Conjugates of α-lactalbumin, β-lactoglobulin, and lysozyme with polysaccharides: Characterization and techno-functional properties.

Conjugates of protein (α-lactalbumin, β-lactoglobulin, and lysozyme) with polysaccharides (guar, locust, pectin, and carboxymethilcellulose) were prepared via Maillard reaction by the dry-heating method. The conjugates were characterizated by using the browning index, extent of reaction, grafting degree, sodium dodecyl sulfate - polyacrilamide gel electrophoresis, fluorescence, and circular dichroism. The emulsifying properties and foaming ability of the formed conjugates were also evaluated. Conjugates with pectin and Lz-CMC system showed an increase in the browning index with the increase of the heating time. Circular dichroism and fluorescence data pointed out to conformational changes of proteins during glycation. The lysozyme (lz) conjugates presented the highest degree of glycation (89.1%). The α-Lactalbumin (α-la) - polysaccharides (PS) conjugates showed foam stability higher than the mixture (α-la + PS), the pure α-la, and the conjugates of β-lactoglobulin (β-lg) and lysozyme (lz) for all studied time (30, 60, and 120 min). The α-la-carboxymethylcellulose (CMC) conjugate presented the highest value of foaming stability (85.71). The pure β-lg shows greater foam stability and volume than β-lg-PS conjugates and mixture (β-lg + PS). The lz conjugates do not exihibit foam stability, except for the lz-CMC conjugate that showed stability up to 60 min. Furthermore, emulsion stability of the systems was affected by sonication time. Conjugates of α-la have greatly potencial applications as novel foaming agents in food industry.