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A method of controlling the porosity of cellular solid foods and its dependence on solids content were investigated. Freeze‐dehydration of cold‐set alginate gels was used to produce tailor‐made porous solids. Gels were composed of sodium alginate, corn starch, oil and other additives necessary to induce gelation. Porosity values were derived from particle and bulk densities utilizing a helium pycnometer and a volumetric displacement method. To achieve a wider range of porosities, the gels were immersed in sucrose solutions of 10 to 60 8Bx. Gel porosity after drying decreased from 0.85 to 0.42 and 0.07 after immersion in the 30 and 60 8Bx 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 8Bx solution, respectively. Preparation and formulation play a significant role in porosity, and they can both be utilized to control its value within the range 0.85–0.04. SEM micrographs revealed changes in the original cellular solid, characterized by numerous large void spaces, to a denser and more uniform appearance of the specimen after immersion in the 60 8Bx sucrose solution. The dry gel system with controlled porosity provides a novel tool for the production of tailor‐made cellular‐solid foods.

The structural and mechanical properties of alginate-starch gel after immersion in sucrose solution was determined. The concentration of the sucrose in the center of the specimen increased exponentially with time. This immersion generally resulted in decreased volume and weight of the wet gels, followed by an increase in relative density of the dried samples and a decrease in their porosity. The population of open and closed pores within the structure of the dried gels was determined, revealing the presence of closed pores, especially at the intermediate time after the beginning of diffusion and before its termination. Compression of the dry gels showed dependency of the strength and brittleness on sucrose diffusion time.

Increasing consumer interest in texture has made it of primary concern in product development, since manipulating texture can provide product differentiation. Successful development requires both comprehensive understanding of texture as perceived by the consumer, and appropriate measurement methods. Perceived texture results from an array of sensory inputs, arising before and during consumption. Sensory analysis methods provide means to express such percepts, but can be time-consuming and expensive. There are relationships between physiological parameters measured in individuals during food consumption, and perceived texture. Such measures can provide simple and rapid indices of texture, if validated before use, as routine tools in product development applications.

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A cellular alginate solid containing oil was prepared by freeze-drying. The oil was incorporated in the matrix by emulsification in the pre-gel state. The alginate-oil gels were immersed in 60 degrees Brix sucrose solution for various periods, before freeze-drying. The extent of the collapse expressing the reduction in sample volume was affected by immersion duration and freeze-drying conditions. Sucrose diffusion during immersion followed an exponential pattern. Effective diffusivity calculated using nonlinear regression gave a value of 3.64 x 10(-)(10) m(2)/s. The effect of relative humidity on water content calculated on a dry basis excluding sucrose showed a significant increase in water content at 75% RH. Image analysis was utilized to quantify the area of the encapsulated oil droplets. The area of the droplets was divided into four subregions defined as (0.02-0.1) x 10(-)(12), (0. 1-1.0) x 10(-)(12), (1-10) x 10(-)(12), and (10-100) x 10(-)(12) m(2). A distribution resembling a Gaussian bell distribution with a maximum of 54% for the (1-10) x 10(-)(12) m(2) area range was found. The number of oil droplets was almost constant for the first three area regions, and then decreased markedly. Oxidation index was not effected by porosity at 0 and 22% RH. A 75% RH and porosity above a critical value of ca. 0.45 was found to increase oxidation significantly. Samples immersed for less than 5.5 h in sucrose solution were mechanically stronger after equilibration at 0 and 22% RH when compared to their counterpart equilibrated at 75% RH. Immersion for more than 24 h resulted in similar mechanical strength irrespective of the RH.