44 MASS. EXPERIMENT STATION BULLETIN 388 



2. The Significance of Tannic Substances and Theobromine in Chocolate Milk. 

 (W. S. Mueller.) The relative toxicity of pure theobromine, pure tannic acid, 

 and two cocoa powders varying in content of tannic .substances was determined by 

 feeding these substances in a basal diet to white rats. Theobromine was non- 

 toxic to albino rats when the ration contained 0.27 percent of this alkaloid, and 

 tannic acid was toxic when the ration contained 2 percent of this substance. 

 These amounts of tannic acid and theobromine in the diets were equal to those 

 in a chocolate milk made with 3.6 percent cocoa powder which contained 12.15 

 percent tannic substances and 1.7 percent theobromine. A cocoa powder con- 

 taining 12.15 percent of tannic substances was more toxic than a cocoa powder 

 containing only 2.67 percent of tannic substances, but was less toxic than pure 

 crystalline tannic acid. A concentrated extract of cocoa was non-toxic to rats 

 when fed at the rate of 8 percent of the ration. The hemoglobin levels of the 

 blood of rats fed theobromine, crystaline tannic acid, and cocoa powder contain- 

 ing varying amounts of tannic substances did not vary from the normal enough 

 to be of any significance. Results from this study indicate that the toxicity from, 

 cocoa can be greatly reduced by selecting a cocoa or chocolate which is low in 

 tannic substances, or preferably by using an extract of cocoa as the flavoring ma- 

 terial when feasible. 



3. The Availability of the Iron of Cocoa and of Additional Iron when Asso- 

 ciated with Cocoa. (F. Kinder, H. S. Mitchell, and W. S. Mueller.) This study is 

 reported by the Department of Home Economics Nutrition. 



4. Effect of Adding Cocoa to Cow's Milk on the Utilization of Calcium and 

 Phosphorus. (M. R. Cooney and VV. S. Mueller.) This study is reported by the. 

 Department of Home Economics Nutrition. 



5. The Bacteriology of Chocolate Milk, Chocolate Syrup, and Cocoa Powders 

 (R. W. Swanson, J. E. Fuller, and W. S. MueUer.) This study is reported by the 

 Department of Bacteriology. 



6. Effect of Cocoa on the Vitamin C Content of Milk. (W. S. Mueller.) Vita- 

 min C is present in fresh raw milk to the extent of 12 to 20 mg. per quart. If 

 this could all be retained, milk would be a significant source of vitamin C, since 

 the higher figure is about half the daily requirements of an adult. Therefore, the 

 handling of milk from the time it is drawn until it is consumed, in a manner 

 which will conserve the vitamin C, is an important problem today. 



If chocolate milk is substituted for plain milk, it is important to know what 

 effect the cocoa has upon the retention of vitamin C. Preliminary studies on the 

 relative retention of vitamin C in plain milk and chocolate milk have been made, 

 using the 2, 6-dichloro-phenol-indophenol in both visual and electrometric titra- 

 tions. Results of these studies indicate that the addition of cocoa to milk hastens 

 the destruction of vitamin C. When both milks were stored, under identical 

 conditions, the plain milk lost 22 percent of the original vitamin C, while the 

 loss for chocolate milk was 77 percent. This difference in loss of vitamin C is 

 typical of the results obtained. Studies are also being made to determine which 

 method is most suitable for measuring the vitamin C content of chocolate milk. 



7. Effect of Cocoa on the Coagulation of Milk. (W. S. Mueller.) It has been 

 reported by a foreign investigator that cacao bean contains an enzyme with 

 rennet effect. Dry, it withstands heating to 248°-284° F. and may, therefore, 

 be found in cocoa powder. The optimum temperature of the enzyme is 149° F. 

 and the optimum pH is below 6.3. By heating a suspension of cocoa powder in 

 water (176° F.), the enzyme will be destroyed. 



Since the knowledge of this enzyme may be of practical interest to the con- 

 sumer as well as to the manufacturer of cocoa, a study was undertaken to deter- 



