Modification of the Secondary Binding Site of Xylanases Illustrates the Impact of Substrate Selectivity on Bread Making

To investigate the importance of substrate selectivity for xylanase functionality in bread making, the secondary binding site (SBS) of xylanases from Bacillus subtilis (XBS) and Pseudoalteromonas haloplanktis was modified. This resulted in two xylanases with increased relative activity toward water-unextractable wheat arabinoxylan (WU-AX) compared to water-extractable wheat arabinoxylan, i.e., an increased substrate selectivity, without changing other biochemical properties. Addition of both modified xylanases in bread making resulted in increased loaf volumes compared to the wild types when using weak flour. Moreover, maximal volume increase was reached at a lower dosage of the mutant compared to wild-type XBS. The modified xylanases were able to solubilize more WU-AX and decreased the average degree of polymerization of soluble arabinoxylan in dough more during fermentation. This possibly allowed for additional water release, which might be responsible for increased loaf volumes. Altered SBS functionality and, as a result, enhanced substrate selectivity most probably caused these differences.status: publishe

Assessing the impact of xylanase activity on the water distribution in wheat dough: A 1H NMR study

The molecular mobility of water and biopolymers in wheat dough and the influence of xylanases thereon was investigated with time domain proton nuclear magnetic resonance relaxometry. To reduce the complexity, model systems containing starch, gluten and/or water-unextractable arabinoxylan (WU-AX) were used. In the starch-WU-AX-water model, starch binds water fast but less strong compared to WU-AX, resulting in water withdrawal from starch during resting. In contrary, WU-AX did not affect the water distribution in a gluten-WU-AX-water system, despite the higher water retention capacity (WRC) of WU-AX compared to gluten. In a starch-gluten-WU-AX-water model and in wheat flour, water was distributed over the different constituents including WU-AX. Addition of xylanase reduced the WRC of WU-AX, resulting in a release of water. Therefore, the beneficial effect of xylanase on dough and bread quality can, in part, be attributed to the redistribution of water, initially bound by WU-AX, between the other flour constituents.status: publishe

Sensitivity of the Bacillus subtilis Xyn A Xylanase and Its Mutants to Different Xylanase Inhibitors Determines Their Activity Profile and Functionality during Bread Making

The importance of inhibition sensitivity for xylanase functionality in bread making was investigated using mutants of the wild-type Bacillus subtilis xylanase (XBSTAXI), sensitive to Triticum aestivum xylanase inhibitor (TAXI). XBSNI, a mutant with reduced sensitivity to TAXI, and XBSTI, a mutant sensitive to all wheat endogenous proteinaceous inhibitors (TAXI, Xylanase Inhibiting Protein and Thaumatin-like Xylanase Inhibitor) were used. The higher inhibition sensitivity of XBSTAXI and XBSTI compared to XBSNI was associated with a respective 7- and 53-fold increase in enzyme dosage required for a maximal increase in bread loaf volume. XBSTI and XBSTAXI were only active during the mixing phase and the beginning of fermentation, while XBSNI was able to hydrolyze arabinoxylan until the end of fermentation. In spite of this difference in activity profile, no differences in loaf volume were observed for the different xylanases at optimal concentrations. Dough extensional viscosity analysis suggests that increased water availability as a result of xylanase activity favors starch-starch and starch-gluten interactions and drives the improvement in bread loaf volume.status: publishe

Insight in the variability of wheat (Triticum aestivum L.) milling co-products and their functionality in bread making

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Wheat milling by-products and their impact on bread making

This study investigates the relationship between the properties of dietary fiber (DF) rich wheat milling by-products and their impact on bread making. From coarse bran over coarse and fine weatings to low grade flour, the content of starch and lipids increased, while that of DF and ash decreased. Enzyme activity levels differed strongly and were not related to other by-product properties. Average particle size of the by-products was positively correlated with DF and ash contents and their hydration properties. When meals from flour and by-products were composed on the same overall starch level to compensate for differences in endosperm contamination in the by-products, bread specific volume was more strongly depressed with fine weatings and low grade flour than with coarse bran and weatings. This suggests that the properties of the former were intrinsically more detrimental to bread making than those of the latter.publisher: Elsevier articletitle: Wheat milling by-products and their impact on bread making journaltitle: Food Chemistry articlelink: http://dx.doi.org/10.1016/j.foodchem.2015.04.048 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved.status: publishe

Mental health nurses' attitudes and perceived self-efficacy toward inpatient aggression: a cross-sectional study of associations with nurse-related characteristics

PURPOSE: To explore mental health nurses' attitude and self-efficacy to adult inpatient aggression, and to explore the association with nurse-related characteristics. DESIGN AND METHOD: Cross-sectional study in a sample of 219 mental health nurses in nine psychiatric hospitals, with stepwise linear regression analysis to detect predictive models. FINDINGS: Female and less experienced nurses were less likely to blame patients for their behavior. Gender, burnout, secondary traumatic stress, and compassion satisfaction accounted for 26.2% of the variability in mental health nurses' self-efficacy toward aggression. PRACTICE IMPLICATIONS:There needs to be attention to professional quality of life for mental health nurses, to provide them with of self-efficacy and a positive attitude toward coping with aggression

Onderzoek en dienstverlening via het expertisecentrum Onderwijsinnovatie: Projectmatig wetenschappelijk onderzoek 2016-2019

Onderzoek en dienstverlening via het expertisecentrum 'onderwijsinnovatie' in de periode 2016-2019 werden volgende onderzoeksprojecten uitgevoerd: - High impact learning: opleiden in flexibele en uitdagende leeromgevingen - Innovatieve en differentiërende houding - Blend - Diverse leraarskamer - Quid Pro Quo: naar een kwaliteitsvolle lerarenopleiding voor M/V met talent - Didactische taalondersteuning voor zaakvakleerkrachten met ex-OKAN-leerlingen in de klas - Context is the key - op weg naar een taalsterk vrijetijdsaanbod voor anderstalige lagereschoolkinderen - Design@school: STEM-didactiek en STEM-effectiviteit in de overgang van basis- naar secundair onderwijs - Wiskunde & computationeel denken via een STEM aanpakstatus: publishe