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August 1, 2022
It has been well over a decade now since a representative of Elea Technology, based in Quakenbrück Germany, came to visit Vincent Corporation. He sent from Germany a small Pulsed Electric Field (PEF) demo unit. The purpose of his visit was to illustrate the advantages of PEF treatment of fruits and vegetables prior to running them through our screw presses.
PEF technology is based on the principal of electroporation (also referred to as electropermeabilization). Exposure of biological cells to pulses of a high voltage electrical field causes openings to form in the cell membrane. Water and soluble solids exit the cell through these new pores, but larger solids (such as starch) remain in the otherwise undamaged cell structure. In the case of fruits and vegetables, a water bath is generally used as the conducting medium.
One of the better illustrations of PEF’s advantages is in potato processing, specifically the production of french fries. In the absence of PEF, potatoes are thermally preheated in a hot water bath for the purposes of softening the potato prior to cutting. With this process it is difficult to heat all the way to the center of the potato without cooking the outside. Replacing this step with a PEF unit has two primary advantages: up to a 90% reduction in energy consumption and a uniformly softer potato.
A good part of the energy savings is as a result of lower boiler operating costs. Additionally, PEF treatment increases heat transfer thus reducing pre-fryer blanching, drying, and frying times.
The softer potato results in a smoother surface on the cut fries, producing higher yield due to less starch loss and fewer fines at cutting. It also significantly reduces knife wear, and less breakage produces longer fries. Reduced oil uptake during the par-frying step, resulting in less make-up oil required, is yet another benefit.
Last year a test was conducted at Food Physics (Elea’s U.S. agent) in Boise, ID with a Vincent CP-4 screw press. Sugar beets were triple-pressed. Yield prior to PEF treatment was 40%, increasing to 60% with PEF treatment. Measured Brix (sugar content) of the juice dropped slightly, but not statistically significantly.
Other applications for PEF technology include inactivating harmful bacteria to extend shelf life (like juice pasteurization), stimulating the growth of beneficial bacteria, and conditioning product prior to freeze drying (resulting in brighter color and a more natural flavor). This technology has also been recommended to processors of seaweed, algaes, and similar aquatic plants used in the production of hydrocolloid food ingredients.
ISSUE #344