Effect of extrusion temperature on the protein aggregation of wheat gluten with the addition of peanut oil during extrusion.

The influence of extrusion temperature on protein components and aggregation of wheat gluten (WG) and wheat gluten-peanut oil complexes (WPE) during extrusion with the addition of peanut oil was studied. Gliadin content and wheat gluten extractability decreased and glutenin content increased as extrusion temperature increased. At the same extrusion temperature, the gliadin content in WPE was higher than that in WG. The addition of peanut oil also resulted in the higher gluten extractability of WPE than WG. Increasing extrusion temperature also increased the average molecular weight of glutenin and gliadin. The decreased free sulfhydryl (SH) and increased disulfide bonds (SS) indicated that wheat gluten aggregation was promoted, via disulfide cross-linking, when extrusion temperature increased. Furthermore, increased temperature promoted the aggregation of gluten by increasing sulfhydryl-disulfide bond (SH-SS) interchange during extrusion. When the secondary structure of wheat gluten was analyzed by circular dichroism, the relative gluten α-helix content was decreased and the relative β-sheet content was increased. Also, the results of scanning electron microscopy (SEM) showed the size of the resultant particles increased with temperature, and the mean particle size of WPE was higher than WG. This research shows that extrusion temperature promotes gluten aggregation of WG and WPE. It provides basic data to support the study of gluten-lipid extrusion in the field of protein processing.