Microbiological Indicators, Food Preservation, and HACCP Principles in Food Safety

Microbiological Quality Indicators

Microorganisms used to assess the safety and quality of food.

Importance of microbiological indicators

They help detect hazards, measure freshness, meet food safety standards, and protect consumers.

Three main types of indicators

Indicator organisms, spoilage organisms, and pathogenic microorganisms.

E. coli

Indicates fecal contamination.

Coliforms

Indicate poor sanitation or hygiene.

Staphylococcus aureus

Causes food poisoning from improper handling.

Listeria monocytogenes

Linked to ready-to-eat foods.

Psychrotrophic bacteria

Cause spoilage in refrigerated foods.

Yeasts and molds

Cause off-flavors, discoloration, and reduced shelf life.

Methods to test for microorganisms

Culture methods (selective media) and molecular methods (PCR, DNA sequencing).

Goal of food preservation

To prevent spoilage, extend shelf life, and maintain quality.

Pasteurization

Mild heat (60-85°C) to kill pathogens. Example: Milk at 72°C for 15 seconds.

Sterilization/canning

High heat (≥121°C for 15 min) to destroy all microbes. Prevents: Clostridium botulinum.

Blanching

Brief heating (90-100°C for 1-5 min) to inactivate enzymes before freezing vegetables.

High Pressure Processing (HPP)

Uses 100-600 MPa pressure to kill microbes without heat.

Pulsed Electric Field (PEF)

Uses electric pulses to damage cell membranes (good for liquids).

UV-C treatment

Uses 200-280 nm light to damage microbial DNA.

Food irradiation

Uses gamma rays/X-rays to kill insects and pathogens (used on meats and spices).

Chemical preservatives

Inhibit spoilage and microbial growth.

Examples of organic acid preservatives

Benzoic acid and Sorbic acid (stop yeast & mold).

Nitrites

Prevent Clostridium botulinum in cured meats.

Sulfites

Prevent browning and oxidation.

Examples of natural preservatives

Salt, sugar, vinegar, essential oils.

Hurdle technology

Combining multiple mild preservation methods (e.g., smoked & salted fish).

HACCP

A preventive food safety system that controls biological, chemical, and physical hazards.

Government agencies requiring HACCP

FDA (for juice) and USDA (for meat and poultry).

Supporting programs with HACCP

GMPs, SSOPs, and personal hygiene programs.

Principle 1 - Hazard Analysis

Identify possible hazards (biological, chemical, physical).

Principle 2 - Identify Critical Control Points (CCPs)

Find points in the process to eliminate or reduce hazards.

Principle 3 - Establish Critical Limits

Set measurable limits like temperature, time, or pH. Example: Cook poultry to 165°F.

Principle 4 - Monitor CCPs

Decide how, when, and who checks if limits are met.

Principle 5 - Establish Corrective Actions

Actions taken if a CCP goes out of control (e.g., reheat, discard).

Principle 6 - Record Keeping

Keep logs for hazards, monitoring, and corrective actions.

Principle 7 - Verification

Confirm the system works through audits or testing.

Importance of HACCP in food microbiology

Prevents microbial contamination and foodborne illness.

Main focus of HACCP

Prevention instead of end-product testing.

Benefit of HACCP recordkeeping

Ensures traceability and verifies food was produced safely.