Critical temperature of freezing—living muscle

Abstract

When an egg is frozen it does not usually return to its original condition—the shell is cracked, a trivial matter due to expansion of the water—the yolk is a stiff paste and the white has divided into a portion of higher and a portion of lower viscosity. Both yolk and white have suffered “irreversible” (the word is convenient) changes somewhere in the cycle of temperature. Eggs can, however, be frozen and thawed without obvious alteration of either yolk or white. Irreversible changes do not always occur and the conditions of reversibility are discussed in an earlier paper (1). They are summarised here as an introduction to the study of the reversibility of living muscle. The freezing point of the yolk of the hen’s egg is –0·65º C. The yolk can readily be supercooled, and supercooling was never found to cause irreversible changes. The yolk can be frozen solid without suffering irreversible change provided the temperature of freezing.” The change of internal state which is the cause of irreversibility can occur in frozen yolk. For example, yolk frozen at –3º C. And then cooled to –11º C. is found to be completely “pasty” when thawed.