The influences of stability of protease activity in the presence of anionic surfactant (DBS) and/or nonionic surfactant (APE) systems upon the removal of blood protein stains were studied by using the fabrics soiled with bovine blood.
In the washing by anionic surfactant·nonionic surfactant·protease systems, the removal efficiency of blood protein stains increased compared with those of anionic surfactant·protease systems. It was deduced that the stability of protease activity in the presence of nonionic surfactants were more superior to that in the presence of anionic surfactant.
In the washing of fabrics soiled with blood with anionic surfactant·nonionic surfactant·protease systems, in particular, when protease was allowed in contact with nonionic surfactant prior to that with anionic surfactant in washing solution, the removal efficiency remarkably increased.
Thus, the increase of detergency of blood protein stains were influenced by the stability of protease activity in the presence of surfactants, and also, the detergency of these stains remarkably participated with additive molar numbers of ethylene oxide and carbon chain length of alkyl groups of nonionic surfactants APE in the presence of anionic surfactant.
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