Texture Evaluation of "Konnyaku"

Abstract

"Konnyaku", a traditional food of Japan, is a moist and elastic gel made from the flour (glucomannan) of the devil's tongue, Amorphophallus konjac K. Koch. The organoleptic analysis of the texture characteristics of this food was carried out on 20 samples of different grades. Close relationships were found between "quality" and "toughness" score, as well as between "quality" and "hardness" score. These subjective reactions were related to 2 kinds of objective indexes: the breaking strength S (g) and the breaking deformation d (cm), both of which were obtained for the specimen of 3.0cm thick by the penetrating test using Okada's jelly-strength tester fitted with a plunger of diameter 0.80 cm. The logarithm of S varied directly with the "hardness" score, and that of S·d varied directly with the "toughness" score. The d value varied directly with the "quality" score. The desirable ranges for this food were estimated to be 500-700g for 3 and 700-1, 000g·cm for S·d.