Alpha-acid Content Research Articles

Evaluation of variability in alpha and beta acid content in European hop varieties (Humulus lupulus L.)

Between 2009 and 2023, European hop varieties were evaluated within genetic resources in the Czech Republic. The objective of this paper was to determine the variability of hop alpha and beta acid contents in the monitored varieties at a single site over the period of fifteen years. At the same time, the trend in which the observed substances decrease or increase was assessed. The lowest average alpha acid content was detected in Strisselspalter (2.96% w/w), while the highest content was found in Herkules (14.03% w/w). The lowest variability in alpha acid content was measured in Vital (14.59%) and Herkules (16.48%). Unlike the aforementioned varieties, Golding exhibits the highest variability (46.28%). All varieties showed a decreasing trend in alpha acid content over the fifteen years of cultivation. Lubelski had the highest decrease in alpha acid content and also showed a high correlation (r² = 0.664). The varieties with the lowest average beta acid content were Celeia (2.77% w/w) and Golding (2.97% w/w). The variety with the highest average beta acid content was Vital (7.30% w/w). All varieties displaied a decreasing trend in beta acid content. Perle had the lowest trend of decrease in beta acid content, while Tradition had the highest trend of decrease. The varieties Strisselspalter, Saaz, Tettnang, Sládek, and Bobek had an alpha/beta acid ratio below 1. However, the variety Bobek showed the highest variability at 32.18%. Herkules had the highest alpha/beta acid ratio (3.20). The most stable alpha/beta acid ratio was found in Marynka (8.41%).

The Expression of Genes Involved in Synthesis of Bitter Acids and Xanthohumol and the Content of These Compounds in Aroma and Bitter Hop under Reduced Nitrogen Fertilisation

Hop (Humulus lupulus) is cultivated for industrial purposes, primarily for brewing, but also for pharmaceutical and cosmetic applications. The hop cones are valued for their secondary metabolites, including bitter acids and prenylflavonoids. The objective of the presented study was to investigate the impact of reducing nitrogen fertilisation on the activity of genes involved in the production of bitter acids and xanthohumol in cultivars Lubelski (aroma) and Magnat (bitter) grown in the field. Furthermore, the content of these compounds was determined. The results demonstrated that the majority of studied genes were expressed at a similar level despite the reduction in the nitrogen dose by 25–30%. Nitrogen dose influenced the activity of genes BCAT2, HS1, and PAL. Moreover, the differences in gene expression were observed between cultivars and developmental stages. The reduction in nitrogen dose did not result in a reduction in secondary metabolite content. The content of alpha and beta acids in Magnat was approximately 14.8% and 3.2%, respectively, while in Lubelski it was approximately 7.7% and 5.8%, respectively. The content of xanthohumol in both cultivars was approximately 0.7%.

Evaluation of the stability of hop pellets subjected to different storage conditions during three years

It is common knowledge that the composition of hops secondary metabolites depends on several factors, among which the storage conditions. In recent years, many studies have been conducted to evaluate changes in the chemical composition of hop products in response to different storage temperatures both in aerobic and anaerobic environments. However, little knowledge exists regarding the storage of hop pellets under modified atmosphere for a very long period of time. The aim of this study is to evaluate the effect on hop quality parameters of different storage conditions on U.S. hop cultivar pellets (Chinook and Nugget) in a three-year trial. Storage in modified atmosphere (atmosphere saturated with 70% nitrogen (N2) and 30% carbon dioxide (CO2) and vacuum storage were tested at two different temperatures, 4 °C and 10 °C. In order to establish the best storage condition, the bitter acids content (HPLC-UV method), the essential oil content (steam distillation method) and the essential oil profile (GC-MS method) were determined and characterised at 0, 6, 12 and 36 months. No statistical differences were observed between samples stored under different atmospheres, while significant differences were highlighted as a result of the storage temperature, e.g. the alpha acids content at 4 °C was significantly higher (P = 0.002). The two hop cultivars showed different behaviours in the storage trial, suggesting that high alpha hop varieties, like Nugget, could be stored even at higher temperatures.

Alpha acids content in Czech hops from the 2023 harvest – forecasts, reality and trends

The most important weather factor for the hop growing season in 2023 was the rainy period in the last decade of July and the first decade of August, which replaced the previously warm and dry weather. Heavy rainfall with a total of 60–100 mm of water and temperatures in the range of 20–25 °C saved the annual hop harvest from the yield decline that occurred in 2022. However, the above-average harvest of nearly 7000 tonnes and a yield of 1.44 t/ha was achieved at the expense of the bitter compound content of most varieties. The alpha acid content of Saaz hops was well below 3.0% w/w in all hop-growing regions, one of the lowest levels for the last 10 years. It is even lower than the extremely hot and dry year 2022 and comparable to 2015. Lower levels of alpha acids were also found in Sládek (4.8–6.7% w/w), Premiant (6.9–7.9% w/w) and Saaz Special (4.3% w/w). The varieties Agnus, Rubín and Vital contained stable amounts of alpha acids in the range of 11–13% w/w, which is about the same as in previous years. The total production of alpha acids in Czech hops from the 2023 harvest was 253 tons, which is average in a longerterm comparison. Saaz hops accounted for only 55% of the total production, although they are grown on 83.3% of the harvest area.

3-year results of hop hybrids testing

Chuvashia has long been the main hop producer in the Soviet Union. Today, the Tsivilsky district of Chuvashia is the northernmost point of the hop breeding process. To revive this crop in the hop farms of the Chuvash Research Institute of Agriculture, the study of hybrids of common hop (Humulus Lupulus L.), grown from seeds obtained from different combinations of varieties of the hop collection of the Chuvash Research Institute of Agriculture is being carried out. The aim of the work is to breed new high-yielding hop varieties of high quality, adapted to the agroclimatic conditions of Chuvashia. The planting of the selection and control nursery was carried out in 2015. The article presents the results of the research for 2020-2022. As a control, 2 varieties were taken. Standard 1 - Podvyazny, has long been the standard in terms of yield, quality, and stability. It belongs to the medium-maturing group of varieties. Standard 2 - Fakir, the best variety of the mid-early group from a series of recently developed varieties. Plants grown from seeds obtained from female plants of Saxon, Marinka, Late Cluster, Porphyry 16 and Plunscher were studied. Male plants of different varieties were used as pollinators by random pollination or by pollen mixture using isolators. A complex of economically useful traits was investigated. The main ones, yield and alpha acid content in cones, are given in the article. Depending on agroclimatic conditions during the years of research, separate hybrid combinations were assigned. Only two combinations - Porfir 16 × SR - 25.3 kg/ha, which showed itself as a medium-ripening variety with an alpha acid content of 5.2% and Saxon × SR - 33 kg/ha - showed itself as a medium-early variety with an alpha acid content of 6.1%. Several combinations also outperformed Podvyazny in some years, either in terms of yield or quality, but there was no consistent outperformance in all three years.

Hop cultivation vs. weather – an eternal theme

The course of weather conditions during the growing season, but also beyond it, decides the economics of hop cultivation every year. Ongoing climate changes manifested by more frequent occurrence of compound hot and dry waves affect hop cultivation not only in the Czech Republic, but in the entire region of Central Europe. The paper evaluates the harvest results (yields, alpha acid content) of four Czech hop varieties in the period 2019–2022 with a focus on the weather diametrically opposed vintages 2021 and 2022 on a specific agricultural farm in the Žatec (Saaz) hop-growing region. While the 2021 vintage was rich in precipitation in the decisive vegetation phase, the 2022 vintage was very dry and hot. The age of the plants significantly influenced the alpha acid content of the varieties Saaz, Sládek and Premiant independently of the vintage. Young growths of the Saaz variety contained at least 60% rel. more alpha acids than older growths (more than 5 years old), while the increase in the Sládek variety was 30–40% rel. and in the Premiant variety 20–25% rel. In the case of the variety Agnus, the age of the plants did not have a demonstrable effect on the content of alpha acids. In 2021 the yields of all varieties were negatively affected by the calamitous occurrence of downy mildew. In 2022, the rainfall deficit was so large that it could not be fully compensated even by the maximum use of drip irrigation. Of the evaluated varieties, the Agnus variety coped best with the different weather conditions of the assessed vintages. This shows that the cultivation of climate resistant varieties is one of the promising but time-consuming ways to face the expected climate changes. Other options include regular renewal of hop growths, consistent regionalization, i.e. planting hop in locations that are suitable for the given variety and efficient use of irrigation systems.

Evaluation of Czech hop varieties (Humulus lupulus L.) in a dry area without irrigation

Since 2017, a field experiment has been conducted in a dry area with 11 Czech hop varieties. The highest yields were achieved by the Uran variety (2.83 t/ha) and Saaz Shine variety (2.76 t/ha), which also exhibited the lowest yield variability, at 11.17% (Saaz Shine) and 12.53% (Uran). The lowest hop yield was recorded by the Harmonie variety (1.17 t/ha), which also showed high yield variability (30.92%). The Bohemie variety had the highest yield variability of hops at 35.26%. While the Gaia (14.66% w/w) and Uran (13.53% w/w) varieties had the highest alpha acid content. Conversely, the Mimosa variety showed the lowest alpha acid content (1.56% w/w) and also the lowest alpha/beta acid ratio (0.29). The Rubín variety reached the highest alpha/beta acid ratio (3.00). The Uran variety exhibited the lowest variability in alpha (6.16%) and beta (6.28%) acid content. In contrast, the Harmonie variety had the highest variability in alpha (59.02%) and beta (38.18%) acid content. The Uran and Saaz Shine varieties are the most suitable for the dry area. Additionally, the Gaia and Saaz Brilliant varieties showed good performance parameters. The hop varieties Vital, Gaia, Saaz Brilliant, and Saaz Shine had the most intense hop aroma, while the Boomerang and Uran varieties had a high intensity of spicy aroma.

COMPARATIVE ESTIMATION OF THE QUALITY OF UKRAINIAN AND EUROPEAN HOP PELLETS

. In Ukraine, hops are basically processed into Type 90 pellets, that are practically indistinguishable in terms of biochemical indicators from hop cones. Pellets of hop are the single domestic source of hop products that can be serve as an alternative to imported pellets and extracts that used in the Ukraine brewing. Comprehensive studies of the evaluation of Type 90 hop pellets of aromatic and bitter varieties produced in Ukraine and European countries allowed establishing that they have different biochemical compositions and consequently, different brewing value. That have been identified differences in the absolute values of indicators such as the mass fraction of alpha acids, beta acids and their composition, xanthohumol, essential oil, the ratio of valuable hop compounds: beta acids to alpha acids and components of the essential oil. It has been determined that in hop pellets of aromatic varieties, the content of alpha acids changing from 3.3% in the Klone 18 variety to 5.9% in the Hallertauer Tradition variety. The content of beta acids, in the investigated pellets, ranges from 3.6% (Klone 18) to 6.7% in the Slavyanka variety. It is established that the hop pellets made from Ukrainian varieties Zagrava and Slavyanka have significantly higher content of beta acid 6.3% and 6.7%, respectively, compared to pellets of foreign varieties. There is a significant advantage in the resin fraction of beta acids over the fraction of alpha acids in the pellets of Slavyanka, Klone 18, Zhatetsky and Zagrava varieties, that they meaning retain a positive coefficient of aromaticity between the content of beta and alpha acids that ranges from 1.18 to 1.37. The content of alpha acids ranges from 8.7% in the Polisky variety to 14.1% in the Magnum variety in the hop pellets of bitter varieties. The content of beta acids in the same pellets ranges from 4.2% to 5.9%. It has been established that the composition of alpha and beta acids in the investigated pellets changes depending on the variety. It has been proven that Ukrainian-produced hop pellets correspond to their international counterparts in terms of their characteristics. Specifically, the biochemical and technological indicators of Klone 18 hop pellets correspond to the characteristics of pellets of the Czech variety Zhatetsky, pellets made from the bitter variety Alta correspond to the biochemical indicators of German Magnum pellets but pellets of varieties such as Slavyanka and Zagrava exceed the world analogies in terms of the composition and quality of bitter substances and essential oil. Based on the comparative biochemical characteristics of Type 90 hop pellets of Ukrainian and European production, the quality of Ukrainian hop products has been found to be at a global level. Certified domestic hop products, specifically Type 90 pellets, can be used do not only by Ukrainian brewers but also by other manufacturers to create new innovative and competitive products with various functional purposes.

Evaluation of variability of the content of alpha and beta acids in Czech bittering hop varieties (Humulus lupulus L.)

Czech bitter varieties were evaluated between 2010 and 2022. Hop varieties displayed an average content of alpha acids between 10.24% w/w (Agnus) and 13.73% w/w (Gaia). Variability below 15%, proved good stability of alpha acids content in all tested bittering hops. All varieties showed a decrease in the content of alpha acids over a period of 13 years of hop cultivation. The highest content of beta acids was determined in Gaia (7.30% w/w). In contrast, the lowest content of beta acids was found in Rubín (3.73% w/w). The new bitter genotypes Uran and 5304 had an average alpha acid content of 11.56% w/w and 10.82% w/w, respectively. Uran showed an average beta acid content of 5.47% w/w and for the genotype 5304 it was 3.61% w/w. In terms of the alpha/beta acids ratio, the hop varieties can be divided into three groups. The first group included the varieties with an alpha/beta acids ratio below 2, i.e. Vital, Boomerang and Gaia. While Agnus and Uran displayed an alpha/beta ratio slightly above 2. The highest alpha/beta ratio above 3 was found in Rubín and the 5303 genotype.

Alpha acids content in Czech hops from harvest 2022 - forecasts, reality and trends

From the brewing and commercial point of view, the content of alpha acids is the most important quality parameter of hops, which is subject to significant annual fluctuations. The established system for evaluating the content of alpha acids in Czech hops consists of pre-harvest and harvest predictions and a detailed analysis of reality based on the analysis of all purchasing lots of raw hops. It is differentiated according to varieties and hop growing areas. This article presents the results of the 2022 harvest, discusses the influence of weather conditions, the age of hop gardens and virus-free seedlings on the harvest results, and the relationship of predictions to reality. The average content of alpha acids in the majority Saaz variety in the Saaz, Auscha and Tirschitz hop growing regions was 2.88, 2.80 and 2.63% by weight in the original respectively. In all areas, the alpha acid content has been significantly affected by the age of the hop growths. Hybrid varieties coped with adverse weather conditions much better than most aromatic hops. The total production of alpha acids in Czech hops from the harvest of 2022 was 182.9 tons, one of the lowest in the last 15 years. It is due to the concurrence of two factors: the low yield per hectare and the content of alpha acids in Saaz hops. The cause was, similarly to Germany, an extreme deficit of precipitation and high temperatures during the vegetation season.

Impact of Temperature on the Bioactive Compound Content of Aqueous Extracts of Humulus lupulus L. with Different Alpha and Beta Acid Content: A New Potential Antifungal Alternative

Hops contain a wide variety of polyphenolic compounds with diverse antimicrobial properties. This study aimed to evaluate the impact of temperature on the bioactive components of samples of aqueous extracts of hops with different characteristics. A central compound rotating design model was used in order to obtain optimal conditions of temperature and extract concentration to inhibit Fusarium oxysporum and Alternaria solani. At intermediate temperatures according to the design of experiments, significant effects on antifungal activity were observed. The optimal conditions with antifungal activity were at a concentration of 160 mg/mL and a temperature of 65 °C to obtain mycelial diameters ≤ 25 mm. The bioactive compounds were shown in the FT-IR spectrum after each heat treatment of both samples; significant changes were observed in the bands between 2786 to 3600 cm−1 and 1022 to 1729 cm−1. The content of total phenols and flavonoids showed a concentration increase of 4.54 to 6.24 mg GAE/g and 6.21 to 8.12 mg QE/g from an initial evaluation temperature of 25 °C to 57.5 °C, respectively, benefited by the heating temperature, enhancing antifungal activity. However, when increasing the temperature ≥90 °C, a tendency to decrease the concentration of bioactive compounds was observed, probably due to their denaturation due to the effect of temperature and exposure time, being non-thermolabile compounds at high temperatures. These aqueous extracts are an alternative to effective natural antifungals.

Evaluation of fine aroma Saaz Shine hop variety

The Saaz Shine variety was registered in 2019. It was tested in two areas, Chrášťany (no irrigation) and Stekník (with irrigation), between 2017 and 2021. An average hop yield in Stekník is 2.62 t/ha and in Chrášťany it is 2.54 t/ha. No conclusive difference in yields was determined. An average content of alpha acids was 4.67% in Chrášťany and 3.18% in Stekník, therefore the content of alpha acids in Saaz from Chrášťany has been proven to be higher than in Stekník. There is a conclusively higher content of essential oils in hops from Chrášťany (0.65g/100 g) than from Stekník (0.34 g/100 g), but the composition of the essential oils is not conclusively different. The aroma of hop cones from both areas is identical. Their moderately intense scent can be described as a fine hop one with a background hint of fruit and citrus.

Evaluation of yield and alpha acid content in selected hop varieties

The stability of the agricultural and technological properties of hop varieties over the course of time and under changing climate is essential for both growers and brewers. This study is a typical case of monitoring 12 hop varieties selected from a collection of hop genetic resources, that were evaluated in the years 2009 to 2021. The assessed parameters were the hop yield and content of alpha acids with a focus on the variability/stability of this characteristics. Only the Pilgrim and Target hop varieties from England showed exceptional hop yield above 3 kg/plant. On the other hand, the lowest hop yield was obtained from the Saaz and Bramling Cross hop varieties, i.e. below 1.5 kg/plant. The lowest variability of hop yield – below 30% – was found in the Savinjski Golding, Bramling Cross and Saaz hop varieties. In contrast, the Bobek, Aurora, Pioneer and Phoenix hop varieties demonstrated the highest variability of hop yield, i.e. above 50%. Further, also Target and Phoenix have the highest content of alpha acids, namely 9.68% w/w and 9.56% w/w, respectively. The lowest content of alpha acids was determined in Saaz, which was the only hop variety with an alpha acid content below 3.0% w/w. The Premiant, Target and Aurora hop varieties exhibited a variability of alpha acid content below 20%. On the contrary, the Bobek and Pilgrim hop varieties had the highest variability of alpha acid content, namely above 30%.

Evaluation of varieties of common hop (Humulus lupulus L.) collection according to agronomic traits

The paper presents the results of 2018-2020 research on the study of 248 Russian and foreign varieties of the collection of common hop (Humulus lupulus L.) in order to identify promising ones with a complex of agronomic traits for developing new varieties adapted to the natural and climatic conditions of the hop-growing regions of the Russian Federation. The research was carried out in the conditions of the Chuvash Republic on dark gray forest heavy loamy soil. Sixty hop varieties in the early-ripening, mid-early and mid-ripening groups with the yields above 26.3 c/ha (weighing more than 3.5 kg of raw cones from one bush) were identified. High-yielding varieties prevailed in the mid-ripening group of the collection (67 %). The adaptability of the collection varieties to natural and climatic conditions was evaluated on the third, fourth and fifth years of the hop plantings (in three tabs). There have been identified six varieties, which in some years of growing exceeded the control variety Podvyazny according to adaptability coefficients (1.23-1.23-1.15): early-ripening English variety Golden Star (1.58-1.37-1.03); mid-early Russian variety Zvenigovsky (1.72-1.16-1.07); mid-ripening Russian variety Serebryanka Kalistovskaya (1.47-1.28-1.17), Guslitsky (1.50-1.26-1.23), Ukrainian Kruglyak-Seryak (1.76-1.44-1.18), Group 4 (1.80-1.80-1.31). The most consistently high results were shown by Group 4, Guslitsky, Kruglyak-Seryak. High-resinous varieties with a high content of alpha acids belonging to different types of hops were noted specifically. According to the complex of agronomic traits and resistance to false powdery mildew, 19 collection varieties have been identified.

Alpha acids content in Czech hops from the harvest of 2021 – forecast, reality, trends

From the brewing and commercial point of view, the content of alpha acids is one of the most important quality parameter of hops, which is subject to significant annual fluctuations. The established system for evaluating the content of alpha acids in Czech hops consists of pre-harvest and harvest predictions and a detailed analysis of reality based on the analysis of all purchasing lots of raw hops. It is differentiated according to varieties and hop growing areas. This article presents the results of the 2021 harvest, discusses the influence of weather conditions, the age of hop gardens and virus-free seedlings on the harvest results, and the relationship of predictions to reality. The average content of alpha acids in the majority Saaz variety in the Žatec, Úštěk and Tršice areas was 4.45, 4.20 and 3.36% by weight in the original respectively. In all areas, the alpha acids content has been significantly affected by the age of the hop growths. The total production of alpha acids in hops harvested in the Czech Republic in 2021 was 414.5 tons. The harvest is the highest in the last 25 years; the result is due to the combination of two factors, both high yield per hectare and high alpha acids content.

Evaluation of resistance to Pseudoperonospora humuli and of the content of alpha acids and hop oils in hops of selected genetic resources of hop Humulus lupulus L.

Twenty hop genotypes were selected for the evaluation of resistance to primary and secondary Pseudoperonospora humuli infection and of alpha acid and hop oil content in the hops. From the wild hop genotypes, two from Canada and one from Belgium showed resistance. Among the registered hop varieties, the Czech varieties Kazbek and Boomerang were the most resistant. Both wild hop genotypes from Canada showed the highest content of alpha acids among the wild hop entries, namely 4% w/w. The lowest variability of the alpha acid content in the wild hop category was found in two wild hop varieties from the Caucasus, one from Austria and one from Lithuania. The highest content of hop oils was determined in two hop genotypes from Canada and two from Belgium. Wild hop genotypes from the Caucasus have the lowest variability of hop oils among the wild hop entries. Two hop genotypes from Canada and one from Belgium were selected for breeding aimed at drought resistance.

Creating a new variety of hop by clone selection method

The article presents the results of breeding work for the creation of new high-yielding varieties of bitter-aromatic hops with a high content of alpha-acids carried out in 2004-2020 in the Chuvash Republic on gray forest soils. The work was done by individual clonal selection of the best hop plants from the collection nursery. Seven high-yielding breeding numbers with a high alpha-acid content were selected from the collection nursery. After passing through all the stages of study in each of the appropriate nurseries from seven numbers, two clones were selected to create new varieties. Data were obtained on the parameters of the initial clonal breeding material, depending on weather conditions and the age of plantings. The selected clones (1-17 bitter-aromatic type and 6-26 bitter type) correspond to the specified indicators: collection of raw hops is not less than 4.0 kg from a bush, the duration of the growing period is 100-120 days, the content of alpha acids is not less than 5.0 %. Documentation on clone 1-17 was sent to the State Variety Commission for registration of a new variety Salampi. The variety is characterized by stable performance and quality indicators. The productivity of the variety is 30.0 c/ha (4.0 kg/bush) with a content of alphaacids of 9.3 %. The Podvyazny standard variety has 26.4 c/ha (3.5 kg/bush), the content of alpha-acids is 8.8 %. Testing of clone 6-26 will be continued to obtain complete and objective data.

Evaluation of Czech hop varieties

Czech hop varieties are evaluated as part of maintenance breeding. Every year, this evaluation includes ten mother plants of each hop variety. Yield is determined in kilograms of fresh hops per plant. The t-test is used to determine significance. Results from the years 2014–2019 show that Gaia and Kazbek have the highest yield (3.17 kg/plant and 3.05 kg/plant, respectively). Their yield is higher than that of the Harmonie, Agnus, Bohemie, Premiant, Sládek, Boomerang and Saaz varieties. Saaz has the lowest hop yield, i.e. 1.85 kg/plant. Bor, Saaz Late, Saaz and Sládek show the lowest variability, which ranges between 20.56 and 20.58%. Gaia has the highest variability (34.33%). Gaia also has the highest alpha acid content (12.30%) with a probability of 95% to 99%. Vital and Boomerang have a higher alpha acid content than other Czech hop varieties (11.09% and 10.81%, respectively) with a probability of 99%. Saaz Late (3.42%) and Saaz (3.06%) have the lowest alpha acid content with a probability of 95% to 99%. The variability of alpha acid content is considerably lower than the hop yield variability. Rubín has the lowest year-on-year variability of all Czech varieties (4.81%). Vital and Gaia have a very low variability (5.63% and 5.72%, respectively). A higher variability of alpha acid content was found in Saaz Late, Premiant, Agnus, Saaz, Kazbek, Bor and Harmonie, ranging between 8.01% and 10.21%.

Efficiency of hop (Humulus L.) growing without cutting of main roots depending upon the underground plant part.

Cutting of main roots in the hop cultivation process is one of the most energy-intensive agrotechnical operations. And it is necessary to execute it in a short time during spring work. The purpose of this research was to determine the efficiency and influence of hop growing without cutting of the main roots in different development terms of shoots in the underground plant part during the spring period on the forming of the yield, cones quality and sparing of human labor and production costs. Research methods used were: field tests, laboratory tests, statistic analysis methods. Resultsof the scientific research proved the possibility of hop growing without cutting of the main roots in conditions of the Ukrainian Northern forest-andsteppe and Polissia zone. It was stated, that the highest broken of shoots percentage (86.9– 88.5%), which enhances yield +0.9 metric Centner from hectare, or +4.3% in comparison with the traditional technology, was recorded in the variants with uncut roots during the spring period until their appearance on the soil surface with the length of 3–5 cm. In the variants with uncut roots with the presence of eyes in the underground plant part and shoots which spread on the soil surface, the percentage of broken off shoots reached 20.0–26.5, and in this case caused the yield reduction of 1.0–1.8 metric Centner from hectare, or by 4.8–8.6% lower than in the control field. Alpha acids content in the hop cones in all given variants was practically identical and made 5.1–6.0%. Calculation of economic efficiency demonstrated, that hop growing technology without cutting of main roots offers the possibility to cut down the time limits (terms) used for this operation, spare human labor by 170 worker/hours and receive pure profit of 6.4 thousands Ukrainian Hryvnia for 1 Ha of hop garden, without losses in quantity and quality of hop cones. It is economically profitable to grow hops without cutting the main roots in comparison with the traditional hop growing technology.

BIOTECHNOLOGY OF PRODUCTION OF YEAST-FREE BREAD USING THE LOCAL STREPTOCOCCUS THERMOPHILUS STRAIN BREEDED BY GORSK GAU AND WILD HOP IN RNO-ALANIA

The modern food industry offers the consumer bread baked with sourdough using various biologically active components of plant origin. In the production of yeast-free bread, it is advisable to use a sourdough from biologically active strains of Streptococcus thermophilus selected by the Gorsk State Agricultural University. The authors have compiled a starter culture from local strains of lactic acid microorganisms selected by the Research Institute of Biotechnology of the Gorsky State Agrarian University. Research was carried out at the Department of Biological and Chemical Technology of the Gorsky State Agrarian University. We also used cones of wild-growing hops from the botanical garden of the Gorsky State Agrarian University in order that the bitter acids present in the hops suppress the putrefactive microflora, do not have a detrimental effect on local strains of lactic acid microorganisms and allow increasing the productivity of the hop starter culture. Yeast-free bread is easily absorbed by the body, does not harm the intestinal microflora, retains useful properties during storage. The flour used in the experiment met the requirements of GOST 26574–85. When using wild-growing hops in the production of bread, useful substances included in its composition were determined that could increase the quality and safety of bread. The content of alpha acids was 6.0%, and that of essential oils was 0.7%, which corresponds to GOST 32912–2014. We used two strains of a lactic acid microorganism of local selection – Streptococcus thermophilus. Hops were extracted for 30 min at a temperature of 96 °C. Laboratory baking of bread was carried out in accordance with GOST 27669–88. Studies have shown that bread prepared using a local strain of Streptococcus thermophilus selected by the Gorsky State Agricultural University and wild-growing hops is of high quality.