[show abstract][hide abstract] ABSTRACT: Using individual grain analyses, the degree of inherent biological variation in germinating barley seeds has been established. Even under homogenous laboratory conditions, the activities of the germination-related enzymes α-amylase, β-amylase and β-glucanase varied by a factor of two to three. The comparison with single grain analyses of different industrially produced malts (steeping systems without aeration, with air suction and pressurised aeration) revealed that the heterogeneity of these malts nearly tripled. This increase may be due to the gradients in O2 and CO2 that arise in large industrial steeping vessels. The most homogenous malting in the industrial systems was achieved without any aeration during steeping. Therefore, to improve homogeneity, the common practise of steep aeration should be omitted. Germination progression was quite different within the three exhaustively aerated attempts, which indicated that gaseous composition was not the only factor affecting germination progression.
[show abstract][hide abstract] ABSTRACT: Fouling in heat exchangers in the food industry causes not only the reduction of the overall system performance, but also a reduction of food quality due to overheating or insufficient heating resulting in potential risk of microbiological contamination. A measure to avoid or at least mitigate fouling is the modification of the heat transferring surface. In order to understand the interaction deposit-surface stainless steel was coated by plasma enhanced chemical vapor deposition and the deposition behavior of whey protein, calcium phosphate and a combination of both was investigated. DLC (diamond-like carbon) coatings, namely a-C:H, a-C:H:Si and a-C:H:Si:O, were fouled at an initial surface temperature of 80 and 120/105 °C and the impact of the surface modification on the fouling resistance, the amount and type of deposit formed and the deposit composition were assessed. The results showed that the surface energy properties affected the first fouling layer formation as well as further stages of build-up and the deposit structure, principally at the lower surface temperature. Moreover the electron donor component significantly influenced the final fouling resistance as well as the deposit mass, suggesting an optimum value of γ− for which deposits have lower adhesive and cohesive strengths and the fouling is minimal.
[show abstract][hide abstract] ABSTRACT: Imidazolin-2-imines represent a particularly basic and nucleophilic subclass of guanidines, and a large variety of these N-donor ligands have become available, inter alia, by the reaction of N-heterocyclic carbenes of the imidazolin-2-ylidene-type with organic azides such as trimethylsilyl azide followed by desilylation. These imidazolin-2-imines serve as precursors for the generation of anionic imidazolin-2-iminato ligands (imidazolin-2-imides), which act as imido-type ligands towards early transition metals and metals in a higher oxidation state and were used as ancillary ligands in a number of homogeneous catalysts, in particular for olefin polymerization and alkyne metathesis. Furthermore, these ligands also form strong metal-nitrogen bonds in lanthanide and actinide complexes. Linking the imidazolin-2-imines to each other or to other functional moieties affords multidentate ligands, and their rich coordination and bioinorganic chemistry developed mainly in the past 10 years comprises almost any transition metal. In addition to a detailed account of the chemistry of imidazolin-2-imides and -imines, the transition and main group element chemistry of their 4,5-dihydro congeners, imidazolidin-2-imides and -imines, is also addressed.