Pasteurisation and sterilisation
Pasteurisation of liquid products in the tube
Fluidised and liquid product industries are increasingly adopting continuous pasteurisation and sterilisation processes using heated plate, tubular or scraped surface heat exchangers followed by cooling and aseptic filling. Slow and uneven heating, over-processing of part of the liquid and crusting (fouling) are typical problems in these equipment which rely on conventional heat transmission methods.
All these problems can be eliminated by using Stalam’s “RF/L” equipment, which has been specifically designed for the continuous pasteurisation and sterilisation in the tube of liquids and other fluidised (i.e. pumpable) products, even with suspended particulates. The “RF/L” system ensures high productivity and energy efficiency levels, outstanding product quality, full guarantee of inactivation of micro-organisms with the minimum possible modification of the product sensorial and physical-chemical characteristics.
There are several leading European food processors who have for a number of years successfully run production lines incorporating Stalam “RF/L” equipment with a typical throughput of 2,000 kg/h.
How it works
The fluid substrate to be treated is continuously pumped through one or more tubes made of a food-grade RF-transparent material and having a suitable diameter according to the specific product. The tubes are placed between especially designed electrodes (these are also different according to the tube diameter and the physical characteristics of the product). The product passing through the tubes is directly heated by the RF field, based on the well known principle of dielectric losses. The intensity of the electromagnetic field, and the consequent heating rate, are controlled by means of a variable capacity coupling circuit. Heating rates from 1 - 2°C/sec (for highly viscous liquids containing suspended solids) up to 50 - 100°C/sec (for low-viscosity liquids with no particulates) are possible, depending on the characteristics of the product. The temperature set point required for pasteurisation or full sterilisation can be reached and controlled with an accuracy of +/-0.5°C.
Stalam can supply the “RF/L” equipment as a stand-alone unit to be fitted in existing production lines, or can provide the entire processing technology, from product feeding to cooling and aseptic filling, complete with CIP system, pigging system, and all necessary ancillary equipment, based on specific customer requirements.
Minimal thermal treatment, better quality, safer product
The rapid and uniform temperature increase within the product, also in the suspended particulates of any size, eliminates the risk of under- or over-processing. The microbial inactivation is performed at lower temperatures and in a shorter time compared to conventional thermal processes. Moreover, a better preservation of the sensorial, chemical and physical characteristics of the product is achieved, with reduced use of additives such as colours, flavours, thickeners, etc. normally used to compensate for product degradations caused by conventional thermal processes.
Fast and flexible process
The Stalam equipment allows an instantaneous heat input, an accurate process control, a high operational flexibility. The equipment can be fitted with a CIP system and with a PIG system for in-line change and recovery of the product, making it very suitable also for small and medium size product batches. The equipment sterility can also be easily maintained in stand-by conditions.
Floor space saving modular system
Multiple RF/L units can be installed in-line to achieve higher production capacities. A reduced factory floor space is required for the whole process, thanks to the small size of each unit.
Minimum maintenance required
Easy cleaning, no crusting (fouling) effect thanks to no contact with any heating element, and low maintenance costs.