Metabolic response of organic strawberries and kiwifruit subjected to PEF assisted-osmotic dehydration

Abstract

This research aims at evaluating the effect of pulsed electric field (PEF) pre-treatment before osmotic dehydration (OD) on physiological changes in organic strawberries and kiwifruits, in terms of metabolic heat production measured by isothermal calorimeter and of tissue damage evaluated by fluorescence microscopy, texture analysis and electrolytes leakage. Fruits pre-treated at two electric field strengths (100 and 200 V/cm) using 100 near-rectangular shaped pulses (pulse width: 10 μs, repetition time: 10 ms) were subjected to OD in hypertonic solutions (40% w/w) of sucrose or trehalose, both with addition of 1 % of calcium lactate. Results showed that OD alone allowed to retain the functionality of the membranes causing only a decrease in the endogenous heat production. The application of low electric field strength (100 V/cm) generally preserved the cell viability, which was drastically reduced following OD treatment. On the contrary, the application of 200 V/cm caused tissue damage and loss of cell vitality, probably due to irreversible electroporation. Industrial application PEF could be an interesting pre-treatment for reducing time and energy necessary for the osmotic dehydration of fruits. However, it is important to understand the implication of the treatment on the tissue metabolism and structure in order to control the effect on the quality of the final product. This study provides some useful information that could be exploited for the industrial production of intermediate moisture fruit products.

Effect of the Pulsed Electric Field Treatment on Physical, Chemical and Structural Changes of Vacuum Impregnated Apple Tissue in Aloe Vera Juices

“…Apple samples subjected to PEF at 125 V/cm and vacuum impregnation showed tial preservation of cell viability, while PEF at higher intensities (212.5 or 300 V/cm) bined with vacuum impregnation led to almost complete loss of cell viability (Figu This phenomenon was observed independently of the PEF position, before or after t process. These results are in line with those obtained by Tylewicz et al [52], who in gated the effect of PEF pre-treatment at 100 or 200 V/cm on the properties of fres osmotically dehydrated kiwi fruit. The researchers observed that PEF pre-treatment V/cm led to the partial preservation of cell viability of osmotically dehydrated fruit, higher PEF intensity (200 V/cm) caused cell death [52].…”

“…These results are in line with those obtained by Tylewicz et al [52], who in gated the effect of PEF pre-treatment at 100 or 200 V/cm on the properties of fres osmotically dehydrated kiwi fruit. The researchers observed that PEF pre-treatment V/cm led to the partial preservation of cell viability of osmotically dehydrated fruit, higher PEF intensity (200 V/cm) caused cell death [52]. Similar behavior was observ the preservation of cell viability in the PEF pre-treated (100 or 200-400 V/cm) osmo drated strawberries [53].…”

Impact of pulsed electric fields (PEF) treatment on the peeling ability of tomatoes and kiwi fruits

“…The increasing energy input from 0.2 to 5.0 kJ/kg for tomatoes and from 0.6 to 12.6 kJ/kg for kiwi fruits leads to increased cell disruption up to 0.85 and 0.84, respectively. Previous studies have reported a similar relationship between PEF intensities and cell disintegration for the same investigated materials (Tylewicz et al, 2019;Andreou et al, 2020). The most intensive PEF treatments (5.0 and 12.6 kJ/kg) resulted in a CDI of 0.85 ± 0.02 for tomatoes and 0.84 ± 0.05 for kiwi fruits.…”

Characterization of Nutritional, Physicochemical, and Phytochemical Composition and Antioxidant Capacity of Three Strawberry “Fragaria × ananassa Duch.” Cultivars (“Primoris”, “Endurance”, and “Portola”) from Western Region of Portugal

“…Bearing in mind the measurement section of strawberry fruits (Figure 1), ten measurements from each sample group were taken. The texture was determined according to the modified method described by Tylewicz, Tappi, Genovese, Mozzon, and Rocculi [17]. Strawberry hardness was recorded by the penetration test with a Texture Analyzer (TA.HDi, Stable Microsystem Ltd., Godalming, UK), using a load cell of 5 kg and a stainless steel cylinder probe with a 2-mm diameter.…”