312 Modern Food Microbiology
preheating levels of nitrite decrease considerably during heating in meats and during postprocessing
storage—more at higher storage temperatures than at lower.
The antibotulinal activity of nitrite is interdependent with pH, salt content, temperature of incubation,
and numbers of botulinal spores. Heat-injured spores are more susceptible to inhibition than uninjured.
Nitrite is more effective under oxidation–reduction potential minus (E ˜
h) than under Eh+ conditions.
Nitrite does not decrease the heat resistance of spores. It is not affected by ascorbate in its antibotulinal actions but does act synergistically with ascorbate in pigment formation. Lactic acid bacteria are
relatively resistant to nitrite (see above). Endospores remain viable in the presence of the antibotulinal
effect and will germinate when transferred to nitrite-free media.
Nitrite has a pK of 3.29 and, consequently, exists as undissociated nitrous acid at low pH values.
The maximum undissociated state and consequent greatest antibacterial activity of nitrous acid are
between pH 4.5 and 5.5.
With respect to its depletion or disappearance in ham, Nordin
141 found the rate to be proportional
to its concentration and to be exponentially related to both temperature and pH. The depletion rate
doubled for every 12.2
◦ C increase in temperature or a 0.86 pH unit decrease and was not affected by
heat denaturation of the ham. These relationships did not apply at room temperature unless the product
was first heat treated, suggesting that viable organisms aided in its depletion.
It appears that the antibotulinal activity of nitrite is due to its inhibition of nonheme, iron–sulfur
enzymes.
FOOD SANITIZERS
A large number of chemicals have been assessed for their efficacy in destroying pathogens on fruits,
vegetables, and meat surfaces. The pathogens of primary concern are the enterohemorrhagic E. coli
strains, L. monocytogenes, and salmonellae. One of the desirable objectives of a food sanitizer is the
capacity to effect a 5-log reduction of the pathogen of concern. In addition to their application to the
surfaces of foods, some of these chemicals are applied directly to the surfaces of food handling and
storage equipment. The chemicals in this section are not food additives as are those in other sections
of this chapter. Brief summaries of those that have received the most attention are presented in the
sections that follow. For a review, see reference 60.
Acidified Sodium Chlorite
Produced by the Alcide Corp., acidified sodium chlorite (ASC) is a product of citric or phosphoric
acid and NaCl, and it is used either as a spray (ca. 5 sec) or dip (ca. 5 minutes exposure) at concentrations
of 1,000 to 1,200 ppm. The antimicrobial species is a product of the dissociation of chlorite that breaks
or disrupts oxidative bonds on the surface of cell membranes in a nonspecific manner.
103 It has been
approved by the U.S. Food and Drug Administration as a sanitizer for poultry, red meat surfaces,
seafoods, some fruits and vegetables, and some processed meats. For poultry, it is used pre-chill and
post-chill on whole or cut-up birds. It may be used in water or ice. Acidic calcium sulfate is a closely
related preparation.
Electrolized oxidizing water
Electrolized oxidizing (EO) water was first demonstrated in Russia in the 1970s, and further shown
in Japan to possess antimicrobial properties. It is prepared in a special device following the addition
preheating levels of nitrite decrease considerably during heating in meats and during postprocessing
storage—more at higher storage temperatures than at lower.
The antibotulinal activity of nitrite is interdependent with pH, salt content, temperature of incubation,
and numbers of botulinal spores. Heat-injured spores are more susceptible to inhibition than uninjured.
Nitrite is more effective under oxidation–reduction potential minus (E ˜
h) than under Eh+ conditions.
Nitrite does not decrease the heat resistance of spores. It is not affected by ascorbate in its antibotulinal actions but does act synergistically with ascorbate in pigment formation. Lactic acid bacteria are
relatively resistant to nitrite (see above). Endospores remain viable in the presence of the antibotulinal
effect and will germinate when transferred to nitrite-free media.
Nitrite has a pK of 3.29 and, consequently, exists as undissociated nitrous acid at low pH values.
The maximum undissociated state and consequent greatest antibacterial activity of nitrous acid are
between pH 4.5 and 5.5.
With respect to its depletion or disappearance in ham, Nordin
141 found the rate to be proportional
to its concentration and to be exponentially related to both temperature and pH. The depletion rate
doubled for every 12.2
◦ C increase in temperature or a 0.86 pH unit decrease and was not affected by
heat denaturation of the ham. These relationships did not apply at room temperature unless the product
was first heat treated, suggesting that viable organisms aided in its depletion.
It appears that the antibotulinal activity of nitrite is due to its inhibition of nonheme, iron–sulfur
enzymes.
FOOD SANITIZERS
A large number of chemicals have been assessed for their efficacy in destroying pathogens on fruits,
vegetables, and meat surfaces. The pathogens of primary concern are the enterohemorrhagic E. coli
strains, L. monocytogenes, and salmonellae. One of the desirable objectives of a food sanitizer is the
capacity to effect a 5-log reduction of the pathogen of concern. In addition to their application to the
surfaces of foods, some of these chemicals are applied directly to the surfaces of food handling and
storage equipment. The chemicals in this section are not food additives as are those in other sections
of this chapter. Brief summaries of those that have received the most attention are presented in the
sections that follow. For a review, see reference 60.
Acidified Sodium Chlorite
Produced by the Alcide Corp., acidified sodium chlorite (ASC) is a product of citric or phosphoric
acid and NaCl, and it is used either as a spray (ca. 5 sec) or dip (ca. 5 minutes exposure) at concentrations
of 1,000 to 1,200 ppm. The antimicrobial species is a product of the dissociation of chlorite that breaks
or disrupts oxidative bonds on the surface of cell membranes in a nonspecific manner.
103 It has been
approved by the U.S. Food and Drug Administration as a sanitizer for poultry, red meat surfaces,
seafoods, some fruits and vegetables, and some processed meats. For poultry, it is used pre-chill and
post-chill on whole or cut-up birds. It may be used in water or ice. Acidic calcium sulfate is a closely
related preparation.
Electrolized oxidizing water
Electrolized oxidizing (EO) water was first demonstrated in Russia in the 1970s, and further shown
in Japan to possess antimicrobial properties. It is prepared in a special device following the addition