Optimization of Roasting Enhances Bioactive Profiles, Antioxidant Activity, and Reduces Lectin Content in Bean Flours: Implications for Functional Plant‐Based Ingredients

ABSTRACT

Roasting is a widely used thermal process for pulses, though prior work has not fully clarified how temperature and duration of roasting together affect phytochemicals, antioxidant, and antinutrient profiles of different pulses. This research applied a central composite design within response surface methodology (RSM‐CCD) on five cultivars, including cranberry, navy, pinto, and yellow beans, along with chickpeas, examining roasting temperatures between 150°C and 220°C and durations of 10–20 min. Before roasting, all samples were soaked for 12 h, followed by dehydration at 50°C before processing in a pilot‐scale oven. Total phenolics, total flavonoids, antioxidant capacity, proanthocyanidins, non‐extractable polymeric proanthocyanidins, carotenoids, and lectin (phytohemagglutinin) activity were each quantified, with the collected data subsequently modeled using quadratic regression. Roasting significantly affected every response, and the models showed strong fit ( R ²  > 0.80 for most). All cultivars peaked at 220°C for 20 min, except yellow beans, which reached their optimum at a comparatively lower temperature of 150°C for the same duration. Among all cultivars, navy beans gained the most in total phenolic increase (up to 514%) and FRAP (21.2 g kg ⁻¹ ), while cranberry beans had a significant increase in total flavonoid content, yielding 13.1 g kg ⁻¹ and DPPH, yielding 50.5%. Lectin content declined drastically up to 85% across all cultivars after processing. These findings demonstrate that controlled roasting effectively reduces lectins while enriching antioxidant activity in bean flour, supporting its suitability for use in nutraceuticals and functional food products.