Characterization of Nitrite-Related Reaction Products in Beer

Abstract

The effect of nitrites in foods and beverages still raises discussion due to the possible formation of harmful nitroso compounds. However, as most of these compounds in beer were not structurally characterized yet, the research about their toxicological relevance for consumers is limited. This study is focused on identification of the products formed by nitrite (or isotopically labeled nitrite 15N) reactions in beer using gas chromatography with tandem mass spectrometry. In total, 19 products were identified, and some of them were structurally characterized and confirmed by comparing retention indices and mass spectra of standard/synthesized compounds. Identified compounds were representatives of nitroso, nitro, oxime, and even cyano compounds. For the peaks which were not structurally identified, primary structural characteristics were also listed. Found products were further screened in 16 authentic beer samples which showed the apparent occurrence of found compounds in non-treated beers.

Natural Occurrence of Nitrite-Related Compounds in Malt and Beer

“…Their identification and structural characterization were individually performed in the previous publication and are summarized in Table 1. 21 A similar treatment was applied to malt when moist malt grains were exposed to nitrogen dioxide under different conditions. First, malt nitrosated at high temperature was incubated at 40 °C and dried at 80 °C since the kilning temperature is also associated with NDMA formation.…”

“…29 It agreed with a primary screening performed on 16 commercial beers in the prior study. 21 However, it does not necessarily imply that they are the most concentrated since each N-product poses a different unknown response factor. Relative responses in malts were generally higher than in beers, which could be possibly caused, among other reasons, by a matrix effect.…”

“…Previously identified N-products, namely, pyruvic acid oxime, 4-cyanophenol, 4-nitrosophenol, nitrosoguaiacol, NPRO, NPRO-O-Et, and 2-methoxy-5-nitrophenol, were detected in the majority of tested samples. 21 There is still a need to reveal structures of unidentified N-products, such as highly abundant N-01 and N-16 or nitrosation products of tyrosine. Although most tyrosine-related N-products were rarely detected (N-14, N-19, N-20, N-21, and N-22), others, such as 4-cyanophenol, were among the abundant and newly found compounds.…”

“…N-products were structurally studied by MS/MS fragmentation and confirmed by a retention index and mass spectrum of laboratory-prepared compounds or standards. Collected structural mass information allowed the development of the specific detection method described in the mentioned paper . The present study applied this method for a semiquantitative screening of found N-products in commercial samples of malts and beers (nearly 200 samples each).…”

“…List of N-Products Formed by the Reaction of Nitrite in a Beer Sample21 A percentage of samples in which a specific N-product was detected. The total number of malt samples was 198 and of beer samples was 191. c The number of beer samples where the analyte was monitored is 69. d The N-product was detected only in the congress wort.…”