Legumin‐T from faba bean legumin: Isolation, partial characterization and surface functional properties

Legumin‐T was prepared by limited tryptic hydrolysis of legumin from faba beans (Vicia faba L.) and was chromatographically purified. It is composed of two principle subunits consisting each of an intact β‐polypeptide chain and a nicked α‐chain of legumin besides minor polypeptides. The molecular mass was (250 ± 11) kDa estimated by gel chromatography. Amino acid analysis showed that the transformation of legumin to legumin‐T resulted in a loss of polar amino acids and an increase of non‐polar hydrophobic amino acids. The time‐dependent surface tension and the surface compressions isotherms showed a rather similar behavior of legumin and legumin‐T. The calculated ratio of the surface areas A/A0 revealed, however, difference between both proteins (legumin: A/A0 = 1, legumin‐T: A/A0 < 1) pointing to an irreversible desorption of legumin‐T from the surface due to compression. The emulsifying activity of legumin‐T was higher than that of the parent legumin.