Appts. for detecting temp. rise in deep frozen foods - includes salt soln. in glass container surrounded by colour indicator means

摘要

Appts. for detecting reheating in a deep-frozen prod. according to the principal patent comprises a liq. having a predetermined solidification point, an enveloping material which holds the liq. and which is degradable, to permit flow of the liq., at about the freezing point of the liq. and means to indicate flow of the liq. when the temp. rises above the liq. freezing point. Improvement comprises using a soln. of a salt as liq., the pH of which is adjusted to a predetermined value. The indicator means comprises a porous body previously impregnated with a substance which will give a clear colour change when moistened by the liq. when it flows. The appts. is used for monitoring the storage of food and provides a visible indication that a certain temp. has been exceeded.