Dive into the O (Oxygen) and M (Moisture) factors of FAT-TOM, crucial for controlling bacterial growth in potentially hazardous foods. Aerobic bacteria, like Salmonella and E. coli, need oxygen to thrive, while anaerobic bacteria, such as Clostridium botulinum, grow in low-oxygen or oxygen-free environments like sealed cans—changing oxygen levels with foil or vacuum-sealing can increase risks, so focus on managing time, temperature, or moisture instead.

Moisture is vital, as pathogenic bacteria require available water to multiply; adding salt or sugar binds water, making it unavailable and preserving foods like baked goods or beef jerky at room temperature.

Dehydrating or freezing also reduces available water—freezing turns it to ice temporarily—but thawed foods must be handled carefully to prevent growth. Mastering these controls ensures food safety and prevents illness.

Read more About the lesson (Optional)

Welcome to the tenth lesson in the Understanding Microorganisms module of the Safe Food Handler Certificate course! In this lesson, you’ll learn about the O (Oxygen) and M (Moisture) in the FAT-TOM acronym, how they affect bacterial growth, and how food handlers can control moisture to prevent foodborne illness. Let’s dive in!

Oxygen (O) in FAT-TOM

Different bacteria have different oxygen needs for growth:

• Aerobic Bacteria: These require oxygen to grow. Examples include Salmonella and E. coli, which thrive in oxygen-rich environments.
• Anaerobic Bacteria: These grow in low-oxygen or oxygen-free environments. Clostridium botulinum (botulism-causing bacteria) is an example, as it thrives in sealed, low-oxygen conditions like canned foods. Controlling oxygen is tricky, so food handlers should focus on managing other FAT-TOM conditions (e.g., time, temperature, or moisture) first. Be aware that changing a food’s oxygen environment (e.g., wrapping in foil or vacuum-sealing) can increase or decrease food safety risks depending on the bacteria present.

Moisture (M) in FAT-TOM

Pathogenic bacteria need available water (moisture) to multiply. Not all water in food is available for bacteria to use:

• Unavailable Water: When solutes like salt or sugar are added to water, they bind with water molecules, forming compounds too large for bacteria to use. This creates a preservative effect, allowing foods like baked goods (containing eggs or milk) or beef jerky to stay safe at room temperature indefinitely due to high sugar or salt content.
• Reducing Available Water: Other methods to make water unavailable include dehydrating (e.g., beef jerky) and freezing. Freezing makes water unavailable temporarily by turning it into ice, but once food thaws, water becomes available again, allowing bacterial growth if not handled properly.

Why This Matters

Understanding oxygen and moisture needs helps food handlers prevent bacterial growth in potentially hazardous foods. While oxygen is hard to control, reducing available water through salt, sugar, dehydration, or freezing can make foods safer. Always monitor thawing and storage conditions, and check course resources for safe handling practices.

Key Takeaways:

• Aerobic bacteria (e.g., Salmonella, E. coli) need oxygen; anaerobic bacteria (e.g., Clostridium botulinum) thrive without it.
• Pathogenic bacteria require available water to grow; adding salt or sugar binds water, making it unavailable.
• Dehydrating or freezing foods reduces available water, but thawed foods must be handled carefully to prevent bacterial growth.