EVAPORATION OF FRUITS. 39 



color of the dry product under proper storage conditions for periods 

 of 12 to 20 months. It is clear that the wide variations in the quantity 

 of sulphur employed and in the time of exposure necessary which are 

 reported by operators are due to such factors as variations in the 

 completeness of combustion of the sulphur, the construction of the 

 bleachers, or the care with which the work is done rather than to 

 regional or varietal differences in the fruit employed. It is clear that 

 in some cases the quantities of sulphur employed are excessive and the 

 bleaching period unnecessarily long; a reduction in both respects to 

 the minimum necessary to produce the desired effect would eliminate 

 a ground for criticism of the product and at the same time effect a 

 slight economy in production. 



As a result of the criticism which has been directed against the 

 practice of sulphuring, considerable effort has been devoted to at- 

 tempts to find satisfactory substitutes for the sulphur treatment, 

 and a very considerable number of treatments have been proposed 

 by various workers. Those which have been most strongly recom- 

 mended substitute for treatment with sulphur fumes, a short treat- 

 ment by dipping into a solution. Among other substances em- 

 ployed are rather dilute solutions of sodium bisulphite, potassium 

 bisulphite, sodium chlorid (common salt), sodium bicarbonate (bak- 

 ing soda), acetic and tartartic acids, and hydrochloric acid. A 

 somewhat detailed study of these and a number of other proposed 

 treatments has been made in the laboratories of the Bureau of Plant 

 Industry, with the general result that none of these treatments can 

 be recommended as an effective substitute for sulphuring. The em- 

 ployment of sodium or potassium bisulphite solution merely changes 

 the method by which sulphurous acid is introduced into the fruit 

 for one which is no more effective and even more difficult to apply 

 with uniformity. The other treatments mentioned vary somewhat 

 in the degree to which they prevent discoloration during the actual 

 drying process, but are alike in that they do not prevent slow 

 spontaneous oxidation and consequent darkening in storage unless 

 used in such concentrations as to give readily perceptible flavor to 

 the fruit. For this reason, and for the further reason that they 

 confer no protection against the deposition on the fruit of the eggs 

 of insects, it is scarcely possible that any of these treatments will 

 displace sulphuring as a commercial practice. 



Slicing, quartering, etc. — After bleaching, the next step in prepar- 

 ing the fruit is slicing, unless instead of being sliced it is quartered or 

 dried whole, as is done to a limited extent. 



The slices are one-fourth inch thick, and in the largest degree 

 possible should be cut at right angles to the hole made through the 

 axis of the apple when the core is removed by the parer, thus pro- 

 ducing the rings, which is the form most desired. Other things being 

 equal, that fruit is sliced the best which contains the largest propor- 

 tion of rings, and this point is given more or less weight in grading 

 the finished product. 



To secure a high percentage of perfect rings, the slicer should 

 have a capacity considerably greater than the maximum demand 

 made upon it; the slicing knives must be kept in perfect condition: 

 and the chute from the bleacher must be so placed that equal distri- 

 bution of fruit to the two sides of the turntable occurs. It is im- 



