Food Microbiology & Safety Program

Applied Microbiology for Food Safety Program: Food Microbiology

• Food microbiology is the study of microorganisms inhabiting, creating, or contaminating food.
• Food microbiology includes microorganisms causing food spoilage, pathogenic microbes transmitted via food, microorganisms used in food production, and microorganisms with beneficial roles like probiotics.

Food Spoilage

• Food spoilage is the process leading to a product becoming undesirable or unacceptable for human consumption.
• Changes in taste, smell, appearance, texture, flavor, and stability of the food can occur.
• Spoilage can also sometimes cause the food to become toxic.

Food Poisoning

• Food poisoning, also known as foodborne diseases, is an illness caused by consuming contaminated food containing pathogens (bacteria, molds, or viruses) or their toxins.
• Common signs and symptoms include nausea, headache, diarrhea, fever, abdominal cramps, and dizziness.
• Food poisoning includes foodborne intoxications and foodborne infections.

Foodborne Intoxications vs Foodborne Infections

• Food intoxication results from ingesting toxins produced by bacteria already present in the food.
• Food infection results from consuming food contaminated with live bacteria that multiply in the body and produce toxins.

Benefits of Microorganisms in Food

• Microorganisms can be beneficial, not just harmful.
• Beneficial effects include fermentation (production of metabolites such as organic acids, antibiotics) and fermented food products like cheese, yogurt, and fermented sausages.
• Other benefits include digesting food, destroying pathogens, producing vitamins, single-cell protein, and producing probiotics.

Single Cell Protein (SCP)

• SCP refers to dead, dry cells of microorganisms (like yeast, fungi, bacteria, and algae).
• SCP offers nutritional value in protein, vitamins, fats, and minerals.
• A need for SCP arises in solving global food scarcity and relieving agricultural sectors.
• SCP technology isn't affected by climate, high growth rate, and substrate flexibility.

Selection Criteria for Microorganisms in SCP Production

• Microorganisms used for SCP production must have high protein and nutritive value.
• They should be non-toxic and non-pathogenic.
• They should be able to utilize different carbon and nitrogen sources.
• They should tolerate moderate growth conditions, pH, temperature, and mineral concentrations.
• They should be resistant to viral infection.

Microorganisms Used in SCP Production

• Algae, cyanobacteria (like Spirulina and Chlorella), yeasts (like Saccharomyces and Candida), molds (like Aspergillus, Trichoderma, and Penicillium), and bacteria (like Bacillus and Lactobacillus) are potential candidates.
• Each group has specific advantages and disadvantages in terms of odor, taste, nutrient content, and yield.

SCP Production Processes

• SCP production typically involves fermentation, screening of potent strains, cultivation, separation, and purification, and drying.
• Methods of fermentation include submerged fermentation (SmF), solid-state fermentation (SSF), and semi-solid fermentation.

Submerged Fermentation (SmF)

• Microorganisms are cultivated in a liquid medium (more than 95% water).
• A bioreactor is typically used for cultivation.
• Critical parameters include aeration, pH control, temperature, and agitation.
• Types of SmF operation include batch, fed-batch, and continuous.

Solid-State Fermentation (SSF)

• Cultivates microorganisms on a solid substrate (like rice, wheat bran) at a specific moisture content.
• A temperature-controlled environment is used.
• The process is usually batch.

Problems Associated with SCP Technology

• High nucleic acid content in some types of SCP.
• Potential for indigestible microbial cell walls.
• Production of unfavorable colors and flavours.
• Slower growth rates and higher contamination risks found in some microbial types.

Probiotics

• Probiotics are live microorganisms that confer health benefits to the host when administered in sufficient amounts.
• Common probiotic microorganisms include lactic acid bacteria (like Lactobacillus and Bifidobacterium), and yeasts (like Saccharomyces boulardii).

Prebiotics

• Prebiotics are non-digestible food ingredients that selectively stimulate the growth and/or activity of one or a limited number of bacteria in the colon, thus improving host health.
• Common examples include fructo-oligosaccharides and galacto-oligosaccharides.

Synbiotics

• Synbiotics combine prebiotics and probiotics, offering synergistic benefits from both components.

Postbiotics

• Postbiotics are products derived from the action of prebiotics or probiotics that offer health benefits similar to probiotics.

Types of Microorganisms Used as Probiotics

• Various types of microorganisms, including lactic acid bacteria, non-lactic acid bacteria, and yeasts, are utilized as probiotics.
• The use of several specific species and types of microbes is discussed.

Mode of Action of Probiotics

• Probiotics exert their effects through mechanisms such as competitive exclusion, pathogen adhesion inhibition, production of antimicrobial substances, and modulation of the immune system.

Detailed Mechanisms of Probiotic Action (Diagram-based)

• Various diagrams illustrate the impact of probiotics on the gut lumen, intestinal barrier, and interactions between probiotics, gut microbiome, and the immune response.

Explore the fascinating world of food microbiology, which examines microorganisms that affect food safety. Understand how these microbes can cause food spoilage and food poisoning, as well as their beneficial roles in food production. This quiz will test your knowledge on key concepts in food microbiology.