A method is described for the determination of N-nitrosoproline
(NOPRO) in cured meat products. NOPRO was extracted with ethyl
acetate from a slurry of cured meat and water after the addition of
ammonium sulfamate and acid. This nitrosamino acid was converted
to the methyl ester and after further purification, it was quantitated
and confirmed by gas liquid chromatography and mass spectroscopy.
Recoveries of 10 μg from spiked samples averaged about 70%.
A capillary column was used to confirm the presence of low
levels of MeNOPRO in the extracts. An oscilloscope, utilizing horizontal
sweep magnification of the mass spectrometer output, was used
to detect the elution of MeNOPRO from the column by monitoring the
m/e 30 ion. The presence of 5 nanograms per injection of concentrated
cured meat extract could be confirmed.
NOPRO was detected in several commercial meat products. Five of six bacon samples analyzed were found to contain NOPRO at
levels ranging from 13-46 ppb. A precooked ham slice and a sample
of breakfast beef contained 22 and 62 ppb NOPRO, respectively.
NOPRO was not detected in a sample of canned chopped ham nor a
wiener sample.
The detection of NOPRO, a non-volatile nitrosamine, in cured
meats suggests that the formation of other non-volatile nitrosamines
is possible. To date, only volatile nitrosamines have been analyzed
and confirmed by mass spectrometry. The ubiquity of proline and
the finding of NOPRO in several different cured meat products suggest
that NOPRO could be an indicator of nitrosation in foods.
Bacon cured in brines containing 800 and 1600 ppm nitrite
contained about 50 and 100 ppm residual nitrite, respectively. Bacons
receiving the lower nitrite level contained no NOPRO while the higher
nitrite treated bacons contained over 100 ppb NOPRO. Frying of bacon
was found to destroy 86 to 100% of NOPRO in the five samples
analyzed. NOPRO has been reported to break down during heating to
nitrosopyrrolidine (NOPYR). However, the levels of NOPRO determined
in raw bacon were not sufficient to produce the amounts of
NOPYR reported in fried bacon if the rate of conversion was similar
to that previously reported in model studies. / Graduation date: 1974
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28195 |
| Date | 20 February 1974 |
| Creators | Ivey, Francis James |
| Contributors | Anglemier, Allen F. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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