The influence of thermal reaction and microbial transformation on the odour of human urine

Abstract

The typical stale urine odour is the consequence of thermal or bacterial degradation. Gas chromatography–mass spectrometry, equipped with a multi‐sniffing port for olfactive evaluation (GC‐MS‐O), was performed to analyse an organic extract of boiled urine originating from seven male donors. This analysis stressed the importance of guaiacol, 2‐methoxy‐4‐ and ‐6‐methyl phenol, 4‐vinyl‐guaiacol, indole, skatole and vanillin in urine malodour. Analysis of the headspace of the highly volatile compounds showed the occurrence of trimethylamine, methyl mercaptan and dimethyl sulfide. However, odour artefacts such as pyrazines, acetyl thiazole and sugar degradation products were formed during the boiling process and represented important background noise. In parallel, fermented urine samples were judged by sniffing to be more characteristic of a urine smell, due to the presence of methional, phenol, p‐cresol and α‐androstenol. The two urine‐isolated Enterobacteriaceae, Escherichia fergusonii and Morganella morganii (urease positive), were particularly efficient at increasing urine pH and generating phenol, p‐cresol, indole, dimethyl sulfide and trimethylamine after 3 days of incubation of sterile male urine at 37 °C. Streptococcus agalactiae produced a high level of α‐androstenol, whereas Micrococcus luteus CIP 103664 and isolated anaerobic bacteria did not produce any malodours. Analytical comparisons between boiled and fermented aged urine revealed that incubation of sterile urine with a bacterial mixture of E. fergusonii, Enterococcus faecalis, Citrobacter koseri, S. agalactiae and M. morganii produced a representative aged urine odour. Copyright © 2013 John Wiley & Sons, Ltd.

Odorant volatile sulfur compounds in cat urine: occurrence of (+/−)‐3,7‐dimethyloct‐3‐sulfanyl‐6‐en‐1‐ol and its cysteine conjugate precursor

“…Two‐dimensional GC experiments were not performed to elucidate the composition of this peak. Para ‐vinylphenol ( 24 ), indole ( 8 ) and the acid 25 found in cat urine also occurred in human urine and contributed to its odour . Finally, sulfur compound (+/−)‐3,7‐dimethyloct‐3‐sulfanyl‐6‐en‐1‐ol ( 11 ) presented a pleasant odour, more citrus than urine, with a NIF = 56%.…”

“…The new commercial lots of apotryptophanase have lost their beta‐lyase activity towards cysteine‐ S ‐conjugates, even if the turnover and specifications for the tryptophan are still valid. For this reason, cat urine was incubated 72 h with Morganella morganii , human urine bacteria having good beta‐lyase activity . We observed that thiol 2 was a minor product compared with methyl thioether ( 9 ).…”

“…Para-vinylphenol (24), indole (8) and the acid 25 found in cat urine also occurred in human urine and contributed to its odour. [23] Finally, sulfur compound (+/À)-3,7-dimethyloct-3-sulfanyl-6-en-1-ol (11) presented a pleasant odour, more citrus than urine, with a NIF = 56%. With a molecular weight of 188, this compound corresponded to chemical formula C 10 H 20 OS and was easily attributed to (+/À)-3,7-dimethyloct-3-sulfanyl-6-en-1-ol (11), thanks to unpublished results obtained during analysis of the flower Lantana camara L. The essential oil of this flower is rich in citral and sulfur compounds.…”

Technologies for the treatment of source-separated urine in the eThekwini Municipality

“…In the collection tanks, urea and other organic substances are degraded by bacteria. The results are high ammonia concentrations, a high pH value and a strong, pungent smell caused by organic degradation products (Udert et al, 2003a;Troccaz et al, 2013). Due to the high pH value, nearly half of the nitrogen can volatilise as free ammonia (Siegrist et al, 2013).…”

Identification of Key Odorants in Used Disposable Absorbent Incontinence Products

“…Although the volatile compounds emitted from urine have been investigated in several studies,13 research focusing on the odor potential of various urinary volatiles via the GC–O technique is sparse. The initial studies in this field have used various extraction and distillation techniques to collect and enrich urinary volatiles 14,15. Unfortunately this approach creates a somewhat-biased picture of what volatile compounds cause odor in urine.…”