DYNAMICS OF SOLIDIFICATION IN 2-PERCENT CORN-STARCH WATER MIXTURES - EFFECT OF VARIATIONS IN FREEZING-RATE ON PRODUCT HOMOGENEITY

Directional solidification studies of gelatinized corn starch-water mi xtures were undertaken in order to examine, in situ, the freezing beha vior of this food model. The solidification rate was controlled by var ying sample cell velocity as it moved from a 25 degrees C hot stage to a -25 degrees C cold stage. While freezing at cell velocities less th an or equal to 7.5 mu m/sec, starch granules were alternately pushed o r entrapped by the advancing solid-liquid interface producing a segreg ated structure consisting of alternating high-starch and low-starch ba nds. At a cell velocity of 10 mu m/sec, the frozen product was homogen eous. The relationship between the solid-liquid interface velocity and segregation behavior was quantified and compared to an existing model of particle-interface interactions.