CAUSE OF EXPLOSION IN CHOCOLATE CANDIES 601 



to the other ingredients. The egg used by manufacturers is 

 the dried material secured in barrel lots. Some of this egg al- 

 bumen was secured and analj'zed for gas-formers with results 

 paralleling those obtained with the fondant. 



In preparing the egg albumen abundant opportunity is afforded 

 for contamination, since the eggs used are not sterilized before 

 breaking. The shell is frequently contaminated by hen feces 

 in the nest. 



Hen feces were next tested for anaerobes. It was necessary 

 to heat at 80°C. for ten minutes to kill off Bad. coli and similar 

 fomis. Anaerobes of the B. sporogcnes type were present in 

 feces secured from two flocks of chickens. Thus a presumptive 

 chain of evidence attaches blame to the egg albumen as the prob- 

 able source of contamination. 



Before using the egg albumen it is necessary to dissolve it by 

 soaking in water for a number of hours. This affords an excel- 

 lent opportunity for the spore formers to grow and be in condi- 

 tion to develop gas when the fondant is prepared and coated 

 with chocolate. The chocolate cover would retard the absorp- 

 tion of air, thus facilitating the growth of the anaerobes. "WTien 

 the fermentation of the sugar has developed sufficient gas pres- 

 sure, the chocolate explodes. 



At tliis time the work was taken up by Miss Grace A. Hill, 

 since appointed bacteriologist in the State College at Pullman, 

 Wash. Miss Hill repeated and extended the work very ma- 

 terially, and her results were embodied as part of her master's 

 thesis (University of Washington, 1920). She analyzed five 

 lots of exploded chocolates secured at different times from indi- 

 vidual firms. In all, 30 trials were made involving approximately 

 150 chocolates. Of these 30 trials, 17 revealed gas forming 

 bacteria, while 13 failed to show them. One of the five lots 

 repeatedly failed to show gas-forming bacteria. 



From the above analyses Miss Hill isolated a spore-forming 

 anaerobe producing gas in sugar bouillon. All the common 

 sugars as well as mannitol, dulcitol and inulin were fermented 

 with gas formation. This organism we have since identified 

 as B. sporogenes by agglutination and cultural studies. 



