38 CIRCULAR 3 6 9, U. S. DEPARTMENT OF AGRICULTURE 



CONFECTIONERY 



Since the insect problems of the candy and nut-meat industries are 

 rather closely associated, it seems logical to discuss them under one 

 heading. Nut meats are highly susceptible to insect attack, and 

 because they are used in large quantities in the manufacture of 

 candy, they constitute an important source of insect infestation in the 

 candy factory. 



Most firms handling nut meats attempt to ship only insect-free 

 nuts. To do this they keep their factories and storage warehouses 

 as free from infestation as possible, in addition to fumigating all 

 outgoing merchandise. A yearly fumigation of the factory with 

 hydrocyanic acid gas, supplemented by constant attention to clean- 

 liness, will reduce insect infestation to a minimum. A dosage of 8 

 ounces of liquid hydrocyanic acid or its equivalent per 1,000 cubic 

 feet is sufficient for this purpose. An exposure of 24 hours is 

 desirable. 



Where nut meats in the shell are stored without cold storage, it 

 sometimes becomes necessary to fumigate the warehouses also. Hy- 

 drocyanic acid is the best fumigant for this purpose and should be 

 applied at the rate of 16 ounces of liquid hydrocyanic acid or its 

 equivalent per 1,000 cubic feet. Excellent results can be obtained 

 in tightly constructed warehouses, even though the bagged nuts are 

 piled in large stacks. If possible, a 48-hour exposure should be 

 given. 



Nuts absorb considerable hydrocyanic acid gas, and therefore a 

 warehouse that has been fumigated cannot be aired out very quickly. 

 Large stacks of bagged nuts hold the gas and give it off slowly over 

 a period of several days. In one fumigation conducted by the writ- 

 ers in an exceptionally tight warehouse, bagged peanuts retained 

 so much of the gas that it was unsafe for workmen to enter the ware- 

 house until it had been aired for 5 days. 



VAULT FUMIGATION FOR NUTS 



Nuts are usually fumigated in atmospheric vaults or vacuum tanks 

 before they leave the factory or go from the storage warehouse to the 

 factory. A 1,000-cubic-foot atmospheric vault will hold about half 

 a carload of bagged nuts, such as peanuts — about two hundred and 

 fifty 100-pound bags of shelled peanuts or 125 such bags of peanuts 

 in the shell. 



A dosage of 3 pounds of ethylene oxide or 25 pounds of the ethy- 

 lene oxide-carbon dioxide mixture per 1,000 cubic feet of space, with 

 an exposure of from 20 to 24 hours, will give excellent results at 

 a cost of from 1 to 3 cents per 100-pound bag, including labor 

 charges. 



Hydrocyanic acid can also be used for fumigating nuts in atmos- 

 pheric vaults, although it is not so popular for this purpose as 

 ethylene oxide. A dosage of one-half pound of liquid hydrocyanic 

 acid or its equivalent is required for each 1,000 cubic feet of space. 



VACUUM FUMIGATION FOR NUT MEATS 



For the vacuum fumigation of nuts the ethylene oxide-carbon 

 dioxide mixture is excellent. A dosage of 30 pounds per 1,000 cubic 



