Kinetics of Formation and Functional Properties of Conjugates Prepared by Dry-State Incubation of β-Lactoglobulin/Acacia Gum Electrostatic Complexes

Abstract

The formation of conjugates between beta-lactoglobulin and acacia gum based on electrostatic complexes formed at pH 4.2 was investigated upon dry-state incubation for up to 14 days at 60 degrees C and 79% relative humidity (RH). By means of SEC-HPLC and RP-HPLC, it was shown that the beta-lactoglobulin incubated alone was able to form polymers with molecular masses higher than 200 kDa until 50% of the initial monomeric protein disappeared after 14 days. In the presence of acacia gum at initial protein to polysaccharide weight mixing ratios of 2:1 and 1:2, only 35% of the initial beta-lactoglobulin monomers disappeared after 14 days. Using RP-HPLC, an apparent reaction order of 2 was found for the disappearance of monomeric beta-lactoglobulin both in the presence or absence of acacia gum. However, the reaction rate was faster in the absence of acacia gum. SDS-PAGE electrophoresis with silver staining confirmed the formation of beta-lactoglobulin/acacia gum conjugates. The solubility curves of the incubated beta-lactoglobulin showed a minimum around pH 4-5. By contrast, the minimum of solubility of the beta-lactoglobulin/acacia gum incubated mixtures shifted to lower pH values compared to initial mixtures. The conjugates exhibited higher foam capacity than the incubated protein as well as lower equilibrium air/water surface tension. Conjugation at ratio 1:2 led to increased interfacial viscosity (300 mN s m(-1) at 0.01 Hz) compared to beta-lactoglobulin alone (100 mN s m(-1) at 0.01 Hz), but similar interfacial elasticity (30-40 mN m(-1)). The foam capacity of the conjugates was significantly higher than that of the incubated beta-lactoglobulin as well as foam expansion and drainage time, especially at pH 5.3, i.e., higher than the pH of formation of the conjugates.

Functional properties of milk proteins as affected by Maillard reaction induced oligomerisation

“…Table 4 shows that increased overrun was obtained for solutions of milk protein/pectin (up to +131%) and milk protein/dextran (up to +109%) Maillard products. These results suggest that complex sugars may benefit the overrun formation of Maillard products, considering that higher overrun post Maillard reaction was also reported for b-lactoglobulin/acacia gum (Schmidt et al, 2005), whey protein/pectin (Mishra et al, 2001) and serum albumin/dextran products (Dickinson & Izgi, 1996).…”

“…Alterations of protein structure (Morgan, Molle, et al, 1999), hydrophobicity (Fechner et al, 2007), surface hydrophobicity (Leonil et al, 1997) and net charge (Nacka et al, 1998; Trofimova & de Jongh, 2004;van Teeffelen et al, 2005) upon Maillard modification may complexly affect surface tension values. Lower surface tension than for untreated proteins was reported for b-lactoglobulin/acacia gum (Schmidt, Bovay, & Frossard, 2005) and b-lactoglobulin/fructooligosaccharide Maillard products (Trofimova & de Jongh, 2004). Comparatively lower molar mass b-lactoglobulin/dextran Maillard products lead to a stronger surface tension diminution than higher molar mass b-lactoglobulin/ dextran products due to slowed adsorption of large conjugates towards surfaces (Dunlap & Côté, 2005) and retarded surface denaturation (Thomas et al, 2004).…”

“…Foam stability may also be promoted by increased viscosity of Maillard product solutions (Ganzevles et al, 2006) and tendentially increased hydrophilicity of proteins (Fechner et al, 2007) post Maillard reaction. In literature, increased stability of protein foams was reported for b-lactoglobulin/glucose (Chevalier, Chobert, Popineau, et al, 2001), b-lactoglobulin/lactose (Chevalier, Chobert, Popineau, et al, 2001;French & Harper, 2003), b-lactoglobulin/acacia gum (Schmidt et al, 2005) and whey protein/pectin Maillard products (Mishra et al, 2001). Other authors obtained lower foam stability for total milk protein post Maillard reaction (Thomas et al, 2004).…”

Production and Application of Lysozyme-Gum Arabic Conjugate in Mayonnaise as a Natural Preservative and Emulsifier

“…It is concluded that covalent attachment of polysaccharide to protein can improve the FS by forming a viscoelastic layer around the bubbles. Also, the higher FC occurs through increasing the surface tension of the bubbles [Schmitt et al, 2005].…”

Physicochemical properties and emulsion stabilization of rice dreg glutelin conjugated with κ‐carrageenan through Maillard reaction

“…34,37,38 Amino acid analysis It is widely known that protein and polysaccharide graft reactions can be performed by covalent binding between the ε-amino groups of proteins and the reducing-end carbonyl groups of polysaccharides. 39 The ε-NH 3 of lysine, arginine and histidine, and the α-NH 3 of protein N-terminus, were commonly regarded as the major locus during the Maillard reaction. 40 Proline 41 and cystine 42 have been reported to be involved in the Maillard reaction as well.…”