Influence of thermomechanical treatment and pH on the denaturation kinetics of highly concentrated whey protein isolate

Quevedo, María Cristina Céspedes; Karbstein, Heike P.; Emin, M. Azad

doi:10.1016/j.jfoodeng.2020.110294

Cited by 12 publications

(5 citation statements)

References 34 publications

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“…Firstly, because depending on protein concentration, the effect of individual process parameters is expected to differ significantly. Moreover, as previously shown in [17,18] the reaction behavior changes with concentration, which might explain the increase in reaction order from 1.5 (concentration <20%) to 1.909-2.262 (concentration >50%). Since the reaction behaviors of βLG and αLA differed from the reaction behavior of mixed systems (WPI), it is expected that changes in the concentration and ratio of βLG and αLA lead to changes in the denaturation and aggregation behavior of complex systems such as WPI.…”

Section: Introductionsupporting

confidence: 59%

“…In contrast, at 70 %, the values of the complex modulus at different shear rates are significantly different, which indicates that the shear stress influences the molecular motion and, thus, the reaction rate significantly. It has been shown for whey proteins that an increase in protein concentration leads to a decrease in molecular mobility and, consequently, in higher values of activation energy, which result in higher onset temperatures [18,19]. By increasing the shear rate, the molecular motion increases, and the reactions activation energy decreases, which leads to lower onset temperatures [16,17].…”

Section: Influence Of Thermomechanical Treatment On the Reaction Behamentioning

confidence: 99%

“…Since the reactivity of the thiol groups decreases with decreasing pH, the high degree of non-covalent bond aggregation probably may arise from this occurrence. Accordingly, previous results showed that the variation of pH had a considerable effect on the denaturation reactions [18]. Regarding the aggregation behavior and the influence of pH on the formation of protein-protein interactions, it is known that for whey protein systems at concentrations below 10%, at pH <7 the thiol groups become less reactive and that non-covalent bonds are increasingly being formed leading to aggregates stabilized via non-covalent and disulfide bonds [31].…”

Section: Influence Of Thermomechanical Treatment On the Protein-protementioning

confidence: 99%

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Influence of Thermomechanical Treatment and Ratio of β-Lactoglobulin and α-Lactalbumin on the Denaturation and Aggregation of Highly Concentrated Whey Protein Systems

Quevedo

Kulozik

Karbstein

et al. 2020

Foods

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The influence of thermomechanical treatment (temperature 60 °C–100 °C and shear rate 0.06 s−1–50 s−1) and mixing ratio of β-lactoglobulin (βLG) and α-lactalbumin (αLA) (5:2 and 1:1) on the denaturation and aggregation of whey protein model systems with a protein concentration of 60% and 70% (w/w) was investigated. An aggregation onset temperature was determined at approx. 80 °C for both systems (5:2 and 1:1 mixing ratio) with a protein concentration of 70% at a shear rate of 0.06 s−1. Increasing the shear rate up to 50 s−1 led to a decrease in the aggregation onset temperature independent of the mixing ratio. By decreasing the protein concentration to 60% in unsheared systems, the aggregation onset temperature decreased compared to that at a protein concentration of 70%. Furthermore, two significantly different onset temperatures were determined when the shear rate was increased to 25 s−1 and 50 s−1, which might result from a shear-induced phase separation. Application of combined thermal and mechanical treatment resulted in overall higher degrees of denaturation independent of the mixing ratio and protein concentration. At the conditions applied, the aggregation of the βLG and αLA mixtures was mainly due to the formation of non-covalent bonds. Although the proportion of disulfide bond aggregation increased with treatment temperature and shear rate, it was higher at a mixing ratio of 5:2 compared to that at 1:1.

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Section: Introductionsupporting

confidence: 59%

Section: Influence Of Thermomechanical Treatment On the Reaction Behamentioning

confidence: 99%

Section: Influence Of Thermomechanical Treatment On the Protein-protementioning

confidence: 99%

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Influence of Thermomechanical Treatment and Ratio of β-Lactoglobulin and α-Lactalbumin on the Denaturation and Aggregation of Highly Concentrated Whey Protein Systems

Quevedo

Kulozik

Karbstein

et al. 2020

Foods

Self Cite

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show abstract

“…In aqueous media, proteins undergo many physicochemical changes such as conformational alterations, denaturation, folding/unfolding processes, and ligand exchange [1][2][3][4][5][6]. These phenomena can be invoked by variations in the temperature and/or the pH of a solution.…”

Section: Introductionmentioning

confidence: 99%

Effect of Tetraphenylborate on Physicochemical Properties of Bovine Serum Albumin

et al. 2021

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The binding interactions of bovine serum albumin (BSA) with tetraphenylborate ions ([B(Ph)4]−) have been investigated by a set of experimental methods (isothermal titration calorimetry, steady-state fluorescence spectroscopy, differential scanning calorimetry and circular dichroism spectroscopy) and molecular dynamics-based computational approaches. Two sets of structurally distinctive binding sites in BSA were found under the experimental conditions (10 mM cacodylate buffer, pH 7, 298.15 K). The obtained results, supported by the competitive interactions experiments of SDS with [B(Ph)4]− for BSA, enabled us to find the potential binding sites in BSA. The first site is located in the subdomain I A of the protein and binds two [B(Ph)4]− ions (logK(ITC)1 = 7.09 ± 0.10; ΔG(ITC)1 = −9.67 ± 0.14 kcal mol−1; ΔH(ITC)1 = −3.14 ± 0.12 kcal mol−1; TΔS(ITC)1 = −6.53 kcal mol−1), whereas the second site is localized in the subdomain III A and binds five ions (logK(ITC)2 = 5.39 ± 0.06; ΔG(ITC)2 = −7.35 ± 0.09 kcal mol−1; ΔH(ITC)2 = 4.00 ± 0.14 kcal mol−1; TΔS(ITC)2 = 11.3 kcal mol−1). The formation of the {[B(Ph)4]−}–BSA complex results in an increase in the thermal stability of the alfa-helical content, correlating with the saturation of the particular BSA binding sites, thus hindering its thermal unfolding.

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“…It is worthwhile to mention that pH also plays a role in whey protein denaturation and gelation by governing protein structures unfolding, as previously reported [52,53]. This could therefore apply to the residual non-denatured and non-gelled protein fraction of the films, ultimately affecting their ability to swell.…”

Section: Swelling Testsmentioning

confidence: 74%

Whey Proteins–Zinc Oxide Bionanocomposite as Antibacterial Films

et al. 2021

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The use of toxic crosslinking agents and reagents in the fabrication of hydrogels is a frequent issue which is particularly concerning for biomedical or food packaging applications. In this study, novel antibacterial bionanocomposite films were obtained through a simple solvent casting technique without using any crosslinking substance. Films were made from a flexible and transparent whey protein matrix containing zinc oxide nanoparticles synthesised via a wet chemical precipitation route. The physicochemical and functional properties of the ZnO nanoparticles and of the composite films were characterised, and their antibacterial activity was tested against S. epidermidis and E. coli. The synthesised ZnO nanoparticles had an average size of about 30 nm and a specific surface area of 49.5 m2/g. The swelling ratio of the bionanocomposite films increased at basic pH, which is an appealing feature in relation to the absorption of chronic wound exudate. A n-ZnO concentration-dependent antibacterial effect was observed for composite films. In particular, marked antibacterial activity was observed against S. epidermidis. Overall, these findings suggest that this novel material can be a promising and sustainable alternative in the design of advanced solutions for wound dressing or food packaging.

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Influence of thermomechanical treatment and pH on the denaturation kinetics of highly concentrated whey protein isolate

Cited by 12 publications

References 34 publications

Influence of Thermomechanical Treatment and Ratio of β-Lactoglobulin and α-Lactalbumin on the Denaturation and Aggregation of Highly Concentrated Whey Protein Systems

Influence of Thermomechanical Treatment and Ratio of β-Lactoglobulin and α-Lactalbumin on the Denaturation and Aggregation of Highly Concentrated Whey Protein Systems

Effect of Tetraphenylborate on Physicochemical Properties of Bovine Serum Albumin

Whey Proteins–Zinc Oxide Bionanocomposite as Antibacterial Films

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