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Modern Food Microbiology
Figure 3–3 Schematic representation of oxidation–reduction potentials relative to the growth of certain microorganisms.
Eh values (reduced) (Figure 3–3). Among the substances in foods that help to maintain reducing
conditions are –SH groups in meats and ascorbic acid, and reducing sugars in fruits and vegetables. In
regard to the maximum positive and negative mV values in Fig. 3–3, not only are they not necessary
for the growth of aerobes or anaerobes, but these extreme values can also be lethal to the respective
group (see EO water section in Chapter 13).
The O/R potential of a food is determined by the following:
1. The characteristic O/R potential of the original food.
2. The poising capacity; that is, the resistance to change in potential of the food.
3. The oxygen tension of the atmosphere about the food.
4. The access that the atmosphere has to the food.
With respect to Eh requirements of microorganisms, some bacteria require reduced conditions for
growth initiation (Eh of about −200 mV), whereas others require a positive Eh for growth. In the
former category are the anaerobic bacteria such as the genus Clostridium; in the latter belong aerobic
Modern Food Microbiology
Figure 3–3 Schematic representation of oxidation–reduction potentials relative to the growth of certain microorganisms.
Eh values (reduced) (Figure 3–3). Among the substances in foods that help to maintain reducing
conditions are –SH groups in meats and ascorbic acid, and reducing sugars in fruits and vegetables. In
regard to the maximum positive and negative mV values in Fig. 3–3, not only are they not necessary
for the growth of aerobes or anaerobes, but these extreme values can also be lethal to the respective
group (see EO water section in Chapter 13).
The O/R potential of a food is determined by the following:
1. The characteristic O/R potential of the original food.
2. The poising capacity; that is, the resistance to change in potential of the food.
3. The oxygen tension of the atmosphere about the food.
4. The access that the atmosphere has to the food.
With respect to Eh requirements of microorganisms, some bacteria require reduced conditions for
growth initiation (Eh of about −200 mV), whereas others require a positive Eh for growth. In the
former category are the anaerobic bacteria such as the genus Clostridium; in the latter belong aerobic