Breweries are exporting their brands overseas, resulting in an increasingly competitive and globalised beer market. Inevitably, the beer experiences varying and prolonged periods of transport and storage prior to consumption. During this process, the flavour of fresh beer deteriorates, leading to the presence of stale flavours and a decrease in the drinkability of the beer. Results reported here show that an increased temperature during beer transport and storage causes significant flavour deterioration, as determined analytically (increase in aldehydes, beer colour and haze formation, decrease in iso-α-acids concentration) and sensorially (increase in overall aging score). Further, laboratory experiments show that the vibration of beer results in a rapid decrease of oxygen. Moreover, inappropriate storage temperature has a negative effect on beer quality and stability, in particular when combined with vibration.For the same beer (X, Y or Z) different letters in superscript represent a significant difference (α = 0.05); SD: standard deviation; n = 3. B. Jaskula-Goiris et al.

In this study, headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were optimized and implemented to investigate the volatile composition of novel floral hop essences prepared from four German aroma hop varieties. In total, 91 different constituents were assigned, which were further grouped into monoterpene hydrocarbons, esters, ketones, aldehydes, furans, and oxygenated and nonoxygenated sesquiterpenes. Most volatiles belong to the ester group, whereas the monoterpene hydrocarbon β-myrcene appears to be the predominant compound in all hop oil preparations investigated. Furthermore, as demonstrated by principal component analysis, varietal floral hop essences are clearly discriminated on the basis of their characteristic volatile composition. Via GC-olfactometry on the floral essence variety Spalter Select, β-myrcene and 2-undecanone were identified as the most potent odorants. Several hop oil constituents were reported for the first time as impact odorants of hop aroma.

BACKGROUND: Beer flavor stability is important to brewers as a result of the increased global demand for beer. Increasing export leads to prolonged periods of transportation and storage and causes fresh flavor deterioration. Therefore, the present study examined the effect of different temperatures in combination with vibrations on beer quality. Beer was exposed to vibrations (50 Hz, 15 m s −2 , simulating transport) at 5, 30 and 45 ∘ C for 22, 38 and 90 h and (for half the samples) aged for 60 days at 30 ∘ C. RESULTS: The results obtained indicated decreased oxygen concentrations as a result of an elevated temperature and vibrations.There was no effect (P > 0.05) on color and a limited effect of temperature and vibrations on iso--acids. The parameters temperature and vibrations have a significant influence (P < 0.05) on aldehyde concentrations, namely total aldehydes, and especially '2-methylpropanal', '2-methylbutanal' and 'furfural'. CONCLUSION: The impact of vibrations on the aldehydes concentrations was substantial when subjected to an elevated temperature. Furthermore, a forced aging test of shorter duration than traditional methods might be developed.

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