Published online by Cambridge University Press: 15 May 2009
The most important of the proteid constituents of milk is casein. From 70 to 90% of the total proteids of milk consists of this substance1. In milk, casein exists as a soluble calcium compound, which is not precipitated by boiling, but from which casein is deposited by the addition of acid or by the action of rennet2. This phenomenon is known as the curdling of milk and is a preliminary to its gastric digestion, both the acid in the stomach and the rennet being capable of producing it. By artificially influencing the nature of its curd we can influence the digestibility of the milk. In human gastric digestion and in the experiments detailed below both acid and rennet are present. The curdling of milk is a necessary preliminary to its digestion in an acid medium, and by influencing this process we can also influence the digestibility of the milk.
page 445 note 1 Our own figure is 93.5%. Stutzer, (Milch als Kinder-Ernährung, Bonn, 1895)Google Scholar gives without stating authority 40%. Lehmann, and Hempel, (Pflüger’s Archiv, vol. LVI. 1894, p. 577) 70%Google Scholar.
page 445 note 2 Hammarsten, , Zur Kenntniss des Kaseins u. der Wirkung des Lab-Fermentes, Abhandl. König. Gesellschaft zu Upsala, 1877.Google ScholarArthus, and Pagés, , Archives de Phys. 1890, p. 331.Google Scholar
page 446 note 1 Arthus, and Pagés, , loc. cit.Google Scholar
page 446 note 2 Courant, , Ueber die Reaktion der Kuh- u. Frauen-Milch. Inaug. Dissertation, Bonn, 1891, p. 39.Google Scholar
page 446 note 3 Beiträge zur Kenntniss des Frauens Kaseins. Inaug. Dissertation, Bern, 1894.Google Scholar
page 446 note 4 Zeitschr. für physiol. Chemie, vol. XXII. p. 575.Google Scholar
page 447 note 1 Epstein, , von Puteren, , Wohlmann, and others, quoted by Soltan, Fenwick, Disorders of Digestion in Infancy, London, 1897.Google Scholar
page 449 note 1 Virchoe’s Archiv, 1898, Band CLII. Heft 1.Google Scholar
page 449 note 2 In some earlier experiments we attempted to estimate the albuminoids digested by the artificial panereatic solution in a manner similar to that adopted in the case of the peptic digestion. The great difficulty of filtering the mixtures after pancreatic digestion, especially in the case of human milk and those milk preparations approaching it in digestibility, led us however to adopt the above method.