Development and Characterization of Extruded Broken Rice and Lupine (<i>Lupinus albus</i>)

Abstract

Mixtures of cereals and legumes result in products with higher content of high biological value proteins. The thermoplastic extrusion promotes the transformation of chemical, physical and nutritional characteristics of the food such as starch gelatinization and promotes the inactivation of anti-nutritional compounds and enzymes. This study aimed to develop products extruded using broken rice and lupine and to evaluate the physical and chemical characteristics of those products. The expansion index (EI), water solubility (WSI), water absorption (WAI), texture and color were determined for the extruded rice, and Scanning Electron Microscopy (SEM) of the extruded rice was also performed. As the rice concentration in the mixture increased, the EI, WSI and WAI values as well as the a* color parameter were increased too, and the brightness was reduced. An increase in the levels of essential amino acids with the addition of lupine grain to the extrudates was observed. SEM analysis identified intact loose starch granules or pellets in the raw materials, and the extruded samples showed a compact and amorphous shape without apparent starch granules. Due to the structural changes and reduced expansion rate of the extruded mixture prepared with lupine and rice grits, use of the extruded mixtures as snacks would not be suitable. However, these mixtures could be used in pre-gelatinized flour to formulate various products to increase the protein level.