The activity of antioxidants compounds in emulsified systems has been intensely studied over the past years; some phenolic molecules, because of their chemical structure, were proven to possess surface activity and thus, besides their antioxidant protective properties, it is also expected that they can affect both the dispersion degree and the physical and chemical stability of the dispersed phase. The aim of this work was to evaluate the effect of some olive oil phenolic antioxidants, tyrosol, hydroxytyrosol and oleuropein on the colloidal properties and oxidative stability of olive oil-in water emulsions stabilized with β-lactoglobulin (BLG). Emulsions were also modulated for their viscosity and water activity by adding, respectively, maltodextrins (MD 7.5-9.9) and NaCl. Emulsions were characterized for their droplet size distribution, microstructure, interfacial protein coverage, physical stability (flocculation and creaming behavior). The oxidative stability was monitored by means of HPSEC of polar compounds and RP-HPLC-DAD analysis of the different oxidized triglyceride species. At the olive oil/water interface, the phenolic compounds did not have significant effects on the ability of BLG to stabilize the interface itself, neither in binary BLG-polyphenol solutions, nor in ternary systems when sodium chloride and maltodextrins were added, individually, to modulate both water activity and viscosity. The addition of the phenolic compounds in emulsions did not affect the colloidal properties, as well as the physical stability. From an antioxidant viewpoint, oleuropein, tyrosol and hydroxytyrosol were proven to slow down the formation of secondary oxidation products, thus improving the chemical stability. The presence of NaCl and maltodextrin showed a significant destabilizing effect on emulsions both on the physical and chemical stability. This research project was funded within the national research project FIRB 2010 - "Futuro in Ricerca" (MIUR, Ministero dell'Istruzione, dell'Università e della Ricerca) aimed at applying a multifunctional and multifactorial approach to study the physical, chemical and sensory properties and stability of olive oil-in-water emulsions
Effect of olive oil phenolic compounds on the properties and stability of olive oil o/w emulsions.
DI MATTIA, CARLA DANIELA;ANDRICH, LUCIA;PITTIA, Paola
2013-01-01
Abstract
The activity of antioxidants compounds in emulsified systems has been intensely studied over the past years; some phenolic molecules, because of their chemical structure, were proven to possess surface activity and thus, besides their antioxidant protective properties, it is also expected that they can affect both the dispersion degree and the physical and chemical stability of the dispersed phase. The aim of this work was to evaluate the effect of some olive oil phenolic antioxidants, tyrosol, hydroxytyrosol and oleuropein on the colloidal properties and oxidative stability of olive oil-in water emulsions stabilized with β-lactoglobulin (BLG). Emulsions were also modulated for their viscosity and water activity by adding, respectively, maltodextrins (MD 7.5-9.9) and NaCl. Emulsions were characterized for their droplet size distribution, microstructure, interfacial protein coverage, physical stability (flocculation and creaming behavior). The oxidative stability was monitored by means of HPSEC of polar compounds and RP-HPLC-DAD analysis of the different oxidized triglyceride species. At the olive oil/water interface, the phenolic compounds did not have significant effects on the ability of BLG to stabilize the interface itself, neither in binary BLG-polyphenol solutions, nor in ternary systems when sodium chloride and maltodextrins were added, individually, to modulate both water activity and viscosity. The addition of the phenolic compounds in emulsions did not affect the colloidal properties, as well as the physical stability. From an antioxidant viewpoint, oleuropein, tyrosol and hydroxytyrosol were proven to slow down the formation of secondary oxidation products, thus improving the chemical stability. The presence of NaCl and maltodextrin showed a significant destabilizing effect on emulsions both on the physical and chemical stability. This research project was funded within the national research project FIRB 2010 - "Futuro in Ricerca" (MIUR, Ministero dell'Istruzione, dell'Università e della Ricerca) aimed at applying a multifunctional and multifactorial approach to study the physical, chemical and sensory properties and stability of olive oil-in-water emulsionsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
