17B-14 |
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X. LIU1, S. Clark1, J. R. Powers1, B. G. Swanson1, and H. H. Hill, Jr.2. (1) Dept. of Food Science & Human Nutrition, Washington State Univ., 106 FSHN Bldg., PO Box 646376, Pullman, WA 99164-6376, (2) Dept. of Chemistry, Washington State Univ., PO Box 644630, Pullman, WA 99164-4630 The objective of this study was to evaluate the influence of high hydrostatic pressure (HHP) treatments on conformation and hydrophobicity of whey protein concentrate (WPC80) solutions. An increase of binding affinity or decrease in apparent dissociation constant indicates improved hydrophobicity, which is positively correlated with functional properties. If functional properties can be enhanced with HHP, HHP treatment to WPC for food ingredient applications may be justified. The effects of HHP treatment (600MPa, 50oC, 0 to 30min) on intrinsic fluorescence of WPC80 solutions and on the binding of aromatic 1-anilino-naphthalene-8-sulfonate (ANS) and aliphatic cis-parinaric acid (CPA) probes were studied at neutral pH. HHP caused an increase in intrinsic fluorescence intensity and a 4 nm red-shift after 30min of treatment, which indicate movement of tryptophan residues of whey proteins from a less-polar to a more polar environment. Come-up time HHP treatment caused a decrease in binding sites for ANS from 40.7 to 22.6. Apparent dissociation constant of ANS increased from 1.2*10-6 M to 4.3*10-6 M during 30min HHP treatment. Thus, HHP caused decreases in binding sites and binding affinity of aromatic hydrophobic probe. HHP treatment did not cause significant changes in the binding sites for CPA, however improved binding affinities were found at come-up time and 10min HHP treatment, with a decrease of apparent dissociation constant from 2.1*10-7 M to 1.1*10-7 M. The binding sites of WPC may be more accessible to aliphatic hydrophobic probe after come-up time and 10min HHP treatment than the native WPC80. These results indicate that HHP causes conformational changes on whey proteins and modifies the hydrophobicity of whey proteins. Aliphatic hydrophobicity is improved after come-up time and 10min HHP treatment. HHP treatment shows great potential for improving functionality of WPC and may provide opportunities for improvement of flavor in reduced fat products.
Session 17B, Dairy Foods: General
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