38 BULLETIN 1141, U. S. DEPARTMENT OF AGRICULTURE. , 



more than 2J. to 3 inches long, as the use of a longer blade leads to 

 wastefulness in trimming. 



In order that high-grade fruit be produced, it is absolutely essen- 

 tial that the number of trimmers be sufficient to prevent the accumu- 

 lation of pared fruit on the tables. Usually two trimmers are able to 

 care for the fruit pared by one machine, but if the fruit be excep- 

 tionally small or of poor quality, a third may be needed. In any case 

 it is necessary to keep the trimming table clear and to get pared fruit 

 into the bleacher without delay, as fruit which has become discolored 

 from standing in the air does not regain its original whiteness in the 

 bleaching process. 



Bleaching. — The fumes of burning sulphur are employed not only 

 to make the fruit white where the freshly cut surfaces have become 

 discolored by contact with the air, but to prevent further discolora- 

 tion after it is sliced. Sulphuring also renders the fruit more readily 

 permeable to moisture and consequently accelerates the drying some- 

 what. It also acts as a deterrent to insects which otherwise might 

 deposit their eggs upon the fruit, either during the drying or subse- 

 quently in storage. 



There have never been definite standards governing the bleaching 

 as to the time required, quantity of sulphur necessary to accomplish 

 the desired end, etc. The aim is to treat until enough of the fumes 

 have been absorbed by the apples to prevent discoloration after they 

 are sliced and exposed to the air. If it is found that the fruit is not 

 retaining its clean, white appearance with the treatment that is being 

 given, either the length of time that the fruit is kept in the bleacher 

 is increased or more sulphur is burned in the customary time lor 

 bleaching. Due caution should be exercised, however, in this con- 

 nection, inasmuch as the bleaching of desiccated fruits with sulphur 

 fumes is open to criticism. The sale of fruit containing sulphurous 

 acid in any considerable quantity is prohibited by the pure-food laws 

 of some States, as well as being restricted in some of the foreign 

 markets. Under the Federal pure-food law, restrictions are also es- 

 tablished with a view to limiting the sulphur-dioxid content to reason- 

 able bounds. (See p. 62.) 



The usual practice is to start the sulphur fumes by putting a few 

 live coals into the receptacle used for the purpose, then adding a small 

 piece or two of stick brimstone. Before this has all been vaporized, 

 more is added. This is continued as long as the bleacher is in opera- 

 tion, sufficient heat being generated to vaporize the sulphur without 

 the further addition of burning coals. 



When apples are dried whole, without slicing or quartering, they 

 require less bleaching than if they are to be sliced, inasmuch as the 

 interior of the fruit does not come in contact with the air. 



The allotted time for bleaching, in a large number of evaporators 

 from which information has been obtained, varies from 20 minutes 

 to If hours. The usual time appears to be about 45 minutes. In ex- 

 perimental work carried on in the laboratories of the Bureau of Plant 

 Industry, in which lots of apples of approximately 100 varieties have 

 been subjected to bleaching for various periods of time and with vary- 

 ing quantities of sulphur, it has been found that exposure to the fumes 

 in a tight bleacher for 30 to 40 minutes, employing sulphur at the rate 

 of 3 to 4J pounds per ton of fruit, has been sufficient to preserve the 



