Tyrosine deposits in brines of salted natural sausage casings of bovine origin

• Tyrosine precipitates from salted natural bovine casings.
• Isolation and purification of tyrosine particles.
• Quantitative analysis of tyrosine precipitate.
• Microbiota.

Tyrosine was identified as the major component of water insoluble white particles recovered from salted bovine small intestines intended for sausage casings. The salt sludge taken from the bottom of the transport casks contained more than 2.5% (w/w) of these particles and the wash-off from the salted intestines yielded 0.04% (w/w). Qualitative analysis by confocal Raman microscopy proved tyrosine as the major constituent with an admixture of phenylalanine. The quantitative amino acid analysis revealed 85.5 ± 2.3% tyrosine and 5.0 ± 0.2% phenylalanine. The amino acid analysis of the brine samples showed a typical protein profile with the highest concentrations being observed for glutamate, leucine, alanine, and lysine. Endogenous proteolytic enzymes of the tissue rather than microbial activities are thought to have been responsible for the tyrosine precipitations.