The Effect of Temperature Upon Some of the Properties of Casein

Abstract

The considerable changes which occur in the behavior of living matter when subjected to high or low temperatures raise interesting questions as to how the temperature affects the behavior of certain substances present in nature.Casein, purified at the point of its maximum flocculation, is able to bind base, forming a salt soluble in water. The amount of casein which passes into solution is not only dependent upon the amount of base added, but also upon the temperature.We propose to study the interdependence of three variables: the base added, the casein dissolved, and the temperature.The properties of casein when dissolved in alkali and combined with base have been studied by a large number of investigators and by different methods. The results obtained may conveniently be considered in terms of the different equivalent combining weights for base that they have ascribed to casein. II. The Equivalent Weight of Casein.The combining weight of casein was investigated before the development of the electrolytic dissociation theory. In 1865, Millon and Commaille (1, 2) stated: " . . . la cas6iae, mati~re unique, s'uniralt sans doute A la plupart des acides min6raux et organiques, et si toutes ces combinalsons 6taient r6ellement bien d6finies, il ressortirait de leur 961

The Effect of Rennin Upon Casein

“…As the calculation of Table VI shows, paracasein is nearly 1.5 times more acid than casein, the capacities of casein and paracasein to bind base standing to one another as the whole numbers 2 and 3 (22). The fact that in using varying amounts of the enzyme one obtains practically identical parcaseins indicates that most of the paracaseins obtained in this investigation are final products of a reaction promoted or brought about by rennin or pepsin.…”

“…The solubility of paracasein inNaOHat 5°C. as compared with the solubility of casein at the same temperature (22). estimating the amount of paracasein dissolved by a given amount of sodium hydroxide, we can measure the combining capacity of this protein as an acid, provided all the base is bound by the protein in solution.…”

The Effect of Rennin Upon Casein

“…2100 +100 gin. may be assigned (2,3) to the equivalent combining weight of casein. The result of our calculation yields 1950 gin.…”

“…dissolves in combination with base to the extent of about 2100 gm. per tool of NaOH added (2,3), most of the paracasein preparations combined with NaOH in this temperature range with a combining weight of 1450 gm.…”