EVAPORATION OF FRUITS. 61 



Experimental data obtained in the laboratories of the Bureau 

 of Plant Industry indicate that treatment of the fruit with live, dry 

 steam in preparation for packing is in every way preferable to 

 dipping in water. The fruit is loosely spread on trays to a depth of 

 2 or 3 inches, the trays are inserted into a tight box built like an 

 ordinal sulphuring box, and steam is turned in through a perfo- 

 rated pipe at the bottom of the box. A treatment of 2 to 4 minutes 

 will raise the temperature of the fruit to 180° F., which will 

 destroy any insect larvae or eggs which might be present and will 

 at the same time render the fruit sufficiently pliable to permit it to 

 be readily packed. The absorption of moisture is very slight, less 

 than one-half of 1 per cent, and as the steaming itself sterilizes 

 the product, sulphuring is neither necessary nor desirable. 



PACKING PRUNES. 



As in the case of other fruits, the packing of prunes should not 

 be begun until the fruit has remained in the conditioning room, 

 with frequent stirring, for 2 or 3 weeks. 



Prunes are graded as to size before they are packed, the different 

 grades being designated as 30's to 40's, 50's to 60's, 90's to 100's, etc., 

 the figures indicating the approximate number of fruits in a pound ; 

 thus " 40's to 50's " means a grade in which 40 to 50 fruits average a 

 pound in weight. 



In packing, the boxes are faced as in the case of other dried and 

 evaporated fruits. The fruit is prepared for packing in various 

 ways, all of which have the same objects in view, which are the soft- 

 ening of the individual fruits so they will pack well when com- 

 pressed, the improvement of the appearance of the fruit, and the 

 guarding against the development of insects. 



The fruit is softened by clipping in solutions variously made up 

 according to the preferences of individual packers. Some use a 

 solution made by dissolving common salt in water at the rate of 1 

 pound to 20 gallons; glycerin, 1 pound to 25 gallons, is also used; 

 many operators employ a solution containing 1 pound of glycerin 

 and 8 ounces to 1 pound of salt in 30 gallons of water. 



The salt solution is cleansing and leaves the skin bright and 

 attractive. The glycerin gives a gloss to the skin. The solution 

 is usually kept hot while dipping is in progress and should prefer- 

 ably be kept at the boiling point. The fruit should remain in the 

 solution only long enough to become heated sufficiently to make it 

 pliable enough to pack. 



In one method of dipping, the fruit is passed through a revolving 

 cylinder processor placed in a horizontal position and in the bottom 

 of which the dipping solution is carried. The interior of the cylin- 

 der is so constructed that as it revolves it carries the prunes around 

 with it. Thus they are in the solution only a portion of the time 

 required to pass the length of the cylinder, which occupies but a very 

 few minutes. Steam is constantly passed into the cylinder, so that 

 when the fruit is not in the solution it is in a hot steam bath. Pass- 

 ing out of this apparatus, the fruit is placed for a short time where 

 the surplus moisture drains away, and the fruit is then packed, com- 

 monly while still hot. 



