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Functional effects of xanthan gum on quality attributes and microstructure of extruded sorghum-wheat composite dough and bread

Jafari, Morteza, Koocheki, Arash, Milani, Elnaz
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2018 v.89 pp. 551-558
breads, cell structures, cooking, dough, extrusion, hardness, ingredients, microstructure, mixing, porosity, scanning electron microscopy, sorghum flour, temperature, wheat, wheat flour, xanthan gum
This study was performed in order to enhance the extruded sorghum-wheat composite dough (SWCD) and bread (SWCB) quality using xanthan gum. In order to investigate the effect of extrusion cooking, extruded (at 10% feed moisture and 160 °C die temperature) and non-extruded sorghum flours were separately substituted with wheat flour at 10:90 sorghum/wheat ratio. In addition, to improve the quality of the final product, xanthan gum (0.5 and 1%) was added during the mixing of doughs ingredients. Results revealed that unlike non-extruded SWCD, addition of xanthan gum to extruded SWCD decreased the dough strength. SEM observation demonstrated that composite dough containing either extruded or non-extruded sorghum had similar structures. On the other hand, in contrast to extruded SWCD, xanthan gum incorporation to non-extruded SWCD formed a uniform structure. Extruded SWCD had less viscous and more solid-like characteristics than the non-extruded SWCD. The elasticity and solidity of both doughs containing extruded and non-extruded sorghum increased with the addition of xanthan gum. In general, it was found that extruded SWCD had the highest (10.75 °C/min) and non-extruded SWCD containing 0.5% xanthan gum had the lowest (7.33 °C/min) heating rates. The crumb cell structure also showed that the addition of xanthan gum increased the average pore size and decreased the number of cells/cm2, total area and pore area fraction (%) of crumb in the extruded SWCB. Bread crumb hardness increased when extruded sorghum flour and xanthan gum were used.