507 



The jirevention of injury to food by insects requires that 

 tAvo things must be done, (1) all insects in their different 

 stages must be destroyed, and (2) insects from without must 

 be prevented from gaining access and reinfesting tlie food or if 

 this is impossible any insects present mnst be ])i'event('(l fi-om 

 further development. 



The destniction of insects in foods may be secured inore or 

 less completely in a variety of ways of which three are of suffi- 

 cient importance for discussion here, 'i'hese are: (1) sterili- 

 zation by dry heat, (2) fumigation by carbon disulfid, or bi- 

 sulphide, and (3) fumigation by hydrocyanic acid gas. 



Tf any insect is subjected to a temperature of 110° F. 

 long enough for the heat to penetrate its tissues they will Ije 

 cooked and the insect in any of its stages w^ill consequently l)e 

 destroyed. In practise it has been found desirable to use 

 somewhat higher temperatures so as to secure quicker penetra- 

 tion of the food material by the heat. It has been found, for 

 instance, that a satisfactory sterilization of peanuts in loose 

 piles may be obtained without injury to their powers of germi- 

 nation if they are subjected to a temperature of 125° F. sus- 

 tained for six hours. The heat desired may be obtained by 

 piping a room for steam heat with radiators calculated for 

 securing the temperature needed and sustained for the time 

 found necessary by experiment to secure sterilization. The 

 application of dry heat is one of the most generally applicable 

 methods of food sterilization and is rapidly coming into wider 

 use. In the home, cereals and flour may be sterilized in the 

 oven if care is taken to secure a low heat so as not to cause 

 scorching. There can be no doubt that if the dried foods im- 

 ])orted into the islands could be treated in a properly construct- 

 ed steam sterilizing plant before being distributed to the stores 

 that much of the present loss in these products now being 

 suffered would be obviated. Occasionally foods can be steril- 

 ized in the sunshine, the direct rays of the sun, especially when 

 shining upon a dark l)ackground, serving to produce sufticient 

 heat for the purpose. This method of application of dry heat 



