20 



•experiments made with rolled oats at the Minnesota Experiment Station- 

 indicate that cooking (four hours) did not increase the solubility of the 

 carbohydrates, and the theory is advanced that the difficulty experienced 

 in digesting- imperfectly cooked oatmeal is due to the large amount of 

 mucilaginous proteid material which surrounds the starch grains and pre- 

 vents their disintegration. It is further argued that when the oatmeal is 

 thoroughly cooked, the protecting action of the proteid substance is over- 

 come and the starch granules are sufficiently broken up to allow the 

 digestive juices to act. The above results with oatmeal show that in our 

 work there was an increase in the solubility of the starch, but that the 

 change towards the dextrin compounds was not sufficient to allow much of 

 it to be thrown down as an alcohol precipitate. There was also an increase 

 in the solubility of the proteid substances. It is certainly evident that the 

 longer periods of cooking increased the amount of soluble matter, and it 

 is quite probable that this would decrease the labor involved in digesting 

 the food. 



With the wheat farinas 27.4 per cent, of the total dry matter of the 

 food was soluble in water at the end of twenty minutes, which increased 

 about 10 points when cooked for two hours. As the solubility was only 

 sightly increased at the five and eight hour periods, it would appear as 

 though the longer cooking was not required with this food. More crude 

 dextrin is found in this case and a noticeable difference is observed in the 

 proteid material as compared with the oatmeal. The heat has apparently 

 coagulated, or rendered insoluble, the protein and it has only very slowly 

 changed again under the influence of the longer cooking. The cornmeal, 

 like the farina, under the influence of heat, formed considerable dextrin 

 and the solubility of the proteids was very little changed by the long boil- 

 ing. 



A very interesting point in connection with these experiments is that 

 the amount of soluble matter obtained from the oat, wheat, and corn 

 meals after twenty minutes' cooking was greater than that from some of 

 the so-called cooked foods and even greater than that obtained from some 

 of the much advertised predigested foods ; while the longer periods of 

 cooking, especially with the rolled oats and farina, rendered nearly as 

 great an amount of the dry matter soluble as was obtained from the best 

 of the malted and cooked foods. It would certainly appear as though 

 some of these ready-to-serve foods would be the better of further cooking 

 before serving. 



Digestibility of Breakfast Foods. 



A knowledge of the composition of a food is absolutely necessary in 

 studying, or estimating, its nutritive value. But this is not sufficient, for 

 it is only that part of the food which is actually digested and absorbed 



"Minnesota Experiment Station Bulletin No. 74. 



