| Arabinoxylan（AX）,with high viscosity and water retention,is the main non-starch polysaccharide in cell walls of wheat.On the one hand,water-extractable arabinoxylan（WEAX）in malt can easily lead to high turbidity and poor filtration performance of wort and beer,but on the other hand,it can improve the antioxidant activity,foam and taste of beer.It will provide data support for the quality improvement of malt and beer to deeply study the structure and function of WEAX.In this research,wheat malts obtained at different germination time were taken as the object,and different proportions wort made of barley malt and wheat malt was prepared by EBC saccharogenic method.The effects of germination time and malt ratio on the structure and antioxidant activity of WEAX were studied,and the special beer with ginger flavor was developed at the same time.The main results are as follows:（1）With the extension of germination time,Kolbach indices,chroma,turbidity,free amino nitrogen and total acid contents gradually increased,while the p H value and viscosity gradually decreased.The extract content increased to 82.2% and remained at the same level,and the diastatic power reached the maximum on the 4th day malt of germination,and then gradually decreased.The activities of various enzymes showed the maximum value on the 4th to 5th day of germination.The total AX content in wheat at germination stage was 5.43% ～ 5.87%;The content of WEAX ranged from 0.54% to 1.56%,and the A/X value ranged from 0.45 to 0.51.The purity of WEAX was 75.10% ～ 83.45%,the A/X value was 0.47 ～ 0.53,and the protein content was less than 0.61%.With the extension of germination time,the weight average molecular weight（Mw）of WEAX decreased gradually,and the Mw of WEAX was the lowest at 88.6 k Da on the 3 d of germination.WEAX had an amorphous structure and its short-range ordered structure decreased with the germination time;DPPH free radical scavenging rate of WEAX increased from 11.34% to 55.79%,ABTS free radical scavenging rate increased from 8.02%to 81.8%,and the maximum scavenging rate was reached at 3 mg/m L and 8 mg/m L,respectively,and then tended to be stable.（2）The content of WEAX in wort mixed with barley malt and wheat malt was from57.81 to 135.49 mg/100 m L.With the increasing wheat malt,the content of WEAX in wort increased gradually.The purity of WEAX was from 70.89% to 86.51%,and the A/X value was 0.44 ～ 0.57.The Mw of WEAX showed an increasing trend.The change of malt composition did not cause significant change of WEAX near-range ordered structure.As the percentage of wheat malt decreases,DPPH free radical scavenging rate of WEAX increased from 15.36% to 66.05%,ABTS free radical scavenging rate increased from 5.72% to 74.82%,and reached the maximum scavenging rate at 4 mg/m L and 8 mg/m L,respectively,and then tended to be stable.（3）Freeze-dried ginger flour in the range of 0 ～ 0.7 g/L was added during wort boiling stage for wheat beer brewing.The content of reducing sugar and total sugar decreased continuously during fermentation,while yeast quantity initially increased and then decreased.Ginger flour addition resulted in the decrease of sugar metabolism rate of yeast in fermentation broth.The content of diacetyl,bitterness value,total reducing power,ABTS and DPPH free radical scavenging ability of ginger beer significantly increased,which was beneficial to delay the aging process during beer storage.The higher amount of ginger flour,the higher amount of gingerol in beer,and the more stable the antioxidant activity of beer during storage. |
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