Effect of pH on the reaction mechanism of thermal denaturation and aggregation of bovine β-lactoglobulin

Leeb, Elena; Haller, Nicole; Kulozik, Ulrich

doi:10.1016/j.idairyj.2017.09.006

Cited by 32 publications

(7 citation statements)

References 31 publications

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“…For other protein systems, like whey and egg proteins, alkaline pH levels led to increased reactivity of thiol groups and subsequently to more disulfide bond formation [ 2 , 35 , 36 ]. The main difference between these protein systems and the patatin system is that patatin lacks internal disulfide bonds.…”

Section: Resultsmentioning

confidence: 99%

Influence of pH, Temperature and Protease Inhibitors on Kinetics and Mechanism of Thermally Induced Aggregation of Potato Proteins

Andlinger

Röscheisen

Hengst

et al. 2021

Foods

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Understanding aggregation in food protein systems is essential to control processes ranging from the stabilization of colloidal dispersions to the formation of macroscopic gels. Patatin rich potato protein isolates (PPI) have promising techno-functionality as alternatives to established proteins from egg white or milk. In this work, the influence of pH and temperature on the kinetics of PPI denaturation and aggregation was investigated as an option for targeted functionalization. At a slightly acidic pH, rates of denaturation and aggregation of the globular patatin in PPI were fast. These aggregates were shown to possess a low amount of disulfide bonds and a high amount of exposed hydrophobic amino acids (S0). Gradually increasing the pH slowed down the rate of denaturation and aggregation and alkaline pH levels led to an increased formation of disulfide bonds within these aggregates, whereas S0 was reduced. Aggregation below denaturation temperature (Td) favored aggregation driven by disulfide bridge formation. Aggregation above Td led to fast unfolding, and initial aggregation was less determined by disulfide bridge formation. Inter-molecular disulfide formation occurred during extended heating times. Blocking different protein interactions revealed that the formation of disulfide bond linked aggregation is preceded by the formation of non-covalent bonds. Overall, the results help to control the kinetics, morphology, and interactions of potato protein aggregation for potential applications in food systems.

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Section: Resultsmentioning

confidence: 99%

Influence of pH, Temperature and Protease Inhibitors on Kinetics and Mechanism of Thermally Induced Aggregation of Potato Proteins

Andlinger

Röscheisen

Hengst

et al. 2021

Foods

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“…Besides the particle size, the reaction rate constant k for particle formation also depends on the pH value. As a result, the concentration of the remaining native protein after heat treatment varies [ 34 , 35 ]. Heat treatment of the different β-Lg solutions therefore did not always result in a full denaturation, as can be seen from the values of the degree of denaturation ( DD ), which varied from 69 to >96% ( Table 1 ).…”

Section: Resultsmentioning

confidence: 99%

“…It has to be noted that although particles exhibited a similar degree of cross-linking ( Table 2 ), they might have differed in their disulfide bond distribution. Due to the influence of the pH value and the heating conditions (temperature and time) on the reactivity of the free thiol group and, thus, the formation of disulfide cross-links [ 35 ], inhomogeneous distributions of disulfide bonds within the particle can occur. This aspect in turn can affect the rearrangement of the particles after adsorption at the interface [ 39 , 40 ].…”

Section: Resultsmentioning

confidence: 99%

Correlation between Physico-Chemical Characteristics of Particulated β-Lactoglobulin and Its Behavior at Air/Water and Oil/Water Interfaces

Kurz

Reitberger

Hengst

et al. 2021

Foods

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It is widely accepted that protein-based particles can efficiently stabilize foams and emulsions. However, it is not fully elucidated which particle properties are decisive for the stabilization of air/water and oil/water interfaces. To unravel this correlation, selected properties of nano-sized soluble β-lactoglobulin particles were changed one at a time. Therefore, particles of (1) variable size but similar zeta potential and degree of cross-linking and (2) similar size but different further properties were produced by heat treatment under a specific combination of pH value and NaCl concentration and then analyzed for their interfacial behavior as well as foaming and emulsifying properties. On the one hand, it was found that the initial phase of protein adsorption at both the air/water and the oil/water interface was mainly influenced by the zeta potential, independent of the particle size. On the other hand, foam stability as resolved from the time-dependent evolution of mean bubble area negatively correlated with disulfide cross-linking, whereas emulsion stability in terms of oil droplet flocculation showed a positive correlation with disulfide cross-linking. In addition, flocculation was more pronounced for larger particles. Concluding from this, foam and emulsion stability are not linked to the same particle properties and, thus, explanatory approaches cannot be used interchangeably.

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“…This may be explained by the lower protein stability due to the higher intramolecular repulsion of the deprotonated groups in the protein. On the other hand, the reactivity of the free thiol groups is expected to increase with increasing pH (Leeb et al, 2018). Higher reactivity of the thiol groups might enhance intermolecular thiol-disulfide exchange reactions and a subsequent irreversible denaturation of the protein (Hoffmann and Van Mil, 1999).…”

Section: Analysis Of the Thermal Stability Of Goat Milk Protein As Affected By Ph And Heatmentioning

confidence: 99%

Change in the structural and functional properties of goat milk protein due to pH and heat

Cheng

et al. 2020

Journal of Dairy Science

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This study was carried out to investigate the effects of pH and heat on the structure and function of milk proteins by comparing goat milk treated under different pH and temperature conditions. The results showed that pH had a significant effect on the thermal stability of goat milk proteins, and the proteins were least thermally stable at pH 7.7. Except for the pH 6.9 goat milk, the surface hydrophobicities of the milk proteins at various pH values reached their maxima at 85°C. The particle size, zeta potential, and content of regular secondary structure also decreased significantly at 85°C, and the turbidity of milk proteins under alkaline pH conditions was lower than that under acidic conditions. It was concluded that alkaline conditions resulted in better emulsion stability and oil-holding capacity, and acidic conditions offered better foaming ability, foam stability, and water-holding capacity for goat milk protein during heat processing. It can also be seen that 85°C was the key temperature for milk proteins after changing the pH of the milk. This paper provides a theoretical basis for optimizing the processing conditions for goat milk and the applications of goat milk proteins.

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Effect of pH on the reaction mechanism of thermal denaturation and aggregation of bovine β-lactoglobulin

Cited by 32 publications

References 31 publications

Influence of pH, Temperature and Protease Inhibitors on Kinetics and Mechanism of Thermally Induced Aggregation of Potato Proteins

Influence of pH, Temperature and Protease Inhibitors on Kinetics and Mechanism of Thermally Induced Aggregation of Potato Proteins

Correlation between Physico-Chemical Characteristics of Particulated β-Lactoglobulin and Its Behavior at Air/Water and Oil/Water Interfaces

Change in the structural and functional properties of goat milk protein due to pH and heat

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