Determination of the degree of substitution of hydrolysed octenylsuccinate-derivatised starch

Aim of the present study was to compare two methods for the determination of the degree of substitution of starch esterified with octenyl succinic anhydride (OSA). A maximum degree of substitution of 0.034 was analysed in commercial samples of hydrolysed OSA starch using a method based on acidification of the free carboxyl group of the OSA-starch molecule after its optimization. In contrast a high degree of substitution up to 0.134 was determined when analysing the same samples using a method based on saponification of the OSA groups. An interference with reducing sugars was hypothesized as possible reason and confirmed by control experiments using different reducing and non reducing low molecular weight carbohydrates.     

Dioxins, dioxin-like PCBs and non-dioxin-like PCBs in dairy products on the German market and the temporal tendency in Schleswig-Holstein

140 Milcherzeugnisse aus verschiedenen Regionen Deutschlands wurden 2006 auf Dioxine, dioxin?hnliche PCB und nicht dioxin?hnliche PCB untersucht. Insgesamt wurden 66 K?se-, 23 Butter- und 51 Quark- bzw. Joghurterzeugnisse analysiert. Die Probenahme erfolgte in Superm?rkten und Einzelhandelsgesch?ften auf der Basis der Produktionsmengen in den einzelnen Bundesl?ndern der Bundesrepublik Deutschland. Die Dioxinkonzentrationen und die Summe der WHO-TEQ blieben weit unter den EU-Grenzwerten von 3 pg WHO-PCDD/F-TEQ/g Fett und 6 pg WHO-PCDD/F-PCB-TEQ/g Fett. Die Dioxingehalte lagen bei niedrigen 0,07–0,53 pg WHO-PCDD/F-TEQ/g Fett mit einem arithmetischen Mittelwert von 0,19 pg WHO-PCDD/F-TEQ/kg Fett. Die WHO-PCDD/F-PCB-TEQ Gehalte lagen zwischen 0,21 und 2,1 pg WHO-TEQ/g Fett, mit einem mittleren Gehalt von 0,76 pg WHO-TEQ/g Fett. Regionale Abh?ngigkeiten und Unterschiede zwischen den einzelnen Produktgruppen konnten nicht festgestellt werden. Langj?hrige Messungen der Dioxingehalte in Butter und K?se aus Schleswig-Holstein zeigen über den Zeitraum von 13 Jahren eine deutliche Abnahme der Gehalte von 0,43 auf 0,19 pg WHO-PCDD/F-TEQ/g Fett.     

Can we improve global food security? A socio-economic and political perspective

Ensuring global food security for a growing population remains a major challenge. This is especially true against the background of increasing food prices paired with growing income levels and changing demand patterns in the developing world. At the same time, climate change and the occurrence of more frequent and extreme natural disasters increase the vulnerability of rural farm households, negatively affecting agricultural production. Given the many dimensions of food security, no simple solution can be found. Promoting productivity of farming and increasing the efficiency of the food marketing system are effective measures contributing to rural development in developing countries. Policy reforms in agriculture and beyond help to reduce distortions and change consumers’ awareness with respect to food waste and resource use inefficiencies related to human diets. What is new in this context is the increasing link of agriculture with other sectors such as the energy and the financial markets. This calls for further research as additional pressure is being put on the global food system.     

Analysis of free amino acids in green coffee beans

To investigate amino acid changes in green coffee beans in the post-harvest period, amino acid concentrations were determined in green beans and after modelled drying, fermentation and storage. After the drying at alternating temperatures up to maximally 40°C, considerable changes in the concentrations of individual amino acids were identified. At the beginning of the storage period, significant changes in concentration were found to a minor extent. Under the condition of drying, it was mainly the concentration of glutamic acid that changed considerably. There was an increase in all the samples by 500 mg/kg dry matter on average, which corresponds to an increase of about 50% of the original value. In contrast, the concentration of aspartic acid in most of the samples decreased clearly due to drying. For the predominant part of the coffee samples, there was a significant increase in the hydrophobic amino acids Val, Phe, Ile and Leu. Changes of the quantities of other amino acids were non-uniform and only insignificant. Constant drying at 80°C for most of the amino acids brought about only minor concentration changes compared to those values obtained at 40°C. Modelled fermentation had no significant effect on the concentrations of the individual amino acids. After a 4-week storage of dried beans, amino acid concentrations did not change further. It is very possible that different post-harvest treatment parameters may influence the amount of aroma precursor compounds in the coffee beans.     

Food security in Tanzania: the challenge of rapid urbanisation

Urbanisation in Tanzania is proceeding apace. This article seeks to identify the challenge posed by rapid urbanisation for food security in Tanzania to 2030, the Sustainable Development Goals horizon. It is hypothesized that urban food security largely depends on the food supply systems and the rural food production potential. The analysis of these interlinkages is based on secondary macro data and own primary micro data. Tanzania has done well to achieve broad self-sufficiency in basic foodstuffs to date, but rapid urbanisation will pose a severe future challenge as regards food security, particularly for the disadvantaged poorer people of the towns and cities in terms of food affordability, stability and food safety. Whether Tanzania can avoid future deterioration in urban food security will depend on how responsive and resilient the urban food supply systems prove to be in the face of continuing urban growth, changing consumption patterns, weak rural–urban food supply linkages and production constraints in the smallholder farming sector.     

Propylen/Propan‐Trennung im Festbettadsorber und durch Membranpermeation

The metal‐organic framework Mg₂(dhtp) with the linker dihydroxyterephthalate is known as MOF‐74 or CPO‐27. Mg₂(dhtp) has been synthesized as powder to measure breakthrough curves in a fixed‐bed adsorber and adsorption isotherms, and as a supported thin membrane layer for permeation studies. The measurement of the breakthrough curves of the binary propylene/propane mixture shows that separation with the fixed bed adsorber is possible. Propylene shows a higher affinity to Mg₂(dhtp). Although the single gas propane flux is slightly higher than the one of propylene, the binary propane/propylene mixture is not separated.     

Partikelcharakterisierung in hochkonzentrierten Dispersionen – Grundlegende Untersuchungen zu einer neuen Ultraschallmethode

A new method for inline characterization of particles in high concentrated dispersions by ultrasonic backscattering is described, that is sensitive against particle size and concentration. Analyzing the backscattering signal yields the sound attenuation as well as a scattering intensity equivalent. The measurement can be performed without sampling and minimally invasive directly in the process.