Effects Of Xylanases On Water Mobility In Dough And Mantou Quality Using NMR And MRI Techniques

To study the role of xylanases in the non-fermented dough, fermented dough andMantou samples, four high-quality wheat samples from Henan Province and threeexogenous xylanases were selected to reveal the effects of xylanases on xylandegradation mechanisms and water mobility in wheat dough. High PerformanceLiquid Chromatography, Nuelear Magnetic Resonnace (NMR) and MagnetieResonnace Imganig (MRI) were used to discuss the effects of xylanases on xylandegradation mechanisms, water mobility in the non-fermented dough and fermenteddough.Besides, Mantou texture was measured during its storage, which were used toprovide scientific reference for Mantou quality and its storage quality.Firstly, the effects of xylanases on dough rheology properties were studied by theKieffer test of TA-XT Plus. The results showed that the resistance to stretching ofdough decreased while the dough extensibility increased with the dosage of xylanasesincreasing. Otherwise, The effects of different xylanases on dough rheologyproperties were different. Among these xylanases, both of xylanases which are fromNovozeymes and China Agricultural University were suitable for the processing ofthe dough.Secondly, the effects of xylanases on water mobility in the non-fermented doughwere measured with NMR technology. The result shows that the content of free waterin the non-femented dough was increased with adding dose of xylanase, and thedough rheology properties were changed by adding xylanase.Thirdly, the effects of xylanases on water mobility in the fermented dough weremeasured with NMR and MRI techniques. The result shows that the content of freewater in the femented dough was increased with adding dose of xylanase. Liquidxylanase was better than solid xylanase. Besides, there was synergy between theyeast and xylanase in dough, which jointly promoted fermentation.Fourthly, to analyse the effects of the xylanases on the content ofwater-extractable arabinxylans in bread, High Performance Liquid Chromatographtechnology were used to determin the change between fermented at0minute and45minute in steamed bread. The results showed that the content of water-extractablearabinxylans in flour increased with growth of xylanases. And also, there was significant corrlelation between the content of water-extractable arabinxylans and thehardness of Mantou.the most suitable adding dose of xylanase was1.5U/g.Finally, the effects of xylanases on shelf life of Mantou samples were to determinewith NMR and TA-XT Plus techniques during storage. The results indicated that theaddition of xylanse to Mantou samples reduced water molecules lossing, which mayhinder their staling rate during0-120hour. However, the samples added liquid statexylanse decreased staling rate during0-36hour, while, increased the staling rateduring36-120hour.