Ancestral vinegar

Ancestral vinegar | New Scientist Lastword: "Ancestral vinegar

Question

During the Second World War we would often find a jelly-like substance in our vinegar bottle. My mother called it 'mother-of-vinegar'. Is it true that if you put this into water it will turn into vinegar? Why don't we see it any more?
M. O'Byrne , By e-mail, no address supplied

Answer

The jelly-like substance mother-of-vinegar is in fact a mass of cells of the bacterium Acetobacter aceti var. xylinum. Acetobacter species are used in the production of vinegar where they oxidise ethanol to ethanoic (acetic) acid, the substance that gives vinegar its characteristic sourness. Nowadays, commercial vinegar is pasteurised before bottling, so you tend not to see mother-of-vinegar develop. In the past, this was not the case.

The gelatinous character of the material is due to the bacterium's ability to produce copious quantities of cellulose. Some strains growing on the surface of an alcoholic liquid can produce a solid gelatinous mass that can grow to several centimetres thick. In the Philippines this property is exploited to make the traditional product known as nata de coco or nata de pina. These are simply cubes of bacterial cellulose sweetened and then eaten as a dessert.

You will not produce vinegar if you add mother-of-vinegar to water, but you will if you add it to an alcoholic liquid such as beer or wine and then leave it exposed to the air for a while.
Martin Adams , Reader in Food Microbiology School of Biomedical and Life Sciences University of Surrey"