Location: Dairy and Functional Foods
2013 Annual Report
2: Develop technologies to modify the level and stability of selected biological active compounds (BACs) in milk and cheese. 2.a: Determine effects of common milk processing procedures and storage conditions on the concentration and stability of the selected BACs in milk. 2.b: Determine the effects of cheese manufacturing techniques and aging on the concentration and stability of selected BACs in cheese and correlate to changes in quality traits. 2.c: Develop low-salt high-moisture model cheese to determine effects of low-salt environment on the concentration and stability of BACs during aging and correlate to changes in quality traits.
One phase of the project will characterize the naturally occurring BACs in milk and identify sources of milk with high levels of BACs; in particular, milk from multiple organic and conventional farms in mid and eastern Pennsylvania will be evaluated for BACs to determine quality and seasonal variations. Another phase will develop technologies to modify the levels and stability of selected BACs in milk and cheese. Milk will be obtained from organic and conventional farms and processed at the DFFRU milk processing pilot plant with portions being used to manufacture high-moisture cheese (Queso Blanco). The effects of common dairy industry milk processing procedures and storage conditions on the concentration and stability of selected BACs will be evaluated. In another phase of the project, low-sodium high-moisture cheese model will be created to evaluate the effect of the low-sodium environment on the stability of the BACs and the quality traits of the cheese.
Examination of proteins present in fresh milk from the two farms has confirmed that the overall identity and composition of milk proteins remained the same between samples, with little variation over time. Although the overall health-value of these two types of milk may be different, the variation is not due to overall protein content. Therefore, emphasis has shifted to identifying the peptides that are responsible for different biological activities and how processing may affect the release of these peptides.
Studies to evaluate the effect of milk processing on the BACs in milk have begun by comparing raw and heat treated (pasteurized or sterilized) whole and skim milk. Initial experiments are comparing concentrations of BACs in the milk following each treatment to identify process-sensitive BACS. A visiting scientist from China is evaluating the impact of milk processing on the digestibility of milk proteins and fats when exposed to conditions that mimic the human stomach and intestines.
Paul, M., Van Hekken, D.L., Brewster, J.D., Tomasula, P.M. 2012. Measuring the antioxidative activities of Queso Fresco after post-packaging high-pressure processing. Advances in Bioscience and Biotechnology. 3:297-303.
Gunther, N.W., Paul, M., Nunez, A., Liu, Y. 2012. pH fractionation and identification of proteins: comparing column isoelectric focusing vs liquid based focusing techniques. Journal of Separation Science. 35(12):1399-1406.
Paul, M., Van Hekken, D.L., Brewster, J.D. 2013. Detection and quantitation of Escherichia coli O157:H7 in raw milk by direct qPCR. International Dairy Journal. 32:53-60. Available: http://authors.elsevier.com/sd/article/S0958694613001192
Van Hekken, D.L., Park, Y.W., Tunick, M.H. 2013. Effects of reducing fat content on the proteolytic and rheological properties of Cheddar-like caprine milk cheese. Small Ruminant Research. 110(1):46-51.
Tunick, M.H., Van Hekken, D.L. 2012. The power law and dynamic rheology in cheese analysis. Book Chapter. Thth, S. and Mussinan, C(eds.) Recent Advances in Analysis of food and flavors, Washington, DC: ACS Books. pp 191-199.