• Korean Journal of Food Science and Technology
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• v.25 no.2
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• pp.94-97
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• 1993

This study was to predict water activity of gelatinized model foods containing moisture, protein and starch with different concentration of humectants such as sodium chlorife and sucrose. The water activity of each samples were determinded by electrical hygrometry. The degree of lowering water activity in model foods with humectant solutions was following order as NaCl>sucrose. Model food $P_2S_1$ was predominant in depression of water activity by humectants than other model foods. The multiple regression equations between water activity and different humectants concentration, compositions and solution ratio of model foods were obtained and $R^2$ values were higher than 0.91.

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.310-316
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• 1988

The gelatinized model food system were prepared by combining moisture, starch and protein, and the textural properties of their gels of different temperatures and times of heating were investigated by the use of Instron Universal Testing Machine. The hardness, springiness, cohesiveness, gumminess and chewiness of model foods had a high correlation with solid content and the regression equations between the hardness of model foods and moisture content heated for 20min. at $80{\circ}C$ were as follows; $H(PS_4)=18.6405-3.8201M+0.1959M^2,\;H(P_1S_1)=244.7933-5.692M+0.0332M^2,\;H(P_4S)=693.0292-16.6884M+0.1005M^2$, The correlation coefficients were $0.996^{**},\;0.998^{**}\;and\;0.998^{**}$, respectively. Total correlations between textural parameters and temperature and heating times were different according to model foods. The correlation between textural parameters was proportional to protein foods, but the hardness and cohesiveness of starch foods showed the relationship of inverse proportion. Under low solid content, the parameters of model foods appeared to decrease as protein content increased. Under high solid content, the parameters of protein foods were higher than those of starch foods above some level of protein content. The regression equation between the hardness and protein content heated for 20min. at $80^{\circ}C$ was as follows; Hardness(20%)=5.6858-13.5670P+$9.7758P^2$ and the correlation coefficient was $0.95^{**}$.

• Korean Journal of Agricultural Science
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• v.22 no.1
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• pp.103-109
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• 1995

The model foods were prepared by simulating mositure, protein and starch, and they were heated for 30 mins, at $80^{\circ}C$ and then cooled at $25^{\circ}C$ in water bath. Their rheological properties were investigated by the use of Brookfield wide-gap rotational viscometer at $30{\sim}60^{\circ}C$, and the rotation speed ranged from 0.6 to 6 rpm and solid content ranged from 8% to 11%, the results obtained were as follows. 1. All the model foods ($P_1S_3$, $P_2S_2$, $P_1S_1$, $P_2S_1$, $P_3S_1$, $P_4S_0$) exhibited pseudoplastic behaviors with yeild stress and were thixotropic foods which showed time - dependent structural decays, but the starch food of 8 ~ 11 % solid content did not show the flow behavior. 2. The correlation between the rheological parameters and the protein content of model foods in various moisture content did not appeared a constant relationship. 3. The change of shear stress against shear rate in high starch foods was larger than that in high protein foods and the structure at initial shear time was decayed with a quatic equation according to the Tiu's Model and structural decay was in parallel with the increase of shear rate. 4. The temperature dependency of the apparent viscosity of $P_1S_2$, and $P_2S_1$ was fully expressed by Arrhenius equation and activation energies of their food were 2.35 and $1.34Kcal/g{\cdot}mol$, respectively.