In the sausages prepared with 150 mg kg1 nitrite the levels of NPIP (Fig. 1D), NHPRO, NPRO, NTCA and NMTCA (Fig. 1B) amounted to 2.6, 10, 40, 70 and 80 lg kg1, thus frying induced an increase in the NPIP (2.6 lg kg1) and the NMTCA (80 lg kg1) levels.