588 IOWA DEPARTMENT OF AGRICULTURE. 



from apple. But these investigations have proven that this acid disappears 

 quite rapidly from vinegar, so that in twenty-four months it had shrunk 

 from an average of 0.55 per cent to 0.02 per cent; while in some older vine- 

 gars it had disappeared entirely. The relation of malic acid to cider vine- 

 gar is being further studied. 



The legal standard of the State for acid, 4i per cent of acetic acid, has 



";• been upheld fully by these results; for apple juice from good ripe apples, 



9 properly managed in fermentation should and does easily give 4i per cent 



acetic acid within two years at cellar temperatures and in less time at higher 



temperatures. 



Concerning solids, the wisdom of the standard is not quite so clear, fn 

 several experiments made in this investigation, vinegars made from pure 

 apple juice and well above the limit in acid contain less than two per cent of 

 solids. 



Among the conditions which may produce vinegar below standard are 

 these: (1) The juice may be poor to start with because made from varieties 

 of apples low in sugar, from green apples or from overripe or decayed 

 apples; or the juice may be watered either directly or by watering the pom- 

 ace and pressing a second time. (2) The fermentation processes may be 

 delayed or disturbed by using dirty fruit or unclean barrels, thus afifording 

 entrance to undesirable organisms and causing the wrong kind of fermenta- 

 tion; the temperature may be too low to insure the necessary activity of 

 favorable organisms; or air may be excluded by filling the barrels too full 

 or putting the bung in too tight so that the bacteria can not live and work. 

 (3) The acetic acid may disappear after its formation, destructive fermenta- 

 tion being encouraged by leaving the bung-hole of the barrel open or the 

 barrel only partially full. 



Briefly summarized, the method to be employed for the manufacture 

 of good vinegar at home, without the use of generators, is this: Use 

 sound, ripe apples, picked or picked up before they have become dirty, 

 if possible, otherwise washed. Observe the ordinary precautions to 

 secure cleanliness in grinding and pressing, and discard all juice from 

 second pressings. If possible, let the juice stand in some large recep- 

 tacle for a few days to settle, then draw off the clear portion into well- 

 cleaned barrels which have been treated with steam or boiling water, filling 

 them only two-thirds or three-fourths full. Leave the bung out, but put in 

 a loose plug of cotton to decrease evaporation and to prevent the entrance 

 of dirt. If these barrels are stored in ordinary cellars, where the tempera- 

 ture does not go below 50° or 45 "^ F. , the alc®holic fermentation will be com- 

 plete in about six months; but by having the storage room at a temperature 

 of 65' or 70° the time can be considerably shortened, and the addition of 

 Fleischmann's compressed yeast or its equivalent at the rate of one cake to 

 five gallons of juice may reduce the time to three months or less. Use a lit- 

 tle water to thoroughly disintegrate the yeast cake before adding it to the 

 juice. The temperature should not go above 70' for any length of time, to 

 avoid loss of the alcohol by evaporation. 



After the sugar has all disappeared from the juice, that is, when the cider 

 has entirel}?^ ceased ' 'working" as revealed by the absence of gas bubbles, 

 draw off the clear portion of the cider, rinse out the barrel, replace the 

 liquid and add two to four quarts of good vinegar containing some "mother," 



