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Pavlovic M.,Slovenian Institute of Hop Research and Brewing | Cerenak A.,Slovenian Institute of Hop Research and Brewing | Pavlovic V.,University of Maribor | Rozman C.,University of Maribor | And 2 more authors.
Computers and Electronics in Agriculture | Year: 2011

Hops (Humulus lupulus L.) essentially contribute to the quality of the taste of beer and its flavor. Experimental hop breeding data from the Slovenian Institute of Hop Research and Brewing were used to create a model of an expert system based on the multi-attribute decision modeling methodology DEX. The DEX-HOP 1.0 model assessed and ranked individual hop hybrids' and hop varieties' breeding potential to be assessed and ranked. The model has 18 attributes, hierarchically grouped within four main attributes: Biology, Chemistry, Morphology and Brewing value. Furthermore, utility functions in the model were defined by sets of elementary decision rules throughout the entire hierarchy for all aggregated attributes. The central part of the model contains 144 decision rules, which were specified according to the model users' previous breeding experiences. Four Slovenian hop hybrids, A1/54, A2/104, A3/112 and A4/122, and a reference hop variety Hallertauer Magnum with the target characteristics of plant resistance and brewing value were used for the model assessment. Based on the breeding experiences and model results, overall and individual attributes' assessments were carried out. A3/112 and A4/122 reached the overall level of the reference variety and were thus assessed as appropriate for further breeding. In contrast, the attributes of A1/54 and A2/104 did not meet expectations in relation to the reference variety. Decisions based on the DEX-HOP 1.0 model assessment offered an additional tool for experts' final decisions in selecting appropriate materials for further breeding or the commercial use of hop plants. Test results validate the application of the model for further research. © 2010 Elsevier B.V.


Hrastar R.,Slovenian Institute of Hop Research and Brewing | Abramovic H.,University of Ljubljana | Kosir I.J.,Slovenian Institute of Hop Research and Brewing
European Journal of Lipid Science and Technology | Year: 2012

Camelina sativa is an alternative, low input oilseed crop with oil of high nutritional value. In Slovenia, C. sativa landrace has been grown by local farmers in the Koroška region since the middle of the 20th century. In our study, we determined oil and glucosinolate content (GLS) of camelina seed and free fatty acid (FFA), peroxide value (PV), iodine value (IV), tocopherol contents (T), and fatty acid profile of camelina oil from ten locations over three consecutive growing seasons. The oil content ranged from 28.78 to 40.21%, while IV, PV, and FFA fell into a range that makes this oil useful in various nutritional applications. Camelina was remarkably rich in essential n-3 α-linolenic acid (33.32-37.65%) and γ-T (532-798mg/kg) in oil, and GLS (16.39-41.43μmol/g) in seed. Due to observed variability, it seems that the seed and oil characteristics of C. sativa landrace are affected by the local environmental conditions at a specific farm location and by variable genotypes between farms as a result of a more than half a century of environmental selection. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Feeding of cabbage flea beetles on various Brassica species can reduce crop productivity. While progressing towards the goal of reducing the use of synthetic pesticides and promotion of environmental protection, we wish to exploit plants' natural resilience. The results of our study carried out in 2009-2010 show that glucosinolate contents vary with plant species and plant organs. Among the indole glucosinolates, all Brassica species (cabbage, oil radish, oil seed rape and white mustard) displayed the presence of glucobrassicin, whose influence on cabbage flea beetles varied according to the plant species. We established that gluconasturtiin content in oil seed rape negatively (r = -0.99) influenced the feeding of flea beetles, while the progoitrin (r = 0.51), sinalbin (r = 0.61) and gluconapin (r = 0.67) stimulated the feeding of flea beetles in this crop. No significant influence of glucobrassicin on flea beetles was detected in oilseed rape, while this glucosinolate negatively influenced the intensity of flea beetles feeding in oil radish and white mustard (r = - 0.32, r = - 0.64). Oil radish thus proved to be the most suitable species as a trap crop for flea beetles. We conclude that protection of the Brassicas against flea beetles can depend on glucosinolate content, but additional tests to confirm practical meaning of this study in environmentally acceptable cabbage production are required.


Terpinc P.,University of Ljubljana | Ceh B.,Slovenian Institute of Hop Research and Brewing | Ulrih N.P.,University of Ljubljana | Abramovic H.,University of Ljubljana
Industrial Crops and Products | Year: 2012

In this work, quantitative correlations between the antioxidant properties and the total phenolic content (TPC) of different oil cake extracts were studied. The oil cakes from camelina (. Camelina sativa), linseed (. Linum usitatissimum), rapeseed (. Brassica napus), and two varieties of white mustard (. Sinapis alba) were analysed as potential sources of antioxidant compounds. Two solvents of different polarity were used to obtain the extracts, resulting in great variation in antioxidant activity. The highest phenolic content was observed for white mustard, followed by camelina, rapeseed and linseed. The antioxidant properties were evaluated by determination of their reducing capacity, free radical scavenging activity and metal chelating ability, by the β-carotene bleaching method and as the effectiveness of inhibition of conjugate diene and triene formation in the bulk oil. The methanolic extracts exhibited higher reducing power (max. rapeseed), 2,2-diphenyl-1-picrylhydrazyl (DPPH·) scavenging activity (max. rapeseed) and chelating ability (max. linseed), while the ethanolic extracts were more efficient in the β-carotene bleaching test (max. camelina). White mustard extracts inhibited conjugate diene and triene formation the most. These various antioxidant activities were compared to the synthetic antioxidant butylated hydroxytoluene (BHT). A lack of positive correlations among the different antioxidant activity assays and total phenolic contents was observed. © 2012.


Lavrencic A.,University of Ljubljana | Levart A.,University of Ljubljana | Kosir I.J.,Slovenian Institute of Hop Research and Brewing | Cerenak A.,Slovenian Institute of Hop Research and Brewing
Journal of the Science of Food and Agriculture | Year: 2014

BACKGROUND: Hop cones contain several antimicrobial substances. The aim of the study was to determine the effects of two hop varieties, Aurora and Dana, on substrate (diet for a dairy cow, producing 30 kg milk daily) in vitro dry matter (DM) and crude protein (CP) degradability and digestibility. RESULTS: In the in vitro trial freshly ground hops were added to the buffered rumen fluid in concentrations simulating the cow's daily intake of 50, 100 and 200 g of hops. Increasing the concentration of hops decreased (P < 0.05) both the average in vitro DM degradabilities of substrate from 725 to 592, 553 and 481 g kg-1, respectively, and in vitro CP degradabilities of substrate from 752 to 566, 561 and 478 g kg-1, respectively. The reduction of in vitro DM and CP degradability is counterbalanced by the (invariable) in vitro DM and CP digestibility. The difference between CP digestibility and degradability represents an estimate of the amount of rumen 'bypass' protein which increased with increasing concentration of hops from 172 to 454 g kg-1. CONCLUSIONS: Decreased DM and CP degradability and increased amount of rumen 'bypass' protein could lower the amounts of protein required by high-producing ruminant animals. However, this supposition needs a validation with in vivo trials. © 2013 Society of Chemical Industry.


Bohinc T.,University of Ljubljana | Hrastar R.,Slovenian Institute of Hop Research and Brewing | Kosir I.J.,Slovenian Institute of Hop Research and Brewing | Trdan S.,University of Ljubljana
Acta Scientiarum - Agronomy | Year: 2013

In 2010, we were determining the contents of glucosinolates in different Brassicas in order to study their influence on feeding of cabbage stink bugs (Eurydema spp.) and the consequent extent of damage. We confirmed that glucosinolates content depends on plant species, plant organs and the time of sampling. In the samples aliphatic glucosinolates (glucoiberin, progoitrin, epiprogoitrin, epiprogoitrin, sinigrin, gluconapin, glucoraphenin, sinalbin) prevailed. Glucobrassicin, an important indolic glucosinolate compound, was detected in all tested Brassicas. Its concentration in the oil radish samples was highest during the first assessment (30 DAS), 8.84 ± 0.65 μmol g-1 ds, while the oilseed rape samples displayed lowest concentration during the last assessment (134 DAS), 4.30 ± 0.80 μmol g-1 ds. The stimulative activity of individual glucosinolates or their negative influence on feeding of cabbage stink bugs in the Brassicas used in our experiment was not uniformly manifested. Based on a two-year field experiment we concluded that oil rape was the most adequate trap crop used to allure cabbage stink bugs. In future, glucosinolates should be employed to a greater extent in environmentally acceptable ways of food production, one of which is also the use of trap crops in order to reduce harmful effects of cabbage stink bugs.


Rojht H.,University of Ljubljana | Kosir I.J.,Slovenian Institute of Hop Research and Brewing | Trdan S.,University of Ljubljana
Journal of Plant Diseases and Protection | Year: 2012

Ethanol extracts of Rosmarinus officinalis, Lavandula angustifolia and Ruta graveolens were tested against adults of Acanthoscelides obtectus and Leptinotarsa decemlineata. Using a newly developed computer tracking system, a choice test revealed that all of the extracts have a repellent action. The highest repellent activity against the bean weevils adults was the ethanol extract of rue, whereas the highest repellent activity against the Colorado potato beetle adults was the lavender extract. We suggest that a cocktail of volatile components in the ethanol extracts was responsible for the observed repellent action. All three of the extracts have insecticidal effects on bean weevils, reducing F1 adult emergence, with no side effects on the germination of the bean plants. In contrast, the extracts did not demonstrate an insecticidal effect on Colorado potato beetles. © Eugen Ulmer KG, Stuttgart.


Pavlovic M.,International Hop Growers Convention IHGC Secretary General | Pavlovic M.,Slovenian Institute of Hop Research and Brewing | Pavlovic V.,University of Maribor
Agrociencia | Year: 2011

Hops (Humulus lupulus L.) are vital for the brewing industry, as they contribute significantly to the organoleptic qualities of beer, including taste and flavor. Experimental hop breeding data from the Slovenian Institute of Hop Research and Brewing (IHPS) were used to create a model based on the multi-attribute decision modeling methodology. The model has 18 attributes hierarchically grouped within four main attributes: Biology, Chemistry, Morphology and Brewing value. Furthermore, utility functions in the model were defined by sets of elementary decision rules throughout the entire hierarchy for all aggregated attributes. The central part of the model contains 144 decision rules, which were specified according to the model users' previous breeding experiences. Four prospective hop hybrids and a reference hop variety with the target characteristics of plant resistance and brewing value were evaluated. Based on the breeding experiences and model results attributes' assessments were carried out. Decisions based on the model evaluation offered an additional tool for experts' final decisions in selecting appropriate materials for further breeding or the commercial use of hop plants.


Ceh B.,Slovenian Institute of Hop Research and Brewing
Plant, Soil and Environment | Year: 2014

The aim of this investigation was to answer if cattle slurry can replace mineral fertiliser calcium ammonium nitrate for hop (Humulus lupulus L.) side-dressings, and if it is suitable to be applied after hop harvest, and also show its impact on N-min content of the soil. Cattle slurry was a more appropriate fertiliser for the second and the third hop side-dressings in the investigated years (2010-2012), which were characterised by a lower than average amount of rainfall and higher temperatures, especially in June and in the first half of July. Despite the lower amount of plantavailable nitrogen in the cattle slurry (which contains also other nutrients and water), the yield of hop cones and the yield of alpha-acids were significantly higher, the NO- 3-N content in the cones was lower, and the N-min in the soil was lower. N-min analyses are urgent, at least in years with uncommon precipitation patterns, to make decisions about subsequent side-dressings. The weather conditions had a significant impact on the yield and the NO- 3-N content of the hop cones but not on the alpha-acid content.


Dezelak M.,Slovenian Institute of Hop Research and Brewing | Zarnkow M.,TU Munich | Becker T.,TU Munich | Kosir I.J.,Slovenian Institute of Hop Research and Brewing
Journal of the Institute of Brewing | Year: 2014

Typical beer contains significant amount of gluten, and being the third most popular beverage worldwide, the commercial production of its gluten-free form is of rising interest. This research aimed to prepare bottom-fermented beverages from buckwheat and quinoa and to explore their physical, chemical and sensory properties. Compared with barley, the analysis of brewing attributes of buckwheat and quinoa showed a lower malt extracts, longer saccharification times, higher total protein and fermentable amino nitrogen content and higher values of the iodine test and colour. Fermentability values, the wort pH and the soluble protein content were similar for barley and buckwheat, but different for quinoa, whereas only values of viscosity and beverage pH were similar between barley and quinoa. Both beverages, especially the quinoa beverage, contained a superior level of metal cations. The fermentable carbohydrate content in the buckwheat wort was comparable to barley but lower in quinoa; however, worts derived from both pseudocereals contained predominantly glucose. The amino acid content of the buckwheat wort was similar to barley, whereas the content in the quinoa beverage was almost twice as high. The content of volatile compounds commonly associated with beer aroma was comparable between the barley and buckwheat beverage but significantly lower in the quinoa; however, the latter contained some distinctive volatile substances not found in the 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 appears quite similar to barley, whereas quinoa shows many unique properties. © 2014 The Institute of Brewing & Distilling.

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