Research Of Arabinoxylan And Xylanase In Wheats And Wheat Malts

Wheat malt is a good raw material for brewing, and the beer is a popular drink in current in the world. Selecting the suitable wheat variety for malting is an effective measure to develop advanced processing of wheat, to enhance the income of peasant, and is helpful to the development of wheat, malting and beer industry. But the arabinoxylans which is rich in wheat malts affect the application of wheat malts in beer brewing, so the research of the content of arabinoxylans and the activities of xylanolytic system is important. In this research the content of arabinoxylans and the activities of xylanase of 11 wheat cultivars were determined and the characteristics of xylanases were researched. The main conclusions were as follows:1 The optimal determination condition of arabinoxylans was 10 mL phloroglucin-glacier acetic acid reagent, react time 20min, and within 30min after cooled the reaction product was stable (P>0.05).2 The No.8, No.9 and No.10 of wheat had the lowest contents of AEAX, which were 0.5811±0.0127%, 0.6605±0.0620% and 0.6603±0.0301%, respectively (P>0.05); the No.9 and No.10 of wheat malts had the lowest content of AEAX, which were 0.9746±0.0085% and 0.7797±0.0508% respectively (P>0.05).3 For content of WEAX, the No.4, No.8 and No.10 of wheats (P>0.05) and the No.7 and No.8 of wheat malts (P>0.05) had the lowest, which were 0.5423±0.0645%, 0.4681±0.0127%, 0.3828±0.0403%, 0.3362±0.0518% and 0.2429±0.0467% severally. No.7 and No.8 was maximum (P>0.05).4 WEAX contents of all the wheat cultivars were declined and xylanases activities of all the wheat cultivars were raised.5 The optimal determination conditions of xylanase activities were as follows: 3 mL DNS, react time 15min, and within 35min the reaction product was stable (P>0.05).6 In the wheats researched, the xylanase activities were between 65.00~85.00 IU/mL, and 100.00~115.00 IU/mL after malting (P>0.05).7 In wheats, the contents of water extractable arabinoxylans and alkaline extractable arabinoxylan showed significant positive correlation (P<0.01), and xylanase activities and the content of arabinoxylans was negative correlation (P<0.05). However, in wheat malts, the contents of water extractable arabinoxylans and alkaline extractable arabinoxylan showed negative correlation(P<0.05), so did xylanase activities and the content of water extractable arabinoxylans(P<0.05), and xylanase activities and the content of alkaline extractable arabinoxylans showed significant positive correlation(P<0.01).8 The optimal temperature of action catalyzed by xylanase was 50oC, optimal pH was 5.5~6.0, optimal concentration of xylan was 1.0000%, optimal ratio of substrate and enzyme was 9/1, and optimal reaction time was 5~9min.9 Lower steep-out moistures can advance the synthesis of alkaline extractable arabinoxylans and the degradation of water extractable arabinoxylans, and enhance the xylanase activities. During malting, the xylanase activities in 20oC and 50oC were highest. So we can properly extension the time of higher activities temperature to enhance the xylanase activities and decrease the content of arabinoxylans.