PEF for vegetable products
Product examples: Vegetable puree, pre-cut vegetables, roots, dryed sweet peppers, peeled tomatoes, vegetable juices and smoothies
Aim PEF treatment: Cell disintegration, stress induction, improved peeling and extraction efficiency, drying enhancement, microbial inactivation, prolonged shelf life
Tomato peeling and extraction
The physical treatment with pulsed electric fields at ambient temperature softens tomatoes and improves peeling efficiency. It can replace the standard thermal treatment needed before potato peeling. Compared to heat treatment PEF treatment requires less energy and reduces energy costs. Another application is lycopene extraction. Lycopene is a carotenoid pigment responsible for the red color in tomatoes. In this application PEF technology increases the extraction yield.
Targeted structural modification allows use of new raw materials. Tough and inconsistent produce like sweet potato, turnip and beet root become easily processable with PEF.
Disintegrating (softening) vegetable tissue before drying with PEF treatment improves mass transport of water. This can be used in dried sweet pepper production. The field strength of the treatment may range from 1,0 to 3,0 kV/cm and the energy delivery is 5 to 10 kJ/kg.
Broccoli & stress response
To induce formation of secondary metabolites in broccoli PEF might also be used. In this application the field strengt is rather low: 0,1 – 0,5 kV/cm. The energy delivery is 0,1 – 1,0 kJ/kg.
- Nutritional enrichment with secondary metabolites due to stress induction on plant cells
- Targeted and controlled vegetable tissue modification
- Enhanced product handling by tissue softening
- Improved peeling and cutting
- Increased process capacity
- For vegetable juice production PEF results in greater extraction and refining yields, longer shelf life, higher process efficiency by large reductions in energy, labor and running costs
- Vitamins, minerals, pigments, antioxidants, flavors and colors are retained producing a healthier, fresher and more appetizing final product
- Proteins are hardly affected
- Extended shelf life results in greater flexibility for production planning
- Continuous process and rapid technique
- 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, peeling, cutting and drying 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.