Peculiar skin taste

My wife of 5 years, 29 yo, 120 lbs, 5'6", healthy, good eating habits, showers twice a day, has had always a peculiar taste to her skin. The taste is exactly that of a tropical fruit, soursop (Spanish guanábana, Portuguese graviola, Annona muricata). It is a sour flavor, which in intimasy is not very rewarding, lets say. You can't smell it, just taste it. It is not related to sweating, as it is present even right after a shower. It is not particular to any body part, but generalized (neck, torso, arms, belly, legs, etc.). She recalls that this has been present before we met as well and previous boyfriends had notice it also. We are clueless of cause and would like to see if this has been reported previously, if it is a condition, what it is called, and if there is any action to bring back or have a somewhat neutral (natural) taste to her skin.
Thanks.