Physicochemical and Functional Properties of Fiber-Rich Hulls from Different Pulses: A Comparative Study

Pulse hulls, the primary byproduct of pulse processing, are increasingly recognized as potential sources of dietary fiber (DF). A systematic evaluation of the pulse hull composition and properties facilitates their potential applications. This study compares proximate composition, physicochemical and functional properties, and antioxidant activities of pulse hulls from the six most prominent pulse types: chickpea, red lentil, yellow pea, cowpea, black bean, and faba bean. All studied samples were found to be rich in DF (49.1–65.4%) while low in protein (3.9–13.9%), ash (2.23–5.03%), and fat (0–0.71%). Scanning electron microscopy revealed distinct surface morphologies across the samples. Variations in the compositional profiles and microstructures resulted in versatile functional properties. Chickpea hull displayed the highest water/oil-holding (5.91 and 1.48 g/g) and water-swelling (4.17 mL/g) capacities. Red lentil hull exhibited the highest glucose adsorption (308.0 mg/g) and exceptional cholesterol-binding (135.2 mg/g) capacities, while the cowpea hull exerted the greatest sodium cholate-binding capacity (29.9 mg/g). Colored hulls (red lentil, faba bean, black bean, cowpea) demonstrated significantly higher total phenolic content (8.5–35.7 mg gallic acid equivalent (GAE)/g) with the highest value for red lentil, as opposed to the light-colored chickpea and yellow pea hulls (<1 mg GAE/g). Antioxidant activities, as assessed by DPPH•, NO•, and oxygen radical absorbance capacity assays, positively correlated with phenolic content (r = 0.992, 0.906, and 0.936, respectively, p < 0.05). These findings highlight the potential efficacy of pulse hulls as antioxidants and fiber-rich ingredients for functional food applications.