scholarly journals Denaturation Behavior and Kinetics of Single- and Multi-Component Protein Systems at Extrusion-Like Conditions

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2145
Author(s):  
Maria Quevedo ◽  
Heike P. Karbstein ◽  
M. Azad Emin
Keyword(s):  
Phase Separation ◽  
Shear Rate ◽  
Whey Protein ◽  
Reaction Order ◽  
Local Level ◽  
Reaction Rates ◽  
Model Systems ◽  
Protein Model ◽  
Kinetics Of ◽  
Component Protein

In this study, the influence of defined extrusion-like treatment conditions on the denaturation behavior and kinetics of single- and multi-component protein model systems at a protein concentration of 70% (w/w) was investigated. α-Lactalbumin (αLA) and β-Lactoglobulin (βLG), and whey protein isolate (WPI) were selected as single- and multi-component protein model systems, respectively. To apply defined extrusion-like conditions, treatment temperatures in the range of 60 and 100 °C, shear rates from 0.06 to 50 s⁻1, and treatment times up to 90 s were chosen. While an aggregation onset temperature was determined at approximately 73 °C for WPI systems at a shear rate of 0.06 s⁻1, two significantly different onset temperatures were determined when the shear rate was increased to 25 and 50 s⁻1. These two different onset temperatures could be related to the main fractions present in whey protein (βLG and αLA), suggesting shear-induced phase separation. Application of additional mechanical treatment resulted in an increase in reaction rates for all the investigated systems. Denaturation was found to follow 2.262 and 1.865 order kinetics for αLA and WPI, respectively. The reaction order of WPI might have resulted from a combination of a lower reaction order in the unsheared system (i.e., fractional first order) and higher reaction order for sheared systems, probably due to phase separation, leading to isolated behavior of each fraction at the local level (i.e., fractional second order).

Kinetics of Phase Separation of Oat β-Glucan/Whey Protein Isolate Binary Mixtures

2009 ◽  
Vol 4 (3) ◽  
pp. 240-247 ◽  
Author(s):  
Vassilis Kontogiorgos ◽  
Susan M. Tosh ◽  
Peter J. Wood
Keyword(s):  
Phase Separation ◽  
Whey Protein ◽  
Binary Mixtures ◽  
Whey Protein Isolate ◽  
Protein Isolate ◽  
Kinetics Of

Gelation by phase separation in a whey protein system: in-situ kinetics of aggregation

2000 ◽  
Vol 79 (3) ◽  
pp. 231-244 ◽  
Author(s):  
D. Renard ◽  
P. Robert ◽  
C. Garnier ◽  
E. Dufour ◽  
J. Lefebvre
Keyword(s):  
Phase Separation ◽  
Whey Protein ◽  
Protein System ◽  
Kinetics Of

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

Foods ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1196
Author(s):  
Maria Quevedo ◽  
Ulrich Kulozik ◽  
Heike P. Karbstein ◽  
M. Azad Emin
Keyword(s):  
Shear Rate ◽  
Whey Protein ◽  
Thermomechanical Treatment ◽  
Protein Concentration ◽  
Treatment Temperature ◽  
Onset Temperature ◽  
Model Systems ◽  
Mixing Ratio ◽  
Covalent Bonds ◽  
Β Lactoglobulin

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.

Kinetics of phase separation during pressure-induced gelation of a whey protein isolate

2009 ◽  
Vol 23 (7) ◽  
pp. 1729-1733 ◽  
Author(s):  
Jin-Song He ◽  
Kangcheng Ruan
Keyword(s):  
Phase Separation ◽  
Whey Protein ◽  
Whey Protein Isolate ◽  
Protein Isolate ◽  
Kinetics Of

Immobilization of Oat Bran Polyphenols in Complex Coacervates of Whey Protein and Malthodextrin

2020 ◽  
Vol 50 (3) ◽  
pp. 460-469
Author(s):  
Damir Zyaitdinov ◽  
Alexandr Ewteew ◽  
Anna Bannikova
Keyword(s):  
Antioxidant Activity ◽  
Enzymatic Hydrolysis ◽  
Whey Protein ◽  
Bioactive Compounds ◽  
Total Phenolic Content ◽  
Phenolic Content ◽  
Wall Material ◽  
Total Phenolic ◽  
Oat Bran ◽  
Kinetics Of

Introduction. Bioactive compounds are a very popular topic of modern food science, especially when it concerns obtaining polyphenols from cereals. The antiradical, antioxidant, and anti-inflammatory properties of these ingredients allow them to inhibit and prevent coronary, artery, and cardiovascular diseases, as well as several types of cancer. Encapsulation is an effective technology that protects bioactive ingredients during processing and storage. In addition, it also prevents any possible interaction with other food constituents. The research objective was to obtain effective tools of controlled delivery of bioactive compounds. The study featured whey protein as a wall material in combination with maltodextrin to encapsulate the bioactives from oat bran. Study objects and methods. The processed material was oat bran. The technology of its biotransformation was based on ultrasound processing and enzymatic hydrolysis. The antioxidant properties were determined using a coulometer of Expert – 006-antioxidants type (Econix-Expert LLC, Moscow, Russia). Separation and quantitative determination of extract were followed using a Stayer HPLC device (Akvilon, Russia) and a system column Phenomenex Luna 5u C18(2) (250×4.6 mm). The total phenolic content was measured by a modified Folin-Ciocalteu method. To prepare microcapsules, whey protein concentrate (WPC) and maltodextrin (MD) solutions were mixed at ratios 6:4, 4:6, and 5:5. After that, the mixes were treated by ultrasonication and 10% w/w of guar gum solution as double wall material. The encapsulation efficiency (EE) was determined as a ratio of encapsulated phenolic content to total phenolic content. A digestion protocol that simulates conditions of the human gastric and intestinal tract was adapted to investigate the release kinetics of the extracts. Results and discussion. Ferulic acid is the main antioxidant in cereals. Its amount during extraction was consistent with published data: 9.2 mg/mL after ultrasound exposure, 9.0 mg/mL after enzymatic extraction, and 8.6 mg/mL after chemical treatment. The antioxidant activity of the obtained polyphenols was quite high and reached 921 cu/mL. It depended on the concentration of the preparation in the solution and the extraction method. The polyphenols obtained by ultrasonic exposure and enzyme preparations proved to have a more pronounced antioxidant activity. The highest EE (95.28%) was recorded at WPC:MD ratio of 60:40. In vitro enzymatic hydrolysis protocol simulating digestion in the gastrointestinal tract was used to study the effect of capsule structural characteristics on the kinetics of polyphenol release. The percentage of o polyphenols released from capsules ranged from 70% to 83% after two hours of digestion, which confirmed the effectiveness of microencapsulation technology. Conclusion. The research confirmed the possibility of using polyphenols obtained by the biotechnological method from oat bran as functional ingredients. Eventually, they may be used in new functional products with bifidogenic properties. Whey protein can be used to encapsulate polyphenols as the wall material of microcapsules.

The effect of electrondonors on the polymerization kinetics of isoprene

1980 ◽  
Vol 45 (12) ◽  
pp. 3338-3346
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Induction Period ◽  
Ethyl Ether ◽  
Reaction Order ◽  
Propagation Rate ◽  
Reaction Scheme ◽  
Polymerization Kinetics ◽  
Polymerization Rate ◽  
Constant Concentration ◽  
Initial Concentration ◽  
Kinetics Of

The effect of small additions of 1-octene, butyl ethyl ether and triethylamine on the polymerization kinetics of isoprene (2-methyl-1,3-butadiene) in benzene initiated with butyllithium was investigated by employing the GLC analysis. The addition of 1-octane was reflected only in a shorter induction period of the reaction; the effect on the propagation rate was insignificant. With the increasing amount of butyl ethyl ether, the polymerization rate increases linearly, while the reaction order with respect to the concentration of triethylamine is variable and increases from 0.33 to 0.66 with the increasing concentration of the initiator. For a constant concentration of triethylamine, the reaction order with respect to the initial concentration of the initiator was found to vary considerably, reaching even negative values. A reaction scheme was suggested, taking into account the competition between two different solvates of alkyllithium.

Kinetics of esterification of monoisopropylphenols with phosphoryl trichloride

1989 ◽  
Vol 54 (5) ◽  
pp. 1311-1317
Author(s):  
Miroslav Magura ◽  
Ján Vojtko ◽  
Ján Ilavský
Keyword(s):  
Liquid Phase ◽  
Rate Constants ◽  
Reaction Rates ◽  
Activation Energies ◽  
The Individual ◽  
Kinetics Of

The kinetics of liquid-phase isothermal esterification of POCl3 with 2-isopropylphenol and 4-isopropylphenol have been studied within the temperature intervals of 110 to 130 and 90 to 110 °C, respectively. The rate constants and activation energies of the individual steps of this three-step reaction have been calculated from the values measured. The reaction rates of the two isomers markedly differ: at 110 °C 4-isopropylphenol reacts faster by the factors of about 7 and 20 for k1 and k3, respectively. This finding can be utilized in preparation of mixed triaryl phosphates, since the alkylation mixture after reaction of phenol with propene contains an excess of 2-isopropylphenol over 4-isopropylphenol.

scholarly journals Kinetics of phase separation in thermally isolated critical binary fluids

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
James P. Donley
Keyword(s):  
Phase Separation ◽  
Binary Fluids ◽  
Kinetics Of

Gas-Phase Anionic Metal Clusters are Model Systems for Surface Oxidation: Kinetics of the Reactions of Mn– with O2 (M = V, Cr, Co, Ni; n = 1–15)

2021 ◽  
Vol 125 (10) ◽  
pp. 2069-2076
Author(s):  
Brendan C. Sweeny ◽  
David C. McDonald ◽  
Nicholas S. Shuman ◽  
Albert A. Viggiano ◽  
Juergen Troe ◽  
...  
Keyword(s):  
Gas Phase ◽  
Oxidation Kinetics ◽  
Metal Clusters ◽  
Surface Oxidation ◽  
Model Systems ◽  
Kinetics Of

Kinetics of the α-α′ phase separation in a 14%Cr oxide dispersion steel at intermediate temperatures

2020 ◽  
pp. 129088
Author(s):  
Yael Templeman ◽  
Malki Pinkas ◽  
Eli Brosh ◽  
Einat Strumza ◽  
Shmuel Hayun ◽  
...  
Keyword(s):  
Phase Separation ◽  
Oxide Dispersion ◽  
Α Phase ◽  
Kinetics Of
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