34 



CIRCULAR 6 3 5, U. S. DEPARTMENT OF AGRICULTURE 



number of beetles and moths flying in the factory and also provide a 

 worthwhile check on the effectiveness of the screening. 



FUMIGATION OF TOBACCO PRODUCTS 



If the safeguards mentioned above are taken, manufactured to- 

 bacco products are exposed to little or no insect infestation in the 

 factory. Manufactured cigarettes leaving the factory for the whole- 

 sale trade are not fumigated owing to the precautions taken in mod- 

 ern factories to prevent infestation. Lots of infested cigarettes re- 

 turned to the manufacturers from wholesale and retail establish- 

 ments should be fumigated before they are received in the factory. 



Manufactured cigars should be safeguarded in the factory against 

 infestation by the cigarette beetle from the time they are made 

 until packed and shipped. This interval may in some instances 

 amount to 40 days or longer. All cigars not kept in cool storage 

 or in an insect-proof humidor during this storage period should 

 be fumigated before they are shipped, especially in the warm months, 

 when the cigarette beetle is migrating. Manufactured cigars should 

 be fumigated in a vacuum chamber with the ethylene oxide-car- 

 bon dioxide mixture at the rate of -to pounds per 1,000 cubic feet with 

 an exposure of 4 hours or with the methyl formate-carbon dioxide 

 mixture at the rate of 50 pounds per 1,000 cubic feet with the same 

 exposure period. 



Manufactured pipe tobacco and plug tobacco are not fumigated at 

 the time of shipment and must be effectively protected during the 

 storage period in factories if losses are to be averted. All goods re- 

 turned owing to insect infestation should be fumigated before they 

 are received in the factory. 



HEAT TREATMENT AND COLD STORAGE 



The first factory process for domestic cigarette types of tobacco, 

 after purchase from the grower, is called redrying. The machines 

 used in this process consist of redriers in which the atmospheric 

 conditions are regulated. The hands of tobacco are transported on 

 sticks by a chain conveyor through these redriers, and the required 

 percentage of moisture is taken from or added to the leaves. In 

 the redriers for cigarette tobacco there are five chambers and the 

 time required for tobacco to pass through them varies for different 

 grades and types of tobacco. A typical operating cycle for flue-cured 

 tobacco and the maximum temperatures reached in each chamber are 

 shown in table 2. All insect infestation present is killed by these high 

 temperatures. Redried tobacco, however, is subject to reinfestation 

 when held in an infested factory or storage warehouse. 



Table 2. 



— Typical operating cycle for redrying flue- 



cured cigarette tobacco 



Process 



Chamber 

 No. 



Maximum 

 tempera- 

 ture 



Exposure 



Process 



Chamber 

 No. 



Maximum 



tempera- Exposure 

 ture 





t= 



°F. 

 160 

 205 

 178 



Minnies 



7 

 6 



7 





4 

 5 



°F. 



90 

 120 



Minutes 



Heating ... 



Ordering 



16 







