Some Physicochemical and Interfacial Properties of Native and Acetylated Legumin from Faba Beans (Vicia faba L.)

Abstract

The influence of acetylation on adsorption kinetics, film compression behavior (air/water), emulsifying properties (n-decane/water emulsions), and conformation of legumin from faba beans was studied. These measurements involved the Wilhelmy plate method, film balance, turbidity measurements, centrifugation, and size exclusion and reversed phase HPLC, UV absorption, and fluorescence probes. While distinct changes in physicochemical properties only occurred above a "critical degree of modification" (approximately 60%) e.g. dissociation and denaturation of the molecule and increased surface hydrophobicity, emulsifying property parameters linearly improved with acetylation as indicated by an increase in the emulsifying activity index of the legumin, improved coalescence stability of the emulsions, and decreased droplet size distribution and protein load of the oil droplets.The measured contact angle due to adsorption of legumin at the Wilhelmy plate distinctly influenced parameters of the Gibbs adsorption isotherms. A correlation between the critical association concentration and the emulsifying activity of the protein samples was also found.

Effect of acetylation and succinylation on solubility profile, water absorption capacity, oil absorption capacity and emulsifying properties of mucuna bean (Mucuna pruriens) protein concentrate

“…Chemical derivatization through acylation of amino acid residues with acetic and succinic anhydride has been used to improve functional properties of many plant proteins including wheat [11], soybean [4], leaf protein [12], peanut [13], sunflower [14], pea [15], cotton seed [16], winged bean [17], Faba bean [18][19][20], soy glycinin [21,22], rapeseed [23][24][25], and chick pea [26]. So far, no literature is available on acylation of mucuna beans.…”

Interfacial behaviour of succinylated faba bean legumin at low ionic strength

“…Legumin was succinylated by addition of dry succinic anhydride to a 1% protein solution under stirring at a constant pH 8.0. The protein content was determined by a micro biuret method [9] and the degree of succinylation by the TNBS method as previously described [10]. The legumin samples were dialysed against distilled water and freeze-dried just after preparation.…”

“…The measuring procedures and the calculation of surface-functional parameters were described in detail previously [10]. Briefly, a Krüss K12 tensiometer fitted with a platinum Wilhelmy plate monitored the reduction of surface tension, r, with time at 20 l 0.1 8C (surface tension of the buffer r 0 = 73.0 l 0.2 mN/m).…”

“…Emulsions (continuous phase: 2 mg protein per ml buffer; disperse phase: n-decane, purify 99.9%, Merck, Germany) were formed by sonication as described previously [10]. The volume fraction of oil was adjusted to v = 0.2, 0.3 and 0.4.…”

“…The volume fraction of oil was adjusted to v = 0.2, 0.3 and 0.4. The average volume/surface diameter D in lm [11] and emulsifying activity index EAI in m 2 oil per g protein [12] were calculated from turbidity measurements on diluted emulsions and from the protein content determined in the separated aqueous phase after centrifugation (3 0006g, 60 min, 20 8C) as described in [10].…”