Main content area

Influence of extrusion variables on the protein in vitro digestibility and protein solubility of extruded soy tarhana

Ainsworth, P., Fuller, D., Plunkett, A., Ibanoglu, S.
Journal of the science of food and agriculture 1999 v.79 no.5 pp. 675-678
fermented foods, wheat flour, yogurt, extrusion, extruded foods, temperature, food processing, food processing equipment, solubility, in vitro digestibility, digestible protein, extruders
Tarhana, supplemented with 150 g kg(-1) full-fat soy flour, was extruded at different extrusion conditions (barrel temperature: 80-120 degrees C; screw speed: 100-300 rpm; feed rate: 10-20 kg h(-1)) using a twin-screw extruder. The effect of extrusion conditions on the in vitro digestibility (PD) of the protein and protein solubility (PS) was investigated using response surface methodology. Regression equations for predicting PD and PS were developed. While the barrel temperature had a significant effect on PD (p < 0.1), feed rate was the most significant variable on PS of the samples (P < 0.05). Since the protein solubility should be high for the instant properties of extruded soy tarhana soup, it is suggested that soy tarhana should be extruded at low feed rates (ie high residence times) while high barrel temperatures should be achieved for the inactivation of antinutritional factors present in the soy flour.