Nonprotein nitrogen compounds in harp seal ( Phoca groenlandica) meat

Abstract

The composition of nonprotein nitrogen (NPN) compounds in manually deboned or mechanically separated seal meat (MSSM) unwashed, or washed, was studied. The NPN contents in manually or mechanically separated meat were 172 and 342 mg %, respectively. The enhanced NPN content in MSSM may influence the storage stability of the product and may contribute to flavour changes during thermal processing of meat. The NPN fraction in manually separated seal meat consisted of nitrogen from carnosine and anserine (79.4 mg %), free amino acids (30 mg %), nucleic acids (23.8 mg %), amines (1.36 mg %) and nucleotides (17.7 mg %). The contents of free amino acids in manually separated meat and unwashed MSSM were 0.21 and 0.35%, respectively. About 55% of the free amino acids consisted of taurine, alanine, glutamine, glutamic acid, leucine and lysine. Fresh seal meat contained 1.48 mg % of trimethylamine N-oxide, which after 8 months of storage at −20°C was almost completely exhausted, forming 0.73 mg % trimethylamine and 0.42 mg % of dimethylamine. Additionally, the presence of 0.30–0.57 mg % of spermidine and 2.98–3.41 mg % of spermine was determined. The nucleic acids content in MSSM varied from 291 to 336 mg %. Removal of both of the amines and nucleic acids enhances the quality of the products by reducing the chance of N-nitrosamine formation in the cured products and formation of crystals and stones in the human urinary tract, respectively.