This odor is caused by the oxidation of polyamines in prostatic fluid. The longer abstinence, the bigger the smell.
This stench is produced by the oxidation of a chemical called refined ammonia. Spermine is one of many important components contained in prostatic secretion. The oxidation of spermine must involve seminal vesicle fluid, and the prostatic fluid obtained by rectal massage generally has no smell of naturally ejaculating semen.
Beauty and maternity knowledge