Ovalbumin thermal Gelation Prediction by Application of Temperature‐Time History

Harte, J.B.; Zabik, Mary E.; Ofoli, Robert Y.; Morgan, Ronnie G.

doi:10.1111/j.1365-2621.1992.tb11271.x

Cited by 3 publications

(3 citation statements)

References 34 publications

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“…Activation energies for protein gelation are not frequently found in the literature. Katsuta and Kinsella (1990) and Harte et al (1992) found for the thermal gelation of serum proteins and ovalbumin values (67-105 and 159 kJ/ mol‚K, respectively) that were much lower than that we have calculated for sunflower protein hydrolysates. Activation energies estimated for the gelation of polysaccharides are even lower (in the range 20-100 kJ/mol‚K; Isozaki et al, 1976;Kawabata and Sawayama, 1976;Mitchell and Blanschard, 1976;Watase and Nishinari, 1981).…”

Section: Resultscontrasting

confidence: 82%

Gelation of Sunflower Globulin Hydrolysates: Rheological and Calorimetric Studies

Sánchez

Burgos

1997

J. Agric. Food Chem.

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Trypsin hydrolysates of sunflower globulins gel when heated. Gelation time and gel strength are exponentially related to concentration. Critical concentration is <1%. Sunflower globulins and their tryptic hydrolysis products have a high thermal stability, compared to most plant proteins, that is slightly affected by pH in the range 6−11. Activation energies for heat denaturation are estimated as 443 ± 9 and 423 ± 22 kJ/mol·K for the globulins and their hydrolysates, respectively. The temperature dependence of the gelation rate follows the Arrhenius law. The activation energy of gelation has been estimated as 315 ± 17 kJ/mol·K. Gelation can take place at about 20 °C below T d, but isothermal gelation experiments (at 5% hydrolysate concentration) reveal that at gelation times a fraction in the range of 15−30% of the total hydrolysate has already been denatured. This fraction becomes greater with decreasing hydrolysate concentration. Keywords: Sunflower globulins; gelation; temperature dependence

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Section: Resultscontrasting

confidence: 82%

Gelation of Sunflower Globulin Hydrolysates: Rheological and Calorimetric Studies

Sánchez

Burgos

1997

J. Agric. Food Chem.

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“…WHC was measured according to the method of Harte et al (1992) with some modifications. Egg white solutions were heated in a water bath Model 9510 (Fisher Scientific, Pittsburg, PA) at 80ЊC for 40 min in 50 mL polycarbonate centrifuge tubes (Nalge Co., Rochester, NY).…”

Section: Determination Of Water-holding Capacity (Whc)mentioning

confidence: 99%

Heat‐induced Egg White Gels as Affected by pH

Handa¹,

Takahashi²,

Kuroda³

et al. 1998

Journal of Food Science

113

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The functional properties of heat-induced egg white gels were investigated at five pH values. Textural characteristics were determined using the Instron Universal Machine. Hardness, elasticity, cohesiveness, chewiness, and fracturability were maximum at pH 11. Hunter L values were maximum at pH 5 and 7. Microstructure studied with electron microscopy was distinctly different at the five pH values. Alkaline gels showed a fine ordered network that might have contributed to excellent textural characteristics. Water-holding capacity (WHC) was high at alkaline pH, but decreased with addition of 2-mercaptoethanol, suggesting that disulfide bonds were important in egg white gels. Sodium dodecyl sulfate (SDS) improved WHC at pH 7 and 9. No significant correlation was observed between textural profiles and WHC.

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“…For most functional applications, denaturation and aggregation is required. Ovalbumin is the major protein in egg albumin, and much work has been conducted on its thermal aggregation and gelation (Clark et al 1981; Doi and Kitabatake 1989; Arntfield et al 1990a,b; Harte et al 1992; Kitabatake and Kinekawa 1995; Van der Linden and Sagis 2001; Weijers et al 2002a). It was found by Smith and Back (Smith and Back 1962) that ovalbumin behaves as a mixture of two proteins, where the amount of S‐ovalbumin depends on the storage time and pH of the eggs.…”

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confidence: 99%

Heat‐induced denaturation and aggregation of ovalbumin at neutral pH described by irreversible first‐order kinetics

et al. 2003

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The heat-induced denaturation kinetics of two different sources of ovalbumin at pH 7 was studied by chromatography and differential scanning calorimetry. The kinetics was found to be independent of protein concentration and salt concentration, but was strongly dependent on temperature. For highly pure ovalbumin, the decrease in nondenatured native protein showed first-order dependence. The activation energy obtained with different techniques varied between 430 and 490 kJ·mole −1 . First-order behavior was studied in detail using differential scanning calorimetry. The calorimetric traces were irreversible and highly scan rate-dependent. The shape of the thermograms as well as the scan rate dependence can be explained by assuming that the thermal denaturation takes place according to a simplified kinetic process N → k D where N is the native state, D is denatured (or another final state) and k a first-order kinetic constant that changes with temperature, according to the Arrhenius equation. A kinetic model for the temperature-induced denaturation and aggregation of ovalbumin is presented. Commercially obtained ovalbumin was found to contain an intermediate-stable fraction (IS) of about 20% that was unable to form aggregates. The denaturation of this fraction did not satisfy first-order kinetics.Keywords: Irreversible transitions; scan-rate dependence; scanning calorimetry; chromatography; protein denaturation; aggregation; globular proteins; ovalbumin Aggregation of proteins is an important process in many biological systems and industrial processes. In biological systems it is required for the assembly of structures with specific functions such as microtubules, blood clots, and viral coatings. The formation of plaques is also related to aggregation of specific proteins that have somehow been modified. The aggregation of proteins is, in general, triggered by a conformational change of the protein induced by heat, enzymatic cleavage, or other processes that affect the folded structure. After this change of structure a series of reactions takes place that lead to the formation of aggregates. In many cases it is not clear what drives the formation of specific structures in these aggregates or the formation of fibrils (Thirumalai et al. 2003). Here we present a study of the heat-induced aggregation of chicken egg white ovalbumin. Ovalbumin is known to form fibrillar types of aggregates upon aggregation and, at high enough protein concentrations, a gel can be formed (Weijers et al. 2002b). It is our aim to use ovalbumin as a model system to study how fibrillar aggregates can be formed and what conditions affect the properties of these aggregates. The results are relevant both to understanding the biological function of proReprint requests to: Mireille Weijers,

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Ovalbumin thermal Gelation Prediction by Application of Temperature‐Time History

Cited by 3 publications

References 34 publications

Gelation of Sunflower Globulin Hydrolysates: Rheological and Calorimetric Studies

Gelation of Sunflower Globulin Hydrolysates: Rheological and Calorimetric Studies

Heat‐induced Egg White Gels as Affected by pH

Heat‐induced denaturation and aggregation of ovalbumin at neutral pH described by irreversible first‐order kinetics

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