29D-26 |
Calcium impregnation effects on structural properties of blanched mushroom tissue |
C. Ortíz1, D. M. SALVATORI1, M. A. Castro2, and S. M. Alzamora3. (1) Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Segurola 3842, Piso 2, "D", Villa Devoto, Buenos Aires, 1419, Argentina, (2) Departamento de Biología, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Nuñez, Buenos Aires, 1428, Argentina, (3) Departamento de Industrias, Facultad de Ciencias Exactas y Naturales - Universidad de Buenos Aires, Santa Maria 300. Tortuguitas, Buenos Aires, 1667, Argentina Calcium impregnation of mushroom may be achieved by means of vacuum impregnation process (VI). Blanching can facilitate solute penetration by acting on membranes and/or cell wall permeability, although changes in structure can affect calcium transport and textural properties of final product. The objective of this work was to evaluate tissue behaviour upon calcium impregnation with previous blanching and to correlate these changes with mechanical properties and calcium distribution in the tissue. VI experiments were carried out at room temperature by immersion of cylindrical samples in agitated isotonic salt aqueous solutions (5.88 % p/p calcium gluconate and lactate salts). A vacuum pressure (50 mmHg) was applied for 15 min of and then atmospheric pressure was maintained for 15 min. For blanching, samples were immersed in water with forced convection (2 min, 100 ºC) and cooled in the impregnation solution. At the end of each stage samples were analyzed for impregnated liquid fraction, calcium content, texture (compression text) and structure (light microscopy). The results indicated that VI, with and without previous blanching, as well as blanching per se would have an important deteriorative effect on textural characteristics (drop of tissue resistance to compression). Treatments produced citoplasmolysis, disruption of cellular membranes, loss of turgor and collapse of cells, which would have contributed to global volumetric shrinkage (ranging between 19 % and 58 % according to the treatment applied). Alterations produced by heating would favour matrix liquid loss during vacuum stage, which would imply a great availability of matrix to external solution in-flow into the pores, as well as into the lumen. This liquid exchange would explain the high final calcium content in previous blanched samples (3800 ppm) as compared to samples only vacuum impregnated (2400 ppm). The results suggest that blanching could significantly increase the impregnation capacity of mushroom tissue.
Session 29D, Food Engineering: Thermal processes
|