Measurement of microstructural changes promoted by ultrasound application on plant materials with different porosity

[Display omitted] •Ultrasound effects in samples of varying porosity and microstructure were evaluated.•Ultrasound had no significant effect on the cell size of eggplant (highly porous).•Apple (medium porosity and largest cells) was the most affected by ultrasound.•All samples showed larger cells after sonication in the vegetable juice.•Generally, ultrasound provoked cell swelling and disruption. This research investigated the effects of ultrasound application (192 ± 6 W/L) on the microstructure of vegetables/fruits with different porosities, cell sizes and patterns (eggplants, beetroots, and apples), submitted to an immersion treatment in different liquids: distilled water, citric acid (1% w/v), and the vegetable/fruit juice, at 25 °C during 5 min. The ultrasound application did not significantly (p > 0.05) affect the size of the cells of the most porous material (eggplant) compared to the samples immersed without ultrasound assistance. The apple samples (with a middle-high porosity and the largest cells) were the most affected by ultrasound application. The median cell areas of samples treated with ultrasound in water and apple juice were 26 and 20% larger than those of samples treated without ultrasound, mainly because of cell wall disruption which caused the cells to merge into bigger clusters, but no effect was observed with the citric acid. Ultrasound application significantly (p