Primary odorants of laundry soiled with sweat/sebum: Influence of lipase on the odor profile

Odorants still attached to laundry soiled with human axillary sweat and sebum after a mild washing procedure [European full-scale, short-cycle wash (20 min wash, 15 min rinse) at 30°C, using color detergent at 3.5 g/L] were extracted and analyzed by aroma extract dilution analysis. Esters (ethyl-2-methylpropanoate and ethylbutanoate), ketones (1-hexen-3-one and 1-octen-3-one) and, in particular, aldehydes [(Z)-4-heptenal, octanal, (E)-2-octenal, methional, (Z)-2-nonenal, (E, Z)-2,6-nonadienal, (E, Z)-2,4-nonadienal, (E, E)-2,4-decadienal, and 4-methoxybenzaldehyde] were identified as primary odorants. Organic acids, which are dominant characteristic odorants in human axillary sweat, were, on the other hand, effectively removed during the washing process. The influence of lipase activity on the odor profile was investigated by analyzing selected sets of textile swatches, sampled from the right/left axillary of male runners, washed in the presence or absence of lipase. The swatches were examined by a sensory ranking analysis prior to the analytical odor analysis. Swatches selected for the subsequent odor analysis possessed greater odor intensity when washed in the presence of lipase than the corresponding swatches washed in the absence of lipase. The aroma extract dilution analysis revealed that aldehydes were present in slightly greater concentrations in swatches washed in the presence of lipase. The aldehydes are believed to be formed through oxidative degradation of triglycerides present in human sebum, which may be facilitated by lipase. Based on sensory panel results and dilution analysis of odorants, the impact of lipase on the odor impression was, however, minor and thus believed to be inadequate as explanation for malodor generation in laundry as experienced by the consumer.