Food Preservation and Microbial Growth

The lecture discusses food microbiology, focusing on how intrinsic and extrinsic factors affect the growth of microorganisms in food. Intrinsic factors include water activity, pH, and nutrient content, while extrinsic factors involve temperature and oxygen availability. The lecture also covers the role of microorganisms in food production, such as in yogurt and cheese making.

What are the two main categories of factors that affect food spoilage?

• Chemical and physical factors

• Nutritional and environmental factors

• Biological and chemical factors

• Intrinsic and extrinsic factors

Why does meat spoil faster than dry beans?

• Meat is exposed to more air

• Meat has higher water activity

• Meat has more nutrients

• Meat has a higher pH

Which type of microorganism can grow in acidic environments?

• Bacteria

• Protozoa

• Fungus

• Viruses

What role do biological barriers play in food preservation?

• They increase nutrient content

• They prevent microbial entry

• They enhance flavor

• They reduce water activity

How does refrigeration affect bacterial growth?

• It slows down bacterial growth

• It kills bacteria

• It increases bacterial growth

• It has no effect on bacteria

What is the effect of removing oxygen from canned foods?

• It enhances flavor

• It prevents bacterial growth

• It reduces nutrient content

• It increases shelf life

Which type of bacteria can grow in both the presence and absence of oxygen?

• Aerobic bacteria

• Thermophiles

• Facultative bacteria

• Anaerobic bacteria

What temperature range do mesophiles prefer for growth?

• 70° to 80°C

• 50° to 60°C

• 25° to 40°C

• 0° to 10°C

Which type of bacteria is commonly found in refrigerated fish?

• Mesophiles

• Psychrophiles

• Halophiles

• Thermophiles

What is one use of microorganisms in food production?

• Reducing fat content

• Enhancing color

• Preserving meat

• Producing yogurt