Detection of factors influencing nitrite determination in meat

A critical assessment was made of the official Spanish method for determining nitrite content in meat, using a 2(k-p) fold-over Plackett–Burman experiment to identify influencing factors (IF) affecting the analytical method; these factors were drawn from seven apparent critical factors (ACF): sample weight (WS), extraction temperature (TE), stirring extraction time (SET), addition of Carrez I reagent (CI-R), addition of Carrez II reagent (CII-R), addition of borax reagent (BR) and color development time (DCT). In the experimental conditions assayed, the analytical method does not require protein precipitation. In addition, a negative effect of the Carrez reagent on nitrite determination was detected; it is thus proposed that this reagent be eliminated, in accordance with AOAC method 973.31. The use of borate improved nitrite extraction, but the WS/BR ratio must be adjusted to determine the best ratio and to eliminate any negative effect when the ratio increases.