以硼砂为对照,考察了16种柠檬酸盐、多元醇及酯系列稳定剂,以及温度、pH、稳定剂用量对3种蛋白酶在洗衣液中稳定性的影响;同时基于洗衣液的主要成分考察了表面活性剂AES,AEO和APG等对蛋白酶活的影响。实验结果表明,柠檬酸盐尤其是柠檬酸铵钙的稳定效果最佳,APG0810和APG1214的稳定效果与硼砂接近。当蛋白酶用量为0.5%时,以柠檬酸铵钙-APG0810-APG1214三元复合体系稳定蛋白酶,含有Purafect 4000L和Purafect Prime 4000L的复合稳定剂体系在pH=7和25 ℃下的3周酶活保持率分别可达到84.3%和71.5%;在pH=8和37 ℃下的3周酶活保持率分别为47.2%和30.4%;硼砂体系pH=7和37 ℃下的3周酶活保持率分别为2.87%和13.5%。此外,AES会较大幅度地降低酶活,而非离子表面活性剂AEO7和AEO9对其酶活无显著影响,但AEO和AES的混合并不能降低AES对酶活的损伤,可以考虑在液体加酶洗涤剂中增加APG和AEO的使用。
With borax as control, the effects of 16 stabilizers of citrate, polyols and esters, temperature, pH and amount of stabilizer on the stability of three proteases in liquid laundry detergent were investigated, and the effects of surfactants AES, AEO and APG on the activity of protease were also investigated based on the main components of liquid laundry detergent. Results show that the stability of citrate, especially calcium ammonium citrate, is the best, and the stability of APG0810 and APG1214 is close to that of borax. When the amount of protease was 0.5%, the three-week activity retention rates of protease stabilized by calcium ammonium citrate-APG0810-APG1214 ternary complex stabilizer system, Purafect 4000L and Purafect Prime 4000L complex stabilizer at pH=7 and 25 ℃ were 84.3% and 71.5%, respectively; the three-week activity retention rates at pH=8 and 37 ℃ were 47.2% and 30.4%, respectively; and the three-week activity retention rates of protease stabilized by borax at pH=7 and 37 ℃ were 2.87% and 13.5%, respectively. In addition, AES can significantly reduce the enzyme activity, while non-ionic surfactants AEO7 and AEO9 did not. However, the mixing of AEO and AES cannot reduce the damage of AES to the enzyme activity. It can be considered to increase the use of APG and AEO in liquid enzyme-enhanced detergents.
