Podcast
Questions and Answers
What are the factors influencing the growth of microorganisms?
What are the factors influencing the growth of microorganisms?
- Physical, biological, and chemical (correct)
- Intrinsic, extrinsic, and implicit
- Redox potential, moisture content, and inhibitory substances
- Processing factors, pH, and water activity
Which factor can be generally classified as implicit?
Which factor can be generally classified as implicit?
- Redox potential
- Biological (correct)
- Moisture content
- Inhibitory substances
What are the most important types of internal factors in food?
What are the most important types of internal factors in food?
- Composition of nutrients, inhibitory substances, and biological structures
- Water activity, moisture content, and inhibitory substances
- Hydrogen ion concentration, water activity, and redox potential (correct)
- pH, water activity, and redox potential
Based on the pH ranges, how can microorganisms be grouped?
Based on the pH ranges, how can microorganisms be grouped?
At what pH range do neutrophiles grow best?
At what pH range do neutrophiles grow best?
What is the pH range for the growth of molds?
What is the pH range for the growth of molds?
At what pH range do acidophiles grow best?
At what pH range do acidophiles grow best?
Study Notes
Microbiology Subfields
- Phycology is the study of algae.
- Virology is the study of viruses.
Applied Microbiology
- Medical microbiology studies the relationship between micro-organisms and human health.
- Agricultural microbiology examines the relationship between micro-organisms and the environment.
- Industrial microbiology/biotechnology focuses on the application of micro-organisms in industry.
- Food microbiology investigates the relationship between micro-organisms and food.
Food Microbiology
- Food microbiologists need to understand microbial structure, classification, and identification of micro-organisms.
- They must also know how micro-organisms grow, the factors that influence growth, and how growth can be controlled.
- Food microbiologists should be aware of microbial nutrition and how to culture micro-organisms in a laboratory.
- The discipline of food microbiology emerged in the 1800s, with pioneer work by Schwann and Pasteur.
Microorganisms and Food
- Protozoa and algae have minimum direct impact on food production, processing, and consumption.
- Algae are used to produce alginates and have potential for use in single-cell protein production.
- Some marine algae species produce toxins that can enter the food chain through seafood.
Importance of Microorganisms in Food
- Micro-organisms play a role in food bioprocessing, food-borne diseases, and food spoilage.
Useful Bacteria in Food Processing
- Acetobacter sp. is necessary for vinegar production and causes spoilage in the wine industry.
Classification of Microorganisms
- By water activity requirement: halophillic bacteria, osmophillic yeasts, and xerophillic fungi.
- By nutrient degradation capacity: proteolytic, lipolytic, sacchrolytic, and pectinolytic microorganisms.
- By staining: Gram-positive and Gram-negative bacteria.
Growth of Microorganisms
- Growth of microorganisms in food is dependent on various parameters.
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Description
Explore the classification of microorganisms based on their requirement of water activity, including halophilic bacteria, osmophilic yeasts, and xerophilic molds. Understand the growth preferences of these organisms and their adaptation to different environmental conditions.
