do pickles, bread, yogurt, wine, beer, and cheese have in
All of these foods are made by fermentation. When you ferment
a food, you encourage growth of "good" microorganisms
in it, while preventing growth of spoilage-causing microorganisms.
Doing this successfully may require special ingredients and
carefully controlled conditions, such as temperature and pH.
By eating spoilage-sensitive parts of the food, and releasing
chemicals as a by-product, the microorganisms help preserve
the food, and change its flavor and texture in interesting
Heres a brief look at how fermentation is used to make
Vegetables. The vegetable is soaked in a salt brine, allowing
the growth of bacteria that eat the vegetables sugars
and produce tart-tasting lactic acid.
Yeasts, added to crushed grapes, eat the grapes sugars
and produce alcohol.
Breads. Yeasts, added
to dough, digest sugars (derived from starches in dough) and
produce carbon dioxide, causing the dough to rise.
Milk bacteria digest the milk sugar lactose and produce lactic
acid, which acts with the added enzyme rennet to curdle the
milk. The cheesemaker drains off the whey and compacts the
curds, which various microbes then ripen into a mature cheese.