Recently more consumers hang and dry their laundries indoor for various reasons. Under these slow drying conditions malodor was sometimes generated. Gas chromatography analysis showed the odorants were composed of medium-chain alcohols, medium-chain aldehydes, ketones, fatty acids, N-compounds and S-compounds. Especially, medium-chain fatty acids were confirmed to make up a characteristic and striking sweaty and sour odor. The malodor is supposed to be formed from sebum and soils by oxidative degradation as well as by metabolism of microorganisms. This study shows that a laundry detergent with an enzyme possessing high protease as well as bacteriolytic activity can prevent washed clothes from malodor generation during such a prolonged drying.

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House dust mites (Dermatophagoides farinae) in bedding and clothes are a major allergen. However, house dust mites cannot be killed by general washing conditions under 50˚C. Therefore, lowtemperature washing conditions must be improved to eliminate house dust mites. Sodium alkyl acyloxybenzene sulfonate (OBS) is a bleach activator that is used to intensify the bleaching effects of some laundry products. The purpose of this study was to evaluate the effect of OBS on the elimination of house dust mites in low-temperature washing conditions. D. farinae was soaked in solutions containing different types of OBS for various durations and at various temperatures. The miticidal effects of the various washing conditions were also evaluated for D. farinae. Then sodium lauroyloxybenzene sulfonate (OBS-12) produced the highest D. farinae mortality rate among the OBS solutions that were examined and had a stronger miticidal effect than available chlorine under general washing conditions. OBS exhibited miticidal effects under general washing conditions at low temperatures. Since OBS is already used as an additive in some laundry products to increase the bleaching activity, OBS can be easily used to kill house dust mites under general washing conditions.

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We evaluated the allergen inactivating effect of colloidal silica by performing enzyme-liked immunosorbent assay (ELISA) whose wells were coated with 150 ng/mL of Japanese cedar pollen allergen (Cry j 1) or mite allergen (Der f 2). The allergens were almost 100% inactivated by 100 microg/mL of colloidal silica having a particle size 5 nm, and the inactivating effect was increased by aluminum binding to the surface of the colloidal silica. The results show that colloidal silica is a promising material for allergen inactivation. Since colloidal silica forms an insoluble nondispersive solid when dried, it is expected that airborne allergens can be reduced by binding them to colloidal silica.