Effect of Vacuum Impregnation Treatments to Improve Quality and Texture of Zucchini (Cucurbita Pepo, L)

Abstract Vacuum Impregnation (VI) is a non-destructive technology, used to introduce external liquids, in the porous structures of food matrices favored by the action of hydrodynamic mechanism as promoted by pressure changes. Previous studies evidenced the potentiality to apply VI to zucchini [2] but no systematic studies have been carried out yet. Aim of this study was to investigate the effect of VI by using mixed solutions containing structuring ability components (maltodextrins, salt and CaCl2) with on quality and microstructural properties of zucchini. Slices of zucchini (0.5-cm thick) ( Cucurbita pepo, L.) were subjected to VI treatments. VI solutions with different solutes composition were investigated: maltodextrines, NaCl and CaCl2 were used to prepare single (1 solute) or mixed (2 and 3 solutes) VI solutions Samples were analysed for total solids, soluble solids, salt and [Ca] content, textural properties (shear force, relaxation test), sensory and microstructure (Cryo-SEM). Mass balance (Solute Gain/Loss, Water Gain/Loss) was also computed. The composition of the VI solution affected mass transfer. A significant change in the textural properties was observed in zucchini processed with VI solutions containing NaCl and MD; the presence of CaCl2 in the VI solution in combination with the other solutes, was able limit the hardness loss and when alone even to determine an hardening effect. Cryo-SEM analysis highlighted a different effect on microstructure of the vegetable tissue due the use of the single or mixed VI solutions. The use of VI mixed solutions made with MD, NaCl and CaCl2 to process zucchini allows to favour solute and water gain while limiting textural and microstructural change