A rapid cadmium reduction method for the determination of nitrate in bacon and curing brines

Abstract

A method has been developed for the extraction of nitrate and nitrite from meat by heating at 80 °C for 10 minutes to coagulate the protein and inactivate nitrate and nitrite reductase activity and subsequently treating with alumina cream. The latter treatment alone was used for the clarification of curing brines. A method for the reduction of nitrate to nitrite by shaking with cadmium has been developed that is quicker, as it takes 5 minutes, than column reduction, which requires 40 to 60 minutes. Quantitative recoveries of nitrate as nitrite were obtained. Methods of determining nitrate as nitrite involving the use of the diazo compounds formed between sulphanilic acid and each of the four coupling agents 1-naphthylamine, N-1-naphthylethylenediamine, 1-naphthylamine-7-sulphonic acid and 1-naphthol were investigated. N-1-Naphthylethylene-diamine is recommended because of the short time (10 minutes) required for maximum colour development.