Protein-water partition coefficients (K(pw)) of neutral organic chemicals were measured using muscle proteins (from chicken, fish, and pig), collagen and gelatin. K(pw) values for these structural proteins were consistently lower than those of bovine serum albumin (BSA), indicating that the use of BSA as a model protein leads to an overestimation of K(pw) for structural proteins. Differences in K(pw) between chicken, fish, and pig muscle proteins were small. Across the structural proteins, K(pw) values were often in the order: muscle proteins > collagen ≥ gelatin. Differences in K(pw) between the structural proteins were relatively large (<2 log units) for nonpolar compounds, and much smaller or insignificant for polar compounds. There were correlations between log K(pw) of muscle proteins and log K(ow) (R(2) = 0.83-0.86, SD: 0.35-0.40, n = 45-46). The polyparameter linear free energy relationship (PP-LFER) models fit even better to the data (R(2) = 0.95, SD: 0.22). The good model fitting suggests that the reversible binding to muscle proteins can be considered to be nonspecific binding. There was an indication that some chemicals may sorb irreversibly to muscle proteins, which needs further research. We found that the partitioning to muscle protein is typically weaker than that to lipids, but that the protein partitioning of an H-bond donor compound can be as strong as the storage lipid partitioning.

The purpose of this study was to compare the antioxidant activity of carotenoids to that of α-tocopherol by using a photochemiluminescence method (PCL). Comparisons to results obtained by using other established methods (α-TEAC, FRAP, DPPH, LPSC) were carried out. A relationship between the chemical structure of carotenoids and their antioxidant activity could be discussed. The number of conjugated double bonds and functional groups had a positive influence. Additionally, the lipophilic antioxidant capacities of selected tomato products were analyzed using PCL and α-TEAC. HPLC was used to identify and quantify contents of carotenoids, tocopherols, and tocotrienols. The raw material fresh tomatoes had the lowest antioxidant effect in both assays due to the lower carotenoid content. Tomato ketchup had the highest AOC in PCL, and tomato puree, in α-TEAC. The antioxidant capacities were mainly dependent on the water content of the samples. Furthermore, a concentration-dependent effect could be observed in both assays.

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