Water Quality Changes with Heating of Tap Water Using Nanbu Iron Kettle and Foreign-made Iron Kettle

Abstract

An iron kettle has widely used for the tea preparation for the long time in Japan. However, low quality and low price iron kettles have spread on the market in Japan recently. We investigated the water quality change during heating with iron kettle to elucidlate the quality scientifically. Tap water was heated by LPG gas heating using Nanbu-made (Mikasa and Marunanbu type) or foreign-made iron kettle, and then, the water quality change was analyzed. In heating of Nanbu-made iron kettles, water quality change were small. On the other hand, in the case of a foreign-made iron kettle, it had the significantly changed, that is, pH rose from 7.00 to 9.40, and total hardness changed from 19.00 to 53.00 mg/L during 30 minutes heating. Furthermore, green tea was prepared using the hot water from both kinds of iron kettle, and then, components were analyzed. Amino acids and tannic acid elution into the tea were more rapid by using Nanbu-made iron kettles compare with foreign-made kettles.