Food shelf life: how packaging extends it

What causes food deterioration

The three main deterioration agents are microorganisms (bacteria, moulds, yeasts), oxygen (fat oxidation, colour change) and physical changes (moisture loss, crystallisation, structural collapse). Effective packaging acts on all three.

• Aerobic bacteria: growth inhibited without O₂ (vacuum) or with high CO₂ (MAP)
• Lipid oxidation (rancidity): eliminated by vacuum, slowed by N₂
• Myoglobin oxidation: managed with controlled O₂ in MAP
• Moisture loss (dehydration): high water vapour barrier film
• Cross-contamination: airtight pack = complete physical barrier

Shelf life comparison by product and technology

The following data refers to optimal refrigeration conditions (+2/+4°C) and maintained cold chain. Any cold chain interruptions drastically reduce these projections.

• Fresh beef: 2 days (air) → 14-21 days (vacuum) → 10-14 days (MAP)
• Salmon fillet: 1-2 days → 8-12 days (vacuum) → 12-18 days (VSP)
• Sliced cooked ham: 3-5 days → 30-40 days (MAP)
• Fresh mozzarella: 3-5 days → 20-30 days (MAP with CO₂/N₂)
• Refrigerated ready meal: 2-3 days → 14-20 days (MAP + pasteurisation)

How to validate shelf life: tests and methods

Declared shelf life must be validated with real or accelerated tests. Real tests include microbiological analyses (total bacterial count, E. coli, Listeria) and sensory analyses (colour, smell, texture) at defined intervals until expiry.

Before launching a new packaged product, at least 3 complete shelf life tests on representative batches of normal production must be carried out.

• Microbiological analysis: every 5-7 days during the test
• Sensory analysis: panel test with 5-10 evaluators
• Seal integrity test: immersion in water with tracer dye
• Residual O₂ measurement: gas chromatography or optical sensors