Extraction and characterization of starch from green-matured cowpea beans (Vigna unguiculata L. Walp.)

Cowpea starch is a non-conventional starch source. The use of green beans in food applications has been limited due to high levels of antinutrients, long cooking times, and high perishability. The objective of this study was to analyze the physicochemical and functional properties of starch from cowpea beans during the green maturation stage. The starch granules had oval and irregular shapes with an average diameter of 16.44 μm. Cowpea bean starch had a high apparent amylose content (47%), indicating its potential for use in bioplastic production. The absolute density was 1.39 g/mL, and the phosphorus content was 0.008%. Its water absorption capacity (68.24 g/100g) was higher than that of oil (53.35 g/100g), an ideal characteristic for applications in baking and confectionery. Thermogravimetric analysis showed good thermal stability, an essential parameter for use in canned products. The starch had a final viscosity of 4250 cP, a minimum of 3154 cP, and a high tendency to retrograde (1099 cP). The pasting temperature was 78 ºC, indicating resistance to swelling. In general, cowpea starch exhibited attractive properties for applications in the bioplastics, baking, and canning industries; however, it is not suitable for products that require a freezing process.