91C-2 |
Combined blanching and vacuum impregnation for enhancing calcium fortification in mushroom tissue |
C. Ortíz, D. M. Salvatori, and S. M. ALZAMORA. Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Segurola 3842, Piso 2, "D", Villa Devoto, Buenos Aires, 1419, Argentina Vacuum impregnation process (VI) has been recently proposed to introduce physiologically active components in highly porous tissues in order to develop functional foods. Blanching prior to VI may enhance matrix impregnation capabilities (i.e. tissue permeability, pore accessibility), although some of the mass transfer mechanisms occurring throughout the different stages may be modified. In mushrooms, shrinkage and loss in weight have been a major problem during thermal processing, making the product easily affected by the opposite flows characteristic of VI: the removal of native liquid during vacuum and the external solution uptake. The objective of this work was to study the feasibility of VI with previous blanching in the development of mushroom fortified with calcium, on the basis of matrix transport properties. VI was conducted at room temperature by immersion of cylindrical samples in agitated isotonic salt aqueous solutions (5.88 % p/p calcium gluconate and lactate salts). A pulse of 15 min was applied at a pressure of 50 mmHg and then atmospheric pressure was maintained for 15 min. For blanching, samples were immersed in saturated vapour (1 and 2 min) or in water with forced convection (2 min at 60, 85 and 100 °C) and then cooled in the impregnation solution. At the end of each stage, samples were analysed for impregnated liquid fraction, calcium content and volume changes. The results showed that, in spite of the significant mass loss and sample deformation, it was possible to incorporate calcium during VI, as well as during cooling stage. Of all blanching procedures studied, only water immersion for 2 min at 100 ºC provoked a significant increase in final calcium concentration when compared to VI without previous blanching (47 % vs. 30 % RDA). These results suggest that blanching in boiling water may be used to enhance impregnation capabilities of mushroom tissue.
Session 91C, Food Engineering: Food process engineering
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