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Robert G Gilbert - One of the best experts on this subject based on the ideXlab platform.
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malt protein inhibition of β amylase alters Starch molecular structure during Barley mashing
Food Hydrocolloids, 2020Co-Authors: Robert G Gilbert, Glen P. FoxAbstract:Abstract The molecular structural changes in Starch in Barley malts during mashing (a major step in brewing beer) with and without protein removal were investigated using size exclusion chromatography. The aim was to uncover how proteins affects Barley Starch degradation in brewing. It was found that for malts containing lower β-amylase activity, protein removal significantly increased fermentable sugar content, whilst no significant change was observed for malts with higher β-amylase, with or without addition of a metalloprotease (Neutrase®). However, metalloprotease addition significantly reduced both the content and molecular sizes of remaining wort-soluble Starches. This suggests that the effects of malt protein removal on Starch degradation, particularly on fermentable sugar production, largely depend on malt enzyme activity, especially that of β-amylase. This provides useful information for brewers: for example, the fact that soluble Starch molecular structure correlates significantly with fermentation efficiency gives a new criterion for selecting Barley varieties for optimal brewing performance.
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molecular brewing molecular structural effects involved in Barley malting and mashing
Carbohydrate Polymers, 2019Co-Authors: Yu Wenwen, Robert G Gilbert, Michael J GidleyAbstract:Ten Barley samples containing varied protein contents were subject to malting followed by mashing to investigate molecular effects of both Barley Starch and Starch- protein interactions on malting and mashing performances, and the underlying mechanism. Starch granular changes were examined using differential scanning calorimetry and scanning electron microscopy. The molecular fine structures of amylose and amylopectin from unmalted and malted grain were obtained using size-exclusion chromatography. The results showed that both amylose and amylopectin polymers were hydrolyzed at the same time during malting. Protein and amylose content in both unmalted and malted Barley significant negatively correlated with fermentable sugar content after mashing. While protein content is currently the main criterion for choosing malting varieties, this study shows that information about Starch molecular structure is also useful for determining the release of fermentable sugars, an important functional property. This provides brewers with some new methods to choose malting Barley.
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The adsorption of α-amylase on Barley proteins affects the in vitro digestion of Starch in Barley flour.
Food chemistry, 2017Co-Authors: Wei Zou, Michael J Gidley, Sushil Dhital, Glen P. Fox, Robert G GilbertAbstract:The conversion of Barley Starch to sugars is a complex enzymic process. Most previous work concerned the biotechnical aspect of in situ Barley enzymes. However, the interactions among the macromolecular substrates and their effects on enzymic catalysis has been little examined. Here, we explore the mechanisms whereby interactions of protein and Starch in Barley flour affect the kinetics of enzymatic hydrolysis of Starch in an in vitro system, using digestion rate data and structural analysis by confocal microscopy. The degradation kinetics of both uncooked Barley flour and of purified Starches are found to be two-step sequential processes. Barley proteins, especially the water-soluble component, are found to retard the digestion of Starch degraded by α-amylase: the enzyme binds with water-insoluble protein and with Starch granules, leading to reduced Starch hydrolysis. These findings are of potential industrial value in both the brewing and food industries.
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the effects of variable nitrogen application on Barley Starch structure under drought stress
Journal of The Institute of Brewing, 2015Co-Authors: Robert G Gilbert, Peter W Gous, Frederick J Warren, Glen P. FoxAbstract:Under well-watered conditions, agronomic yield increases have been observed to correlate with nitrogen supply. Thus there is a need for proper fertilizer regimes to increase both metabolic and regulatory processes during kernel development in cereal crops. However, the impact of varying levels of nitrogen application on Starch biosynthesis, structure and properties in grain under drought stress is not well known. This study examines the impact of different nitrogen application rates, in conjunction with drought stress, on Starch biosynthesis in Barley (Hordeum vulgare L.) grain. The proportions of short amylopectin branches and long amylose branches in the grain of Fitzroy and Grout were higher under drought stress with high nitrogen. This suggests that Starch biosynthesis was affected, probably owing to early termination of grain fill. These changes in the long branches can affect Starch properties, such as the rates of enzymatic degradation, and hence fermentability and nutritional value. In contrast, the chain length distribution (CLD) of the debranched Starch from the grain grown under favourable conditions (Hermitage) did not show the same level of qualitative variations among the nitrogen treatments. The similar CLDs between these grain samples suggest that Starch biosynthesis was not negatively impacted by the different nitrogen applications. However, with the grain under drought stress conditions, the results indicate that Starch biosynthesis and quality could be impacted by nitrogen application. This has the potential to give rise to beneficial structural changes that are useful for some value-added products.
Eric Bertoft - One of the best experts on this subject based on the ideXlab platform.
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effect of diurnal photosynthetic activity on the fine structure of amylopectin from normal and waxy Barley Starch
International Journal of Biological Macromolecules, 2017Co-Authors: Avi Goldstein, George Amponsah Annor, Andreas Blennow, Eric BertoftAbstract:The impact of diurnal photosynthetic activity on the fine structure of the amylopectin fraction of Starch synthesized by normal Barley (NBS) and waxy Barley (WBS), the latter completely devoid of amylose biosynthesis, was determined following the cultivation under normal diurnal or constant light growing conditions. The amylopectin fine structures were analysed by characterizing its unit chain length profiles after enzymatic debranching as well as its φ,β-limit dextrins and its clusters and building blocks after their partial and complete hydrolysis with α-amylase from Bacillus amyloliquefaciens, respectively. Regardless of lighting conditions, no structural effects were found when comparing both the amylopectin side-chain distribution and the internal chain fragments of these amylopectins. However, the diurnally grown NBS and WBS both showed larger amylopectin clusters and these had lower branching density and longer average chain lengths than clusters derived from plants grown under constant light conditions. Amylopectin clusters from diurnally grown plants also consisted of a greater number of building blocks, and shorter inter-block chain lengths compared to clusters derived from plants grown under constant light. Our data demonstrate that the diurnal light regime influences the fine structure of the amylopectin component both in amylose and non-amylose Starch granules.
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influence of diurnal photosynthetic activity on the morphology structure and thermal properties of normal and waxy Barley Starch
International Journal of Biological Macromolecules, 2017Co-Authors: Avi Goldstein, Kim H Hebelstrup, George Amponsah Annor, Varatharajan Vamadevan, Ian J Tetlow, Jacob J K Kirkensgaard, Kell Mortensen, Andreas Blennow, Eric BertoftAbstract:Abstract This study investigated the influence of diurnal photosynthetic activity on the morphology, molecular composition, crystallinity, and gelatinization properties of normal Barley Starch (NBS) and waxy Barley Starch (WBS) granules from plants cultivated in a greenhouse under normal diurnal (16 h light) or constant light photosynthetic conditions. Growth rings were observed in all Starch samples regardless of lighting conditions. The size distribution of whole and debranched WBS analyzed by gel-permeation chromatography did not appear to be influenced by the different lighting regimes, however, a greater relative crystallinity measured by wide-angle X-ray scattering and greater crystalline quality as judged by differential scanning calorimetry was observed under the diurnal lighting regime. NBS cultivated under the diurnal photosynthetic lighting regime displayed lower amylose content (18.7%), and shorter amylose chains than its counterpart grown under constant light. Although the relative crystallinity of NBS was not influenced by lighting conditions, lower onset, peak, and completion gelatinization temperatures were observed in diurnally grown NBS compared to constant light conditions. It is concluded that normal Barley Starch is less influenced by the diurnal photosynthetic lighting regime than amylose-free Barley Starch suggesting a role of amylose to prevent structural disorder and increase Starch granule robustness against environmental cues.
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thermal properties of Barley Starch and its relation to Starch characteristics
International Journal of Biological Macromolecules, 2015Co-Authors: Anna Kallman, Varatharajan Vamadevan, Eric Bertoft, Kristine Koch, Koushik Seetharaman, Per Aman, Roger AnderssonAbstract:Amylopectin fine structure and Starch gelatinization and retrogradation were studied in 10 different Barley cultivars/breeding lines. Clusters and building blocks were isolated from the amylopectin by α-amylase from Bacillus amyloliquefaciens and their structure was characterized. Gelatinization was studied at a Starch:water ratio of 1:3, and retrogradation was studied on gelatinized Starch at Starch:water ratio of 1:2, by differential scanning calorimetry. Three Barley cultivars/breeding lines possessed the amo1 mutation, and they all had a lower molar proportion of chains of DP ≥38 and more of large building blocks. The amo1 mutation also resulted in a higher gelatinization temperature and a broader temperature interval during gelatinization. Overall, small clusters with a dense structure resulted in a higher gelatinization temperature while retrogradation was promoted by short chains in the amylopectin and many large building blocks.
Glen P. Fox - One of the best experts on this subject based on the ideXlab platform.
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malt protein inhibition of β amylase alters Starch molecular structure during Barley mashing
Food Hydrocolloids, 2020Co-Authors: Robert G Gilbert, Glen P. FoxAbstract:Abstract The molecular structural changes in Starch in Barley malts during mashing (a major step in brewing beer) with and without protein removal were investigated using size exclusion chromatography. The aim was to uncover how proteins affects Barley Starch degradation in brewing. It was found that for malts containing lower β-amylase activity, protein removal significantly increased fermentable sugar content, whilst no significant change was observed for malts with higher β-amylase, with or without addition of a metalloprotease (Neutrase®). However, metalloprotease addition significantly reduced both the content and molecular sizes of remaining wort-soluble Starches. This suggests that the effects of malt protein removal on Starch degradation, particularly on fermentable sugar production, largely depend on malt enzyme activity, especially that of β-amylase. This provides useful information for brewers: for example, the fact that soluble Starch molecular structure correlates significantly with fermentation efficiency gives a new criterion for selecting Barley varieties for optimal brewing performance.
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The adsorption of α-amylase on Barley proteins affects the in vitro digestion of Starch in Barley flour.
Food chemistry, 2017Co-Authors: Wei Zou, Michael J Gidley, Sushil Dhital, Glen P. Fox, Robert G GilbertAbstract:The conversion of Barley Starch to sugars is a complex enzymic process. Most previous work concerned the biotechnical aspect of in situ Barley enzymes. However, the interactions among the macromolecular substrates and their effects on enzymic catalysis has been little examined. Here, we explore the mechanisms whereby interactions of protein and Starch in Barley flour affect the kinetics of enzymatic hydrolysis of Starch in an in vitro system, using digestion rate data and structural analysis by confocal microscopy. The degradation kinetics of both uncooked Barley flour and of purified Starches are found to be two-step sequential processes. Barley proteins, especially the water-soluble component, are found to retard the digestion of Starch degraded by α-amylase: the enzyme binds with water-insoluble protein and with Starch granules, leading to reduced Starch hydrolysis. These findings are of potential industrial value in both the brewing and food industries.
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the effects of variable nitrogen application on Barley Starch structure under drought stress
Journal of The Institute of Brewing, 2015Co-Authors: Robert G Gilbert, Peter W Gous, Frederick J Warren, Glen P. FoxAbstract:Under well-watered conditions, agronomic yield increases have been observed to correlate with nitrogen supply. Thus there is a need for proper fertilizer regimes to increase both metabolic and regulatory processes during kernel development in cereal crops. However, the impact of varying levels of nitrogen application on Starch biosynthesis, structure and properties in grain under drought stress is not well known. This study examines the impact of different nitrogen application rates, in conjunction with drought stress, on Starch biosynthesis in Barley (Hordeum vulgare L.) grain. The proportions of short amylopectin branches and long amylose branches in the grain of Fitzroy and Grout were higher under drought stress with high nitrogen. This suggests that Starch biosynthesis was affected, probably owing to early termination of grain fill. These changes in the long branches can affect Starch properties, such as the rates of enzymatic degradation, and hence fermentability and nutritional value. In contrast, the chain length distribution (CLD) of the debranched Starch from the grain grown under favourable conditions (Hermitage) did not show the same level of qualitative variations among the nitrogen treatments. The similar CLDs between these grain samples suggest that Starch biosynthesis was not negatively impacted by the different nitrogen applications. However, with the grain under drought stress conditions, the results indicate that Starch biosynthesis and quality could be impacted by nitrogen application. This has the potential to give rise to beneficial structural changes that are useful for some value-added products.
Christophe M. Courtin - One of the best experts on this subject based on the ideXlab platform.
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Accurate quantification of small and large Starch granules in Barley and malt
Carbohydrate polymers, 2019Co-Authors: Charlotte F. De Schepper, Niels A. Langenaeken, P. Michiels, Christophe M. CourtinAbstract:The proportion of small and large Starch granules in Barley and malt is often neglected, leading to underestimation of their importance in processes in which they are used. This study aimed to accurately determine the volume and number based percentages of small and large Starch granules for three Barley varieties, their micro-malted malts and three commercial malts. Quantitative Starch isolation was performed and Starch granule proportions were estimated using microscopic and image analysis, taking the non-sphericity of the large Starch granules into account. Results show that Barley Starch consists of 32-39 volume% of small Starch granules. Upon malting, this percentage is reduced to 17-27 volume%, showing that small granules are hydrolyzed faster than large granules during this process. The analyzed commercial malt samples have a small Starch granule content of 22-25 volume%. Malt hence still contains a substantial amount of small Starch granules, which can be expected to impact processing.
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Different gelatinization characteristics of small and large Barley Starch granules impact their enzymatic hydrolysis and sugar production during mashing
Food Chemistry, 2019Co-Authors: Niels A. Langenaeken, Charlotte F. De Schepper, David P. De Schutter, Christophe M. CourtinAbstract:Abstract This study investigates the impact of different gelatinization characteristics of small and large Barley Starch granules on their enzymatic hydrolysis and sugar production during mashing. Therefore, a Barley malt suspension was consecutively incubated at 45, 62, 72 and 78 °C to monitor Starch behavior and enzymatic Starch hydrolysis and sugar production. The combination of microscopic and rapid visco analyses showed that small Starch granules persisted longer in the system and were present non-gelatinized at temperatures higher than 62 °C. HPAEC-PAD analysis showed that 8% of the total amount of Starch, predominantly small granules, gelatinized at temperatures between 62 °C and 78 °C. Due to their delayed gelatinization in this system, their enzymatic hydrolysis yielded relatively more dextrins compared to what was observed for large granules. It was concluded that small granules should be taken into account when optimizing enzymatic hydrolysis of Barley Starch, like in brewing, distilling or bio-ethanol production.
Avi Goldstein - One of the best experts on this subject based on the ideXlab platform.
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effect of diurnal photosynthetic activity on the fine structure of amylopectin from normal and waxy Barley Starch
International Journal of Biological Macromolecules, 2017Co-Authors: Avi Goldstein, George Amponsah Annor, Andreas Blennow, Eric BertoftAbstract:The impact of diurnal photosynthetic activity on the fine structure of the amylopectin fraction of Starch synthesized by normal Barley (NBS) and waxy Barley (WBS), the latter completely devoid of amylose biosynthesis, was determined following the cultivation under normal diurnal or constant light growing conditions. The amylopectin fine structures were analysed by characterizing its unit chain length profiles after enzymatic debranching as well as its φ,β-limit dextrins and its clusters and building blocks after their partial and complete hydrolysis with α-amylase from Bacillus amyloliquefaciens, respectively. Regardless of lighting conditions, no structural effects were found when comparing both the amylopectin side-chain distribution and the internal chain fragments of these amylopectins. However, the diurnally grown NBS and WBS both showed larger amylopectin clusters and these had lower branching density and longer average chain lengths than clusters derived from plants grown under constant light conditions. Amylopectin clusters from diurnally grown plants also consisted of a greater number of building blocks, and shorter inter-block chain lengths compared to clusters derived from plants grown under constant light. Our data demonstrate that the diurnal light regime influences the fine structure of the amylopectin component both in amylose and non-amylose Starch granules.
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influence of diurnal photosynthetic activity on the morphology structure and thermal properties of normal and waxy Barley Starch
International Journal of Biological Macromolecules, 2017Co-Authors: Avi Goldstein, Kim H Hebelstrup, George Amponsah Annor, Varatharajan Vamadevan, Ian J Tetlow, Jacob J K Kirkensgaard, Kell Mortensen, Andreas Blennow, Eric BertoftAbstract:Abstract This study investigated the influence of diurnal photosynthetic activity on the morphology, molecular composition, crystallinity, and gelatinization properties of normal Barley Starch (NBS) and waxy Barley Starch (WBS) granules from plants cultivated in a greenhouse under normal diurnal (16 h light) or constant light photosynthetic conditions. Growth rings were observed in all Starch samples regardless of lighting conditions. The size distribution of whole and debranched WBS analyzed by gel-permeation chromatography did not appear to be influenced by the different lighting regimes, however, a greater relative crystallinity measured by wide-angle X-ray scattering and greater crystalline quality as judged by differential scanning calorimetry was observed under the diurnal lighting regime. NBS cultivated under the diurnal photosynthetic lighting regime displayed lower amylose content (18.7%), and shorter amylose chains than its counterpart grown under constant light. Although the relative crystallinity of NBS was not influenced by lighting conditions, lower onset, peak, and completion gelatinization temperatures were observed in diurnally grown NBS compared to constant light conditions. It is concluded that normal Barley Starch is less influenced by the diurnal photosynthetic lighting regime than amylose-free Barley Starch suggesting a role of amylose to prevent structural disorder and increase Starch granule robustness against environmental cues.