Raw materials

Hard resins – components of brewing value

Research carried out between 2003 and 2009 showed a certain trend that the ratio of hard resins to alpha acids increases with increased quality of bitterness. The lower the ratio, the higher the alpha acid content and the lower the content of hard resins, resulting in a harsher bitterness. Based on these analyses, the author Jens Eiken proposes a new method of classifying hops which also regards different hop products and hop varieties as well as the time of addition.

Raw materials

High quality malting barley – advances in breeding

High quality malting barley has been enhanced through advances in barley breeding to create a superior product for the premium market. However, general appreciation for this product is lacking. This plays a role in judging its value and therefore its price acceptance in commercial trading. From the current perspective, it appears that the long years invested in breeding malting barley have apparently not paid off.

Raw materials

Ten steps for planning a brewery renovation or expansion project

Demands on modern breweries are in a constant state of flux as a consequence of scientific advances and fluctuations in growth. Obsolete equipment is replaced with new technology, batch sizes are modified and processes optimized. These changes underscore the need for realistic and future-oriented planning. Of course, there are experts who specialize in planning and designing breweries. Nonetheless, it is always a good idea to devote some time to deliberation on the matter before consulting equipment manufacturers and engineers.

Raw materials

It is not possible to produce hops without using plant pesticides. Already in spring, German hop growers have to face pests which populate the hop plants and the fresh shoots. The pests are able to cause serious damage.

Hopsteiner

In order to produce beers with a unique character that can easily be distinguished from other brands, brewers worldwide depend more and more on new and special varieties. Bravo has been proven in commercial production for several years, and the brewers’ feedback has been enthusiastic.

Raw materials

The use of wheat bran as a new adjunct in brewing at 25 % of total grist in combination with the use of a xylanase in the mashing step was tested by brewing control and bran-brewed lager beers. Sensory analysis revealed marked improvements in taste profile due to bran-brewing, with statistically significant increase in body, smoothness and warming notes, and a decrease in acetaldehyde, after-bitterness, drying and grainy attributes. A detailed physico-chemical analysis of the beers was performed. Key parameters on which a significant impact was demonstrated include increased content of arabinoxylan-oligosaccharides (AXOS), ferulic acid, and soluble protein, and lowered content of aldehydes, the latter indicative of reduced oxidation during brewing..

Raw materials

The oxygen permeability of PET bottles has a significant influence on the shelf-life of beverages that are sensitive to oxygen. To reduce the permeability, PET is blended with barrier materials like MXD6 (MXD6 is a mainly aliphatic polyamide resin which contains meta-xylylene groups). The aim of this study was to investigate the temperature dependence of oxygen permeation through PET/MXD6 blends. The oxygen content inside water-filled PET/MXD6-blend bottles with 2, 5 and 8 % wt. of MXD6 was determined at 5, 23, 38, and 55 °C. The MXD6 was applied both purely and with a catalyst that is enabling it to work as an oxygen absorber. The results were compared to PET bottles not containing MXD6. The oxygen partial pressure inside the bottles was measured as gaseous oxygen using an optical-chemical sensor. The activation energy of oxygen permeation was calculated to be in the range from 32.8 kJ/mol for PET bottles without MXD6 and up to 43.4 kJ/mol for PET bottles with 8 wt-% for the passive barrier of MXD6. In the barrier PET bottles with MXD6 in combination with a catalyst, the oxygen content in the water-filled PET bottles remained up to 0.2 mg O2/L dissolved oxygen for a period of 6 months, depending mainly on the MXD6 concentration. This range was consistent for all applied temperatures. These data serve as a basis for the prediction/calculation of oxygen permeability of PET barrier materials at different temperatures and further for developing a standardization of oxygen absorber characterization concerning absorber kinetics and oxygen barrier.

Raw materials

The screening of styrene concentrations during different stages of wheat beer production shows that in opposite to thermal processes like mashing and wort boiling the primary and secondary fermentation contribute most to the styrene content in final beers. Therefore, the enzymatic decarboxylation of cinnamic acid by brewers’ yeast is the predominant kind of reaction. Styrene concentrations in bottled beer were up to 25 ppb. In addition, the results of the screening were compared with the precursor concentration of cinnamic acid in the corresponding pitching wort. A linear correlation could not be found. Moreover, the influence of various manufacturing considerations like the kind of fermentation or the ratio of wheat grist load is shown..

Raw materials

Complex lupulin gland-specific cDNA library from Osvald’s clone 72 hop was constructed to dissect regulation of biosynthetic pathway(s) leading to the accumulation of hop bitter acids and prenylflavonoids with promising health-beneficial activities. From this cDNA library we isolated first hop-specific allelic isoforms of transcription factors (TF) bHLH (HlbHLH2, GeneBank AC:FR751553) and WD40 (HlWD40_1, AC:NM_122360) which are involved in combinatorial control of light-responsive and tissue-specific activation of phenylpropanoid pathway. HlbHLH2 and HlWD40_1 are quite lupulin gland-specific and, according to our transient expression experiments, they form specific complexes with another novel hop TF HlMyb2 (AC:FN646081) and previously isolated lupulin gland-specific HlMyb3 (AC:AM501509)..

Raw materials

The quantification of trace substances in raw materials, mash, wort and beer is becoming more frequently required by brewers. Stable isotope dilution assay (SIDA) coupled to gas chromatography mass spectrometry or liquid chromatography mass spectrometry instrumentation is a sensitive and highly specific technique for precise quantification of trace substances from complex matrices. The current paper elucidates the basic principles of stable isotope dilution assays and presents practical applications related to brewing. It emphasizes the importance of isotope standards in multi-step sample clean-up procedures and answers the question why SIDA is (so far) not widely used in brewery quality control.

BrewingScience - Monatsschrift für Brauwissenschaft, 64 (November/December 2011), pp. 140-150

Raw materials

It is generally recognized that flavour quality and flavour(in)stability cannot be grasped by one parameter, since the multitude of flavour chemicals involved. To identify beer chemistry changes during staling in commercial pilsner beer, an integrated analytical-sensorial methodology using multivariate statistical analysis was applied on samples subjected to ageing at 30 °C. Application of this technique to model the taste(in)stability in an objective way, offers the opportunity to more thoroughly investigate the influence of raw materials, brewing methods and applied technologies on flavour stability. The models obtained showed differences in aging behaviour of six commercial pale lager beers..