title: Influence of pH on viscoelastic properties of heat-induced gels obtained with a β-Lactoglobulin fraction isolated from bovine milk whey hydrolysates.
abstract: A β-Lactoglobulin fraction (r-βLg) was isolated from whey hydrolysates produced with cardosins from Cynara cardunculus. The impact of the hydrolysis process on the r-βLg structure and the rheological properties of heat-induced gels obtained thereafter were studied at different pH values. Differences were observed between r-βLg and commercial β-Lg used as control. Higher values for the fluorescence emission intensity and red shifts of the emission wavelength of r-βLg suggested changes in its tertiary structure and more solvent-exposed tryptophan residues. Circular dichroism spectra also supported these evidences indicating that hydrolysis yielded an intermediate (non-native) β-Lg state. The thermal history of r-βLg through the new adopted conformation improved the microstructure of the gels at acidic pH. So, a new microstructure with better rheological characteristics (higher conformational flexibility and lower rigidity) and greater water holding ability was founded for r-βLg gel. These results were reflected in the microstructural analysis by scanning electron microscopy.
authors.affiliation: Analytical and Food Chemistry Department, Faculty of Sciences, University of Vigo, As Lagoas, 32004 Ourense, Spain. Electronic address: nataliatelle@uvigo.es.
authors.forename: Natalia
authors.initials: N
authors.lastname: Estévez
authors.affiliation: International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715 Braga, Portugal.
authors.forename: Pablo
authors.initials: P
authors.lastname: Fuciños
authors.affiliation: Applied Physics Department, Faculty of Sciences, University of Vigo, As Lagoas, 32004 Ourense, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Bargiela
authors.affiliation: Institute of Biotechnological and Chemical Processes (CONICET), Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, Suipacha 570, S2002RLK Rosario, Argentina.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Picó
authors.affiliation: Institute of Biotechnological and Chemical Processes (CONICET), Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, Suipacha 570, S2002RLK Rosario, Argentina.
authors.forename: Nadia Woitovich
authors.initials: NW
authors.lastname: Valetti
authors.affiliation: Applied Physics Department, Faculty of Sciences, University of Vigo, As Lagoas, 32004 Ourense, Spain.
authors.forename: Clara Asunción
authors.initials: CA
authors.lastname: Tovar
authors.affiliation: Analytical and Food Chemistry Department, Faculty of Sciences, University of Vigo, As Lagoas, 32004 Ourense, Spain.
authors.forename: M Luisa
authors.initials: ML
authors.lastname: Rúa
mesh_terms: D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D005453:Fluorescence; D005782:Gels / Q000737:chemistry; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007782:Lactoglobulins / Q000737:chemistry* / Q000302:isolation & purification* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D012212:Rheology; D014364:Tryptophan / Q000032:analysis; D000067796:Whey / Q000737:chemistry*; D000067816:Whey Proteins
chemical_list: D005782:Gels; D007782:Lactoglobulins; D000067816:Whey Proteins; D014364:Tryptophan
keywords: Conformational changes; Enzymatic hydrolysis; Gelation; Rheological properties; Whey protein; β-Lactoglobulin