10 Dec, ion 



Evaporation of Apples. 



74;^, 



evaiiorators concur. They have been worked out empirically by 

 practical evaporators who found that best results wei'e obtained when 

 the temperatures suggested were used, and may need modification when 

 exhaustive studies of the whole subject have been made. 



In the kiln evaporator, at least 95 per cent, of operators maintain a 

 temperature of 155-165 degrees for the first five or six hours after the 

 kiln is filled. If the temperature is raised higher than the second figure 

 named, the cellular structure of the fruit is destroyed by expansion of 

 the contained vapour and serious loss of sugar by bleeding occurs ; unless 

 the temperature is kept up to this level, the surfaces of the fruit become 

 .slimy, and the subsequent drying is retarded. After the first five or six 



.1' i<" 



Fig. XXIV. — An Efficient Under-cut Power SUcer of Large Capacity. 



hours, some operators allow the temperature to go down to 130 or 135 

 degrees, open the ventilators widely, and continue the drying by using 

 large volumes of air at lower temperature for ten to twelve hours, after 

 which the temperature is brought up to 175-180 degrees, and kept there 

 until the drying is completed. Users of this method claim for it that it 

 is economical of fuel — a claim which seems to be well establislied — and 

 also that it makes a more springy, " lively " product, which resists ex- 

 posure to unfavorable conditions much better than fruit dried with a 

 uniform temperature. This second claim does not appear to be fully 

 substantiated, and most operators carry the fruit through the whole 

 process at a temperature of approximately 160 degrees. 



