1854 Kp:port of Farmers' Institutes 



even until recent years it was thought that the oxygen of the air 

 caused the decomposition of food. Scientists have proven that it 

 is not the oxygen which causes fermentation and putrefaction, but 

 bacteria and other small plant growths. So. while Appert's 

 theory of the cause of the spoiling of food was incorrect, yet the 

 world owes him a debt of gratitude since his method of preserving 

 it by sealing and corking was correct. 



Bacteria and yeast exist in the air, in the soil and on all vege- 

 table and animal substances. Bacteria are one-celled and so 

 small that they can be seen only by aid of a microscope. In 

 growing this single cell divides forming two cells. This grows 

 on so rapidly that it has been estimated that one single bacterium 

 may produce seventeen million similar growths in twenty-four 

 hours. To grow it is necessary to have moisture, warmth and 

 proper food. 



Yeasts wdiich are also one-celled grow less rapidly. A bud de- 

 velops, breaks off and forms a new yeast plant. 



Spoiling of food is caused by the development of bacteria 

 or yeast. Most germs require air to grow, but there is one kind 

 of bacteria that grows without air, and if it is sealed up in a can 

 it spoils the contents of the can. 



Bacteria grow best in foods containing nitrogen such as meat, 

 fish, eggs, peas, beans and milk — especially in warm weather. 

 Bacteria do not grow so fast in sweet substances while yeasts de- 

 velop very rapidly in such. Some vegetable foods contain so 

 much acid that very few bacteria or yeast attack tliem, as lemons, 

 cranberries and rhubarb. 



So it comes about that canned fruits are more commonly 

 spoiled by yeast than bacteria. When fruits are preserved with 

 large amounts of sugar they need not to be hermetically sealed 

 to protect them from bacteria and yeasts, since the thick syrup is 

 not favorable to their growth. However, these are best put up 

 in small self-sealing jars because mold grows freely on moist 

 sugary substances exposed to the air. 



Every housekeeper is familiar wnth molds which during warm 

 and moist weather grow upon all sorts of starchy materials, such 

 as boiled potatoes, brea<l, mush, etc., as well as fresh canned and 

 preserved fruits. Molds grow from spores which are always 



