The Experts below are selected from a list of 3645 Experts worldwide ranked by ideXlab platform
Jan A. Delcour - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the xylan breakdown potential of eight mesophilic Endoxylanases
Enzyme and microbial technology, 2011Co-Authors: Sven Cuyvers, Jan A. Delcour, Emmie Dornez, Karolien Moers, Annick Pollet, Christophe M. CourtinAbstract:In biomass degradation using simultaneous saccharification and fermentation (SSF), there is a need for efficient biomass degrading enzymes that can work at lower temperatures suitable for yeast fermentation. As xylan is an important lignocellulosic biomass constituent, this study aimed at investigating the possible differences in xylan breakdown potential of Endoxylanases using eight different Endoxylanases at conditions relevant for SSF. Both solubilising and degrading capacities of the Endoxylanases were investigated using water-insoluble and water-soluble oat spelt xylan as model substrates for biomass xylan. Results showed that selecting for combinations of Endoxylanases that are efficient at solubilising xylan on the one hand and degrading it to large extent on the other hand, coupled to high specific activities, seems the best option for complete xylan breakdown in lignocellulosic biomass conversion using SSF.
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effects of fungicide treatment n fertilisation and harvest date on arabinoxylan endoxylanase activity and endoxylanase inhibitor levels in wheat kernels
Journal of Cereal Science, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Iris J. Joye, Bart De Ketelaere, Jonathan Lenartz, Carine Massaux, Bernard Bodson, Christophe M. CourtinAbstract:Fungicide treatment had a significant impact on endoxylanase activity and XIP levels, but did not affect arabinoxylan (AX) and TAXI levels. The different response of TAXI and XIP type inhibitors to fungicide treatment is interesting. N-fertilisation did not affect AX levels, but significantly increased TAXI and XIP type inhibitor levels. Wheat-associated microbial endoxylanase activity levels were also affected by nitrogen supply, but levels of the endogenous enzyme did not change, except when sprouting occurred. The weather conditions before harvest had no influence on total AX (TOT-AX) and inhibitor levels, but had a large impact on both microbial and endogenous endoxylanase activity and water extractable AX (WE-AX) levels. Under most conditions, endoxylanase activity levels were related to those of α-amylases, liquefaction numbers (LN) and specific weights. WE-AX levels were often weakly but significantly correlated with endoxylanase activity levels, indicating that it is possible that part of the WE-AX in wheat originates from AX degradation by Endoxylanases in the field. These results clearly indicate that agronomic circumstances significantly affect the levels of AX, Endoxylanases and their inhibitors in wheat, and consequently could affect wheat quality.
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Contribution of wheat endogenous and wheat kernel associated microbial Endoxylanases to changes in the arabinoxylan population during breadmaking
Journal of agricultural and food chemistry, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Sven Cuyvers, Christophe M. CourtinAbstract:Wheat kernel associated Endoxylanases consist of a majority of microbial Endoxylanases and a minority of endogenous Endoxylanases. At least part of these enzymes can be expected to end up in wheat flour upon milling. In this study, the contribution of both types of these Endoxylanases to changes in the arabinoxylan (AX) population during wheat flour breadmaking was assessed. To this end, wheat flour produced from two wheat varieties with different endoxylanase activity levels, both before and after sodium hypochlorite surface treatment of the wheat kernels, was used in a straight dough breadmaking procedure. Monitoring of the AX population during the breadmaking process showed that changes in AX are to a large extent caused by endogenous Endoxylanases, whereas the contribution of microbial Endoxylanases to these changes was generally very low. The latter points to a limited contamination of wheat flour with microbial enzymes during milling or to an extensive inactivation of these wheat flour associated microbial Endoxylanases by endoxylanase inhibitors, present in wheat flour. When all wheat kernel associated microbial Endoxylanases were first washed from the kernels and then added to the bread recipe, they drastically affected the AX population, suggesting that they can have a large impact on whole meal breadmaking.
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Effects of genotype, harvest year and genotype-by-harvest year interactions on arabinoxylan, endoxylanase activity and endoxylanase inhibitor levels in wheat kernels
Journal of Cereal Science, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Iris J. Joye, Bart De Ketelaere, Jonathan Lenartz, Carine Massaux, Bernard Bodson, Christophe M. CourtinAbstract:Abstract The effects of genotype, harvest year and their interaction on the levels of arabinoxylans (AX), Endoxylanases and endoxylanase inhibitors in wheat were studied using 14 varieties grown in three successive growing periods with diverse climatological conditions. Relations with more commonly evaluated wheat characteristics such as yield, thousand kernel weight, specific weight, protein level, Hagberg falling number (HFN) and α -amylase activity level were examined. Water extractable arabinoxylan (WE-AX) levels in wheat varied much more than total arabinoxylan (TOT-AX) levels. This variability was mainly genetically determined, but harvest year also had an important effect. Total endoxylanase activity levels varied more than a factor of 20 between the different wheat samples. Endogenous Endoxylanases typically accounted for only 10–15% of this activity, while wheat-associated microbial Endoxylanases accounted for the remaining 85–90%. However, when preharvest sprouting occurred, the contribution of endogenous Endoxylanases could sometimes amount to over 40% of this total activity. Endogenous endoxylanase activity levels were mainly determined by the interaction of genotype and harvest year, while wheat-associated microbial endoxylanase activity levels were predominantly determined by genotype alone. Endogenous and microbial endoxylanase activity levels were strongly correlated, suggesting that wheat varieties which are susceptible to preharvest sprouting are often also susceptible to microbial contamination. The TAXI and XIP-type endoxylanase inhibitor levels varied by a factor of 8 and 1.8, respectively. They were mainly determined by genotype and were rather similar in the different growing periods.
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Impact of wheat flour-associated Endoxylanases on arabinoxylan in dough after mixing and resting.
Journal of agricultural and food chemistry, 2007Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Sven Cuyvers, Christophe M. CourtinAbstract:The impact of varying levels of endoxylanase activity in wheat flour on arabinoxylan (AX) in mixed and rested dough was studied using eight industrially milled wheat flour fractions with varying endoxylanase activity levels. Analysis of the levels of reducing end xylose (RX) and solubilized AX (S-AX) formed during mixing and resting and their correlation with the endoxylanase activity in the flour milling fractions showed that solubilization of AX during the mixing phase is mainly due to mechanical forces, while solubilization of AX during resting is caused by endoxylanase activity. Moreover, solubilization of AX during the dough resting phase is more outspoken than that during the mixing phase. Besides endoxylanase activity, there were significant xylosidase and arabinofuranosidase activities during the dough resting phase. The results indicate that wheat flour-associated Endoxylanases can alter part of the AX in dough, thereby changing their functionality in bread making and potentially affecting dough and end product properties.
Christophe M. Courtin - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the xylan breakdown potential of eight mesophilic Endoxylanases
Enzyme and microbial technology, 2011Co-Authors: Sven Cuyvers, Jan A. Delcour, Emmie Dornez, Karolien Moers, Annick Pollet, Christophe M. CourtinAbstract:In biomass degradation using simultaneous saccharification and fermentation (SSF), there is a need for efficient biomass degrading enzymes that can work at lower temperatures suitable for yeast fermentation. As xylan is an important lignocellulosic biomass constituent, this study aimed at investigating the possible differences in xylan breakdown potential of Endoxylanases using eight different Endoxylanases at conditions relevant for SSF. Both solubilising and degrading capacities of the Endoxylanases were investigated using water-insoluble and water-soluble oat spelt xylan as model substrates for biomass xylan. Results showed that selecting for combinations of Endoxylanases that are efficient at solubilising xylan on the one hand and degrading it to large extent on the other hand, coupled to high specific activities, seems the best option for complete xylan breakdown in lignocellulosic biomass conversion using SSF.
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effects of fungicide treatment n fertilisation and harvest date on arabinoxylan endoxylanase activity and endoxylanase inhibitor levels in wheat kernels
Journal of Cereal Science, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Iris J. Joye, Bart De Ketelaere, Jonathan Lenartz, Carine Massaux, Bernard Bodson, Christophe M. CourtinAbstract:Fungicide treatment had a significant impact on endoxylanase activity and XIP levels, but did not affect arabinoxylan (AX) and TAXI levels. The different response of TAXI and XIP type inhibitors to fungicide treatment is interesting. N-fertilisation did not affect AX levels, but significantly increased TAXI and XIP type inhibitor levels. Wheat-associated microbial endoxylanase activity levels were also affected by nitrogen supply, but levels of the endogenous enzyme did not change, except when sprouting occurred. The weather conditions before harvest had no influence on total AX (TOT-AX) and inhibitor levels, but had a large impact on both microbial and endogenous endoxylanase activity and water extractable AX (WE-AX) levels. Under most conditions, endoxylanase activity levels were related to those of α-amylases, liquefaction numbers (LN) and specific weights. WE-AX levels were often weakly but significantly correlated with endoxylanase activity levels, indicating that it is possible that part of the WE-AX in wheat originates from AX degradation by Endoxylanases in the field. These results clearly indicate that agronomic circumstances significantly affect the levels of AX, Endoxylanases and their inhibitors in wheat, and consequently could affect wheat quality.
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Contribution of wheat endogenous and wheat kernel associated microbial Endoxylanases to changes in the arabinoxylan population during breadmaking
Journal of agricultural and food chemistry, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Sven Cuyvers, Christophe M. CourtinAbstract:Wheat kernel associated Endoxylanases consist of a majority of microbial Endoxylanases and a minority of endogenous Endoxylanases. At least part of these enzymes can be expected to end up in wheat flour upon milling. In this study, the contribution of both types of these Endoxylanases to changes in the arabinoxylan (AX) population during wheat flour breadmaking was assessed. To this end, wheat flour produced from two wheat varieties with different endoxylanase activity levels, both before and after sodium hypochlorite surface treatment of the wheat kernels, was used in a straight dough breadmaking procedure. Monitoring of the AX population during the breadmaking process showed that changes in AX are to a large extent caused by endogenous Endoxylanases, whereas the contribution of microbial Endoxylanases to these changes was generally very low. The latter points to a limited contamination of wheat flour with microbial enzymes during milling or to an extensive inactivation of these wheat flour associated microbial Endoxylanases by endoxylanase inhibitors, present in wheat flour. When all wheat kernel associated microbial Endoxylanases were first washed from the kernels and then added to the bread recipe, they drastically affected the AX population, suggesting that they can have a large impact on whole meal breadmaking.
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Effects of genotype, harvest year and genotype-by-harvest year interactions on arabinoxylan, endoxylanase activity and endoxylanase inhibitor levels in wheat kernels
Journal of Cereal Science, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Iris J. Joye, Bart De Ketelaere, Jonathan Lenartz, Carine Massaux, Bernard Bodson, Christophe M. CourtinAbstract:Abstract The effects of genotype, harvest year and their interaction on the levels of arabinoxylans (AX), Endoxylanases and endoxylanase inhibitors in wheat were studied using 14 varieties grown in three successive growing periods with diverse climatological conditions. Relations with more commonly evaluated wheat characteristics such as yield, thousand kernel weight, specific weight, protein level, Hagberg falling number (HFN) and α -amylase activity level were examined. Water extractable arabinoxylan (WE-AX) levels in wheat varied much more than total arabinoxylan (TOT-AX) levels. This variability was mainly genetically determined, but harvest year also had an important effect. Total endoxylanase activity levels varied more than a factor of 20 between the different wheat samples. Endogenous Endoxylanases typically accounted for only 10–15% of this activity, while wheat-associated microbial Endoxylanases accounted for the remaining 85–90%. However, when preharvest sprouting occurred, the contribution of endogenous Endoxylanases could sometimes amount to over 40% of this total activity. Endogenous endoxylanase activity levels were mainly determined by the interaction of genotype and harvest year, while wheat-associated microbial endoxylanase activity levels were predominantly determined by genotype alone. Endogenous and microbial endoxylanase activity levels were strongly correlated, suggesting that wheat varieties which are susceptible to preharvest sprouting are often also susceptible to microbial contamination. The TAXI and XIP-type endoxylanase inhibitor levels varied by a factor of 8 and 1.8, respectively. They were mainly determined by genotype and were rather similar in the different growing periods.
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Impact of wheat flour-associated Endoxylanases on arabinoxylan in dough after mixing and resting.
Journal of agricultural and food chemistry, 2007Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Sven Cuyvers, Christophe M. CourtinAbstract:The impact of varying levels of endoxylanase activity in wheat flour on arabinoxylan (AX) in mixed and rested dough was studied using eight industrially milled wheat flour fractions with varying endoxylanase activity levels. Analysis of the levels of reducing end xylose (RX) and solubilized AX (S-AX) formed during mixing and resting and their correlation with the endoxylanase activity in the flour milling fractions showed that solubilization of AX during the mixing phase is mainly due to mechanical forces, while solubilization of AX during resting is caused by endoxylanase activity. Moreover, solubilization of AX during the dough resting phase is more outspoken than that during the mixing phase. Besides endoxylanase activity, there were significant xylosidase and arabinofuranosidase activities during the dough resting phase. The results indicate that wheat flour-associated Endoxylanases can alter part of the AX in dough, thereby changing their functionality in bread making and potentially affecting dough and end product properties.
Kurt Gebruers - One of the best experts on this subject based on the ideXlab platform.
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effects of fungicide treatment n fertilisation and harvest date on arabinoxylan endoxylanase activity and endoxylanase inhibitor levels in wheat kernels
Journal of Cereal Science, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Iris J. Joye, Bart De Ketelaere, Jonathan Lenartz, Carine Massaux, Bernard Bodson, Christophe M. CourtinAbstract:Fungicide treatment had a significant impact on endoxylanase activity and XIP levels, but did not affect arabinoxylan (AX) and TAXI levels. The different response of TAXI and XIP type inhibitors to fungicide treatment is interesting. N-fertilisation did not affect AX levels, but significantly increased TAXI and XIP type inhibitor levels. Wheat-associated microbial endoxylanase activity levels were also affected by nitrogen supply, but levels of the endogenous enzyme did not change, except when sprouting occurred. The weather conditions before harvest had no influence on total AX (TOT-AX) and inhibitor levels, but had a large impact on both microbial and endogenous endoxylanase activity and water extractable AX (WE-AX) levels. Under most conditions, endoxylanase activity levels were related to those of α-amylases, liquefaction numbers (LN) and specific weights. WE-AX levels were often weakly but significantly correlated with endoxylanase activity levels, indicating that it is possible that part of the WE-AX in wheat originates from AX degradation by Endoxylanases in the field. These results clearly indicate that agronomic circumstances significantly affect the levels of AX, Endoxylanases and their inhibitors in wheat, and consequently could affect wheat quality.
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Contribution of wheat endogenous and wheat kernel associated microbial Endoxylanases to changes in the arabinoxylan population during breadmaking
Journal of agricultural and food chemistry, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Sven Cuyvers, Christophe M. CourtinAbstract:Wheat kernel associated Endoxylanases consist of a majority of microbial Endoxylanases and a minority of endogenous Endoxylanases. At least part of these enzymes can be expected to end up in wheat flour upon milling. In this study, the contribution of both types of these Endoxylanases to changes in the arabinoxylan (AX) population during wheat flour breadmaking was assessed. To this end, wheat flour produced from two wheat varieties with different endoxylanase activity levels, both before and after sodium hypochlorite surface treatment of the wheat kernels, was used in a straight dough breadmaking procedure. Monitoring of the AX population during the breadmaking process showed that changes in AX are to a large extent caused by endogenous Endoxylanases, whereas the contribution of microbial Endoxylanases to these changes was generally very low. The latter points to a limited contamination of wheat flour with microbial enzymes during milling or to an extensive inactivation of these wheat flour associated microbial Endoxylanases by endoxylanase inhibitors, present in wheat flour. When all wheat kernel associated microbial Endoxylanases were first washed from the kernels and then added to the bread recipe, they drastically affected the AX population, suggesting that they can have a large impact on whole meal breadmaking.
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Effects of genotype, harvest year and genotype-by-harvest year interactions on arabinoxylan, endoxylanase activity and endoxylanase inhibitor levels in wheat kernels
Journal of Cereal Science, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Iris J. Joye, Bart De Ketelaere, Jonathan Lenartz, Carine Massaux, Bernard Bodson, Christophe M. CourtinAbstract:Abstract The effects of genotype, harvest year and their interaction on the levels of arabinoxylans (AX), Endoxylanases and endoxylanase inhibitors in wheat were studied using 14 varieties grown in three successive growing periods with diverse climatological conditions. Relations with more commonly evaluated wheat characteristics such as yield, thousand kernel weight, specific weight, protein level, Hagberg falling number (HFN) and α -amylase activity level were examined. Water extractable arabinoxylan (WE-AX) levels in wheat varied much more than total arabinoxylan (TOT-AX) levels. This variability was mainly genetically determined, but harvest year also had an important effect. Total endoxylanase activity levels varied more than a factor of 20 between the different wheat samples. Endogenous Endoxylanases typically accounted for only 10–15% of this activity, while wheat-associated microbial Endoxylanases accounted for the remaining 85–90%. However, when preharvest sprouting occurred, the contribution of endogenous Endoxylanases could sometimes amount to over 40% of this total activity. Endogenous endoxylanase activity levels were mainly determined by the interaction of genotype and harvest year, while wheat-associated microbial endoxylanase activity levels were predominantly determined by genotype alone. Endogenous and microbial endoxylanase activity levels were strongly correlated, suggesting that wheat varieties which are susceptible to preharvest sprouting are often also susceptible to microbial contamination. The TAXI and XIP-type endoxylanase inhibitor levels varied by a factor of 8 and 1.8, respectively. They were mainly determined by genotype and were rather similar in the different growing periods.
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Impact of wheat flour-associated Endoxylanases on arabinoxylan in dough after mixing and resting.
Journal of agricultural and food chemistry, 2007Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Sven Cuyvers, Christophe M. CourtinAbstract:The impact of varying levels of endoxylanase activity in wheat flour on arabinoxylan (AX) in mixed and rested dough was studied using eight industrially milled wheat flour fractions with varying endoxylanase activity levels. Analysis of the levels of reducing end xylose (RX) and solubilized AX (S-AX) formed during mixing and resting and their correlation with the endoxylanase activity in the flour milling fractions showed that solubilization of AX during the mixing phase is mainly due to mechanical forces, while solubilization of AX during resting is caused by endoxylanase activity. Moreover, solubilization of AX during the dough resting phase is more outspoken than that during the mixing phase. Besides endoxylanase activity, there were significant xylosidase and arabinofuranosidase activities during the dough resting phase. The results indicate that wheat flour-associated Endoxylanases can alter part of the AX in dough, thereby changing their functionality in bread making and potentially affecting dough and end product properties.
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Insight into the distribution of arabinoxylans, Endoxylanases, and endoxylanase inhibitors in industrial wheat roller mill streams.
Journal of agricultural and food chemistry, 2006Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Stefan Wiame, Christophe M. CourtinAbstract:To gain insight into the distribution of arabinoxylans (AX), Endoxylanases, and endoxylanase inhibitors in industrial wheat roller milling, all streams, that is, 54 flour fractions, 4 bran fractions, and the germ, were analyzed for ash, starch, and protein contents, α-amylase activity levels, total (TOT-AX) and water-extractable arabinoxylan (WE-AX) contents, endoxylanase activity levels, and endoxylanase inhibitor (TAXI and XIP) contents. In general, bran fractions were significantly richer in TOT-AX and WE-AX contents, endoxylanase activity levels, and endoxylanase inhibitor contents than germ and, even more so, than flour fractions. In the 54 different flour fractions, minimal and maximal values for TOT-AX and WE-AX contents differed by ca. 2-fold, whereas they differed by ca. 15-fold for endoxylanase activity levels. The latter were positively correlated with ash and negatively correlated with starch content, suggesting that the endoxylanase activity in flour is strongly influenced by the level of bra...
Emmie Dornez - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the xylan breakdown potential of eight mesophilic Endoxylanases
Enzyme and microbial technology, 2011Co-Authors: Sven Cuyvers, Jan A. Delcour, Emmie Dornez, Karolien Moers, Annick Pollet, Christophe M. CourtinAbstract:In biomass degradation using simultaneous saccharification and fermentation (SSF), there is a need for efficient biomass degrading enzymes that can work at lower temperatures suitable for yeast fermentation. As xylan is an important lignocellulosic biomass constituent, this study aimed at investigating the possible differences in xylan breakdown potential of Endoxylanases using eight different Endoxylanases at conditions relevant for SSF. Both solubilising and degrading capacities of the Endoxylanases were investigated using water-insoluble and water-soluble oat spelt xylan as model substrates for biomass xylan. Results showed that selecting for combinations of Endoxylanases that are efficient at solubilising xylan on the one hand and degrading it to large extent on the other hand, coupled to high specific activities, seems the best option for complete xylan breakdown in lignocellulosic biomass conversion using SSF.
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effects of fungicide treatment n fertilisation and harvest date on arabinoxylan endoxylanase activity and endoxylanase inhibitor levels in wheat kernels
Journal of Cereal Science, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Iris J. Joye, Bart De Ketelaere, Jonathan Lenartz, Carine Massaux, Bernard Bodson, Christophe M. CourtinAbstract:Fungicide treatment had a significant impact on endoxylanase activity and XIP levels, but did not affect arabinoxylan (AX) and TAXI levels. The different response of TAXI and XIP type inhibitors to fungicide treatment is interesting. N-fertilisation did not affect AX levels, but significantly increased TAXI and XIP type inhibitor levels. Wheat-associated microbial endoxylanase activity levels were also affected by nitrogen supply, but levels of the endogenous enzyme did not change, except when sprouting occurred. The weather conditions before harvest had no influence on total AX (TOT-AX) and inhibitor levels, but had a large impact on both microbial and endogenous endoxylanase activity and water extractable AX (WE-AX) levels. Under most conditions, endoxylanase activity levels were related to those of α-amylases, liquefaction numbers (LN) and specific weights. WE-AX levels were often weakly but significantly correlated with endoxylanase activity levels, indicating that it is possible that part of the WE-AX in wheat originates from AX degradation by Endoxylanases in the field. These results clearly indicate that agronomic circumstances significantly affect the levels of AX, Endoxylanases and their inhibitors in wheat, and consequently could affect wheat quality.
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Contribution of wheat endogenous and wheat kernel associated microbial Endoxylanases to changes in the arabinoxylan population during breadmaking
Journal of agricultural and food chemistry, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Sven Cuyvers, Christophe M. CourtinAbstract:Wheat kernel associated Endoxylanases consist of a majority of microbial Endoxylanases and a minority of endogenous Endoxylanases. At least part of these enzymes can be expected to end up in wheat flour upon milling. In this study, the contribution of both types of these Endoxylanases to changes in the arabinoxylan (AX) population during wheat flour breadmaking was assessed. To this end, wheat flour produced from two wheat varieties with different endoxylanase activity levels, both before and after sodium hypochlorite surface treatment of the wheat kernels, was used in a straight dough breadmaking procedure. Monitoring of the AX population during the breadmaking process showed that changes in AX are to a large extent caused by endogenous Endoxylanases, whereas the contribution of microbial Endoxylanases to these changes was generally very low. The latter points to a limited contamination of wheat flour with microbial enzymes during milling or to an extensive inactivation of these wheat flour associated microbial Endoxylanases by endoxylanase inhibitors, present in wheat flour. When all wheat kernel associated microbial Endoxylanases were first washed from the kernels and then added to the bread recipe, they drastically affected the AX population, suggesting that they can have a large impact on whole meal breadmaking.
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Effects of genotype, harvest year and genotype-by-harvest year interactions on arabinoxylan, endoxylanase activity and endoxylanase inhibitor levels in wheat kernels
Journal of Cereal Science, 2008Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Iris J. Joye, Bart De Ketelaere, Jonathan Lenartz, Carine Massaux, Bernard Bodson, Christophe M. CourtinAbstract:Abstract The effects of genotype, harvest year and their interaction on the levels of arabinoxylans (AX), Endoxylanases and endoxylanase inhibitors in wheat were studied using 14 varieties grown in three successive growing periods with diverse climatological conditions. Relations with more commonly evaluated wheat characteristics such as yield, thousand kernel weight, specific weight, protein level, Hagberg falling number (HFN) and α -amylase activity level were examined. Water extractable arabinoxylan (WE-AX) levels in wheat varied much more than total arabinoxylan (TOT-AX) levels. This variability was mainly genetically determined, but harvest year also had an important effect. Total endoxylanase activity levels varied more than a factor of 20 between the different wheat samples. Endogenous Endoxylanases typically accounted for only 10–15% of this activity, while wheat-associated microbial Endoxylanases accounted for the remaining 85–90%. However, when preharvest sprouting occurred, the contribution of endogenous Endoxylanases could sometimes amount to over 40% of this total activity. Endogenous endoxylanase activity levels were mainly determined by the interaction of genotype and harvest year, while wheat-associated microbial endoxylanase activity levels were predominantly determined by genotype alone. Endogenous and microbial endoxylanase activity levels were strongly correlated, suggesting that wheat varieties which are susceptible to preharvest sprouting are often also susceptible to microbial contamination. The TAXI and XIP-type endoxylanase inhibitor levels varied by a factor of 8 and 1.8, respectively. They were mainly determined by genotype and were rather similar in the different growing periods.
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Impact of wheat flour-associated Endoxylanases on arabinoxylan in dough after mixing and resting.
Journal of agricultural and food chemistry, 2007Co-Authors: Emmie Dornez, Kurt Gebruers, Jan A. Delcour, Sven Cuyvers, Christophe M. CourtinAbstract:The impact of varying levels of endoxylanase activity in wheat flour on arabinoxylan (AX) in mixed and rested dough was studied using eight industrially milled wheat flour fractions with varying endoxylanase activity levels. Analysis of the levels of reducing end xylose (RX) and solubilized AX (S-AX) formed during mixing and resting and their correlation with the endoxylanase activity in the flour milling fractions showed that solubilization of AX during the mixing phase is mainly due to mechanical forces, while solubilization of AX during resting is caused by endoxylanase activity. Moreover, solubilization of AX during the dough resting phase is more outspoken than that during the mixing phase. Besides endoxylanase activity, there were significant xylosidase and arabinofuranosidase activities during the dough resting phase. The results indicate that wheat flour-associated Endoxylanases can alter part of the AX in dough, thereby changing their functionality in bread making and potentially affecting dough and end product properties.
Hans Goesaert - One of the best experts on this subject based on the ideXlab platform.
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Purification and characterization of a XIP-type endoxylanase inhibitor from Rice (Oryza sativa)
Journal of enzyme inhibition and medicinal chemistry, 2005Co-Authors: Hans Goesaert, Kurt Gebruers, Christophe M. Courtin, Jan A. DelcourAbstract:A rice XIP-type inhibitor was purified by affinity chromatography with an immobilized Aspergillus aculeatus family 10 endoxylanase. Rice XIP is a monomeric protein, with a molecular mass of ca. 32 kDa and a pI of ca. 5.6. Its N-terminal amino acid sequence was identical to that of a rice chitinase homologue, demonstrating the difficulty when using sequence information to differentiate between endoxylanase inhibitors and (putative) chitinases in rice. Rice XIP inhibited different Endoxylanases to a varying degree. In particular, it most strongly inhibited family 10 Endoxylanases from A. niger and A. oryzae, while several family 11 enzymes from Bacillus subtilis, A. niger and Trichoderma sp. were not sensitive to inhibition. The above mentioned A. aculeatus endoxylanase was not inhibited either, although gel permeation chromatography revealed that it complexed rice XIP in a 1:1 molar stoichiometric ratio.
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Occurrence of proteinaceous endoxylanase inhibitors in cereals
Biochimica et biophysica acta, 2004Co-Authors: Hans Goesaert, Kurt Gebruers, Jan A. Delcour, Christophe M. Courtin, Johan Robben, Giles O. Elliott, Paul A. Kroon, Nathalie JugeAbstract:Cereals contain proteinaceous inhibitors of Endoxylanases, which affect the efficiency and functionality of these enzymes in cereal processing. This review relates their first discovery in wheat and the subsequent purification of two distinct classes of endoxylanase inhibitors, namely Triticum aestivum xylanase inhibitor (TAXI)-type and xylanase inhibitor protein (XIP)-type inhibitors in cereals. Both inhibitor classes occur in monocots as multi-isoform families. The reported data provide an overview of the relative quantitative and qualitative variation of these inhibitors in cereals. Wheat and rye are particularly rich in TAXI-type and XIP-type inhibitors with the latter inhibitors being more abundant. Lower inhibitor levels are present in durum wheat and barley, while maize contains solely XIP-type inhibitors. No inhibitors have been isolated from rice, oats and buckwheat.
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Properties of TAXI-type endoxylanase inhibitors
Biochimica et biophysica acta, 2004Co-Authors: Kurt Gebruers, Christophe M. Courtin, Hans Goesaert, Johan Robben, Kristof Brijs, Katleen Fierens, Stefaan Sansen, Anja Rabijns, Gert Raedschelders, Jens Frisbæk SørensenAbstract:Two types of proteinaceous endoxylanase inhibitors occur in different cereals, i.e. the TAXI [Triticum aestivum endoxylanase inhibitor]-type and XIP [endoxylanase inhibiting protein]-type inhibitors. The present paper focuses on the TAXI-type proteins and deals with their structural characteristics and the identification, characterisation and heterologous expression of a TAXI gene from wheat. In addition, to shed light on the mechanism by which TAXI-type endoxylanase inhibitors work, the enzyme specificity, the optimal conditions for maximal inhibition activity, the molar complexation ratio and the inhibition kinetics of the inhibitors are explained and the effect of mutations of an endoxylanase on the inhibition by TAXIs is discussed.
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TAXI type endoxylanase inhibitors in different cereals.
Journal of agricultural and food chemistry, 2003Co-Authors: Hans Goesaert, Kurt Gebruers, Christophe M. Courtin, Kristof Brijs, Jan A. DelcourAbstract:An affinity-based purification procedure with the immobilized family 11 Bacillus subtilis endoxylanase XynA allowed us to obtain high yields of highly pure endoxylanase inhibitor fractions from rye, barley, and durum wheat. In contrast, no inhibitors interacting with the B. subtilis endoxylanase affinity column are present in corn, buckwheat, rice, and oats. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis and inhibitor specificity showed that the isolated inhibitors belonged to the TAXI endoxylanase inhibitor family, thus providing a view on the diversity of this cereal inhibitor family. The isolated inhibitors are basic proteins of ca. 40 kDa, occurring in two molecular forms, with pI values of ca. 8.5 (durum wheat) and ca. 9.0 (rye, barley). They are, in general, strong inhibitors of family 11 Endoxylanases but not of family 10 Endoxylanases. Because cereal endogenous Endoxylanases belong to the latter family, this probably indicates that they do not influence cereal metabolic processes. For the first time, endoxylanase inhibitors, similar to TAXI I and TAXI II from wheat, were isolated from durum wheat and characterized. For each cereal, high-resolution cation exchange chromatography revealed the presence of multiple isoinhibitors, each of which occurs in two molecular forms. However, in durum wheat and barley, a single isoform is predominantly present.
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Molecular identification of wheat endoxylanase inhibitor TAXI-I1, member of a new class of plant proteins.
FEBS Letters, 2003Co-Authors: Katleen Fierens, Kurt Gebruers, Christophe M. Courtin, Hans Goesaert, Johan Robben, Guido Volckaert, Kristof Brijs, Steven Van Campenhout, Gert Raedschelders, Jan A. DelcourAbstract:Triticum aestivum endoxylanase inhibitors (TAXIs) are wheat proteins that inhibit family 11 Endoxylanases commonly used in different (bio)technological processes. Here, we report on the identification of the TAXI-I gene which encodes a mature protein of 381 amino acids with a calculated molecular mass of 38.8 kDa. When expressed in Escherichia coli, the recombinant protein had the specificity and inhibitory activity of natural TAXI-I, providing conclusive evidence that the isolated gene encodes an endoxylanase inhibitor. Bioinformatical analysis indicated that no conserved domains nor motifs common to other known proteins are present. Sequence analysis revealed similarity with a glycoprotein of carrot and with gene families in Arabidopsis thaliana and rice, all with unknown functions. Our data indicate that TAXI-I belongs to a newly identified class of plant proteins for which a molecular function as glycoside hydrolase inhibitor can now be suggested.