在本文中，通过筛选三种α-淀粉酶，以甜菊苷的转化率为指标，选用一种耐酸性的中温α-淀粉酶，其商品名称为高峰淀粉酶，将供体可溶性淀粉水解为葡萄糖基引入甜菊苷中对甜菊糖进行酶法改性以改善其味质。经试验后，对酶法催化工艺进行优化，最佳工艺条件为：供体淀粉浓度为100 g/L，底物比例(甜菊糖:淀粉)为1:10 (m/m)，反应温度为60 ℃，加酶量为1.5 U/mL。改性后的甜菊糖产品采用高效液相色谱(HPLC)法测定甜菊苷的转化率，结果为42.5%。最后对酶法改性后甜菊糖产品进行感官味质评定，结果表明经酶法改性后的甜菊糖，味质得到显著的改善，甜味变得清淡且味道柔和，有微弱的苦味，但低浓度下基本无后苦味。经α-淀粉酶催化甜菊糖后能达到预期的味质效果，且大大降低了酶成本，为甜菊糖提供了理论与工业化基础。

In order to improve taste quality, enzymatic modification of stevia by grafting glucose was investigated using soluble starch as glucose donor. The hydrolysis was catalyzed by acid-resistant mesophilic α-amylase, whose trade name is Taka-diastase, that was screened from three different α-amylases. Using stevioside conversion rate as an indicator, the enzymatic processes were optimized and the optimum conditions obtained were donor starch concentration 100 g/L, substrate ratio 1:10 (m/m), reaction temperature 60 ℃, and enzyme concentration 1.50 U/mL. The conversion rate of the modified stevioside was determined as 42.5% by high performance liquid chromatography (HPLC). The organoleptic evaluation results showed that the enzymatic modification improved the taste quality of stevia significantly. The sweetness became mild and soft, and a slight bitter taste still remains at high concentration, but disappears at low concentration. Desirable taste quality with significantly reduced production cost could be achieved by enzymatic modification of stevia.

重庆市人力资源和社会保障局技能专家工作室项目（渝人社发[2012]236号）