Evaluation of plant tissue structures subjected to the pulsed electric field using optical coherence tomography

The pulsed electric field (PEF) is one of the non-thermal methods used in the food industry for prolonging food suitability or obtaining better quality end products. The structure of fruit and vegetable tissues subjected to PEF treatment changes under the influence of short-term high voltage electrical impulses. In this process, the hydrophilic spaces in the cell membranes occur. The authors present the results of the assessment of structural changes in fruits subjected to PEF, using the textural analysis of sub-peel layers. The images were obtained by optical coherence tomography (OCT) at an infrared wavelength of 1300 nm. The OCT cross-sections revealed the zone of strong infrared light reflection from internal structures indicating the loss of parenchymatic tissue integrity. The intensity of these changes depended on fruit type and used parameters of PEF. The OCT method can be used to assess noninvasively the suitability of fruit for further stages of processing, e.g. in PEF assisted pressing of fruit juice.