Gas Chromatographic Method for Measurement of Water Activity in the Presence of Waffles

Abstract

A gas chromatographic technique was investigated in order to determine water activities and equiliblium ethyl alcohol vapor concentrations correctly, in the presence of volatiles, without opening packages. Headspace gases of samples were analyzed, using a gas chromatograph equipped with TCD, Porapak S(Waters Ltd.)column and gas sampling device whose temperature was controlled. Water activities and equilibrium ethyl alcohol vapor concentrations were calculated from the contents of air, water and ethyl alcohol vapor. I it was important to keep the temperature constantly for precise results. The flexible containers which were suitable for measurements were prepared. Standard deviations in measurements of a sponge cake to which ethyl alcohol was added were as follows: water activity-0.004(C. V. 0.5%), equilibrium ethyl alcohol vapor concentration-0.008% (C. V. 1.0%).