Vol.:(0123456789) 1 3 Food Measure DOI 10.1007/s11694-017-9649-4 ORIGINAL PAPER Physicochemical and sensory properties of extruded sorghum–wheat composite bread Morteza Jafari 1  · Arash Koocheki 1  · Elnaz Milani 2   Received: 20 April 2017 / Accepted: 25 September 2017 © Springer Science+Business Media, LLC 2017 benefts through bioactive compounds such as high fber content and phenolic compounds [2], sorghum is rarely consumed due to its unacceptable sensorial properties [3]. However, sorghum four is used in some food products such as gluten-free [4–6] and composite [7, 8] breads. Generally, substitution of wheat four with other gluten free fours such as sorghum reduces the specifc volume and overall acceptability of fnal bread and increase its crumb hardness [9]. In order to enhance this defect, several tech- nics such as gum incorporation [10, 11], heat treatment [4], heat-moisture treatment [12] and extrusion cooking [13–18] could be used. Extrusion cooking is a high temperature short time (HTST) process used for starchy and/or protein-rich food materials. During extrusion cooking, the combination of feed moisture, pressure, die temperature and mechanical shear of screw results in molecular changes and chemical reactions such as starch gelatinization, protein denaturation, complex formation between amylose and lipids, degrada- tion of pigments and modifcation of sensory characteristics [14–16]. The physicochemical properties of the extrudate are infuence by the nature of raw material, four particle sizes, screw speed, feed moisture and die temperature. However, feed moisture and die temperature have the highest impact on four extrudate [14, 15, 18–20]. Extrusion cooking alters dough and bread properties through partial gelatinization of starch granules. The infu- ence of extruded wheat four [14], wheat bran [13], hemp/ rice blend [16], rice four [15], sorghum four [18] and fnger millet [21] on textural and sensory properties of gluten and gluten-free dough and breads have previously been studied. However, the infuence of extrusion cooking on sorghum four and its efect on sorghum–wheat composite dough and bread is not fully understood. Therefore, the aim of the pre- sent study was to evaluate the efect of feed moisture and die Abstract Sorghum four was extruded at 110 and 160 °C die temperature with 10, 14 and 18% feed moisture. The efect of extruded sorghum four incorporation (10%) on physical (moisture, specifc volume, crumb cell structure, color and crumb texture) and sensory properties of sor- ghum–wheat composite bread were evaluated. The extrusion cooking of sorghum four increased the bread crumb mois- ture, hardness and redness whereas it decreased its crumb lightness. Extrusion cooking increased the number of cells/ cm 2 , produced smaller average pore size with low pore area fraction and decreased the specifc volume in the composite bread and formed denser bread structure. Sensory results indicated that the extrusion cooking reduced the sandy prop- erties of sorghum, improved the sorghum–wheat bread favor and increased the overall acceptability of sorghum–wheat bread. Keywords Sorghum four · Extrusion cooking · Composite bread · Image analysis · Sensory properties Introduction Sorghum (Sorghum bicolor L. Moench) is a drought–tolerant crop grow in semi-arid regions of the world [1]. Although the consumption of whole sorghum four would bring health * Arash Koocheki koocheki@um.ac.ir 1 Department of Food Science and Technology, Ferdowsi University of Mashhad (FUM), P. O. Box: 91775-1163, Mashhad, Iran 2 Iranian Academic Center for Education Culture and Research (ACECR), Mashhad, Iran