30C-15 |
Biochemical characterization of Moth bean (Vigna aconitifolia L.) proteins |
M. VENKATACHALAM, H. H. Kshirsagar, R. Tiwari, and S. K. Sathe. Department of Nutrition, Food and Exercise Sciences, Florida State University, 402 Sandels Bldg., College of Human Sciences, Tallahassee, FL 32306-1493 Moth bean is a popular tropical legume that is valued for its nutritional and sensory attributes. Agronomic characteristics as well as nutrient and antinutrient composition of moth bean have been investigated. However, biochemical properties of moth bean proteins remain largely unexplored. Moth bean seeds were ground to approximately 40-mesh flour and the flour was defatted using petroleum ether. Seed protein content was determined by micro-Kjeldahl method (N X 6.25). Albumin, globulin, prolamin, and glutelin fractions were prepared from defatted flour. Polyacrylamide gel electrophoresis was used to study protein polypeptide composition. Periodic acid-Schiff staining procedure was used to detect presence of glycoproteins. Amino acid composition of proteins was determined by using Waters Pico-Tag column amino acid analyzer. Protein in vitro digestibility was assessed at 37oC using pepsin (protein to pepsin ratio of 100:1 w/w) and 50 mM HCl as the digestion buffer. Moth seeds contained 24% protein on a dry weight basis. The globulin fraction was the predominant fraction that accounted for ~ 60% of the total soluble proteins in the seeds. The globulin fraction was composed of a major glycopeptide with estimated molecular weight (MW) 53 kDa and several additional peptides in the MW range 14-32 kDa. Sulfur amino acids were the first limiting amino acids in total seed proteins. Native and heat denatured albumin and glutelin fractions were readily hydrolyzed, in < 30 min, by pepsin at 37oC. Although native globulin was resistant to pepsin, heat denatured globulin (100oC, 30 min, boiling water bath) was completely digested by pepsin in < 30 min at 37oC.
Session 30C, Food Chemistry: Proteins
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