PREPARING AND PRESERVING FOOD 



89 



These plants are called fiiniji (fun'ji). Like every other 

 form of life these fungi must have food, and we find 

 them wherever there is a food supply and wherever 

 their surroundings permit growth. 



When plan-ts and animals die, the food of their 

 bodies is used by fungi. Did you ever wonder what 

 becomes of all the dead leaves, logs, and branches 

 of trees when they die in the woods? Fungi cause 

 them to decay, and eventually the organic material is 

 changed back into inorganic material and goes back 

 to the soil and to the air. On the other hand, meats, 

 fruits, vegetables, and other foodstuffs are attacked by 

 fungi and used for their food, thus becoming unfit for 

 our use. It is a constant struggle for man to keep food 

 in a state of preservation until he is ready to use it. 



What are fungi? There are four general types of 

 fungi, but only three of them are of importance in 

 destroying our food. They are molds, yeast, and bacteria. 



Have you ever examined a piece of moldy bread? 

 Most of us are familiar with the musty odor which 

 comes from things on which molds are growing. There 

 are many varieties of molds. If you examine them 

 under a strong magnifying glass you will see that 

 they bear spore cups which contain many spores. These 

 may be black, yellow, blue, or green. Each of these 

 tiny spores is capable of growing into a new mold 

 plant when it comes in contact with warm, moist 

 food. 



Bacteria are tiny one-celled plants which live on either 

 dead or living material. Like molds, they destroy the 

 things on which they grow. If they grow in food, 

 they spoil it, yet strangely enough their presence is 

 desirable in making a few foods such as sauerkraut 

 and some kinds of cheese. Thus bacteria may be 

 beneficial or harmful. If they grow on dead leaves and 

 dead animals and change the dead organic material to 

 soil, we consider them very useful. Those which cause 

 foods to spoil or cause diseases are classified as harm- 

 ful types. 



Bacteria seem to be everywhere. Many of them 

 form spores, although not in the same way as molds. 

 These spores are carried around in the air. We eat 

 them with our foods ; we drink them and breathe them 

 by the millions. Most of them do us no harm. Those 

 which cause disease we shall study in a later unit. 



Yeasts are also small single-celled plants, microscopic 

 in size. They are somewhat larger, however, than 

 most bacteria and are found in fruit juices or where 

 sugar is fermenting. These organisms use sugar for 

 food and change it to carbon dioxide and alcohol. 

 This process is known as fermentation. It is used in 

 bread making to produce carbon dioxide, which makes 

 the dough rise, and in distilling industries to produce 

 alcohol. 



Yeasts reproduce by a process called budding. 



Little "buds" grow out from the end of the cell and 

 finally get to be as large as the parent cell. Yeasts 

 also reproduce by spores which are carried around 

 as dust in the air. Like mold and bacteria spores they 

 may fall on certain foods and cause them to spoil. 

 How may foods be preserved? Drying was one of 

 the first methods ever used to preserve food. Bacteria, 

 yeast, and molds cannot grow where there is no mois- 

 ture. This method of food preservation was in use 

 thousands of years ago and is practiced today. Meats, 

 fish, and different fruits such as apples, peaches, 

 prunes, and raisins are preserved by this method. 



International News Photos, Inc. 



FIG. 130. FIG DRYING 



Salting is another old method used to preserve food. 

 Bacteria and other fungi are unable to live in a strong 

 salt solution. 



Many other chemicals, called preservatives, prevent 

 the growth of fungi in foods. Sugar, when used in a 

 concentrated form, is a good preservative. Fruits are 

 sometimes preserved by boiling them in sugar syrup. 

 Fruits may also be dried and then "sugared." Certain 

 acids destroy or prevent bacterial growth. Vinegar 

 (acetic acid) is perhaps the most widely used acid 

 preservative. Benzoic and salicylic acids destroy fun- 

 gi, but there is some question as to the advisability 

 of their use in foods. They may be slightly harmful to 

 some people. 



Canning has been found to be one of the most satis- 

 factory methods to prevent foods from spoiling. The 

 common method consists of sterilizing the food and 

 the cans by boiling them in water. The action of 

 the heat kills bacteria and spores. The food is then 

 put into the cans and sealed with can tops that have 

 also been sterilized. In recent years the cold pack 

 method of canning has come into use. The process 

 consists of putting the cold, uncooked fruit or vege- 

 tables into jars or cans and sealing them. The cans 

 are then heated in boiling water or a pressure cooker 

 until all bacteria or spores are killed. 



