gluconic acid distilled with hydrochloric acid gave traces of furfural; so also with sulphuric acid and manganic oxide.
In addition to them there is in milk an organism resembling Mycoderma aceti, which transforms milk sugar into gluconic acid.
The process is reversible; mannose can be converted to mannonic acid, thence to gluconic acid, thence to glucose.
gluconic acid glu·con·ic acid (glōō-kŏn'ĭk)
An acid formed from the oxidation of glucose and other sugars.