Effect of natural colourants and nitrites on colour attributes of frankfurters.

The colour attributes in a control and six more treatments of frankfurters (18% fat) produced with natural colourants and two levels of NaNO(2) (0 and 150 mg/kg) were studied. The following natural colourants, permitted by the EU 94/36 guideline, were used: E 100 curcumin (CU), E 120 carminic acid (CA), E 150a caramel (CR), E 160a beta-carotene (BC), E 160g paprika-extract (PE) and E162 betanin (B). CA, B, BC and PE significantly increased the redness of batter, while BC, PE and CU increased (p<0.05) the yellowness. NaNO(2) decreased (p<0.05) the redness of batters in all treatments. Frankfurters with CA had the highest a* value followed by those with BC, PE and B. BC, PE and B increased the yellowness of frankfurters. NaNO(2) increased (p<0.05) the redness of frankfurters in all treatments. The storage of frankfurters for 4 weeks had no effect on redness and yellowness of frankfurters. Exposure either for 2 h in sunlight or for 4 h in artificial light had no significant effect on redness and yellowness of frankfurters from all treatments. Canned frankfurters (117°) with B had the greatest decrease in redness while those with BC the greatest increase in yellowness. Frankfurters with B were the most acceptable from the consumers according to their colour followed by those with PE. Frankfurters with B had also the highest score for overall acceptability, followed by those with CA and nitrites. By employing discriminant analysis on the data, equations were derived for the identification of the natural colourant used in the production of frankfurters. Results from frankfurters, produced with 0, 3.6, 14.4 and 28.8 mg of pure B kg and 100 and 150 mg/kg NaNO(2), have shown that the level of NaNO(2) can be reduced from 150 to 100 mg/kg with appropriate increase in B level and frankfurters with 14.4 mg B/kg were the most acceptable from the consumers according to their colour.