Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2010
Publication Date: 3/16/2010
Citation: Mora-Gutierrez, A., Attaie, R., Farrell Jr, H.M. 2010. Lipid oxidation in algae oil-in-water emulsions stabilized by bovine and caprine caseins. Journal of Agricultural and Food Chemistry. 58:5131-5139. DOI: 10.1021/904343F. Interpretive Summary: Marketing studies in the US have shown a dramatic trend toward home replacement meals. Cheese sauces used in these prepared meals represent a challenge for food processors in terms of body and meltability. These and other new dairy products are becoming important sources of protein in the diet. However, dairy products are traditionally low in important poly unsaturated fatty acids (PUFA) which have many health benefits. These fatty acids when added directly to dairy products are subject to deterioration due to heat processing. One way to add them to cheese foods would be to coat them with a protective layer of protein. The major proteins of milk are called caseins, and based on three dimensional models developed at ERRC, they should be ideal at coating and stabilizing PUFA. This research showed that both bovine and caprine caseins could be successfully used to coat and stabilize PUFA droplets in a size and manner which would make them suitable for addition to dairy products. This makes use of one dairy product to help fortify other dairy products with PUFA in a stable environment that will not generate off flavors. This information will aid cheese manufactures who are attempting to streamline their processes and enhance nutritional quality of their products.
Technical Abstract: Caseins (alpha S1-, alpha S2-, and beta-casein) are phosphoproteins that are capable of binding transition metals and scavenging free radicals, these properties make them good candidates to be used as natural antioxidants in oil-in-water emulsions. Caprine casein exhibits variability in aS1-casein content generated by genetic polymorphism. This variability in composition could lead to altered anti-oxidant properties. Thus, the ability of two caprine caseins differing in aS1-casein content to inhibit lipid oxidation in algae oil-in-water emulsions at 5% oil were investigated and compared to bovine caseinate. All caseins inhibited the formation of lipid oxidation at pH 7.0 as determined by lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS). However, caprine caseins were in general more effective inhibitors of lipid oxidation than the bovine caseins which may be attributed to their altered casein amino acid content and/or metal binding capabilities. The combination of the carotenoids with bovine and caprine caseins was highly effective at repressing oxidation leading to the speculation that the caseins may inhibit the loss of the carotenoids and/or react with and enhance the carotenoid activity, again some differences between caprine and bovine caseins were observed with caprine caseins being slightly more effective in the presence of carotenoids.