10 CIRCULAR 5 9, U. S. DEPARTMENT OF AGRICULTURE 



waxy or oily materials on the surface of the apple, so that the residue 

 can be more effectively reached by the cleaning solution. 



Winesap, Arkansas Black, Delicious, and Jonathan apples have 

 been subjected to solution temperatures as high as 160° F. in com- 

 mercial washers with the acid concentration as high as 3 per cent to 

 determine the possibilities of injury from warm acid solution. 



Some injury was manifest at temperatures above 120° F., and it 

 must be emphasized that these extreme temperatures are not recom- 

 mended but are mentioned merely to indicate that there is a suffi- 

 cient factor of safety at temperatures ranging from 90° to 100°. At 

 these temperatures no injury to the fruit or adverse effect was ob- 

 served on apples held for considerable periods of time in common 

 storage as well as in cold storage. There was no significant increase 

 in fruit temperature during the time that it was commonly exposed 

 to the warm solution in the washers. 



It is not probable that warming the cleaning solution will be 

 necessary in order to clean satisfactorily the average lots of fruit 

 when this is done soon after they are picked, but it is suggested for 

 fruit that is difficult to clean or in cases where consistent cleaning to 

 the world tolerance can not be obtained by other means. 



ADJUSTMENT AND CARE OF EQUIPMENT 



The proper adjustment of the washing equipment should not be 

 overlooked at any time. All parts of it should be kept in proper 

 condition to give maximum service. This applies especially to 

 screens, spray openings, pipes, and pumping equipment. Each ma- 

 chine has an estimated capacity which should not be exceeded unless 

 the operator is certain that the cleaning efficiency is not thereby 

 jeopardized or the fruit subjected to danger of injury. jSTo washing 

 equipment will give satisfaction unless it has a chance to do its 

 best work. 



No fruit should be left in washing machines or dipping tanks dur- 

 ing rest periods or when it is necessary to discontinue operations. 



METHODS OF RINSING 



The rinsing of the fruit is a very important part of the washing 

 process. Proper rinsing can do much toward eliminating the danger 

 of injury to fruit from soluble arsenic and from decay. 



Three methods of rinsing are available : 



(1) The use of fresh water only for rinsing. This is perhaps the 

 ideal condition, but it is not always possible where there is a scarcity 

 of water. 



(2) The recirculation of part of the rinse water. In this case the 

 fresh water is best added as a final spray or flood over the fruit as it 

 leaves the rinsing section. The first rinse water as the fruit enters 

 the rinsing section should preferably be discarded. In this way the 

 larger part of the acid solution and spores on the fruit will not be 

 carried into the recirculated rinse water. 



(3) The recirculation of the rinse water to which some substance 

 like lime is added to neutralize the hydrochloric acid carried over 

 on the fruit and to render insoluble the arsenic remaining on the 

 fruit after washing. In this case it may not be necessary to provide 

 a final fresh-water rinse, but one can be profitably provided for the 

 fruit just as it enters the rinsing section, this water to be entirely 



