Abstract
Fuki(Japanese butterbur), Petasites japonicus, is a wild vegetable widely used as a cooking material because of its unique taste and toughness. As the plant is seasonally harvested and rarely cultured, materials are often boiled for preservation and preparation for further cooking. However, the materials should be treated in 0.4% calcium lactate solution(CLS, a foodindustrial cooking solution permitted for edible wild plants)to avoid losing toughness during boiling. In the present study, the author examined the possibility of substituting deep seawater(DSW)and electro-dialyzed deep seawater (EDDSW) for CLS. The plants boiled in DSW, EDDSW or CLS left more toughness than those boiled in Fuki well(conventional)fresh water. The cutting force of EDDSW-treated plants was equivalent to CLS-treated plants. The EDDSW effect was quite definite(p=0.14%)and stable, whereas the effect of DSW was hardly defined and unstable. In preliminary sensory evaluations, Fuki cooked with EDDSW showed good toughness. The contents of calcium, magnesium and hexametaphosphatesoluble pectin in Fuki cooked with DSW and EDDSW were more than those in conventional water. These results suggested that divalent cations, such as Mg2+ and Ca2+, likely interact with pectin to form insoluble pectic substances. As with other results of cooking in various kinds of ion solutions, we assumed that calcium ions play a main role in the firming of boiled Fuki, and EDDSW might be a usable substitute for calcium lactate.
