Optimisation of mild-acidic protein extraction from defatted sunflower (Helianthus annuus L.) meal

For protein isolation from defatted sunflower meal, mild-acidic extraction was investigated to minimise concomitant oxidation and polymerisation of phenolic compounds and their irreversible binding to proteins. Because of the impaired solubility of sunflower proteins at low pH, the potential of sodium chloride (NaCl) to improve protein extractability was firstly screened for pH 2–11. Increasing NaCl concentrations of the aqueous solvent (c_NaCl) up to 2.8 mol/L enhanced the relative protein yield to almost 80% at ambient temperature and pH 5.6–7.4. As to improved protein recovery at minimal interactions with phenolic acids, the concerted effects of pH (3.2–7.4), c_NaCl (1–3 mol/L), temperature (T, 15–45 °C), and meal-to-solvent ratio (MSR, 0.03 and 0.05 g/mL) on the protein concentration of the extract (c_PE) and the relative protein yield (RPY) were examined, using response surface methodology (RSM). Aside from the prevailing influence of pH value and salt concentration, elevated temperature slightly enhanced protein extraction, whereas MSR mainly influenced c_PE, but hardly RPY. Calculated models proved suitable for the evaluation of extraction processes and the prediction of optimum conditions in terms of high protein yields at the lowest pH possible. Extraction at pH 6.0 was shown to be an appropriate compromise yielding 76–83% of the meal protein, depending on the constraints given. With elevated NaCl concentrations compensating for unfavourable pH conditions, mild-acidic extraction was found to be suitable for the recovery of high-quality sunflower protein in terms of light-coloured protein isolates.     

Evaluation of real-time PCR results at the limit of detection

Real-time polymerase chain reaction (real-time PCR) facilitates to detect DNA fragments at very low copy numbers. Positive results, e.g. for unauthorized genetically modified organism (GMO) contamination or for allergens, may raise safety concerns and have far-reaching consequences. However, in case of very low concentrations of DNA samples, results for the same product lot or even for identical samples from different laboratories may differ. Therefore, an approach for a standardized interpretation and reporting of results obtained by real-time PCR at the limit of detection (LOD) is proposed. A quality control DNA sample containing the target at the LOD (95?%) is analysed in parallel with the real DNA sample and the respective C _T values are compared. In addition, practical approaches for in house and precision-based estimation of the LOD are presented. The proposed approach may also contribute to the current discussion on implementing a technical solution to handle DNA traces in specimen, e.g. for the detection of unauthorized GMO.     

A New Validation of Relevant Substances for the Evaluation of Beer Aging Depending on the Employed Boiling System

During the last years changes in aging indicators have been observed, supposedly resulting from modern brewing technology. The Research Brewery Weihenstephan (Forschungsbrauerei Weihenstephan) offers excellent opportunities for comparing different modern wort boiling systems under semi‐industrial conditions. Employing three different boiling systems, nine brews were produced. The resulting worts were compared regarding the most common wort parameters. Furthermore the influence of the different boiling systems on aging indicators in the resulting beers was analyzed using a newly developed mass spectrometry‐based method. The decrease in the total amount of aging indicators in industrial beers over the last years is very likely the result of lower thermal intake in modern brewhouse equipment. The total amount of aging indicators is sufficient to describe the differences in modern boiling systems. In summary, 2‐furfural dominates all other indicators in terms of thermal influence. 2‐Furfuryl ethyl ether can be suggested as good indicator of aging as postulated by Eichhorn, whereas β‐damascenone is questionable as an aging indicator. Supplementary experiments were carried out to investigate the role of the aging indicators as stale flavour components. Because of synergistic effects, many stale flavour compounds act as aroma compounds and not only as indicators.     

Determination of Relaxation Moduli and Poisson‘s Ratio in Uniaxially Loaded Solid Polyethylene Foam Specimens as Part of Full Material Characterization

The mechanical behavior of a solid polyethylene foam is characterizedby a constitutive equation which is of second order in the linearstrain tensor. It turns out that for the determination of the sixtime dependent material functions relaxation tests intension/compression, torsion and, for instance, in isotropic tension andcompression are necessary. For tension/compression tests theexperimental procedure is described in detail. Main emphasis is givento the methods of optical deformation measurement techniques. Resultsfor the relaxation moduli in tension/compression and for the Poissonsratio are presented.     

Carbon nanotubes and mesenchymal stem cells: biocompatibility, proliferation and differentiation

The synergy of the unique properties of carbon nanotubes (CNT) with the remarkable potential of human mesenchymal stem cells (hMSC) provides an exciting opportunity for novel therapeutic modalities. However, little is known about the impact of CNT on hMSC behavior. We report the effect of CNT on hMSC renewal, metabolic activity, and differentiation. Furthermore, we tracked the intracellular movement of CNT through the cytoplasm to a nuclear location and assessed effects on cellular ultra structure.     

Application of infrared ATR spectroscopy to in situ reaction monitoring

The infrared horizontal ATR technique was adapted to be applied for in situ reaction monitoring even at high pressure and high temperature. Different types of reactors and flow cells were built which can be used for recording IR ATR spectra at pressures up to 200 bar and temperatures up to 300°C.

The use of the horizontal ATR technique is shown by the following application examples:

• addition reaction of n-butyl isocyanate with butyric alcohol;

• investigation of the equilibrium of isocyanate, HCl and carbamic acid chloride at elevated pressure and temperature;

• monitoring the polycondensation of bifunctional alcohols and carbonic acids;

• recording spectra of polymer melts at 280°C.