Study on Metabolic Consequences of Vacuum Impregnation of Apple Tissue

Vacuum Impregnation in food industry is an interesting process particularly in semy-dry fruit processing. At the beginning of the process the pressure is reduced and the internal gas in the product pores is expanded and partially flows out, after that, when atmospheric pressure is restored and residual gas is compressed, the external liquid flows into the pores. Although vacuum impregnation process has been widely studied, the metabolic consequences of the vacuum impregnation with different solutions on fruit tissue are still not well understood. The aim of this work was to study the metabolic consequences of vacuum impregnation on apple tissue. In particular, the respiration rate and the possibility of vesicular transport within the cells were explored. The apple pieces were vacuum impregnated with isotonic sucrose solution. The respiration rate was measured on fresh and vacuum impregnated samples. The endocytosis marker FM 4-64 was impregnated together with the sucrose solution in presence or absence of Chloroquine. The samples were examined under fluorescent light in a Nikon upright microscope (Eclipse Ti-U, Nikon Co, Japan) equipped with a Nikon digital video camera (digital sight DS-Qi1Mc, Nikon Co, Japan) at a magnification of 4, 10 and 20 x. The respiration rate of apple pieces was lower after the vacuum impregnation process respect to untreated samples. The microscopic observation showed small vesicle formation around the plasma membrane 0.5 h after the vacuum impregnation treatment. The density of vesicles became higher during storage at 10°C, and 24h after vacuum impregnation treatment very high density of vesicles was observed giving impression that they are accumulating within the cells.