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Food Additives & Contaminants Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfac19
Volatile, non‐volatile and total N‐nitroso compounds in bacon a
a
b
R. C. Massey , P. E. Key , R. A. Jones & G. L. Logan
b
a
Food Safety Directorate, Food Science Laboratory , Ministry of Agriculture, Fisheries and Food , Colney Lane, Norwich, NR4 7UQ, UK b
School of Chemical Sciences , University of East Anglia , Norwich, NR4 7TJ, UK Published online: 10 Jan 2009.
To cite this article: R. C. Massey , P. E. Key , R. A. Jones & G. L. Logan (1991) Volatile, non‐volatile and total N‐nitroso compounds in bacon, Food Additives & Contaminants, 8:5, 585-598, DOI: 10.1080/02652039109374012 To link to this article: http://dx.doi.org/10.1080/02652039109374012
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sublicensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
FOOD ADDITIVES AND CONTAMINANTS, 1991, VOL. 8, NO. 5, 5 8 5 - 5 9 8
Volatile, non-volatile and total N-nitroso compounds in bacon R. C. MASSEY†, P. E. KEY†, R. A. JONES‡ and G. L. LOGAN‡ † Ministry of Agriculture, Fisheries and Food, Food Safety Directorate, Food Science Laboratory, Colney Lane, Norwich NR4 7UQ, UK; ‡ School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, UK
Downloaded by [Stockholm University Library] at 05:35 26 August 2015
(Received 24 June 1991; revised 14 August 1991; accepted 14 August 1991) Twenty-five smoked and unsmoked fried bacon samples have been analysed by a group selective procedure to measure the concentration of apparent total N-nitroso compounds (ATNC). The levels of a range of individual N-nitroso compounds, including simple volatile N-nitrosamines, N-nitrosothiazolidines, N-nitrosoamino acids and Nnitrosothiazolidine carboxylic acids have also been examined. Concentrations of ATNC varied from 430 to 6800 µg(N-NO)/kg with a mean of 2700 µg(N-NO)/kg. Protein-bound N-nitrosoproline was the most abundant compound detected in unsmoked bacon, mean 260 µg/kg, and on average accounted for 4% of the ATNC concentration. For smoked bacon, bound N-nitrosoproline was detected in levels of up to 890 µg/kg and contributed 5% to the ATNC total. The most abundant compound present in smoked bacon was N-nitrosothiazolidine-4-carboxylic acid, mean 660 µg/kg, and this accounted for 6% of the ATNC. N-Nitrosothiazolidine, mean 340 µg/kg, and 2-(hydroxymethyl)-3nitrosothiazolidine-4-carboxylic acid, mean 180 µg/kg, were the next most prominent compounds detected in smoked bacon. The combined sum of all the individual N-nitroso compounds measured accounted for, on average, 16% of the total ATNC. The identities of the N-nitroso compounds comprising the majority of the ATNC in bacon remain unknown. Keywords: N-nitroso compounds, N-nitrosamines, bacon
Introduction
The occurrence of JV-nitroso compounds in foodstuffs is of concern as many of them exhibit carcinogenic properties in animal feeding studies (Magee and Barnes 1967). As a consequence considerable effort has gone into determining whether these compounds occur in the diet. Analytical methods for volatile Af-nitrosamines are well established and it is known that these compounds may occur in trace amounts in products such as beer (Sen et al. 1980, Massey et al. 1990) and cured meats (Gray et al. 1982, Vecchio et al. 1986). Procedures for non-volatile N-nitroso compounds are less well advanced although methods have been developed for certain classes such as the N-nitrosoamino acids (Sen et al. 1983, Tricker etal. 1984). A measure of the concentration of all the N-nitroso compounds in a sample may be obtained using the group selective procedure devised by Walters etal. (1978a). As with any such technique the method is potentially susceptible to false positive interferences from non Af-nitroso compounds. In recognition of this possibility the species measured by the method are referred to as apparent total Nnitroso compounds (ATNC). In fact the technique shows a high selectivity towards © Crown Copyright 1992.
Downloaded by [Stockholm University Library] at 05:35 26 August 2015
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R. C. Massey et al.
N-nitroso compounds (Walters et al. 1978b, Massey 1988) and ATNC have not been observed above the 20 /tg(N-NO)/kg limit of detection in the majority of foods so far examined including bread, biscuits, tea and coffee as made up for consumption and dairy produce such as yoghurt and cheese manufactured without added nitrate (Massey etal. 1984, Massey and Key 1989). The non-detection of ATNC in a foodstuff does not of itself guarantee the absence of very low levels of individual Af-nitroso compounds. For instance, it is well established (Gough et al. 1977) that cheese manufactured without added nitrate, as well as cheese made with nitrate, may occasionally contain detectable amounts of Af-nitrosodimethylamine, generally up to 5 ftg/kg; these values are however below the detection limit of the ATNC assay. One of the advantages of the group selective procedure is that it enables those foods that contain relatively high levels of ATNC to be identified and further investigated. Application of the assay to bacon (Massey et al. 1984, 1988) revealed ATNC levels in the range 360 to 2400 /
Food Additives & Contaminants Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfac19
Volatile, non‐volatile and total N‐nitroso compounds in bacon a
a
b
R. C. Massey , P. E. Key , R. A. Jones & G. L. Logan
b
a
Food Safety Directorate, Food Science Laboratory , Ministry of Agriculture, Fisheries and Food , Colney Lane, Norwich, NR4 7UQ, UK b
School of Chemical Sciences , University of East Anglia , Norwich, NR4 7TJ, UK Published online: 10 Jan 2009.
To cite this article: R. C. Massey , P. E. Key , R. A. Jones & G. L. Logan (1991) Volatile, non‐volatile and total N‐nitroso compounds in bacon, Food Additives & Contaminants, 8:5, 585-598, DOI: 10.1080/02652039109374012 To link to this article: http://dx.doi.org/10.1080/02652039109374012
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sublicensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
FOOD ADDITIVES AND CONTAMINANTS, 1991, VOL. 8, NO. 5, 5 8 5 - 5 9 8
Volatile, non-volatile and total N-nitroso compounds in bacon R. C. MASSEY†, P. E. KEY†, R. A. JONES‡ and G. L. LOGAN‡ † Ministry of Agriculture, Fisheries and Food, Food Safety Directorate, Food Science Laboratory, Colney Lane, Norwich NR4 7UQ, UK; ‡ School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, UK
Downloaded by [Stockholm University Library] at 05:35 26 August 2015
(Received 24 June 1991; revised 14 August 1991; accepted 14 August 1991) Twenty-five smoked and unsmoked fried bacon samples have been analysed by a group selective procedure to measure the concentration of apparent total N-nitroso compounds (ATNC). The levels of a range of individual N-nitroso compounds, including simple volatile N-nitrosamines, N-nitrosothiazolidines, N-nitrosoamino acids and Nnitrosothiazolidine carboxylic acids have also been examined. Concentrations of ATNC varied from 430 to 6800 µg(N-NO)/kg with a mean of 2700 µg(N-NO)/kg. Protein-bound N-nitrosoproline was the most abundant compound detected in unsmoked bacon, mean 260 µg/kg, and on average accounted for 4% of the ATNC concentration. For smoked bacon, bound N-nitrosoproline was detected in levels of up to 890 µg/kg and contributed 5% to the ATNC total. The most abundant compound present in smoked bacon was N-nitrosothiazolidine-4-carboxylic acid, mean 660 µg/kg, and this accounted for 6% of the ATNC. N-Nitrosothiazolidine, mean 340 µg/kg, and 2-(hydroxymethyl)-3nitrosothiazolidine-4-carboxylic acid, mean 180 µg/kg, were the next most prominent compounds detected in smoked bacon. The combined sum of all the individual N-nitroso compounds measured accounted for, on average, 16% of the total ATNC. The identities of the N-nitroso compounds comprising the majority of the ATNC in bacon remain unknown. Keywords: N-nitroso compounds, N-nitrosamines, bacon
Introduction
The occurrence of JV-nitroso compounds in foodstuffs is of concern as many of them exhibit carcinogenic properties in animal feeding studies (Magee and Barnes 1967). As a consequence considerable effort has gone into determining whether these compounds occur in the diet. Analytical methods for volatile Af-nitrosamines are well established and it is known that these compounds may occur in trace amounts in products such as beer (Sen et al. 1980, Massey et al. 1990) and cured meats (Gray et al. 1982, Vecchio et al. 1986). Procedures for non-volatile N-nitroso compounds are less well advanced although methods have been developed for certain classes such as the N-nitrosoamino acids (Sen et al. 1983, Tricker etal. 1984). A measure of the concentration of all the N-nitroso compounds in a sample may be obtained using the group selective procedure devised by Walters etal. (1978a). As with any such technique the method is potentially susceptible to false positive interferences from non Af-nitroso compounds. In recognition of this possibility the species measured by the method are referred to as apparent total Nnitroso compounds (ATNC). In fact the technique shows a high selectivity towards © Crown Copyright 1992.
Downloaded by [Stockholm University Library] at 05:35 26 August 2015
586
R. C. Massey et al.
N-nitroso compounds (Walters et al. 1978b, Massey 1988) and ATNC have not been observed above the 20 /tg(N-NO)/kg limit of detection in the majority of foods so far examined including bread, biscuits, tea and coffee as made up for consumption and dairy produce such as yoghurt and cheese manufactured without added nitrate (Massey etal. 1984, Massey and Key 1989). The non-detection of ATNC in a foodstuff does not of itself guarantee the absence of very low levels of individual Af-nitroso compounds. For instance, it is well established (Gough et al. 1977) that cheese manufactured without added nitrate, as well as cheese made with nitrate, may occasionally contain detectable amounts of Af-nitrosodimethylamine, generally up to 5 ftg/kg; these values are however below the detection limit of the ATNC assay. One of the advantages of the group selective procedure is that it enables those foods that contain relatively high levels of ATNC to be identified and further investigated. Application of the assay to bacon (Massey et al. 1984, 1988) revealed ATNC levels in the range 360 to 2400 /
