Agriculture Reference
In-Depth Information
microbiological contamination of the jar
contents and is
also used in some
countries as a flour improving agent [73-74].
It was found that AZDC
decomposes into gases (primarily nitrogen and carbon dioxide) during the heat
treatment process and can leave trace amounts of residues such as biurea,
urazole, cyanuric acid and cyamelide. Furthermore, studies have confirmed the
presence of SEM as a by-product of AZDC treated gaskets in jarred foods
[75].
Reported levels of SEM in food in glass jars have been found to be
variable in the range of non detectable (<1 ngg
-1
) up to 25 ngg
-1
. Besides baby
food, other similarly packaged products have been found to have traces of
SEM including fruit juices, jams, sterilized vegetables, pickles, mayonnaise,
mustard, sauces, and ketchup. However, baby food had by far the highest
concentrations of SEM, probably because of the higher ratio of gasket area to
food mass for these small package
sizes [74].
In response to these findings,
restrictions were introduced to eliminate this source of contamination.
Because SEM is known to react with chemicals such as carbonyl compounds,
and these functional groups are present in food, some or all SEM is likely to be
bound rather than free. Therefore, it is necessary to base any analytical method
on initial hydrolysis and subsequent derivatization to determinate free and
reversibly-bound residues of SEM in baby food [74]. Currently, AZDC is
suspended from use in EU countries (Commission Directive, 2004).
The formation of SEM during the baking of bread [76-77] and flour-
coated poultry products [78] was also confirmed when the use of AZDC as an
additive in flour was examined. SEM formation has additionally been
observed in samples such as carrageen (a seaweed extract used as a food
additive), starch and egg white powder treated with hypochlorite solutions
containing 12% active chlorine [78]. Hypochlorite is commonly used for
carrageen bleaching or water disinfection and also as a disinfectant during egg
breaking procedures [79]. SEM also occurs naturally in particular crustaceans
such as shrimp, prawn, and crab, generating queries over its suitability as a
marker for detection purposes in these species [80-82].
Nitrofurazone has been found to accumulate over time in both avian eyes
as well as the pig retina, and has been suggested as an alternative marker to
SEM for the monitoring of NFZ abuse [52, 83]. In one study [72] proteins
from rat liver had been isolated and examined for the presence of tissue bound
metabolite, SEM. Albumin and glutathione S-transferase proteins contained
high concentrations of bound
SEM, suggesting their potential use as
biomarkers for the detection of nitrofurazone exposure. Additionally, a novel
method for the detection of biurea to discriminate between nitrofurazone and
