Jana Olšovská

The well-known hop variety, Saaz, which gives the Pilsner lager beer its characteristic hop aroma, may be threatened by climate change in the future. Therefore, new Saaz-related hop varieties, including Saaz Late, Saaz Brilliant, Saaz Comfort, and Saaz Shine, were recently bred. A comparison study was carried out to evaluate whether these varieties are acceptable for traditional lagers. For this purpose, sensorial and chemical analyses of hops and related beers, namely, an analysis of hop resins and oils, were performed. Sensory profiles of Saaz varieties are very similar (fine, hoppy aroma; floral; herbal), except for Saaz Comfort, which has a slightly higher aroma intensity, and Saaz Shine, which has the most noticeable fruity scent, with traces of citrus. The chemical profiles are also very similar, with α-humulene, β-pinene, (E)-β-farnesene, β-caryophyllene, and myrcene being the most abundant. Decoction mashing and kettle hopping technology with bottom fermentation show that the compared varieties result in very similar lager beers with hoppy, floral, herbal, fruity, and spicy aromas. Typical hop oils include farnesol, linalool, methyl geranate, β-pinene, and limonene. The high concentration of farnesol in beer correlates with the concentrations of (E)-β-farnesene and farnesol in hops. New Saaz varieties are widely used to produce Pilsner lager without affecting the traditional sensory aroma of this widespread style. Varieties have a higher yield of approximately 25% and bitter acid concentrations of approximately 15%, with Saaz Comfort comprising approximately 100%. Furthermore, the concentration of hop oils is approximately 40% higher in Saaz Shine than a traditional Saaz variety. Moreover, Saaz Shine and Saaz Comfort have very good resistance to drought, which is an important property from a climate change perspective.

The hop variety Saaz is well known over the world and is usually used for brewing of lager beers. Recently, the new related varieties Saaz Late, Brilliant, Comfort, and Shine were registered. Information about these varieties is splintered and often available only in the Czech language in regional journals. This review (i) summarizes previously published data (breeding history, genetic data, basic parameters such as yield, sensory profile, concentrations of key technologically important hop compounds), (ii) presents long-term data (2004–2021), and (iii) shows similarities/differences among these varieties. All Saaz varieties are typically fine aroma hops with a relatively low content of alpha bitter acids ranging from 5 to 7 wt%, cohumulone amounts lower than 30% rel., and hop oil content of about 1.0 wt%. Even though the new varieties have no identical chemical parameters to the original Saaz, they can substitute this established standard as well. Furthermore, the varieties Saaz Comfort and Saaz Shine show high resistance to Pseudoperonospora humuli as well as very good tolerance to drought.

The well-known hop variety Saaz, which gives the Pilsner lager beer characteristic hop aroma may be threatened by climate change in the future. Therefore, new Saaz-related hop varieties, Saaz Late, Saaz Brilliant, Saaz Comfort, and Saaz Shine were bred recently. To evaluate whether these varieties are ac-ceptable for traditional lagers, their comparison was carried out. For this purpose, sensorial and chemical analyses of hops and related beer including namely analysis of hop resins and hop oils were performed. Sensory profiles of Saaz varieties are very similar (fine hoppy aroma, floral, herbal) except for Saaz Comfort which has a little higher aroma intensity, and Saaz Shine which has the most noticeable fruity scent with traces of citrusy of all. Also, the chemical profiles are very close, α-humulene, β-pinene, (E)-β-farnesene, β-caryophyllene, and myrcene are the most abundant. As a result of decoction mashing and kettle-hopping technology with bottom fermentation, are very similar lager beers with hoppy, floral, herbal, fruity, and spicy aromas. Typical hop oils are farnesol, linalool, methyl geranate, β-pinene, and limonene. The high concentration of farnesol in beer correlates with the concentration of (E)-β-farnesene and farnesol in hops. New Saaz varieties are well used for the production of the Pilsner type of lager without affecting the traditional sensory aroma of this widespread style. Varieties have a higher yield and concentration of bitter acids and hop oils. Moreover, Saaz Shine and Saaz Comfort have very good re-sistance to drought, which is an important property from a climate change perspective.

Despite sufficient control of volatile N-nitrosamines in foods and beverages, little attention remained on nonvolatile nitroso compounds, which are mostly unknown and relative to nitrite reactions. In a recent study, new compounds related to reactions of nitrite in beer were pyruvic acid oxime, 4-nitrosophenol, 4-cyanophenol, N-nitrosoproline ethyl ester, nitrosoguaiacol, and 2-methoxy-5-nitrophenol, as well as the already known N-nitrosoproline. The present study is intended to observe their natural occurrence in commercial beers and malts. All 22 nitrite-related products (N-products) were monitored in almost 200 samples of beers and malts. As many as 17 N-products were detected in malts, and all 22 N-products were found in beers. The hierarchical clustering grouped samples based on similarities of detected N-products by frequency of their appearance and level of response. Between N-products and N-nitrosodimethylamine concentrations in malts, only moderate Pearson correlations were found. The same applied to N-product correlations with the apparent total nitroso compound determination in beers.

Climate change can negatively influence hop yield and its quality. Cultivation areas limited by the prohibition of using water from small water sources are most at risk. In order to prevent these areas from completely disappearing in the future, planting hops with varieties or genotypes tolerant to drought could be a promising solution. Therefore, Czech hop breeding targets drought-tolerant genotypes with high crop yield and stability of quantitative and qualitative parameters which will also be well-usable in the Czech brewing industry. Twelve promising genotypes (5165 (Uran), 5194, 5304, 5348, 5398, 5432, 5461, 5464, 5465, 5646, 5669, and 5693) were selected after measurement of their physiological parameters and their basic chemical and sensorial properties were determined. Simultaneously, they were assessed from the point of view of brewing quality using sensory and chemical analysis using a brewing test. For this purpose, experimental beer using identical decoction single-hopped technology, where a hop aroma was highlighted using hopping in a whirlpool was prepared. The results show that three genotypes belong to the category of bitter varieties (5165, 5194, and 5304), whereas the other are genotypes exhibiting the character of aromatic varieties. From a grower’s point of view, genotypes 5165 (Uran), 5194, 5348, 5398, and 5461 show a very high yield. The overall impression of all beer samples is very good, bitterness is fine in most samples and hop aroma is mostly hoppy, herbal, woody, spicy, and in some cases also fruity (5304, 5461, 5465, 5646, and 5693).

Non-microbial beer turbidity of lager beers often indicates a technological problem. Therefore, the occurrence of permanent haze in filtered and stabilized beer should not be underestimated. In this study, practical examples from industrial breweries, where several types of non-microbiological haze of colloidal were identified, are presented. These examples of haze were caused by slightly different factors, and as a result, they had a different microscopic image. It is often accompanied by mechanical impurities and sometimes by microorganisms that function as nucleation centers. Moreover, a very interesting example of almost brilliant permanent beer haze caused by the destruction of yeast cells with the following pouring intracellular contents of cells into beer is introduced. This phenomenon, which could be called “precedent”, was caused by a bad physiological condition of yeasts cells and inappropriately chosen yeast separation technology.

A miniaturized and improved method for Apparent Total Nitroso Compounds determination in liquid matrices was developed. The main improvement is based on a miniaturized and modified apparatus for chemical denitrosation of nitroso compounds by hydrogen bromide in a glacial acetic acid mixture. The reaction is carried out in a teflon reaction coil while the reaction product, gaseous nitric oxide, is drifted to a chemiluminescence detector by the flow of argon together with a vacuum obtained by the detector's oil pump. The apparatus significantly increased the efficiency of the Apparent Total N-Nitroso Compounds determination (compared to the previous method), specifically, the dead volume of the apparatus was significantly decreased, and the effect of the reverse reaction was eliminated as well. The apparatus shortens the analysis time (1.4 min/injection), further it provides a lower detection limit (3 μg(N-NO)/l), quantification limit (10 μg(N-NO)/l), and method uncertainty (15%), and is simpler for the operation.

The effect of nitrites in foods and beverages still raises discussion due to the possible formation of harmful nitroso compounds. However, as most of these compounds in beer were not structurally characterized yet, the research about their toxicological relevance for consumers is limited. This study is focused on identification of the products formed by nitrite (or isotopically labeled nitrite ¹⁵N) reactions in beer using gas chromatography with tandem mass spectrometry. In total, 19 products were identified, and some of them were structurally characterized and confirmed by comparing retention indices and mass spectra of standard/synthesized compounds. Identified compounds were representatives of nitroso, nitro, oxime, and even cyano compounds. For the peaks which were not structurally identified, primary structural characteristics were also listed. Found products were further screened in 16 authentic beer samples which showed the apparent occurrence of found compounds in non-treated beers.

A new simultaneous method for determination of 16 heterocyclic compounds using SPE sample preparation and GC-MS determination was developed regarding increasing interest of the role of sensory active compounds in beer. LiChrolut® EN SPE columns proved to be optimal for both, a mixture of analytes with a different polarity and such complicated matrix as beer. Recoveries of individual analytes are about 100% except for three compounds (2-methylpyridine about 30%, maltol and furaneol about 50%); repeatability, uncertainty and LOQ are satisfactory for the method application. The method was used for monitoring of heterocyclic compounds formation during roasting, mashing, hop boiling and fermentation. To summarize, during roasting of malt, the concentration of oxygen heterocycle compounds (OHC) increases more rapidly in comparison with nitrogen heterocycles compounds (NHC) till a critical point where OHC starts to decrease and NHC starts to be formed sharper (with the exception of 2-acetylpyrrole which is similar to OHC). Finally, the total concentration of NHC during fermentation rapidly decreases whilst the OHC concentration is influenced by many factors, e.g., fermentation conditions and yeast strain.

The dependence of FA profiles in barley and malt on variety and geographical origin using an optimized method was determined. FA profiles from 6 Czech varieties, each from 5 localities during two crop years were studied. The extraction of lipids and FA with hexane by fluidized bed extraction and a hydrolysis of lipids prior to derivatization of FA was used. The statistical processing of FA profiles led to a differentiation of samples; the importance of distinguishing parameters decreases in the order of crop year ˃ geographical origin ˃ variety. Nevertheless, the differentiation of tested varieties using FA profiles coresponds to a varietal pedigree. When the total lipid content was considered, a statistical difference between two varieties (Malz and Sunshine) and two tested localities was found. The profile of FA in barley grains is influenced by the land type and climate conditions. Due to a high level of barley varieties crossbreeding, the chemical profiling of FA is not a reliable tool for a varietal determination, however, it reflects the variety origin.