Browsing by Subject "Barley"

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  • Chen, Yike Jr (Helsingin yliopisto, 2018)
    Cereal β-glucan, or (1→3)(1→4)-β-D-glucan, has unique viscous and gelling properties, which are related to its physiological effects. The increased viscosity in human gastrointestinal tract by β-glucan is considered a key factor for its health benefits. However, the possible gelling ability of β-glucan in human intestine and its relation to the physiological functionality have not been investigated. The aims of this study were to investigate the possible structure formation of β-glucan at physiological conditions and to understand gelation difference between oat and barley β-glucan (OBG and BBG, respectively). Additionally, the effects of phytate and molecular weight (MW) on structure formation of β-glucan were studied. Oat (ROBG14, ROBG22) and barley bran concentrates (RBBG18) were used for in vitro studies in upper gut model. OBG14 was extracted from oat concentrates and used for further producing phytate-removed OBG (PR-OBG) or enzymatically degraded OBG (ENZ-OBG). The effect of phytate or molecular weight on gelation of beta-glucan was studied by comparing the gelation of PR-OBG or ENZ-OBG to OBG14 after 2 h and 1 d. The effect of β-glucan source was studied with medium viscosity oat (MOBG) and barley (MBBG) β-glucan with same molecular weight and concentration on day 1 and day 4. The extracted samples were first dissolved at physiological T 37°C for 2 h and the gel properties of the samples were measured with oscillatory measurements. OBG showed more structure formation than BBG at low concentrations in both studies with in vitro digestion model and extracted β-glucan samples at physiological temperature. In vitro RBBG18 (β-glucan content of the in vitro extract 0.6%) showed liquid-like behavior and no hysteresis obtained, indicating no structure formation. ROBG14 (β-glucan content 0.5%) and ROBG22 (β-glucan content 0.6%) showed entangled network, with similar crossover frequencies, 0.07 and 0.1 Hz, respectively. 1.5% MOBG showed liquid-like behavior on day 1, but storage modulus (G’) increased during storage. The undissolved particles in watery medium of MBBG indicated 37°C was not enough for partial dissolution which could lead to gel. At the same concentration (1%), both PR-OBG and OBG14 showed weak gel structure, with slightly higher G’ in PR-OBG. This indicated that phytate is not the reason for better gelation of OBG than BBG, which was hypothesized due to higher residual phytate in OBG than BBG. ENZ-OBG (0.7%) had lower G’ than OBG14 (0.7%), which indicated more structure formed in higher MW OBG at 2 h. To conclude, OBG is more prone to structure formation than BBG at physiological conditions. Phytate was not the reason for better gelation of OBG than BBG.
  • Iso-Kokkila, Marijke (Helsingin yliopisto, 2020)
    Barley has been cultivated throughout the world for centuries. During that time, it has experienced different climatic conditions and selective pressure. The consecutive genetic variation gives us a valuable source to explore various components of yield and stress resilience. In this research field experiments were performed on 24 European barley cultivar and landrace genotypes, as well as laboratory experiments on 15 genotypes; 13 cultivated and 2 genetically modified genotypes. The aim of the field tests was to examine the genotypic variation in Finnish weather conditions during two growth seasons in Viikki and to find out how stomatal conductance differs between varieties and whether it can be connected to yield. The aim of the laboratory tests conducted in Tartu was to examine the genotypic variation in the ability of barley seedlings’ stomata to react to changes in environmental conditions with high vapor pressure deficit and abscisic acid treatment. The reason for this study is the ongoing climate change, which challenges breeders to create new resilient varieties for future climatic conditions. In addition to genomic data and genetic tools a wide variety of genotype data is needed to capture valuable traits that different varieties possess. The hypothesis of this study was to find differences in gas exchange, that could be useful considering breeding of resilient barley cultivars adapted to future climatic conditions. The tests conducted in field and laboratory conditions demonstrated, that genotypic variation could be found among here tested barley varieties. In the experiments we found several interesting cultivars, that could be tested further to verify their usefulness in breeding resilient barley cultivars for future climatic conditions.
  • Huang, Xin; Sontag-Strohm, Tuula; Stoddard, Frederick L.; Kato, Yoji (2017)
    Elimination of celiac-toxic prolamin peptides and proteins is essential for Triticeae products to be gluten-free. Instead of enzymatic hydrolysis, in this study we investigated metal-catalyzed oxidation of two model peptides, QQPFP, and PQPQLPY, together with a hordein isolate from barley (Hordeum vulgare L.). We established a multiple reaction monitoring (MRM) LC-MS method to detect and quantify proline oxidation fragments. In addition to fragmentation, aggregation and side chain modifications were identified, including free thiol loss, carbonyl formation, and dityrosine formation. The immunoreactivity of the oxidized hordein isolate was considerably decreased in all metal-catalyzed oxidation systems. Cleavage of peptides or protein fragments at the numerous proline residues partially accounts for the decrease. Metal-catalyzed oxidation can thus be used in the modification and elimination of celiac-toxic peptides and proteins. (C) 2016 Elsevier Ltd. All rights reserved.