The Digestibility of Protein of Dried Milk Manufactured by Different Processes

Abstract

Summary 1. The preliminary experiment shows that there is considerable difference in peptic digestion of protein in different makes of dried milk. With some makes of dried milk the protein is even more digestible than fresh milk. The order of the digestibilities from the highest is Klim, Kintaro, Lactogen, fresh milk, and Morinaga. 2. The protein digestibility of dried milk is influenced by the acidity of the reconstituted milk from dried milk. The digestibilities increase with acidities. 3. The addition of hydrochloric acid improves the peptic digestion in artificial digestion experiment. The digestibility is improved in all samples. It is, however, more striking with low acid milk. 4. Freshly opened dried milk is more digestible than that which was exposed for air after opening the tins. It is advisable therefore to open the tin of any dried milk when consumed. 5. Although the artificial digestion is greatly promoted by addition of hydrochloric acid and the difference between different brands is much reduced, the order of the digestibilities is not changed. The better digestible dried milk with pepsin alone is also better with addition of hydrochloric acid. In this experiment the order of the digestibilities from the highestis Kintaro, Klim, Lactogen, and Morinaga. The order of Klim and Kintaro was changed in this experiment from the result in the preliminary experiment in which the difference was very slight in favor of Klim. Otherwise the order is exactly the same. 6. The experiment with white rats shows much less difference in digestibilities among different makes of dried milk, but it also proves that the dried milk which shows a better protein digestibility with pepsin has the higher digestibility with white rats. The order of the digestibilities with white rats is exactly the same as the results in the artificial digestion experiment, Kintaro the first, Klim the second, Lactogen the third, andMorinaga the fourth. 7. The disadvantage in protein digestibility of Morinaga dried milk seems to be in its manipulation of milk in drying. Apparently the neutralization and addition of sucrose before drying impair the digestibility.