pulsed vacuum acidification (PVA) to improve the rate of pH reduction of Zucchini was studied. Two pressures at 400 mbar and 200 mbar maintained for a vacuum period of 2 to 5 min before the restoration of atmospheric pressure, were applied. Results stated that PVA may be used to significantly increase the rate of hydrogen ions diffusion into zucchini due to the increase of acid solution-vegetable tissue contact area. The study of the response of vegetable tissue confirmed the importance of the initial vacuum pulse on total, gas and liquid volume changes. The results suggested the low rigidity of zucchini tissues and highlighted the differences in terms of porosity reduction due to the impregnation level and the compression of pores at both the vacuum pressure studied. The remaining void fraction after PVA was in agreement with a greater impregnation at high vacuum pressure leading to a greater acidification rate.
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