on the roof of a house by the Florida Coastal Monitoring Program during landfall of Hurricane Ivan on the Florida panhandle in 2004 are analyzed. Rather than using peak values, which could vary due to the stochastic nature of the data, a probabilistic analysis is performed to characterize extreme values of pressure coefficients and associated wind loads. It is shown that the pressure coefficient time series follows a three parameter Gamma distribution, while the peak pressure follows a two-parameter Gumbel distribution. The analysis yields a probability of non-exceedance of a given threshold of the pressure or load coefficients. For this specific house and specific storm, the 80 percentile load coefficient value of the probability of non-exceedance is −1.7. This is discussed in the context of ASCE 7 GCp values.     

Thermal degradation of betacyanins in juices from purple pitaya [<Emphasis Type="Italic">Hylocereus polyrhizus</Emphasis> (Weber) Britton &; Rose] monitored by high-performance liquid chromatography–tandem mass spectometric analyses

Changes in betacyanin content and colour shade of juices from purple pitaya [Hylocereus polyrhizus (Weber) Britton & Rose] as affected by thermal processing and consecutive cold storage to allow pigment reconstitution were investigated. Pigments from purple pitaya displayed higher stability than earlier investigations on betalains suggested. A novel high-performance liquid chromatography method was established, allowing simultaneous detection of genuine pigments of purple pitaya juice together with their degradation products. In addition to previously described betanin cleavage products (betalamic acid, cyclo-dopa 5-O--glucoside) further degradation products generated after decarboxylation and/or dehydration of phyllocactin and hylocerenin, respectively, were found. Moreover, neobetanin was identified as a thermal degradation product of betanin for the first time. With this newly developed high-performance liquid chromatography method, heating of purple pitaya juice and a commercial pitaya juice concentrate was proven by the detection of thermal betacyanin degradation products that had not been described, so far.     

Utilization of mango peels as a source of pectin and polyphenolics

Two different options for the combined recovery of pectin and phenolic compounds from mango peels, a byproduct of industrial mango processing, were developed. After extraction of dried mango peels with diluted sulfuric acid, the phenolic compounds were adsorbed using a styrene–divinylbenzene copolymerisate resin, and pectin was obtained from the effluent by precipitation with ethanol. Phenolic compounds were recovered from the resin with methanol and the eluate was lyophilized (Process I). Alternatively, the pectin was precipitated by adding the crude extract to ethanol. After removal of the organic solvent, the phenolic compounds were obtained from the aqueous phase of the precipitation bath using the adsorbent resin as described before (Process II). While in total, 129.4 mg/g polyphenols were detected in the lyophilizate obtained from Process I, only 71.0 mg/g dm could be recoverd from Process II. The profiles of the polyphenols were almost identical, revealing that during pectin precipitation preferential adsorption of polyphenolic compounds to the pectin may be excluded. Besides the characterization of the pectins and the phenolic compounds, investigations into the influence of the drying temperature on the polyphenolic content of the peels were carried out, indicating a significant loss of flavonol glycosides depending on heat exposure. On the other hand, some xanthone glycosides were formed during the drying process. Furthermore, antioxidative capacities of the lyophilized eluates were investigated using the DPPH, TEAC and FRAP assays. The antioxidative capacity of the extracts exceeded that of mangiferin and quercetin 3-O-glucoside, respectively, thus demonstrating mango peels to be a suitable source of health-beneficial compounds. The lyophilizates obtained from Process I showed higher antioxidative capacities in all three assays. These findings indicate a correlation between the amount of phenolic compounds and the antioxidative capacity.

Industrial relevance

Byproducts of mango processing amount to 35–60% of the total fruit weight. Their complete exploitation for further product recovery is a promising measure from both an environmental and economic point of view. In our previous study mango peels were found to be a rich source of pectin, with a high degree of esterification and phenolic compounds, like flavonol O- and xanthone C-glycosides. Therefore, two alternative processes for the combined recovery of pectin and polyphenols, which can easily be integrated in an existing pectin production process, were developed in the present study.     

Fatty acids and triacylglycerols in the seed oils of Saudi Arabian date (Phoenix dactylifera L.) palms

Total lipids, fatty acids and triacylglycerols in seeds of the four Saudi Arabian date cultivars ‘Anbra’, ‘Megadwel’, ‘Sacai’ and ‘Sfwai’ were analysed. Total lipid contents ranged between 7.3 and 8.6%. Oleic, lauric and myristic acid represented the most abundant fatty acids in date seed oil. HPLC-DAD-ESI-MSⁿ analysis enabled the identification of 40 triacylglycerols with equivalent carbon number (ECN) 36–54, of which 17 were detected for the first time. Triacylglycerols mainly comprised LaOL, LaLaL, LaML, MML/LaPL and LaOO. ‘Anbra’ oil was characterised by highest proportions of saturated fatty acids and triacylglycerols with ECN 36 and 48–54. Unsaturated fatty acids prevailed in the three remaining varieties. Elevated proportions of triacylglycerols with medium ECNs were found in ‘Megadwel’ and ‘Sfwai’ oils. Aside from highest total lipid contents, ‘Sacai’ seeds predominantly contained triacylglycerols with low ECNs. Multivariate statistical analyses elucidated varietal influences on the fatty acid and triacylglycerol composition of date seed oil.     

Die silikatische Versiegelung elektrolytisch verzinkter Oberflächen – ein Schutzsystem für Bauteile in Kontakt mit Magnesium

The silicate sealing of galvanized surfaces – a protective system for components in contact with magnesium A silicate sealing of zinc galvanized surfaces assembled to magnesium alloys as a protection from galvanic corrosion is presented. The sealing is amorphous-nano-crystalline in structure, thermically stable and deposited on chromate coated zinc-surfaces. The sealing serves on the one hand as an electrically (poor conductivity) insolator and on the other hand as a diffusion barrier for mass transport. In this work structural features are discussed by means of TEM-analyses. Electrochemical investigations in combination with corrosion-tests relevant to practical experience are presented. Further a series of chemical reactions during deposition of the silicate layer is suggested and it is discussed under which conditions on an industrial scale best performance of depositing the silicate sealing is reached.     

The Influence of Subsurface Temperature Measurements on the Determination of Transient Wall-Side Boundary Conditions: An Analytical Tool

An analytical approximation for the two-dimensional heat conduction problem with temporally and spatially oscillating thermal boundary conditions is presented. In addition, simplified expressions for the damping and phase shift of the temperature signal between the surface and a “measurement” position inside the wall are derived and their validity in dependency on the inverse Fourier number is shown. The solution algorithm is implemented in a MATLAB program and made available for other researchers. In two case studies, the analytical solution is applied in order to evaluate the ability of experimental systems to measure instantaneous and local heat transfer coefficients as well as temperatures on a boundary.     

Elektrolytische Abscheidung von Aluminium‐Magnesium‐Legierungen aus aluminiumorganischen Komplexelektrolyten

Electrolytic Deposition of Aluminium‐Magnesium‐Alloys from Electrolytes Containing Organo‐Aluminium Complexes The galvanic deposition of pure aluminium from fluoride‐containing electrolytes has been developed further and for the first time aluminium and magnesium have been deposited from a toluene‐solution of a halide‐free organo‐aluminium complex electrolyte. The rate of incorporation of magnesium can be controlled over a wide range by either adjusting the composition of the aluminium‐magnesium anode or by using separate aluminium or magnesium anodic circuits. The current efficiency for both anode and cathode approaches 100%. The resulting coating is optically attractive and, depending upon the magnesium‐content or the cathodic current density, can be formed as a dull or polished surface. Investigations using an electron microscope show that the surface, in contrast to that of pure aluminium, consists of spherical particles. The aluminium‐magnesium coating provides excellent protection against the corrosion of magnesium components. Electrochemical investigations using, for example 25% by weight magnesium incorporation, indicate a pronounced passivity interval compared to the alloy AZ91hp. In contrast to galvanic zinc‐plated and silicate‐sealed examples, cyclic corrosion tests on screws simulating 10 years of exposure, show no corrosion.