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Basar P.,Food Republic | Von Rege H.,Food Republic | Kosar K.,Research Institute for Brewing and Malting | Sachambula L.,Research Institute for Brewing and Malting | Kubizniakova P.,Research Institute for Brewing and Malting
BrewingScience | Year: 2014

One of the long term issues the malt producers and brewers deal with is contamination of barley and malt with Fusarium mould. Fusarium sp. contributes to beer gushing, formation of red grains, production of several carcinogenic toxins and other negative phenomenons. Different methods are used to reduce Fusarium sp. growth but none of them is fully effective. This presentation describes a concept with Chlorine dioxide (ClO2) added during steeping and germination of barley. Laboratory, semi industrial as well as industrial trial proved functionality of ClO2 application on malt during steeping and germination to push back Fusarium sp. Particularly, use of chlorine dioxide during germination was found to have most impact on controlling Fusarium growth. This application has also positive impact on gushing, red grains and it does not influence quality of the produced malt. No residues of ClO2 and its by-products were found in the malt and there were no quality changes in the wort produced from malt treated with ClO2. Source


Dusek M.,Research Institute for Brewing and Malting | Olsovska J.,Research Institute for Brewing and Malting | Krofta K.,Hop Research Institute Co. | Jurkova M.,Research Institute for Brewing and Malting | Mikyska A.,Research Institute for Brewing and Malting
Journal of Agricultural and Food Chemistry | Year: 2014

Hops represent an important source of β-acids with antimicrobial and sensory properties. Transformation products of β-acids formed during their oxidation, mainly hulupones, have been shown to have an interesting kind of bitterness. Their structures were recently elucidated using LC-TOFMS and 1D/2D NMR in solution after thermal treatment of the hop β-acids. This study demonstrates the advantages of MS detection with high resolution and accurate mass measurements. The structure of transformation products in an experimental solution of oxidized β-acids was elucidated using a newly developed method by hybrid quadrupole-Orbitrap MS. In addition to already known structures, two new ones were identified and named epoxycohulupone and epoxyhulupone. The method was verified on real samples; the profiles of these products in Sládek hops harvested in 2008 and 2012 and in corresponding beers were compared. For this purpose, a new QuEChERS assay was used for the preparation of beer samples. © 2014 American Chemical Society. Source


Dusek M.,Research Institute for Brewing and Malting | Jandovska V.,Research Institute for Brewing and Malting | Jandovska V.,Charles University | Cermak P.,Thomayers Hospital Videnska | And 2 more authors.
Talanta | Year: 2016

The phenolic compounds, secondary metabolites of hops represent a large family of compounds that could be subsequently divided into smaller groups based on the similarities between their chemical structures. The antibacterial, antifungal and antiviral properties of hops are well known, but there is a lack of information about antimicrobial activities of individual hop compounds. This study was carried out with an objective to identify compounds present in hops that have potential antibacterial activity. In the first stage of experiment, the active compounds with potential anti-microbial activity had to be extracted from hop cones. Therefore, minced hop cones were applied on solid growth medium inoculated with Staphylococcus aureus. The active substances that migrated into the medium created an inhibition zone. In the second stage of experiment, the inhibition zones were cut out from Petri dishes, active compounds were extracted from these zones and consequently analyzed using LC-HRMS. These complex assays were developed and optimized. The data were acquired by using a quadrupole-orbitrap hybrid mass spectrometer by targeted-MS2 experiment in both ionization modes. The MS method has been developed as a screening method with a subsequent fragmentation of compound of interest on the base of inclusion mass list. The unknown compounds extracted from inhibition zones have been identified either by searching against a database or their structure has been elucidated on the basis of their fragmentation spectra. On the basis of this experiment the list of active compounds with potential anti-microbial activities was enhanced. © 2016 Elsevier B.V. All rights reserved. Source


Jurkova M.,Research Institute for Brewing and Malting | Cejka P.,Research Institute for Brewing and Malting | Sterba K.,Research Institute for Brewing and Malting | Olsovska J.,Research Institute for Brewing and Malting
Food Analytical Methods | Year: 2014

Beside ethanol, carbohydrates are the main source of total energy in beer. While analyses of fermentable carbohydrates are important from the technological point of view, the total content of carbohydrates is relevant in terms of nutrition. A high-performance liquid chromatography (HPLC) method with refractometric (RI) detection was developed for determination of total carbohydrate content in beer. Using enzymatic reaction with amyloglucosidase, the carbohydrates were cleaved to yield glucose and short glucose oligomers of less than 10 units, and separated on HPLC ion exchanger Rezex RSO-Oligosaccharide column in Ag+ mode. Optimum parameters were established for the enzymatic sample treatment and for the HPLC separation of reaction products. Calibration curves of glucose, fructose, maltose and simultaneously analyzed glycerol ranged from 0.001 to 0.5 g/100 ml, correlation coefficients of all calibration curves were 0.9999. The instrumental limits of quantification were 0.001 g/100 ml and they were verified using repetitive injections, with coefficient of variation (CV) less than 10 % in five replicates. The method limit of quantification was 0.01 g/100 ml since it was necessary to dilute the beer samples before chromatographic analysis. Recovery of the method in non-alcoholic and alcoholic beer was 98.5 %, and 92.3 %, respectively. Finally, ten non-alcoholic and 15 alcoholic beers from Czech market were analyzed using the method, the average content of total carbohydrates in non-alcoholic and alcoholic beers being 4.21 and 3.70 g/100 ml, respectively. These results are in a good correlation with the real extract of beer, which is on average 4.58 and 4.27 g/100 ml. © 2014 Springer Science+Business Media New York. Source


Cejka P.,Research Institute for Brewing and Malting | Culik J.,Research Institute for Brewing and Malting | Horak T.,Research Institute for Brewing and Malting | Jurkova M.,Research Institute for Brewing and Malting | Olsovska J.,Research Institute for Brewing and Malting
Journal of Agricultural and Food Chemistry | Year: 2013

The rate of beer aging is affected by storage conditions including largely time and temperature. Although bottled beer is commonly stored for up to 1 year, sensorial damage of it is quite frequent. Therefore, a method for retrospective determination of temperature of stored beer was developed. The method is based on the determination of selected carbonyl compounds called as "aging indicators", which are formed during beer aging. The aging indicators were determined using GC-MS after precolumn derivatization with O-(2,3,4,5,6- pentaflourobenzyl)hydroxylamine hydrochloride, and their profile was correlated with the development of old flavor evolving under defined conditions (temperature, time) using both a mathematical and statistical apparatus. Three approaches, including calculation from regression graph, multiple linear regression, and neural networks, were employed. The ultimate uncertainty of the method ranged from 3.0 to 11.0 C depending on the approach used. Furthermore, the assay was extended to include prediction of beer tendency to sensory aging from freshly bottled beer. © 2013 American Chemical Society. Source

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