Starch conversion during extrusion as affected by added gelatin

Waxy maize starch was modified by twin-screw extrusion cooking in the prese nce and absence of gelatin. X-ray diffraction, microscopy, rheology, and di fferential scanning calorimetry studies showed that, at constant specific m echanical energy and extruder heater temperatures, the degree of starch con version decreased with increasing levels of gelatin. It was hypothesized th at during extrusion cooking, the gelatin acts as a lubricant, protecting th e starch from being converted since more mechanical energy would be dissipa ted in the gelatin phase than the starch phase.