THE RAISIN INDUSTRY. 139 



heat from the surface of the tray will help to dry the grapes. This 

 of course only refers to localities where the temperature during the first 

 drying is very high. The warmer it is the closer should the bunches 

 be packed on the trays, and on the contrary when later on in the 

 season, or when the drying weather is unfavorable, plenty of space 

 should be given the grapes. It is often said that grapes, to make good 

 raisins, should not only dry, but cure. There is much truth in this. 

 Good raisins should dry and cure at the same time, by which is meant 

 that a chemical process is taking place, which is something else than 

 the mere evaporation of the water in the grape. The heat necessary 

 and favorable for drying the grapes is different in different localities. 

 At certain temperatures the raisins will get cooked and spoil, assume 

 a red color, lose their sweetness, become sour and hard, and covered 

 with large, sharply defined corrugations, signs of a very inferior or 

 even entirely worthless raisin. In Riverside the grapes are said to 

 cook at from 98 to 100 degrees Fahrenheit in the shade. In Frenso 

 the grapes dry and cure well up to a temperature of 105 degrees, and 

 in El Cajon they do not spoil until 103 degrees are reached. I would 

 think that from 90 to 103 degrees in the shade would be the best 

 temperature for drying perfectly ripe and sweet Muscat grapes. When 

 the grapes are very ripe, a much higher temperature will not injure 

 them, while unripe and sour grapes, especially of the second crop, 

 will burn or cook at a lower temperature than would be the proper 

 one for ripe grapes. 



It is not always advisable to stop picking when the heat becomes ./ 

 too great. A better method is to stack the trays in the field, so as to 

 protect the raisins from the sun. When the heat subsides, the trays 

 are again spread. The expense and trouble of stacking the trays is 

 not as great as may be supposed, and a few hours will generally 

 suffice to stack a large vineyard with the regular^picking gang. 

 Some packers have suggested that to secure good raisins the trays 

 should be stacked for several weeks in the beginning of the period of 

 drying. For the production of our usual dark-colored raisins this is 

 not necessary nor even advisable, .except when the heat is such that 

 the raisins would cook and spoil. With a little experience this cook- 

 ing of the grapes can be readily detected by the smell emitted by the 

 grapes, As soon as they are in the least injured by the heat, a cooked 

 flavor begins to pervade the whole vineyard. When this peculiar 

 flavor is noticed, and when the berries begin to show small red and 

 soft blotches on the side facing the afternoon sun, the stacking should 

 be commenced as quickly as possible. If the trays are kept in piles 

 for several days, the injured grapes will partially recover and at least 

 to some extent regain their color. Greatly injured grapes will dry 

 much slower, sometimes remaining several weeks behind those which 

 were not injured by the sun. Slightly discolored raisins may partially 

 regain their color by sweating, but they will not improve otherwise. 



After the trays are filled with grapes, the best way is to put several ^/ 

 rows of trays together, or rather to place the trays from three rows of 

 vines along one of the spaces between the rows. This gives more 

 compactness to the crop, makes it easier to handle the trays, and 



