Food Microbiology: Intrinsic and Extrinsic Factors

This set of flashcards covers key concepts related to intrinsic and extrinsic factors affecting microbial growth in food, based on the provided lecture notes.

What are the two main categories of factors affecting microorganisms in foods?

Intrinsic effects and Extrinsic effects.

What do intrinsic parameters refer to in food microbiology?

Factors inherently related to the food itself, like biological structures, nutrient content, moisture content, oxidation-reduction potential, pH, and antimicrobial constituents.

What is the role of moisture content in microbial growth in food?

Moisture content is critical as microorganisms require water for growth; the availability influences their survival and proliferation.

What types of organisms can utilize sugars as a source of energy?

Microorganisms such as bacteria and yeasts can utilize sugars for energy.

How does pH affect microbial growth in foods?

pH affects enzyme functioning and nutrient transport, with each species having an optimum pH for growth.

What are weak acids and why are they significant in food microbiology?

Weak acids can cross cell membranes and lower intracellular pH, negatively affecting microbial metabolism.

What is water activity (aw) and why is it important?

Water activity measures the availability of water in food that microorganisms can utilize for growth.

What is the effect of high relative humidity on food?

High relative humidity can lead to moisture gain in food, affecting its water activity and encouraging microbial growth.

Name common antimicrobial constituents found in foods.

Natural constituents with antimicrobial properties include essential oils from spices like garlic and thyme, and proteins like lysozyme in eggs.

What are extrinsic parameters in food microbiology?

Factors related to the food's storage environment, such as temperature, humidity, and gas concentrations.

Define the term 'implicit effects' in relation to microbial growth in foods.

Implicit effects are interactions between different microorganisms that impact the overall microbial community in food.

What is the significance of temperature in food storage?

Temperature is crucial for controlling the shelf life and safety of perishable foods; it determines microbial growth rates.

What does a D-value represent in food microbiology?

The time required at a specific temperature to reduce the viable microbial population by one logarithmic cycle.