Solution and Solid State Studies of Urea Derivatives of DITIPIRAM Acting as Powerful Anion Receptors.

Herein, we present the synthesis and anion binding studies of a family of homologous molecular receptors 4-7 based on a DITIPIRAM (8-propyldithieno-[3,2-b:2',3'-e]-pyridine-3,5-di-amine) platform decorated with various urea para-phenyl substituents (NO2, F, CF3, and Me). Solution, X-ray, and DFT studies reveal that the presented host-guest system offers a convergent array of four urea NH hydrogen bond donors to anions allowing the formation of remarkably stable complexes with carboxylates (acetate, benzoate) and chloride anions in solution, even in competitive solvent mixtures such as DMSO-d6/H2O 99.5/0.5 (v/v) and DMSO-d3/MeOH-d3 9:1 (v/v). The most effective derivatives among the series turned out to be receptors 5 and 6 containing electron-withdrawing F- and -CF3para-substituents, respectively.

Process Proteomics of Beer Reveals a Dynamic Proteome with Extensive Modifications.

Modern beer production is a complex industrial process. However, some of its biochemical details remain unclear. Using mass spectrometry proteomics, we have performed a global untargeted analysis of the proteins present across time during nanoscale beer production. Samples included sweet wort produced by a high temperature infusion mash, hopped wort, and bright beer. This analysis identified over 200 unique proteins from barley and yeast, emphasizing the complexity of the process and product. We then used data independent SWATH-MS to quantitatively compare the relative abundance of these proteins throughout the process. This identified large and significant changes in the proteome at each process step. These changes described enrichment of proteins by their biophysical properties, and identified the appearance of dominant yeast proteins during fermentation. Altered levels of malt modification also quantitatively changed the proteomes throughout the process. Detailed inspection of the proteomic data revealed that many proteins were modified by protease digestion, glycation, or oxidation during the processing steps. This work demonstrates the opportunities offered by modern mass spectrometry proteomics in understanding the ancient process of beer production.

TRFLP analysis reveals that fungi rather than bacteria are associated with premature yeast flocculation in brewing.

Premature yeast flocculation (PYF) is a sporadic fermentation problem in the brewing industry that results in incomplete yeast utilization of fermentable sugars in wort. Culture-independent, PCR-based fingerprinting techniques were applied in this study to identify the associations between the occurrence of the PYF problem during brewery fermentation with barley malt-associated microbial communities (both bacteria and fungi). Striking differences in the microbial DNA fingerprint patterns for fungi between PYF positive (PYF +ve) and negative (PYF -ve) barley malts were observed using the terminal restriction fragment length polymorphism (TRFLP) technique. The presence of terminal restriction fragments (TRFs) of 360-460 bp size range, for fungal HaeIII restriction enzyme-derived TRFLP profiles appeared to vary substantially between PYF +ve and PYF -ve samples. The source of the barley malt did not influence the fungal taxa implicated in PYF. TRFLP analysis indicates bacterial taxa are unlikely to be important in causing PYF. Virtual digestion of fungal sequences tentatively linked HaeIII TRFs in the 360-460 bp size range to a diverse range of yeast/yeast-like species. Findings from this study suggest that direct monitoring of barley malt samples using molecular methods could potentially be an efficient and viable alternative for monitoring PYF during brewery fermentations.

Water uptake in barley grain: Physiology; genetics and industrial applications.

Water uptake by mature barley grains initiates germination and is the first stage in the malting process. Here we have investigated the effects of starchy endosperm cell wall thickness on water uptake, together with the effects of varying amounts of the wall polysaccharide, (1,3;1,4)-ß-glucan. In the latter case, we examined mutant barley lines from a mutant library and transgenic barley lines in which the (1,3;1,4)-ß-glucan synthase gene, HvCslF6, was down-regulated by RNA interference. Neither cell wall thickness nor the levels of grain (1,3;1,4)-ß-glucan were significantly correlated with water uptake but are likely to influence modification during malting. However, when a barley mapping population was phenotyped for rate of water uptake into grain, quantitative trait locus (QTL) analysis identified specific regions of chromosomes 4H, 5H and 7H that accounted for approximately 17%, 18% and 11%, respectively, of the phenotypic variation. These data indicate that variation in water uptake rates by elite malting cultivars of barley is genetically controlled and a number of candidate genes that might control the trait were identified under the QTL. The genomics data raise the possibility that the genetic variation in water uptake rates might be exploited by breeders for the benefit of the malting and brewing industries.

(E)-1-(2,3,6-trimethylphenyl)buta-1,3-diene: a potent grape-derived odorant in wine.

(E)-1-(2,3,6-Trimethylphenyl)buta-1,3-diene (TPB) was identified as a potent odorant in acid hydrolysates of crude glycoconjugate fractions isolated from grapes and grape vine leaves. TPB was also identified in a Semillon wine, using gas chromatography/mass spectrometry, by co-injection with an authentic sample. TPB had an aroma detection threshold of 40 ng/L in a neutral white wine and the concentration of TPB in four out of five white wines analyzed ranged from 50 to 210 ng/L.