a b s t r a c t
Three types of gels including tapioca starch gel, fish gel and mixed gels of both (cassava starch: fish ¼ 1:1)
were prepared under different thermal conditions. Slices (4 mm thick) derived from these the gels were
dehydrated to a final moisture content of 7% in a microwave vacuum dryer. The micro/macro structure
and selected quality parameters of the dried gel chips were measured e.g. shape, relative volume, bulk
density, texture, color, sensory and microstructure. The measured gel characteristics were analyzed and
related to structure development and selected quality attributes. Both fish and mixed gel chips expanded
in both diameter and thickness while the starch gel chips shrank in diameter, but expanded in thickness;
the former two represented a continuous cross-section composed of a cellular structure and expanded
uniformly in thickness while the latter developed an open cross-section and the center expanded more
than the edge region, indicative of a disc and pillow shape, respectively. The higher severity of thermal
treatment favored greater expansion and reduced hardness and bulk density, and increased crispness in
the mixed gel chips; they developed a smooth and fine surface and pore wall but decreased lightness and
whiteness due to starch gelatinization in the starch and mixed gel chips. Only the partial dried mixed gel
chips are acceptable to the panelists. A homogenous co-gel in the mixed gel contributed to the higher
uniform expansion and cellular structure. These findings will help developing the restructured microwave
vacuum-dried product by blending the starch with the fish.