Purification and Characterization of Pinto Bean Protein Using Membrane Technology

Area of Science:

• Food Science
• Biotechnology
• Sustainable Processing

Background:

• Pinto beans are a rich source of protein and phytonutrients.
• Conventional alkaline protein extraction methods suffer from low yield, purity, and environmental concerns due to wastewater generation.
• Membrane technology presents a promising alternative for efficient and environmentally friendly protein extraction.

Purpose of the Study:

• To develop and evaluate a combined membrane-based processing scheme for pinto bean protein extraction.
• To characterize the functional properties of the extracted pinto bean protein concentrates.
• To compare the functional properties with commercial soy protein isolate.

Main Methods:

• A multi-step process involving alkaline extraction (pH 10.5), ultrafiltration (CF=5.5), diafiltration (DV=4), and isoelectric precipitation (pH 4.5).
• Freeze-drying was employed for final product stabilization.
• Analysis of nitrogen solubility index (NSI), water/oil holding capacity, emulsifying, and foaming properties.

Main Results:

• High protein recovery (85.5%) from pinto bean flour.
• Production of precipitated protein concentrate (PPC, 86.4% protein) and acid-soluble protein concentrate (ASP-C, 56.3% protein).
• PPC exhibited superior emulsifying activity, while ASP-C showed high NSI and oil-holding capacity; both had comparable foaming properties to soy protein isolate.

Conclusions:

• The developed membrane technology-based process is effective for producing high-purity pinto bean protein concentrates.
• Pinto bean proteins possess valuable functional properties suitable for food applications.
• The study confirms the commercial potential of pinto bean protein isolates as a sustainable alternative to soy protein.