<P> In Orissa, India, it is practical to store rice by burying it underground . This method helps to store for three to six months during the dry season . </P> <P> Butter and similar substances have been preserved as bog butter in Irish peat bogs for centuries . </P> <P> Some foods, such as many cheeses, wines, and beers, use specific micro-organisms that combat spoilage from other less - benign organisms . These micro-organisms keep pathogens in check by creating an environment toxic for themselves and other micro-organisms by producing acid or alcohol . Methods of fermentation include, but are not limited to, starter micro-organisms, salt, hops, controlled (usually cool) temperatures and controlled (usually low) levels of oxygen . These methods are used to create the specific controlled conditions that will support the desirable organisms that produce food fit for human consumption . </P> <P> Fermentation is the microbial conversion of starch and sugars into alcohol . Not only can fermentation produce alcohol, but it can also be a valuable preservation technique . Fermentation can also make foods more nutritious and palatable . For example, drinking water in the Middle Ages was dangerous because it often contained pathogens that could spread disease . When the water is made into beer, the boiling during the brewing process kills any bacteria in the water that could make people sick . Additionally, the water now has the nutrients from the barley and other ingredients, and the microorganisms can also produce vitamins as they ferment . </P>

Which methods of food preservation would we use