| 摘要 |
PURPOSE:To measure the water activity (indication numeral of relative humidity indicated by food water content) of food easily by enclosing a humidity indicator consisting of a moisture absorber and a pigment in a nonpermeable container together with the food, and observing a change in color. CONSTITUTION:A moisture permeable sheet 2 carrying a sheet 3 obtained by impregnating filter paper, etc., with solution of a dye which discolores with water, e.g. a Co salt and drying it is provided on one surface of the moisture absorber 1 carrying a water soluble moisture absorptive material such as CaCl2 in filter paper, etc. Then, an opaque water-permeable colorless sheet 4 is provided thereupon to obtain the moisture indicator; one or plural (e.g. three) indicators for measuring water activity are fixed between plastic thin plates 6 and 6 having holes in the center parts by using an adhesive 7. Those humidity indicators are put in the airtight container together with the food and the state of develope or disolor of the coloring agent 3 at a specific time later is observed to detect the water activity of the food easily. Thus, optimum water activity, or water activity elapsed with the storage of the food is detected to utilize the detection result for the storage of the food, etc. |
