Physicochemical and morphological characterization of black bean (Phaseolus vulgaris L.) starch and potential application in nano-encapsulation by spray drying

Abstract

The objective of this work was to analyze the morphological and physicochemical properties of bean starch and its use in nanoencapsulation by spray drying. Starch purity was 81.21 ± 1.43% db with a resistant starch content higher than a commercial corn starch, but with a high protein content and a low amylose content. Starch granules presented smooth surfaces, polyhedral shape and sizes from ~ 1 to 6.3 µm. Black bean starch exhibited an A-type X-ray diffraction pattern with a crystallinity highest than corn starch. Black bean starch showed higher thermal stability than a commercial corn starch. At 90 °C, solubility was 31.0% and swelling power was 31.2 g g−1. The black bean starch gel showed a high stability under refrigeration and freeze–thaw. Small particles and viscosity profile suggested the potential application of black bean starch as wall material during nano spray drying. Black bean starch tends to form spherical aggregates during nano spray drying due to the protein content. Capsules size was in the range of 1.0–2.5 µm, however were observed agglomerated particles by SEM. The encapsulation efficiency of L-ascorbic acid was 36.88 ± 0.55%. The results indicate that black bean starch possesses properties with potential applications in food industries.