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SDS-PAGE Analysis of Soluble Proteins in Reconstituted Milk Exposed to Different Heat Treatments

View Article: PubMed Central

ABSTRACT

This paper deals with the investigation of the impact of the heat treatment of reconstituted skim milk conducted at different temperatures, and the adding of demineralized whey on the protein solubility, soluble protein composition and interactions involved between proteins in a chemical complex. Commercial skim milk has been reconstituted and heat treated at 75°C, 85°C and 90°C for 20 minutes. Demineralized whey has been added in concentrations of 0.5%, 1.0 and 2.0%. The soluble protein composition has been determined by the polyacrilamide gel electrophoresis (SDS-PAGE) and by the densitometric analysis. Due to the different changes occurred during treatments at different temperatures, proteins of heat-treated samples containing added demineralized whey have had significantly different solubility. At lower temperatures (75°C and 85°C) the adding of demineralized whey decreased the protein solubility by 5.28%-26.41%, while the addition of demineralized whey performed at 90°C increased the soluble protein content by 5.61%-28.89%. Heat treatments, as well as the addition of demineralized whey, have induced high molecular weight complex formation. β-Lg, α-La and κ-casein are involved in high molecular weight complexes. The disulfide interactions between denatured molecules of these proteins are mostly responsible for the formation of coaggregates. The level of their interactions and the soluble protein composition are determined by the degree of temperature.

No MeSH data available.


Related in: MedlinePlus

The electrophoretic* and comparative densitometric analysis of the reconstituted skim milk with demineralized whey added, treated at 85 °C for 20 minutes. a. The electrophoretic analysis of the reconstituted milk with 0.5% (1, 2), 1.0% (3, 4), and 2.0% (5, 6) of demineralized whey added; Na-caseinate (7) and molecular weight standards (8). b. The comparative densitometric analysis of the heat treated samples, treated without () and with () 0.5% of the demineralized whey c. Comparative densitometric analysis of the samples treated with 0%, 0.5%, 1% and 2.0% of the demineralized whey added.*1, 3, 5 samples without 2-mercaptoethanol, and 2, 4, 6 samples with 2-mercaptoethanol.
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f6-sensors-07-00371: The electrophoretic* and comparative densitometric analysis of the reconstituted skim milk with demineralized whey added, treated at 85 °C for 20 minutes. a. The electrophoretic analysis of the reconstituted milk with 0.5% (1, 2), 1.0% (3, 4), and 2.0% (5, 6) of demineralized whey added; Na-caseinate (7) and molecular weight standards (8). b. The comparative densitometric analysis of the heat treated samples, treated without () and with () 0.5% of the demineralized whey c. Comparative densitometric analysis of the samples treated with 0%, 0.5%, 1% and 2.0% of the demineralized whey added.*1, 3, 5 samples without 2-mercaptoethanol, and 2, 4, 6 samples with 2-mercaptoethanol.

Mentions: The addition of demineralized whey to the reconstituted skim milk had different effects on the soluble protein composition, as shown in Figures 5, 6 and 7. At lower temperature (75°C), the addition of DW in concentration of 0.5% has caused the increase of the soluble aggregates content as well as the increase of the individual whey protein content (Fig. 5b). Further increase of DW content (1.0%-2.0%) has promoted the interaction between proteins and the formation of the insoluble co-aggregates.


SDS-PAGE Analysis of Soluble Proteins in Reconstituted Milk Exposed to Different Heat Treatments
The electrophoretic* and comparative densitometric analysis of the reconstituted skim milk with demineralized whey added, treated at 85 °C for 20 minutes. a. The electrophoretic analysis of the reconstituted milk with 0.5% (1, 2), 1.0% (3, 4), and 2.0% (5, 6) of demineralized whey added; Na-caseinate (7) and molecular weight standards (8). b. The comparative densitometric analysis of the heat treated samples, treated without () and with () 0.5% of the demineralized whey c. Comparative densitometric analysis of the samples treated with 0%, 0.5%, 1% and 2.0% of the demineralized whey added.*1, 3, 5 samples without 2-mercaptoethanol, and 2, 4, 6 samples with 2-mercaptoethanol.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3756726&req=5

f6-sensors-07-00371: The electrophoretic* and comparative densitometric analysis of the reconstituted skim milk with demineralized whey added, treated at 85 °C for 20 minutes. a. The electrophoretic analysis of the reconstituted milk with 0.5% (1, 2), 1.0% (3, 4), and 2.0% (5, 6) of demineralized whey added; Na-caseinate (7) and molecular weight standards (8). b. The comparative densitometric analysis of the heat treated samples, treated without () and with () 0.5% of the demineralized whey c. Comparative densitometric analysis of the samples treated with 0%, 0.5%, 1% and 2.0% of the demineralized whey added.*1, 3, 5 samples without 2-mercaptoethanol, and 2, 4, 6 samples with 2-mercaptoethanol.
Mentions: The addition of demineralized whey to the reconstituted skim milk had different effects on the soluble protein composition, as shown in Figures 5, 6 and 7. At lower temperature (75°C), the addition of DW in concentration of 0.5% has caused the increase of the soluble aggregates content as well as the increase of the individual whey protein content (Fig. 5b). Further increase of DW content (1.0%-2.0%) has promoted the interaction between proteins and the formation of the insoluble co-aggregates.

View Article: PubMed Central

ABSTRACT

This paper deals with the investigation of the impact of the heat treatment of reconstituted skim milk conducted at different temperatures, and the adding of demineralized whey on the protein solubility, soluble protein composition and interactions involved between proteins in a chemical complex. Commercial skim milk has been reconstituted and heat treated at 75°C, 85°C and 90°C for 20 minutes. Demineralized whey has been added in concentrations of 0.5%, 1.0 and 2.0%. The soluble protein composition has been determined by the polyacrilamide gel electrophoresis (SDS-PAGE) and by the densitometric analysis. Due to the different changes occurred during treatments at different temperatures, proteins of heat-treated samples containing added demineralized whey have had significantly different solubility. At lower temperatures (75°C and 85°C) the adding of demineralized whey decreased the protein solubility by 5.28%-26.41%, while the addition of demineralized whey performed at 90°C increased the soluble protein content by 5.61%-28.89%. Heat treatments, as well as the addition of demineralized whey, have induced high molecular weight complex formation. β-Lg, α-La and κ-casein are involved in high molecular weight complexes. The disulfide interactions between denatured molecules of these proteins are mostly responsible for the formation of coaggregates. The level of their interactions and the soluble protein composition are determined by the degree of temperature.

No MeSH data available.


Related in: MedlinePlus