Effect on Microbial Growth and Ecology

Redox potential exerts an important selective effect on the microflora of a food since it will decide the type of microorganism that can grow in that food. Microbial growth can occur over a wide spectrum of redox potential. However, individual microorganisms have their own redox ranges over which they can grow. Based on their ability to use free oxygen, microorganisms have been classified as

1. Aerobic when they require free oxygen.

2. Anaerobic when they grow best in the absence of free oxygen.

3. Facultative when they grow well either aerobically or anaerobically.

Molds are aerobic, most yeast grows best aerobically and bacteria may be aerobic, anaerobic, or facultative. A high (oxidizing) potential favours aerobes but will permit the growth of facultative organisms also, and a low (reducing) potential favours anaerobic or facultative organisms. Growth of an organism may alter the O-R potential of a food enough to inhibit other organisms. Anaerobes, for example, may lower the O-R potential to a level, which is inhibitory to aerobes.