28 CIRCULAR 619, U. S. DEPARTMENT OF AGRICULTURE 



several weeks. An alternative method is to place the dried product in 

 large friction-top cans for curing, thus insuring complete protection 

 from contamination and insect infestation. The cans may be filled 

 to advantage with inert gas such as carbon dioxide or nitrogen. 



Leafy vegetables, like spinach, must remain in the drier until the 

 moisture content of the stems is very low. At this point the product 

 is bulky and the leaves are brittle. For economy in packing and 

 handling, it is desirable to reduce the bulk by compression. For this 

 purpose the leaves are exposed to currents of cool damp air until they 

 have reabsorbed just enough moisture to make them slightly flexible. 



INSECTS ATTACKING DRIED FRUITS 



Products should be packed in the final containers or stored in 

 insectproof intermediate containers as soon as practicable after 

 equalization of moisture content in the curing bins {14). 



The two generally recognized methods of insect control are fumiga- 

 tion {2) and heat treatment (7, 8). 



PACKING AND STORING 



For convenience in handling and to facilitate the application of heat 

 or fumigation, products should be packed in the room where they were 

 cured and stored. Such a room should be strictly clean, dry, cool, and 

 well-ventilated. The doors should fit tightly, and the windows should 

 be covered with fine-mesh screen to exclude dust and insects. An 

 abundance of light assists in detecting the presence of insects and in 

 keeping the room clean. 



The types of containers chosen for packing will depend largely upon 

 the severity of the storage conditions, with particular reference to the 

 humidity and to chances of insect infestation. An ideal container 

 would be one which, while moderate in cost, would keep the product 

 from absorbing moisture when exposed to the most severe conditions 

 of storage and shipment, and would be impervious to insects. Sealed 

 tin cans and glass jars give absolute protection against moisture 

 absorption and insect infestation. Friction-top cans are nearly as 

 good. Tin containers, necessary for export shipments of dehydrated 

 foods, are more expensive than paper containers. Wooden boxes are 

 generally used for bulk goods. Liners of heavy paper or cardboard, 

 and sometimes additional liners of waxed paper, are used. The use of 

 moistureproof cellophane packages is increasing. 



All types of paper containers with which experiments have been 

 made allow the absorption of moisture when the products are stored in 

 damp places. Also paper containers do not give perfect protection 

 against all insects, some of which can bore holes in paper, while the lar- 

 val forms of others are so small that they can crawl through the slight- 

 est imperfections at the joints where the cartons are sealed. Most 

 products, however, keep satisfactorily in double or triple moisture- 

 proof cellophane or waxed-paper bags packed in waxed, moistureproof 

 cartons, provided the initial moisture content is low and no live insects 

 in any form enter the package. Packing in insectproof and moisture- 

 proof packages cannot be too greatly stressed. 





