Effect of osmotic dehydration on the quality of air-dried Porphyra.

VALENCIA RODRÍGUEZ T., ROJAS A.M., CAMPOS C.A. Y GERSCHENSON L.N.

LEBENSMITTEL-WISSENSCHAFT UND-TECHNOLOGIE-FOOD SCIENCE AND TECHNOLOGY

Academic Press-ELSEVIER Sci. Ltd. Institut fur Lebensmittel-und Emahrungswissenschaften.

Lugar: ETH-Zentrum, CH-8092 Zurich, Suiza.; Año: 2003 vol. 36 p. 415 - 422

0023-6438

Abstract: Osmosis with a solution of NaCl and sucrose to depress the water activity (aW) to 0.970 and the pH to 3.0 was assayed as a pre-treatment to air-drying of red seaweeds (Porphyra columbina Montagne). Air-drying was performed at 30°C and 14%-relative humidity. Process characteristics, colour and flow pattern and rehydration ability of the milled product, were evaluated to determine the usefulness of osmosis. The aW attained after 2 h of drying was similar to both osmosed and noosmosed Porphyra and higher than monolayer water activity for both products. Consequently, no additional benefits concerning stability during storage were observed, after applying osmosis. Moreover, severe changes in colour occurred. Powder flowability evaluated through the measurement of compressibility and cohesiveness decreased with pre-treatment, which also determined a more plastic behavior. In summary, osmotic dehydration as a pre-treatment for air-drying seaweeds did not seem to improve the final product quality.