The focus of the current study was to investigate the physicochemical properties of a corn starch-sponge matrix prepared at a low concentration below gel forming by freeze-drying. The effect of variables(starch concentration, heating temperature, and heating hold time) on the physicochemical properties of the samples was analyzed by response-surface methodology. Regression models on the properties of samples such as hardness, springiness, and water solubility index(WSI) showed high correlation coefficients(r>0.95) and significant F values, but regression models for the other properties(swelling power, apparent viscosity, reducing sugar content, and digestibility) showed them to have relatively low significance. Sample hardness of sample showed the highest value at condition of 90℃ and 5%, whereas springiness was at a maximum at 130℃ and 5%. Also, at 1% of starch concentration, mechanical properties were greatly decreased as the relative humidity increased, compared with the 3% and 5%, especially in the hardness of samples. The WSI showed an increasing trend with heating temperature regardless of starch concentration. Overall, the physicochemical properties of freeze-dried corn starch-sponge matrix were influenced much more by starch concentration and heating temperature than by heating hold time. The results of this study show that the basic properties of freeze-dried corn starch-sponge matrix can be used for the specific food applications or as a functional material for its stability.

• 김한수 | Han Soo Kim