UV-C treatment is a non-thermal process used to reduce the microbial load on food surfaces, on packaging material and in clear liquids. Because the light penetrates only a few millimetres, it is a surface treatment: it complements, rather than replaces, hygiene management. In the United States the use of UV on food is permitted under 21 CFR 179.39 with a maximum energy of 0.5 W per square metre at 253.7 nm.
UV-C is effective on exposed surfaces and in optically clear liquids. It cannot reach inside a solid food or under a fold of packaging film, so 'sterilisation' is only achieved where the light actually arrives.
UV is placed on conveyor belts before filling, in laminar-flow hoods, on cup and lid surfaces, and in the water used for washing produce. Each position has its own required dose and residence time.
Because UV is invisible and leaves no residue, the dose must be measured. Lamps age and quartz windows soil, so periodic measurement with a calibrated meter is the only way to show that the process is still within specification.
| Food surfaces | Direct UV-C on belt | Fruit, vegetables, cheese rind |
|---|---|---|
| Food surfaces | Direct UV-C on belt | Fruit, vegetables, cheese rind |
| Packaging | Cup, lid and film treatment before filling | Dairy cups, beverage closures |
| Clear liquids | Annular flow reactors | Juice, drinking water, brine |
UV is chosen where heat would damage the product and where chemical residues are unacceptable.
Cup and lid surface treatment
Cap and closure disinfection
Wash water and surface treatment
Mould control on surfaces and air
Surface decontamination on the line
Sterile zone and film treatment
In food processing UV is used as a critical control point, so the dose delivered to the product must be documented.
| Surface dose (mJ/cm2) | Proves the CCP is still effective | UV-int140 / UV-int150 |
|---|---|---|
| Surface dose (mJ/cm2) | Proves the CCP is still effective | UV-int140 / UV-int150 |
| Lamp and reflector output | Detects ageing before the CCP fails | UV-int150 / UV-intS |
| UV-C irradiance (mW/cm2) | Checked after any lamp or reflector change | UV-intM / UV-int160 |
UV is a surface treatment; the penetration depth in most foods is well under a millimetre.
Lamps age and quartz soils; without periodic dose measurement the process silently drifts out of specification.
Roughness, shadowing and colour of the food surface all change the effective dose - flat, smooth surfaces are treated far more reliably than irregular ones.