PEF for Fruit Treatment

Product Examples: Fruit compote, fruit puree, pre-cut fruits.

Aim of PEF Treatment: Microbial inactivation for increased shelf life, cell disintegration, and structure modification for enhanced extraction and refining efficiency.

Cold Fruit Extraction

PEF treatment applied to solid whole fruits results in tissue softening through the permeabilization of cell membranes. This softening enhances subsequent fruit extraction at ambient temperature, beneficial for producing purees and compotes from fruits like mango, apricot, peach, and apple, as well as for juice production. The enhanced extraction process also leads to higher refining yields and cost reduction. Cold refining processes are advantageous in terms of product quality and retaining vitamins, flavor compounds, antioxidants, pigments, and overall freshness. Necessary field strengths for enhancing mass transport and juice release range from 1.0 to 3.0 kV/cm, with energy delivery of 3 to 10 kJ/kg.

Structure Modification of Strawberry

PEF treatment applied to strawberries leads to tissue softening by reducing turgor pressure. Required field strengths are between 0.5 and 1.0 kV/cm, with energy delivery ranging from 0.5 to 5.0 kJ/kg.

Shelf Life Increase

Increasing the shelf life of liquid fruit products like purees, juices, and smoothies requires higher field strength and energy input for PEF treatment, specifically 10 to 20 kV/cm and 50 to 120 kJ/kg.

Other Fruit Applications

Sterilization of Low Acid Products

Sterilization of low acid products like banana and kiwi puree to prevent color change and inactivate spores and enzymes. For instance, standard thermal treatment of these purees at 130-135°C (266-275°F) causes color changes to pink for banana and brown for kiwi at 90-95°C (194-203°F). Product and process improvements are achievable by using lower temperatures followed by PEF treatment in less than a second.

Benefits of PEF

  • Targeted and controlled structure modification.
  • Enhanced product handling due to tissue softening.
  • Improved extraction and refining.
  • Increased process capacity.
  • For fruit juice production, PEF results in higher extraction and refining yields, longer shelf life, and higher process efficiency with significant reductions in energy, labor, and running costs.
  • Retention of vitamins, minerals, pigments, antioxidants, flavors, and colors, producing a healthier, fresher, and more appetizing final product.
  • Minimal impact on proteins.
  • Extended shelf life enhances flexibility in production planning.
  • Continuous process and rapid technique.
  • Compact equipment footprint and quick process startup.
  • Low energy requirements.

More Information

Limitations

For microbial inactivation in liquids, PEF is applicable to pumpable products with a particle diameter of less than 20 mm. The shelf life is comparable to that of thermally pasteurized foods.
For cell disintegration (tissue softening) to enhance extraction and refining efficiency, there are no size limitations for the raw products.

Equipment

Pulsemaster has developed industrial-scale equipment, named Conditioner, with treatment capacities up to 5,000 liters per hour (1320 US gallons per hour) for microbial inactivation and up to 50,000 kg/h (110,000 lb/h) for cell disintegration.

Costs

On a commercial scale, total costs are expected to be around 1 Euro/ton (0.1 Eurocent per liter or kg) for plant cell treatment and 10 Euro/ton (1 Eurocent per liter or kg) for microbial inactivation. In US dollars, this equates to approximately 0.056 US Dollarcent per lb for plant cell disintegration and 4.92 US Dollarcent per gallon for microbial inactivation of liquids.

PEF + Fruit Products?