ABSTRACT
Vacuum impregnation (VI) technologies have been explored in many elds, including foods and nonfoods. Its application in foods has been enlightened due to the expanded exploration of food properties from the macroscopic level to the microscopic and mesoscopic levels. The study of fruit microstructure describes (1) microscale as individual cells (cell walls, cell membranes, internal organelles, intracellular spaces/voids, etc.); (2) meso-scale as tissues (similar cells with specic functions, intercellular substances and spaces, etc.); and (3) macro-scale as whole foods (color, texture, avor, taste, concentration of functional compounds, etc.) (Mebatsion et al. 2008). The knowledge of microscopic and mesoscopic properties of foods suggests applicability of promoting mass transfer/diffusion of substances through cells/tissues under controlled vacuum pressure. Especially, the discovery of voids (e.g., intercellular and intracellular spaces, capillaries, and pores), that contain native gases and/or liquids ensures usefulness of vacuum pressure for substance impregnation into foods. Proper vacuum management can manipulate the voids to release native gases, water, and liquids, and take in an external liquid through permeable tissues, cell walls, and/or membranes. Utilization of forced vacuum pressure significantly increases mass transfer rate of native and external fluids (Fito et al. 2002).
