A COMPARATIVE STUDY OF EXTRACTION AND QUANTIFICATION METHODS OF PROTEIN ISOLATED FROM BEANS

Abstract

Background: Beans serve as a significant source of protein, minerals, and plant-derived micronutrients, holding social and economic importance. Their consumption is linked to numerous health benefits, including reducing the risk of cardiovascular disease, obesity, and diabetes. Plant-based proteins are also environmentally advantageous, as their production requires fewer natural resources and results in a smaller carbon footprint than animal-derived proteins. This study explores protein extraction methods from beans and assesses analytical techniques for protein quantification.

Objective: To examine various protein extraction and quantification techniques from beans, focusing on four primary analytical methods: SDS-PAGE, Bradford, Lowry, and spectrophotometry.

Methods: Proteins were extracted from bean samples using standardized cell disruption, solubilization, enrichment, and digestion techniques. Four analytical methods were then applied to quantify the proteins: SDS-PAGE (for molecular weight separation), Bradford (dye-binding assay), Lowry (colorimetric assay), and spectrophotometry (UV absorption at 280 nm). Each method’s precision, sensitivity, and compatibility with bean protein extracts were evaluated.

Results: SDS-PAGE effectively separated proteins in the 5-250 kDa range with a 95% consistency in molecular weight determination. The Bradford method detected protein concentrations as low as 1 µg/mL, while the Lowry method demonstrated a 10-fold sensitivity increase over spectrophotometry, which was limited by UV interference. Both Bradford and Lowry were modified for specific protein compositions, with Bradford showing less interference.

Conclusion: The Bradford method demonstrated the greatest adaptability and minimal interference in bean protein quantification, whereas SDS-PAGE proved optimal for protein fraction analysis. These findings suggest the continued development of extraction and quantification techniques to meet the increasing demand for plant-based proteins.