Method and device for monitoring handling conditions

A method for monitoring the handling conditions of an object, the estimated keeping-quality time of which requires the object to be handled under certain predetermined conditions, the method comprising the steps of:

• inserting into the object a device consisting of a substantially flat, elongate casing having a slot-shaped space between two opposed walls of the casing, and an elongate slide-shaped body inserted in said slot-shaped space, which is movable into and out of the slot-shaped space and which is provided at one end with means for indicating by colour change an exceeding and a falling-short of said predetermined conditions, said indicating means containing at least three compositions selected from
• (a) temperature-sensitive compositions with controlled colour change and pH shift upon freezing or at a selected temperature below freezing point, the temperature-sensitive composition having a first component including an aqueous solution which contains a buffer and which upon a change of temperature of the aqueous solution between a first temperature above its freezing point and a second temperature at or below its freezing point exhibits a pH shift, and the temperature-sensitive compositions further containing as additional components a regulator entailing a change of proton conductivity of the aqueous solution upon freezing so as to affect the pH shift upon freezing, and at least one pH indicator exhibiting colour change upon pH shift;
• and
• (b) time-temperature-sensitive enzymatic compositions containing an enzyme, an enzymatic substrate and a pH indicator, the enzymatic compositions having the ability to integrate the function of time and temperature to bring about a colour change;
• said at least three compositions including:
• a first time-temperature-sensitive enzymatic composition changing colour when 10-30% of the estimated keeping-quality time has been consumed;
• a second time-temperature-sensitive enzymatic composition changing colour when 30-60% of the estimated keeping-quality time has been consumed;
• a third time-temperature-sensitive enzymatic composition changing colour when 60-100% of the estimated keeping-quality time has been consumed;
• and
• removing for monitoring purposes the slide-shaped body inserted into the slot-shaped space of the casing, from said slot-shaped for visual observation of the colour of said indicating means.