Infusion kills milk bacteria
7 Jun 2004
A rapid heating-and-cooling system developed by Invensys APV could help manufacturers of baby milk and milk concentrates improve the control of bacterial levels in their products, the company says.
The Instant Infusion System (IIS) is said to kill a 'substantially greater number of bacteria spores' than other heat-based processes.The system uses a steam-heated infusion chamber to raise the temperature of the product from 55-75 degrees C to 140 degrees C within 0.2 seconds.
Milk enters the top of the chamber, which is under vacuum to ensure maximum heat transfer, after preheating in a heat exchanger, and is dispersed in a circular pattern through a delamination nozzle. This prevents the product from atomising into tiny droplets. Steam is pumped into the chamber from the side, moving towards the centre by laminar flow, and condenses into the product, raising the temperature.
This prevents uncontrolled homogenisation, says Invensys. The hot product comes into contact with the lower part of the infusion chamber, which is cooled by a water jacket, generating a thin film of condensate which prevents product fouling.
The hot product then flows into a rotary holding cell containing a gear pump, which holds the product at the required temperature for less than half a second. Leaving this section, it enters a vacuum chamber, which strips out the steam to a condenser.
The product can then be pumped to a spray drier or heat exchanger for final cooling.
Invensys has already had much interest in the process, with companies in the Czech Republic, China, Vietnam, Denmark, Germany, Switzerland and the UK all committed to using it.
