STRUCTURAL AND FUNCTIONAL-CHANGES OF FABA BEAN LEGUMIN DURING SUPER-LIMITED TRYPTIC HYDROLYSIS

The influence of a super-limited tryptic hydrolysis on physicochemical and surface functional properties of faba bean legumin has been studi ed using size-exclusion HPLC, SDS-PAGE, UV and fluorescence spectrosco py, fluorescence probe techniques, surface tension measurements as wel l as determination of emulsifying activity index (EAI) and emulsion dr oplets diameter (D). The extent of legumin hydrolysis comprised the ra nge between about 14 and 60 split peptide bonds per molecule resulting in a stepwise decrease of legumin molecular weight to 240 kDa (legumi n-T) via discrete intermediates with characteristic subunit patterns. These changes are accompanied by an increase in the surface hydrophobi city and the exposure of aromatic chromophores. No differences were fo und in the surface tension between the variously hydrolyzed legumin sa mples. Best emulsifying properties (highest EAI and lowest D values) w ere attained after a rather low tryptic hydrolysis (about 30 split pep tide bonds per mel). Further hydrolysis impaired the emulsifying param eter which were, however, higher (EAI) or lower (D) than those for nat ive legumin.