Definitions of fermentation

  1. a process in which an agent causes an organic substance to break down into simpler substances; especially, the anaerobic breakdown of sugar into alcohol
  2. The process of undergoing an effervescent change, as by the action of yeast; in a wider sense ( Physiol. Chem.), the transformation of an organic substance into new compounds by the action of a ferment, either formed or unorganized. It differs in kind according to the nature of the ferment which causes it.
  3. A state of agitation or excitement, as of the intellect or the feelings.
  4. A chemical change accompanied by effervescence, or bubbling up; working, as of yeast in liquor; excitement; agitation.
  5. The conversion of an organic substance into new compounds in presence of a ferment. Fermentation differs in kind according to the nature of the substance which promotes it. Sugar in solution is liable to two principal kinds of fermentation ( vinous and lactic), both of which are probably due to the growth in the liquid of a mould or fungus. Fermentation may be checked or altogether prevented by anything which prevents the growth of the fungus, as by keeping away from the liquid the spores or germs from which the fungus springs, by the liquid being either too hot or too cold for its development, by its containing too much sugar, or by the presence of a substance ( called an antiseptic) which acts as a poison on the fungus. Vinous fermentation is produced by the growth of the yeast- plant ( see YEAST); lactic fermentation is due to the presence in the liquid of Penicillium glaucum ( common blue mould). In vinous fermentation the sugar is converted into carbonic acid and alcohol, the nitrogenous element being assimilated by the rapidly developing ova of the ferment. Lactic fermentation takes place in milk in the process of becoming sour, when the sugar of the milk is converted into lactic acid. ( see under LACTIC.) Acetous fermentation occurs in liquids which have already undergone vinous fermentation. When exposed to the atmosphere such liquids become sour, and vinegar is produced. This change is probably due to the growth of a fungus, Mycoderma aceti ( the vinegar- plant). Other kinds of fermentation are benzoic fermentation, in which, amongst other matters, the essential oil of bitter almonds is formed; and sinapic fermentation, occurring in mustard moistened with water, during which oil of mustard is produced. For an explanation of fermentation, in relation to the origin and spread of contagious diseases, see GERM THEORY. - Figuratively, the state of being in high activity or commotion; agitation; excitement, as of the intellect or feelings, a society, etc. " The founders of the English Church wrote and acted in an age of violent intellectual fermentation and of constant action and reaction."- Macaulay.
  6. Fermentative, fermentable.
  7. A chemical decomposition of an organic compound, as of sugar in the production of alcohol.
  8. Commotion; excitement.
  9. Originally the decomposition which takes place in dead organic matter when exposed to the action of moisture and air under a moderate heat, now properly a change of the like kind which takes place in an organic substance, not naturally liable to it, when acted on by a body in the above state of decomposition, hence called a ferment; an agitation among the ideas or feelings of the mind caused by some disturbing influence that tends materially to modify them.
  10. A working or frothing up of any substance under the influence of warmth, air, and moisture; an internal motion caused by decomposition; the process of converting the juice of the grape into wine, or the liquid extract of malt into an alcoholic liquor, as beer.
  11. Any of the transformations occurring in organic substances caused by the presence of a ferment.