Abstract
Nori Porphyra spp. is one of the most important seavegetables (edible seaweeds) in Japan. Texture, especially the softness as well as a color and gloss, has recently become to be an important factor for the quality of sheet-like dried nori called hoshi nori. The purpose of this study is to build up a profile of favorable texture of hoshi nori.
The elongation and rupture strength of six samples were measured by a tensipressor. Sensory evaluation was practiced by five professional technicians. They recoreded the rank of softness employing a line scale method.
For the dried samples, the order of elongation and rupture strength agreed essentially with the rank of softness by sensory evaluation. However, the degree of the strength was different from the results of the sensory evaluation. For the wetted samples, the order of the rupture strength did not agree with that for the dried ones, but with the order of the time required to peel into nori pieces in water. The result of the sensory evaluation showed a tendency to separate into only two textural categories, i.e. soft and firm. A similar tendency was observed for the peeling time. These results suggested that there are two sensory systems in our mouth; one was a system perceived nori as soft on the basis of the force to slide each piece of nori, and another was a system that perceived nori as firm on the basis of the force to bite it off.
