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Sensors 2007, 7(3), 371-383; doi:10.3390/s7030371
Article

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

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Received: 26 February 2007; Accepted: 15 March 2006 / Published: 23 March 2007
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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.
Keywords: casein; whey proteins; heat treatment; disulfide interaction. casein; whey proteins; heat treatment; disulfide interaction.
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Jovanovic, S.; Barac, M.; Macej, O.; Vucic, T.; Lacnjevac, C. SDS-PAGE Analysis of Soluble Proteins in Reconstituted Milk Exposed to Different Heat Treatments. Sensors 2007, 7, 371-383.

AMA Style

Jovanovic S, Barac M, Macej O, Vucic T, Lacnjevac C. SDS-PAGE Analysis of Soluble Proteins in Reconstituted Milk Exposed to Different Heat Treatments. Sensors. 2007; 7(3):371-383.

Chicago/Turabian Style

Jovanovic, Snezana; Barac, Miroljub; Macej, Ognjen; Vucic, Tanja; Lacnjevac, Caslav. 2007. "SDS-PAGE Analysis of Soluble Proteins in Reconstituted Milk Exposed to Different Heat Treatments." Sensors 7, no. 3: 371-383.


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