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A procedure suitable for a selective high-performance liquid chromatographic (HPLC) analysis of the imino acid hydroxyproline in the presence of a large excess of amino acids is proposed. To deaminate the amino acids, the well-known reaction with nitrous acid is exploited. The N-nitroso derivatives of imino acids obtained are extracted in ethyl acetate, denitrosated by hydrobromic acid, and treated with dabsyl-chloride. The final HPLC separations are carried out on a reversed-phase column in a rapid isocratic run. The use of the cis isomer of hydroxyproline as an internal standard allows good reproducibility. As an application of the described method, the hydroxyproline content in samples containing collagen and an excess of bovine serum albumine (up to 20:1) is determined.

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Summary. The lipolytic activity of Micrococcaceae on pork fat was investigated by their growth in a fat containing medium. Thirty‐three free fatty acids were detected of which 6 had a carbon chain with < 8 atoms, and were not present in the original fat. In addition to the free fatty acids the formation of 15 carbonyl compounds was detected, most of which were identified. The result of these investigations, and their influence on the microflora of dry sausages has been analysed.