低水分食品の吸湿によるテクスチャー変化

概要

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The effect of absorped moisture on the textural properties of low-moisture foods was investigated. Thirty-one kinds of confectionery and dry goods on the market w(ere left standing at six levels of relative humidity controlled by a saturated salt solution. The breaking force and initial elastic modulus of the moisture-equilibrated samples w[ere measured, and the test samples were classified into two groups. One group (I) comprised those samples which gradually became softer in texture, and the other group (II) which retained a similar texture to the original one or became harder than the original one. It was found that the samples in both groups began to change their texture at around 68%RH. The water sorption isotherm of each test sample was measured at the six levels of relative humidify. Both groups of samples exhibited on S-shaped line with two inflexion points. The monolayer water content of all samples was calculated by the BET method to be 2.5- 14/100 g of dry matter. Most samples, however, either remaind unsoftened or were temporarily hardened in the limited range from monolayer to multilayer. The softening phenomenon started above approx. 5% water content with group I, but above approx. 10% water content had no effect with group II. In comparison with the group II samples, those in group I had less monolayer water content and much free water under high-moisture conditions.
社団法人日本家政学会の論文
1997-07-15