以面粉为原料进行挤压膨化，以成曲糖化酶活力为评价指标，研究挤压膨化参数对白汤酱油成曲糖化酶活力的影响。通过单因素试验分别研究了面粉含水率、螺杆转速、喂料速度和套筒温度对糖化酶活力的影响。在单因素的基础上进行响应面试验，对挤压膨化参数进行优化。结果表明，最佳的挤压膨化参数为面粉含水率45%，螺杆转速100 r/min，喂料速度10 kg/h，套筒温度80 °C，在此条件下，糖化酶活力为1293.49 U/g。利用高糖化酶活力的成曲，采用低盐固态发酵方式进行白汤酱油酿造，测得白汤酱油的氨基酸态氮含量为0.65 g/100mL，还原糖含量为243.25 mg/mL，酱油口味清甜，酱香浓郁。

Wheat flour was used as material to be extruded and made for koji of white soy sauce. The glucoamylase activity of koji is regarded as the index. The effect of different extrusion parameters on the glacoamylase activity of koji were studied. By single factor experiment, the effect of the moisture content of flour, screw speed, feeding spend and barrel temperature on the glucoamylase activity were investigated. Then the extrusion parameters were optimized by Response Surface Methodology (RSM). The results showed that the optimal glucoamylase activity was 1293.49 U/gunder the following extrusion conditions, including moisture content of 40%, screw speed of 100 r/min, feeding speed of 10kg/h, and barrel temperature of 80 °C. The koji of higher glucoamylase activity was utilized to ferment and the brewing experiment of white soy sauce was conducted by low-salt solid-state fermentation. After the end of fermentation, the contents of amino acid nitrogen and reducing sugar were 0.65 g/100mL and 243.25 mg/mL respectively in the white soy sauce. The white soy sauce tasted sweet and showed good flavor.