Functional properties of pregelatinized and cross-linked cassava starch obtained by extrusion with sodium trimetaphosphate

Cassava starch was cross-linked with sodium trimetaphosphate (STMP) on a Ce realtec single-screw extruder at different extrusion temperatures and conce ntrations of STMP and NaOH. The effect of variables on functional propertie s of the products was analysed by the response-surface methodology; The deg ree of substitution (DS) was influenced by NaOH and phosphorus level, and i ncreased when their concentration increased. Extrusion temperature affected water absorption, cold viscosity and gel characteristics. The introduction of phosphate groups by cross-linking, with maximum DS of 1.5 x 10(-4), inc reased the gel strength, water absorption index, resistance to high tempera ture and shear, and decreased gel cohesiveness, starch clarity and water so lubility index. The products had different DS and degree of gelatinization and thus can be applied in several kinds of foods. (C) 2001 Elsevier Scienc e Ltd. All rights reserved.