Heme proteins and oxidation in fresh and processed meats - Oxidation in Foods and Beverages and Antioxidant Applications - page 96

sodium nitrite is limited to 120 ppm, 550 ppm sodium ascorbate must be utilized
to ensure that nearly all of the sodium nitrite is converted to nitric oxide, sodium
nitrate cannot be used, and the bacon should be fried at a temperature not greater
than 340 ëF for 3min per side to ensure that nitrosamines do not form during
frying (Code of Federal Regulations 9 424.22). To date there has been no link
between the use of nitrite in meats and cancer development in humans. Most of
the sodium nitrite is converted to nitric oxide during meat processing which
decreases reactivity of Hb and Mb during storage as noted earlier (see Sections
4.2 and 4.7). The meat industry continues to use sodium nitrite not only because
it inhibits pigment and lipid oxidation but also because sodium nitrite is an
excellent antimicrobial that limits food-borne illness outbreaks. The pink color
that results from curing with sodium nitrite is also desirable in cured products. A
new trend is to add celery powder to meat formulations in order to cure the
product without adding the pure chemical form of sodium nitrite. Celery is a rich
source of sodium nitrate (Walker, 1990). A bacterial culture (that is added to the
meat formulation) reduces the nitrate to nitrite (and the nitrite is then converted
to nitric oxide which fixes to the iron of Hb and Mb) so that the meat is cured
during processing. This type of product is more `label-friendly' since sodium
nitrite does not appear as an added ingredient.
The perception of sodium nitrite may change from a liability to that of a
beneficial ingredient in cured meats. There is recent evidence that dietary nitrite
at low doses (50mg/L drinking water) actually decreases processes associated
with the development of vascular disease (Stokes et al., 2009). Sodium nitrite is
converted to nitric oxide by bacteria in human saliva (Bryan, 2006). Nitric oxide
dilates blood vessels, decreases inflammation and protects biomolecules from
oxidative events (Bryan et al., 2007).
4.9 Sources of further information and advice
The National Center for Biotechnology Information (NCBI) can be used to
obtain amino acid sequences and three dimensional structures for different
hemoglobins and myoglobins. Software programs such as PyMOL are available
to measure distances between different atoms in a structure and to hide parts of
the molecule so that specific interactions can be observed. Other useful
references are:
ANTONI, E. & BRUNONI, M. (1971) Hemoglobin and myoglobin in their reactions with
ligands, Amsterdam, North-Holland.
NELSON, D. L. & COX, M. M. (2000) Protein function. Lehninger Principles of Biochemistry,
3rd edn. New York, Worth Publishing.
4.10 References
ALAYASH, A. I., BROCKNER RYAN, B. A., EICH, R. F., OLSON, J. S. & CASHON, R. E. (1999)
Reactions of sperm whale myoglobin with hydrogen peroxide. Effects of distal