TAILOR-MADE POROUS SOLID FOODS

A method of controlling the porosity of cellular solid foods and its d ependence on solids content were investigated. Freeze-dehydration of c old-set alginate gels was used to produce tailor-made porous solids. G els were composed of sodium alginate, corn starch, oil and other addit ives necessary to induce gelation. Porosity values were derived from p article and bulk densities utilizing a helium pycnometer and a volumet ric displacement method. To achieve a wider range of porosities, the g els were immersed in sucrose solutions of 10 to 60 degrees Bx. Gel por osity after drying decreased from 0.85 to 0.42 and 0.07 after immersio n in the 30 and 60 degrees Bx solution for 183 and 158 h, respectively . Similarly, after immersing gels containing an additional 5% soy oil, porosity decreased to 0.36 and 0.04 after 165 and 158 h, in 30 and 60 degrees Bx solution, respectively. Preparation and formulation play a significant role in porosity, and they can both be utilized to contro l its value within the range 0.85-0.04. SEM micrographs revealed chang es in the original cellular solid, characterized by numerous large voi d spaces, to a denser and more uniform appearance of the specimen afte r immersion in the 60 degrees Bx sucrose solution. The dry gel system with controlled porosity provides a novel tool for the production of t ailor-made cellular-solid foods.