PEF treatment of beverages
Product examples: Smoothies, smoothie purees, fruit juices, vegetable juices and other beverages.
Aim PEF treatment: Microbial inactivation, cell disintegration, enhancement of extraction and refining efficiency, shelf life prolonging
By permeabilizing cell membranes of micro-organisms PEF enables a targeted shelf life increase, retaining product quality and freshness. For preservation of juices a field strength of 10-20 kV/cm and energy delivery of 50-120 kJ/kg is appropriate. The shelf life of cold pasteurized drinks is comparable to that of thermally pasteurized foods. Challenges: enzymes are not fully inactivated after PEF treatment.
Sterilization by a combined heat and PEF treatment is also possible. Challenges here are the effect on enzymes, spores and aseptic filling. (See also: Enzymes)
Low acid products
Sterilization by combined heat and PEF treatment can be used in low acid products like banana and kiwi puree to avoid color change and to inactivate spores and enzymes. For example, a standard thermal treatment of these purees is at 130-135°C (266-275 F); due to this temperature the puree color changes to pink for banana and to brown for kiwi at 90-95°C (194-203 F). Product and process can be improved by using a lower temperature followed by PEF treatment in less than a second.
Fruit extraction enhancement
Application: fruit extraction to obtain purees from fruits like mango, apricot, peach and apple. See: solids/ fruit products.
- Longer shelf life without the drawbacks of thermal pasteurization
- Vitamins, minerals, pigments and flavors are retained
- Healthier, fresher and more appetizing pasteurized beverages are the result
- Proteins are hardly affected
- Continuous and fast technique
- For juice production: higher pressing yields
- Higher extraction and refining yields
- Higher process efficiency thanks to large reductions in energy, labor and running costs
- The extended shelf life results in greater flexibility for production planning
- Small equipment footprint, quick start-up of the process
- Low energy requirement
For preservation of liquids (microbial inactivation) PEF is applicable to pumpable products with a particle diameter of less than 20 mm. For cell disintegration purposes (tissue softening) to enhance extraction and refining efficiency there are no size limitations to the raw products.
Pulsemaster has developed industrial scale equipment – named Conditioner – with treatment capacities up to 5,000 l/h (1320 US gal./h) for microbial inactivation and up to 50,000 kg/h (110,000 lb/h) for cell disintegration.
On a commercial scale total costs of 1 Euro/ton (= 0.1 Eurocent per liter or kg) for treatment of plant cells and 10 Euro/ton (= 1 Eurocent per liter or kg) for microbial inactivation have to be expected. In US Dollar this is approximately 0.056 US Dollarcent per lb for cell disintegration of plant cells and 4.92 US Dollarcent per gallon for microbial inactivation of liquids.