IMPACT OF DROUGHT STRESS ON TOTAL PHENOLS, BUTANOLSOLUBLE POLYPHENOLS, AND VANILLIN IN THREE FABA BEAN (VICIA FABA L.) CULTIVARS

Abstract

The phenolic makeup of legumes plays a key role in their nutritional quality, antioxidant capacity, and how they respond to environmental stress. This study investigated how drought stress influences total phenols (TP), butanol- soluble polyphenols, and vanillin- reactive compounds in three faba bean (Vicia faba L.) cultivars: Reinablanca, Aquadulce L., and Alfred. Plants experienced both traditional (T) and selected (S) post- harvest treatments to examine how genotype and drought stress affect phenolic metabolism. TP levels ranged from 46. 53 mg/g DM in Reinablanca T to 92. 68 mg/g DM in Alfred S, with Alfred consistently showing the highest levels under drought conditions. Butanol-soluble polyphenols followed a similar trend, reaching 109.35. 35 mg/g DM in Alfred S, which indicates a strong link between TP and polymerized phenolics. In contrast, vanillin content dropped under the selected treatment across all cultivars, with Reinablanca T having the highest level at 41.40 mg/g DM. This suggests a metabolic trade- off where stress- driven phenolic production may limit precursors for flavor- related compounds. The different cultivars responded uniquely: Alfred showed the highest potential for bioactive properties, Reinablanca maintained higher vanillin levels under traditional treatments, and Aquadulce L. exhibited intermediate traits but had higher butanol- soluble phenolics during drought stress. These findings show that drought stress boosts antioxidant phenolics while decreasing flavor- related vanillin, reflecting an adaptive shift in metabolism. Overall, Alfred stands out as a promising cultivar for functional foods or nutraceuticals owing to its strong antioxidant properties, while Reinablanca might be better suited for products focused on sensory qualities. This research offers valuable insights into how stress affects phenolic metabolism in legumes and guides strategies for selecting cultivars and managing post- harvest treatments to improve both nutritional and sensory qualities.