222 STATE BOARD OF AGRICULTURE. 



of cookery, without bothering her head about any studies on fermenta- 

 tion relating to bread making, nor to bacteria themselves, as long as they 

 were not big enough to be seen and remarked on — to her disadvantage. 



Of the materials used in cooking, the yeast is perhaps one of the most 

 perplexing. In this little bit of compressed yeast I now hold up before 

 you we have a growing plant. This plant differs very much in its action 

 and aims (if it has any) from the plants grown for the production of our 

 staple crops, wheat and corn. The wheat crop is the perfected seed pro- 

 duced by the wheat plant. The crisp, sweet loaf of bread is not the per- 

 fected seed of the yeast plant. I use this comparison to direct your 

 attention to the fact that the yeast plant is planted in the sponge, not to 

 produce the fruit of this peculiar little plant, but, as we may express it, 

 to change the character of the soil in which the yeast plant grows. As 

 we all know, the prime object of setting the sponge with yeast is to pro- 

 duce lightness in the bread. The sponge is light, when the yeast plant, 

 by its lively growth in the flour and other materials used in setting the 

 sponge, has formed from these materials alcohol and a gas, — carbon 

 dioxide. 



Nowadays, how careful is the wideawake farmer in selecting his seed 

 for planting, and how careful is he to cultivate thoroughly to destroy 

 the weeds. But do we ever regard this yeast as a plant, and do weever 

 ask is it pure and true to name — are there any weed seeds in it? 



These queries which are naturally suggested when we are contemplat- 

 ing a bag of seed wheat, have equal force when we consider a cake of 

 compressed yeast. The microscope has done much to help clear up the 

 yeast question. Briefly mentioned, the facts regarding yeast are these: 

 First, starting with a yeast plant which is strong and healthy, if grown 

 in the same medium (i. e., on the same soil) indefinitely, it soon becomes 

 weak and runs out. Second, the temperature at which it thrives best is 

 from 68 to 70 degrees. Third, wherever we find compressed yeast it 

 always contains some weed seeds (bacteria). Fourth, these bacteria 

 thrive best at a high temperature, 75 and 80 degrees — (they produce 

 lactic acid from the materials in our sponge). Fifth, if the compressed 

 yeast is old and has been exposed to the air, the bacteria will be strong, 

 the yeast weak. The weeds will grow faster there than the yeast, and 

 instead of having alcohol and carbon dioxide produced in our bread pan, 

 lactic acid is made and the bread is sour, and somebody else makes acid 

 remarks. 



(In reply to question.) 



No; the alcohol produced by growth of the yeast plant doesn't remain 

 in the loaf — it is dissipated in the oven. Sometime in the future we may 

 see placed upon the market perfectly pure yeast, put up in such a manner 

 that the bacteria of lactic fermentation cannot get at it. When that day 

 comes, making sour bread will be nearer a lost art than it is at present. 



Bacteria are quite the stylish subject of conversation nowadays, and 

 well they may be when we are working in kitchen science, for the results 

 of these indefatigable little workmen — in spoiled can fruit which you 

 have taken such trouble and care to prepare during the hot days of June 

 and July for the winter's supply. Canning time in summer, what a trial 

 that is on the farm. To make your work easier, June grass and timothy 

 are ripe about the time that cherries, strawberries, raspberries should 



