Raw and freeze-dried yams (Nagaimo, Ichouimo and Tsukuneimo) were studied for use as karukan material.
1) A significant correlation was apparent between the specific gravity of the dough and the expansion ratio of karukan, with the correlation coefficient of
r=-0.960. Both the raw and freeze-dried Nagaimo had a small expansion ratio, while both Ichouimo and Tsukuneimo had a large expansion ratio.
2) The sponge effect of karukan made from raw yam was large, while the effect from freeze-dried yam was small in a cross section by an image analysis.
3) Close agreement between the rheological properties and sensory evaluation scores was obtained. Karukan made from Nagaimo was disliked in the sensory evaluation, having high hardness and cohesiveness.
4) Karukan made from freeze-dried Ichouimo was most liked for its characteristics in the sensory analysis, having large expansion, and being dry and soft.
5) Raw and freeze-dried Ichouimo and Tsukuneimo yams were thus found to be good for making karukan.
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