• Korean Journal of Food Science and Technology
• /
• v.26 no.4
• /
• pp.442-447
• /
• 1994

Effect of different mixing ratio of non-glutinous and glutinous rice on physical and rheological properties of extrudate prepared in a single screw extruder were examined. The extrusion conditions in term of screw speeds, moisture content and die temperature were 258 rpm, 18% and $120^{\circ}C$, respectively. The resisdence time distribution of the most of materials were within 30 second and small portion of them went up to 80 second. The expansion ratio was the highest value (2.93) for 70% of glutinous rice in the mixture, while the lowest value for 100% of non-glutinous rice. Breaking strength was in the range between 1,051g and 1,117g for $10{\sim}20%$ of glutinous rice in the mixture, while the lowest value (737g) for 80%r of glutinous rice. As the amount of glutinous rice increased, L and a values were increased and b value was decreased. The uncooked cold paste viscosity had 400 B.U. for 100% non-glutinous rice , while no peak for the 100% glutinous rice. As the amount of glutinous rice increased up to 100%, the water absorption index (WAI) was decreased, while water solubility index (WSI) was increased. The rheological properties of extrudate were accounted by the law of Oswald. The flow behavior index of extrudate was less than 1.0, which showed pseudoplastic behavior. Yield stress was the highest value for 20% of glutinous rice in the mixture and the lowest value for $80{\sim}100%$ of glutinous; rice. Number of air cell was between 128 and 159 for $80{\sim}100%$ of glutinous rice in the mixture, while $81{\sim}84%$ for $0{\sim}20%$ of glutinous rice. The degree of shapefact was increased more when the mixtures of glutinous and non-glutinous rice was used than when glutinous or non-glutinous rice was only used.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.27 no.1
• /
• pp.13-26
• /
• 1994

The present study was focused on investigation of proper processing conditions to develop physicochemical properties of extrudates using sea mustard and corn by single extruder. Response surface analysis was used to evaluate effects of extrusion variables on the quality of the extrudates. Physicochemical dependence variables of sea mustard extrudates with corn grits show a significance correlation of within $5\%$. Among the various dependence variables, the expansion ratio showed a high correlation with bulk density, break strength, water solubility index and yellowness. Bulk density correlated closely with water solubility index; break strength with water absorption index and lightness, and water absorption index with lightness. Water solubility index and lightness showed a significance correlation with yellowness of within $0.5\%$. Three dimensional graphic analysis on response surface regression was conducted with each of the dependent variables which revealed statistically significant relationship to independent variables: $15{\sim}21\%$ moisture content, $10{\sim}30\%$ sea mustard content and $95{\sim}115^{\circ}C$ die temperature. Expansion ratio decreased with increasing moisture and sea mustard content. It showed the highest value at $18\%$ moisture content, $10\%$ sea mustard content and $95^{\circ}C$ die temperature. and the lowest value was at $21\%$ moisture content, $30\%$ sea mustard content and $105^{\circ}C$ die temperature. Bulk density was highest at $21\%$ moisture content, $30\%$ sea mustard content and $105^{\circ}C$ die temperature. On the other hand, it was lowest at $18\%$ moisture content, $10\%$ sea mustard content and $95^{\circ}C$ die temperature. Break strength was highest at $18\%$ moisture content, $10\%$ sea mustard content and $115^{\circ}C$ die temperature, but lowest at $21\%$ moisture content, $30\%$ sea mustard content and $105^{\circ}C$ die temperature. Water solubility index increased in the range of $43.9{\sim}54.8\%$ as the moisture content increased.