CHEMICAL AND MORPHOLOGICAL EVALUATION OF STARCHES FROM LEGUMES AND APPLICATION OF THE EXTRACTION RESIDUES IN EXPANDED EXTRUDED SNACKS

Abstract

Starches from legumes (carioca bean, white bean and chickpea) were extracted, aiming at their chemical and morphological characterization, as well as evaluating the use ofthe extraction residues to elaborate expanded extruded snacks. The analyses carried out for the starches and their respective residues were moisture, proteins, lipids, ash, dietary fiber and carbohydrates. The starches were also evaluated with respect to their morphological characteristics, using Scanning Electron Microscopy (SEM). The residues were used in formulations containing corn flour to produce expanded extruded snacks. These snacks were evaluated as to their expansion index (EI), water absorption index (WAI) and water solubility index (WSI). WAI and WSI analyses were also performed for the residues. The results demonstrated that the starches presented similar composition regarding moisture and carbohydrates, with a high carbohydrate content (close to 91%). The starch granules presented sizes between 15 and 25μm and a flat oval shape, with the chickpea starch granules being the smallest with a tendency to form agglomerates. The residues presented significant amounts ofcarbohydrates (between 70 and 75%), apart from expressive quantities ofdietary fibers (between 25 and 39%). In the evaluation ofWAI and WSI ofthe residues, IAA values were close for the sources studied (close to 11g/g), WSI was greater for carioca bean (close to 15.6%). The snacks containing the carioca bean residues had the highest EI value (6.3), while the highest values for WAI and WSI (respectively, 14.4g/g and 31.1%) were found for the snacks with white bean residues.

Keywords

• Thermoplastic extrusion
• snacks
• dietary fiber
• Phaseolus vulgaris L.
• Cicer arietinum L