Ultrasound-Assisted Soaking and Solution Effects on the Anti-Nutritional Quality and Physical Properties of Legume Seeds

Abstract

This study investigates the effects of soaking method (ultrasound-assisted soaking (UAS) and conventional soaking (CS)), soaking solutions with varying pH (distilled water (W), citric acid (CA), and sodium bicarbonate (SB)), and soaking times (4, 8, and 12 h) on anti-nutritional factors (phytic acid (PA) and trypsin inhibitor (TI) contents), moisture absorption, and hardness of chickpeas, beans, and soybeans. Additionally, the study examined changes in soluble solids content (SSC), pH, turbidity, and color of the soaking solutions. While the soaking method and solution significantly (p < 0.05) affected TI content in seeds, they had no notable impact on PA content. The most notable reductions in PA were observed following 12 h of CS: 27.0% in chickpeas and 38.9% in soybeans soaked in water, and 30.5% in beans soaked in sodium bicarbonate. Sodium bicarbonate was more effective than citric acid and water in reducing TI. UAS generally led to greater TI reductions compared to CS, although its effectiveness was reduced in sodium bicarbonate. UAS resulted in higher hydration rates across all solutions. Chickpeas and beans soaked in citric acid for 4 h and soybeans soaked in citric acid for 12 h exhibited the lowest hardness values. UAS notably increased SSC, turbidity, and pH changes in the soaking solutions compared to CS.