Dionex Corporation (1998) found the nitrite and nitrate contentsin ham to be 11.6 and 5.4 mg/kg, respectively, whereas salamicontained 108.0 mg/kg nitrite and 98.5 mg/kg nitrate. Usingcapillary electrophoresis, the nitrite and nitrate content in salamidetected were 24.3 and 43.6 mg/kg, respectively (Öztekin et al.,2002). Compared to their findings, the current study showed thatthe salami contained no nitrite but much more nitrate at142.5 mg/kg (Table 2). Although the extraction methods were similarthe temperature used in our study was higher, apart from thedifferences that may be attributed to the manufacturing practices.Stalikas, Konidari, and Nanos (2003) used similar extraction temperatureand reported that nitrate and nitrite contents in salamiwere 54 and 84 mg/kg, respectively. Thus differences are morelikely to be due to the manufacturing processes.It was reported by Dennis, Key, Papworth, Pointer, and Massey(1990) that the mean nitrite content in bacon was 24.0 mg/kg andfor nitrate was 43.0 mg/kg, whereas nitrite and nitrate in ham were56.0 and 22.0 mg/kg, respectively. They used similar extraction anddetection methods but with an anion exchange column. Both baconand ham products in this study contained less nitrate and nitrite(Table 2) in comparison. Siu and Henshall (1998) who foundthat nitrite and nitrate contents in salami were 108.0 and98.5 mg/kg, respectively, and 11.6 and 5.4 mg/kg for ham, respectively.Sample extraction procedures used in the current study
were similar to Marshall and Trenerry (1996), but they omitted
the heating step. This may explain the low nitrite content of less
than 10 mg/kg in salami, leg ham and bacon. However the nitrate
contents were higher at 141.5, 132.5 and 48.0 mg/kg, respectively.
Different cured meat products may require different ratio of nitrite
and nitrate as preservatives. Since fresh meat does not naturally
contain nitrite (Table 2), its nitrite and nitrate contents have not
been extensively tested. However, based on this study, the nitrate
content in minced beef and medallion beef were within the range
found in cured meat products (Table 2).
It was demonstrated that recovery increases as the meat solids
decreases (Usher & Telling, 1975). Hence using smaller meat samples
should reduce the effects of interfering substances, which was
demonstrated in this study (Table 2). Furthermore, most interference
can be eliminated by UV detection. However, chloride ions
maybe detected by UV as positive or negative peaks in the wavelength
used for nitrate and nitrite and are eluted before nitrite
(Di Matteo & Esposito, 1997). Chloride peaks were not present at
214 nm in this study, which suggests that chloride ions did not
interfere with nitrite quantification since nitrite recovery was
above 92% for both meat and vegetable samples (Tables 1 and 2).
Due to its reactive nature, nitrite analysis from food does not
give a true representation of the total nitrite added. Furthermore,
nitrite added to meat is usually present as nitric oxide bound with
other food components such as myoglobin (5–15%), sulphydryl
groups (5–15%), lipids (1–5%), proteins (20–30%), as nitrate
(<10%), and as free nitrite (10–15%) (Zanardi, Dazzi, Madarena, &
Chizzolini, 2002). Therefore recovery range may be quite large as
a result of nitrite’s reactive nature and its attachment to other food
components. However, because only free nitrite can participate in
nitrosation, other methods of food extraction estimate the total nitrite
present by releasing food-bound nitrite. This may over estimate
the significance of dietary nitrite and the etiology of gastric
cancer. Hot water extraction to quantify free nitrite available to
participate in nitrosation was used in this study.
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