Enzymes as Detergent Additives Present estimates are that fully one third of all the home laundry products in use today incorporate an ensyme to improve their overall efficiency. This dramat.ic acceptance of the biologicd catalysts as laundry additives had its origin in Europe and was made possible by the development of enzyme systems with t,he appropriate characteristics. These include activity and stability a t high pH and relatively high temperature, and compatibility with sodium tripolyphosphate and other detergent components incompatible with many other enzymes. The enzymes ourrently enjoying most favor with the detergent manufacturers w e protease and amylase. It has been established that the most dramatic laundering results are obtained with enzymes isolated from varieties of Bacillus sublilis. When this microorgmism is grown under certain prescribed conditions, s. type of protease is produced that has several unique characteristics, making it most suitable for use as a laundry additive. Under these conditions, compatibility with sodium tripolyphosphate, sodium perborate, sodium metasilicate, tetra sodium pyrophosphate, carboxymethylcellulose, nitrilotriacelic acid, the nonionic and the anionic surfactant is excellent, Compatibility with the cationicsurfactant is fair, whereasit isvery poor with sodium hypoehlorite. Today there is increasing interest in what can be described as the "second generation" enzymes, that is, the eamhination products containing an amylase as well as the protease. Variebies of Bacillus sublilis also secrete an amylase that is functional a t the high pH ol laundry products and reasonably compat.ihle with most of the components normally found in theseproducts. The fact that it is the proteolytic enzymes that are ubiquitously employed as laundry additives has prompted speculation regarding their influence on natural fibers such as wool and silk. Our laboratory investigated this by either successively washing wool and silk swatches, or allowing them to soak for prolonged periods of time, after which measurements were made of changes in weight, tensile strength, or area. I n order to evaluate the effectiveness of the enzymes as laundry additives under practical conditions, but a t the same time, with some degree of standrtrdiziltion and reproducibility, standard test fabrics were employed and a soaking or full cycle operation was approximated in the laboratory. I t is observed that the detergent plus enzyme has a temperature optimum between 40 and 50°C. On the assumption that a typical wool or silk garment would not he washed more bhan ten times a. year, ten successive washes. with drvinr . - in between each wash, were performed. A 24-hr soak was employed in certain of the studies. The data indicate that under practical use conditions covering the equivalent of a t least one year's washing, an enzyme typical of today's laundry additives does not adversely affect the weight,, tensile strength, or shape of the natural fibers, wool and silk.
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780 / Jovrnol of Chemiml Education
