076: Influence of Salts on Soaking Characteristics of Pinto and Black Beans

Introduction

Common beans (Phaseolus vulgaris L.) are known for their nutritional and functional attributes. The quality of beans is influenced by their chemical and physical characteristics, which processing seeks to enhance or preserve. Soaking is a conventional pre-treatment used to reduce hard-to-cook phenomenon and eliminate undesirable compounds in beans. Although soaking is a crucial step in bean processing, most research has concentrated on post-cooking changes, with limited attention given to its standalone effects on key attributes such as polyphenol content, antioxidant activity, color, and texture. The objective of this study was to investigate the influence of soaking with and without salts on the chemical and physical properties of pinto and black beans.

Methods

Pinto and black beans were soaked in water, 1% NaHCO3, 1% NaHCO3+1%NaCl, 2%NaHCO3, and 2%NaHCO3+1%NaCl solutions. Key parameters, including polyphenol content (total polyphenol content-TPC, total flavonoid content-TFC), antioxidant capacities (ferric reducing antioxidant power, DPPH % radical scavenging activity, IC50, and trolox equivalent antioxidant capacity), hardness, and color, were analyzed at intervals of 6, 12, 18, and 24 hours.

Results

Unsoaked pinto beans exhibited higher polyphenol levels compared to black beans. However, black beans demonstrated 5.4% to 78.3% greater antioxidant capacity and were 36.7% harder than pinto beans. Soaking led to TPC reductions of 1.6–38.0% in pinto beans and 5.4–27.4% in black beans, along with TFC losses of 11.9–63.5% and 1.8–57.5%, respectively for pinto beans and black beans, with time. The inclusion of salts during soaking increased polyphenol and antioxidant losses, with higher NaHCO3 concentrations causing more pronounced reductions. While NaCl treatments had minimal impact on hardness and effectively preserved the color of the beans.

Significance

These findings provide critical insights for refining pre-processing methods in bean production, enabling the enhancement of nutritional and functional qualities. This contributes to improved processing practices and product quality within the food industry.

Authors: M. Yakubu, J. Boateng