Sensorial behavior of beer is influenced by the hop variety. In our study, the sensory profile of kettle and kettle+dry single hopped beers from different hop genotypes and an impact of dry hopping on the beer sensory and volatiles profile was investigated. Pilot brews (50L) of 12 % pale lager were prepared in kettle and kettle+dry variants using 7 new Slovenian, 4 Czech varieties and American variety Citra as control. Using GC/MS method, essential oil composition in hops and beers was accessed in order to clarify links to the beer sensory profile both in kettle and dry hopping mode. To determine the sensory quality of beer, descriptive and bitterness lingering assessment methods were employed. Changes in the essential oils and aroma profile after three months of storage were evaluated. Results showed differences in the hop oils profile in kettle hopped beers among genotypes. In the case of dry hopping, the monoterpene alcohols (r=0.60) and monoterpene hydrocarbons (r=0.74) content in beer increased, in dependence on the dose in hops. Hoppy flavor correlated with monoterpene alcohols and hydrocarbons in beer. Dry hopped beers tended to higher bitterness aftertaste compared with kettle hopped beers. Both, kettle and dry hopped beers of all genotypes showed good sensory acceptance (3 - 4.5; 9 points scale). After 3 months of storage, the content of most beer volatiles decreased by several tens of percent, it was reflected by significant decrease of the hoppy flavor. Sensory aging of kettle and dry hopped beers was comparable.
Linalool, an important substance in hoppy, aromatic beer, is one of the most aromatic components of essential oils in hops. Linalool concentration, among those of other substances, could be used to distinguish among hops varieties. As such, an effective, repeatable, and high-through put method is required; a new method based on fluidized-bed extraction combined with detection by gas chromatography-mass spectrometry was developed and is presented in this study. This method is faster than the reference method, which uses steam distillation; it also reduces the possibility of thermal changes. Because this method saves organic solvent, energy, and sample amount, it can be considered a green method. Good repeatability of the method (8.0 mg/kg) was achieved with 3-hepten-1-ol as an internal standard. The detection limit of linalool is 1.0 mg/kg, and the limit of quantification is 3.5 mg/kg. Good agreement was achieved between the results of the new and steam-distillation methods. In addi%tion, 59 samples of hops from four important Czech varieties (Agnus, Premiant, Saaz, and Sládek) from the 2013 harvest were analyzed, and the content of linalool was correlated with the content of bitter acids in xyz 3-D projection; four separate and clearly limited clusters that corresponded to the four tested varieties were obtained.
COBISS.SI-ID: 3961132
One of the common and efficient cost reduction measures in the industrial scale is serial repitching of the yeast biomass, which has not been studied for the buckwheat and quinoa beer fermentation before. In that manner we have monitored possible changes in yeast's proteins and chromosomal DNA during eleven serial repitchings of the yeast Saccharomyces pastorianus strain TUM 34/70 for fermentation of the barley, buckwheat and quinoa wort. Karyotypes showed changes in regard to the raw materials used and many responsible candidate proteins are suggested which could cause these differences. Different relative expression of some protein bands was also linked to the proteins involved in yeast stress response and proteins involved in fermentation performance. Results suggest that serial repitching of the strain TUM 34/70 seems suitable for the production of gluten-free beer-like beverages from buckwheat and quinoa.
COBISS.SI-ID: 650380
This research was aimed to prepare bottom-fermented beverages from the buckwheat and quinoa grain and explore their physical, chemical, and sensory properties. Compared to barley, the analysis of brewing attributes of buckwheat and quinoa showed lower malt extract, longer saccharification time, higher total protein and fermentable amino nitrogen content, and higher values of iodine test and color of buckwheat and quinoa. The fermentability values, the wort pH and the soluble protein content is similar for barley and buckwheat but different for quinoa. Both beverages, especially the quinoa beverage, contained a superior level of metal cations. The profile of volatile compounds commonly associated with beer aroma was comparable between the barley and buckwheat beverage but significantly lower in quinoa. The latter contained some distinctive volatile substances not found in other beverages. The organoleptic perception of the buckwheat beverage was better than that of the quinoa, although both showed a good general acceptance. In general buckwheat is similar to typical barley whereas the quinoa shows many unique properties.
COBISS.SI-ID: 652172