3.5. Rehydration ratio (RR)
Rehydration ratio of extrudates extruded for different experimental conditions are listed in Table 2. The values of RR varied from 49 g/100 g to 205 g/100 g. The regression equation for the relationship between rehydration ratio (YRR) and independent variables is shown in Table 3. Barrel temperature and material moisture content were significant for RR, temperature was the most significant factor and all interaction among protein content, material moisture content and barrel temperature were also significant. The response surface plot of rehydration ratio of extrudates are presented in Fig. 3 (A:140 C, B:160 C, C:180 C). These figures showed RR have more complicated trend under different extrusion conditions. Under lower barrel temperature (140 C),
higher protein content resulted in higher RR. When the temperature
was increased to 160 C, an increase protein content at high
moisture content (45 g/100 g, dry basis) slightly decreased the RR,
but increase protein content at a up to a high low moisture
content (35 g/100 g, dry basis) increased the RR. With barrel
temperature at 180 C, RR decreased with an increase in protein
content.