Optimizing Mechanical, Moisture-Based, and Enzymatic Pretreatments to Improve Dehulling Outcomes and Nutritional Quality in Four US Dry Bean Market Classes.

Dry beans (Phaseolus vulgaris L.) are a nutrient-dense and sustainable protein source, with potential for use as a food ingredient, but strong adhesion between the seed coat and cotyledon limits processing efficiency. This study evaluated mechanical and moisture-based pretreatments, with and without enzymatic supplementation, to improve dehulling performance across four major US market classes (black, pinto, navy, and Great Northern) and assessed the nutritional quality of resulting cotyledon and hull fractions. Small-scale trials identified that moisture tempering to 40% combined with bran-cracking was the primary driver of improved dehulling (dehulling index [DI] = 0.84 ± 0.01), with low enzyme addition providing a comparable DI (DI = 0.84 ± 0.01). Validation trials across four market classes confirmed that bran-cracking with 40% moisture tempering achieved consistently high performance (DE = 82%-89%, DD = 95%-100%, DI = 0.64-0.68), while enzyme addition provided no statistically significant additional benefit at the validation scale. Compositional analysis showed that hulls contained 33.2 ± 1.5% crude fiber and 6%-16% protein, while cotyledons contained 12.4 ± 3.5% crude fiber and 19%-24% protein; across all pretreatments, cotyledon protein concentration remained stable, supporting its suitability as a consistent, protein-dense ingredient stream. These findings demonstrate that moisture tempering combined with mechanical bran-cracking constitutes a practical, enzyme-free framework for enhancing dry bean dehulling while supporting value-added utilization of hulls as functional, fiber-rich ingredients. PRACTICAL APPLICATIONS: This work identifies moisture tempering combined with mechanical bran-cracking as the primary driver of improved dry bean dehulling performance-a practical, enzyme-free pretreatment strategy applicable across multiple US market classes. By enabling cleaner separation and recovering fiber-rich hull fractions as functional, clean-label ingredients, this approach supports reduced waste and expanded ingredient opportunities in pulse-processing operations.