FACTORS AFFECTING THE DEVELOPMENT OF CLOSTRIDIUM BOTULINUM IN WHOLE MILK

Area of Science:

• Food Microbiology
• Bacterial Growth Kinetics
• Sterilization Processes

Background:

• Clostridium botulinum poses a significant food safety risk.
• Understanding factors influencing its growth in dairy is crucial.
• Sterilization and medium age are potential modulators of bacterial development.

Purpose of the Study:

• To investigate the impact of milk sterilization methods and medium aging on Clostridium botulinum type 62A development.
• To analyze the relationship between sterilization parameters, oxidation-reduction potential, and bacterial lag phase.
• To determine the role of autoreduction in sterilized milk on C. botulinum growth.

Main Methods:

• Whole milk was autoclaved at 121°C for 18 or 30 minutes.
• Inoculation with C. botulinum spores (2,000–5,000 spores/mL).
• Oxidation-reduction (Eh) potential measurements and oval tube counting for culture development.

Main Results:

• Sterilization time influenced initial Eh and autoreductive capacity; shorter sterilization (18 min) resulted in higher initial Eh (234 mV) and longer lag phase (7 days) compared to 30 min (192 mV, 5 days).
• Autoreduction occurred in sterilized milk, with Eh decreasing over time.
• Inoculating milk 3-5 days post-sterilization shortened the lag phase compared to immediate inoculation.

Conclusions:

• Sterilization technique and medium aging are critical factors affecting C. botulinum type 62A lag phase.
• The autoreductive capacity of sterilized whole milk is a major determinant in the growth of C. botulinum.
• Optimizing sterilization and considering medium age can influence bacterial proliferation in dairy products.