20 MASS. EXPERIMENT STATION BULLETIN 388 



The Bacteriology of Choc3late Syrups, Cocoa Powders, and Chocolate Milk. 



(James E. Fuller and R. W. ^'wanson, in cooperation with W. S. Mueller of the 

 Department of Dairy Industry.) Bacteria counts showed wide variation in the 

 numbers of bacteria in the different syrups and powders. Most of the bacteria 

 identified were aerobic sporulating bacteria of the Bacillus subtilis group. No 

 Gram-negative bacteria of intestinal type were found, which would indicate 

 that the syrups and powders were free from intestinal contamination. Bacteria 

 of this type inoculated into solutions of the syrups and powders survived only 

 a few days. 



Growth of bacteria was not as rapid, nor were the counts as large, in milk with 

 syrups or powders added as in the same milk supply without the addition. Thus, 

 it appears that the syrups and powders had some inhibitory effect on bacterial 

 growth. Further studies indicated that the tannins present in the syrups and 

 powders were responsible for the inhibition. Oxalic acid and theobromine, in 

 concentrations found in chocolate or cocoa, had no apparent effect on bacterial 

 growth. Molds and yeasts appeared to be more active than bacteria in causing 

 spoilage of chocolate milk. 



Studies of Methods for Determining the Sanitary Quality of Drinking Utensils. 



(Ralph L. France, W. E. Cas?idy, and James E. Fuller.) Work en this project 

 has been completed, with the following results: (1) A swabbing method is the best 

 for recovering bacteria from the lips of a glass. (2) A wet swab is more efficient 

 than a dry or moist swab. (3) The most satisfactory suspending fluid is one having 

 the following composition: 2.5 cc. of 0.04 M MgS04, 2.5 cc. of 0.01 M CaClg, 

 0.5 cc. of 0.001 M FeCla, and 1.25 cc. of Butterfield's buffered phosphate solu- 

 tion made up to 1003 cr. with distilled water. (4) The most satisfactory plating 

 medium was one with the following substances: Neopeptone, 10 grams; yeast 

 extract, 5 grams; de.>vtrose, 0.5 gram; NaCl, 5 grams; and agar, 15 grams. The 

 reaction of this medium is adjusted to pH 7.5. (5) Inoculation of a swab, or 1 cc. 

 of a 1/10 dilution of washings from the swab, into dextrose broth frequently re- 

 vealed the presence of mouth streptococci. This test has considerable sanitary 

 significance when used in conjunction with the count. The addition of potassium 

 tellurite to the dextrose broth failed to eliminate interfering organisms. 



The Effectiveness of Certain Detergents and Procedures Employed for the 

 Cleansing of Eating and Drinking Utensils. (Ralph L. France.) Field studies 

 have been made of the methods employed in the cleansing and sanitization of 

 eating and drinking utensils in public establishments throughout this area. Bac- 

 teriological examinations indicate that these methods are not satisfactory. Work 

 is being continued on this project. 



Laboratory Service. (Ralph L. France.) Following is a list of the types and 

 numbers of examinations made during the past year. 



Milk (bacteria counts) 895 



Ice cream (bacteria counts) 153 



Water 124 



Eating and drinking utensils 120 



Miscellaneous 106 



Butter fat: 71 



Solids: 22 



Mastitis: 12 



Burlap: 1 



Total 1,398 



