PH influences the interfacial properties of blue whiting (M. poutassou) and whey protein hydrolysates determining the physical stability of fish oil-in-water emulsions. (January 2022)

• Record Type: Journal Article
• Authors: Ruiz-Álvarez, José María; del Castillo-Santaella, Teresa; Maldonado-Valderrama, Julia; Guadix, Antonio; Guadix, Emilia M.; García-Moreno, Pedro J.
• Is Part Of: Food hydrocolloids. Volume 122(2022)
• Publication Date: 2022-01
• Subjects: Fish oil-in-water emulsions -- Protein hydrolysates -- Emulsifier peptides -- Interfacial tension -- Interfacial dilatational rheology -- Physical stability; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2021.107075
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: This work investigates the influence of the interfacial properties of whey protein (WPH) and blue whiting protein (BPH) hydrolysates on the physical stability of fish oil-in-water emulsions stabilized with these hydrolysates at pH 2 or 8. Measurements of interfacial tension and dilatational rheology confirmed that pH is a key factor affecting these interfacial properties of WPH and BPH. WPH, when tested at 1 and 10 mg/mL, showed a higher interfacial activity at pH 8 when compared to pH 2 or to BPH at pH 8 or 2, despite having a lower protein content. Moreover, when tested at 0.1 and 1 mg/mL, the dilatational modulus of WPH was significantly higher at pH 8 than at pH 2. These findings correlate with the formation of smaller oil droplets and a more resistant interfacial peptide layer for WPH at pH 8, hence explaining the improved physical stability of the 5% fish oil-in-water emulsion stabilized with WPH at pH 8. BPH did not show significant differences in interfacial activity with pH but exhibited significantly higher dilatational elasticity and viscosity at pH 2 compared to pH 8 (when measured at 0.1 mg/mL and 0.01 or 0.1 Hz). This correlates with the formation of stable 5% fish oil-in-water emulsions with BPH at pH 2 but not at pH 8. Graphical abstract: Image 1 Highlights: Blue whiting (BPH) and whey protein (WPH) hydrolysates emulsified fish oil. WPH and BPH provided different physical stability to fish oil-in-water emulsions. pH influenced differently the interfacial properties of WPH and BPH. WPH showed higher interfacial adsorption and dilatational elasticity at pH 8. BPH showed higher interfacial dilatational elasticity and viscosity at pH 2.