Examine how heat affects sodium caseinate in dairy products.Sodium caseinate finds use as an ingredient in many dairy foods. When they are processed, many of these products are heated. Temperatures greater than 75 C induce an interaction between denatured de·na·ture tr.v. de·na·tured, de·na·tur·ing, de·na·tures 1. To change the nature or natural qualities of. 2. whey proteins and micellar k-casein by means of disulfide bonds. However, little information is available on the behavior of the sodium caseinate in milk-based systems during heating. Scientists at the University of Guelph The University of Guelph is a medium-sized university located in Guelph, Ontario, established in 1964. While the U of G offers degrees in many different disciplines, the university is best known for its focus on life sciences, based in part on a long-standing history of studied the behavior of sodium caseinate in heated skim milk that had been fortified with sodium caseinate. Their efforts provide insight into the behavior of sodium caseinate in prepared milk-based foods. They prepared and heated mixed samples of skim milk and sodium caseinate for different time-temperature combinations. Ultracentrifugation ultracentrifugation /ul·tra·cen·trif·u·ga·tion/ (ul?trah-sen-trif?u-ga´shun) subjection of material to an exceedingly high centrifugal force, which will separate and sediment the molecules of a substance. was employed to separate the solutions into serum and pellet fractions. Protein aggregates from the fractions were separated using size exclusion high-performance liquid chromatography (HPLC HPLC high-performance liquid chromatography. HPLC high performance liquid chromatography. HPLC High-performance liquid chromatography Lab instrumentation A highly sensitive analytic method in which analytes are placed ). They were further characterized using reversed phase HPLC. Analysis of the unheated serum fractions showed the presence of two protein peaks. One peak, which increased in size with increasing sodium caseinate concentrations, contained all four casein casein (kā`sēn), well-defined group of proteins found in milk, constituting about 80% of the proteins in cow's milk, but only 40% in human milk. proteins. The other contained the major whey proteins. Heating caused a considerable decrease in the whey protein peak. This was accompanied by the appearance of a third peak of a complex of whey proteins and k-casein, which increased with temperature and sodium caseinate concentrations. This behavior pattern appeared to reach completion after the peaks were heated at 85 C for 20 min. Conversely, the casein peak changed more significantly at higher temperatures--above 85 C--especially at elevated sodium caseinate concentrations. Investigators saw only small changes in the pellet samples from the different milks. These results suggest that most of the proteins in the added sodium caseinate do not participate in normal heat-induced interactions in milk. However, at elevated temperatures the caseins from the caseinate undergo a separate reaction that causes their precipitation. Further information. Douglas Dalgleish, Department of Food Science, University of Guelph, Ontario Agricultural College The Ontario Agricultural College (OAC) began in 1874 as an associate agricultural college of the University of Toronto. Its first building was Moreton Lodge, located where Johnston Hall now stands, which included classrooms, residences, a library, and a dining room. , Guelph, N1G 2W1 Ontario, Canada; phone: 519-824-4120; fax: 519-824-6631; URL URL in full Uniform Resource Locator Address of a resource on the Internet. The resource can be any type of file stored on a server, such as a Web page, a text file, a graphics file, or an application program. : http://www.uoguelph.ca/OAC/foodsci. |
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