Location: Plant Polymer Research
Title: Extraction and characterization of protein in four common dry beans (Phaseolus vulgaris L.) Authors
Submitted to: International Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 15, 2014
Publication Date: N/A
Interpretive Summary: We produced a high-protein product from common dry beans with properties that would benefit food and nonfood systems. Our research provided fundamental data that would identify the most viable applications for the bean protein concentrate and will be of interest to R & D scientists, food technologists and polymer chemists. Developing new uses and markets for dry bean protein will expand the utilization of 2.3 billion lbs of dry beans produced mainly for food in the U.S. and certainly generate additional income for our dry bean growers. In our study, we extracted protein from four common beans (black, dark red kidney, great northern, and pinto) by using warm (45°C) aqueous saline solution and obtained moderate-to-high protein recoveries. Our spray-dried extracts had high protein purities (80%), which classified them as protein concentrates. We determined that the bean protein concentrates contained notable amounts of amino acids that are nutritionally essential, as well as those with reactive side chains that can participate in various chemical reactions. We observed that all our bean protein concentrates were highly soluble in very acidic (pH 2), neutral (pH 7) and highly alkaline (pH 10) aqueous solutions. Thus, three protein classes could be fractionated from bean protein concentrates to yield products with distictly different functionalities that they may be used in many food systems and nonfood applications (e.g., adhesives, which are very alkaline).
Technical Abstract: Chemical and functional properties are important for identifying possible value-added uses of protein in the common bean (Phaseolus vulgaris L.). Protein was extracted from four common beans (black, dark red kidney, great northern, and pinto) by using 0.5 M NaCl at 45°C. Protein extraction efficiency was 65-77%. The recovered spray-dried extracts had 80% crude protein (db), which classifies them as protein concentrates. The beans and protein concentrates had nearly identical SDS-PAGE band patterns, which showed 10-12 distinct bands with M.W. range of 6.5-107 kDa. They also had very similar amino acid profiles, which showed notable amounts of nutritionally essential amino acids and those with reactive side chains. All bean protein samples were least soluble (10-28% soluble proteins) at pH near 4.5 and were highly soluble at pHs 2, 7 and 10 (50-94% soluble proteins). The solubility behavior indicates that acid-soluble, neutral pH-soluble, and alkali-soluble proteins could be fractionated from the ground beans or protein concentrates to yield products that they may be used in a variety of food and non-food applications.