Primary odorants of naturally soiled laundry: Influence of lipase on the odour profile

Odorants still attached to laundry soiled with human axillary sweat and sebum, after a mild washing procedure, were extracted and analysed 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 dominating, characteristic odorants in human axillary sweat, were, on the other hand, effectively removed during wash. The influence of lipase activity on the odour profile was investigated by analysing selected sets of textile swatches, sampled from the right/left axillary of male runners, washed in the presence/absence of lipase.

The swatches were examined by a sensory ranking analysis prior to the analytical odour analysis. Swatches selected for the subsequent odour analysis possessed greater odour 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 generally the aldehydes were present in slightly higher concentrations in swatches washed in the presence of lipase.

Many of the aldehydes identified are well known lipid oxidation products, which are believed to be formed through oxidative degradation of triglycerides present in human sebum - a process that may be facilitated by lipase.