Starch Conversion During Extrusion as Affected by Added Gelatin

Waxy maize starch was modified by twin‐screw extrusion cooking in the presence and absence of gelatin. X‐ray diffraction, microscopy, rheology, and differential scanning calorimetry studies showed that, at constant specific mechanical energy and extruder heater temperatures, the degree of starch conversion decreased with increasing levels of gelatin. It was hypothesized that during extrusion cooking, the gelatin acts as a lubricant, protecting the starch from being converted since more mechanical energy would be dissipated in the gelatin phase than the starch phase.