Valorization of Agro-Industry-Rejected Common Bean Grains for Starch Film Development: Advancing Sustainable and Comprehensive Resource Utilization

This study examines the potential use of rejected and discarded grains from the common bean industry as a starch source for producing plasticized films with glycerol. The observed morphological characteristics of starch granules from discarded grains were diverse, with round, oval, and kidney-like shapes and sizes ranging from 7 to 34 µm. We determined the pasting profile: the pasting temperature (GT) fell between 72 °C and 74 °C, while the peak viscosity (Pv) demonstrated a significant rise at 10% and 15% starch concentrations. To better understand pasting behavior, mathematical modeling was employed to predict Pv behavior, with an R2 value of 0.98. All film formulations were successful, yielding transparent, homogeneous, odorless, flexible films with smooth surfaces. Scanning electron microscopy analysis of the films revealed a flawless surface devoid of fissures, cracks, and pores, displaying a rough texture with a consistent structure and some starch granules resembling empty sacks due to amylose and amylopectin leaching. The highest tensile strength was observed with 6% starch and 1.5 mL of glycerol and the lowest with 4.5% starch and 3.9 mL of glycerol. The findings suggest that starch derived from discarded grains from the bean industry has unique characteristics and properties, making it a promising alternative source for intelligent packaging development.