[HTT18-P07] Usefulness of strontium isotope composition for determining the geographical origin of wasabi and potato
キーワード：産地判別、ストロンチウム安定同位体比、ワサビ、バレイショ、静岡
Originally, the use of strontium isotope ratios (87Sr/86Sr) was restricted to geology and petrology, but they have been used as a particularly effective tracer of geographical food origin, as plants reflect the strontium isotope composition of the regionally based rock, soil, and water. This study aims to evaluate the usefulness of 87Sr/86Sr for determining the geographical origin of wasabi (Japanese horseradish) and potato, which are specialty crops in Shizuoka Prefecture, Japan.
Wasabi is cultivated in springs and streams located at the top of rivers, where dissolved element and isotopic compositions in water would reflect the geological characteristics without the effects of atmospheric deposition and human activity. We collected wasabi and water samples from 40 locations of major production areas in Japan: Shizuoka, Iwate, Nagano, Tokyo, and Shimane. These samples were subjected to trace elements and 87Sr/86Sr analyses. The 87Sr/86Sr values differed, based on the geological characteristics of their site locations, and the value of wasabi was well accorded with that of water in the same location. The wasabi samples collected from Izu Peninsula and Mt. Fuji regions in Shizuoka, where young volcanic rocks such as Quaternary basalts are distributed, had low 87Sr/86Sr (below 0.7040), whereas those from Nagano and Tokyo, where older rocks such as Mesozoic granites and accretionary complex are distributed, showed higher ratios (over 0.7095). We conclude that 87Sr/86Sr value of wasabi allowed us to distinguish the production area clearly.
On the other hand, the 87Sr/86Sr values of crops cultivated in the field are considered to be partly affected by precipitation and fertilizer. Therefore we conducted field survey and planter test for potato in Shizuoka. Field survey was conducted at Mishima, in eastern part of Shizuoka prefecture, and at Mikatahara, in western part of it, and 87Sr/86Sr of potato and soil exchangeable fraction were compared. As a result, there was a correlation between potato and soil in 87Sr/86Sr, although the effects of precipitation and fertilizer were observed. The planter test suggests that the influence of fertilizer on 87Sr/86Sr varies depending on the amount of exchangeable Sr contained in the original soil.
Wasabi is cultivated in springs and streams located at the top of rivers, where dissolved element and isotopic compositions in water would reflect the geological characteristics without the effects of atmospheric deposition and human activity. We collected wasabi and water samples from 40 locations of major production areas in Japan: Shizuoka, Iwate, Nagano, Tokyo, and Shimane. These samples were subjected to trace elements and 87Sr/86Sr analyses. The 87Sr/86Sr values differed, based on the geological characteristics of their site locations, and the value of wasabi was well accorded with that of water in the same location. The wasabi samples collected from Izu Peninsula and Mt. Fuji regions in Shizuoka, where young volcanic rocks such as Quaternary basalts are distributed, had low 87Sr/86Sr (below 0.7040), whereas those from Nagano and Tokyo, where older rocks such as Mesozoic granites and accretionary complex are distributed, showed higher ratios (over 0.7095). We conclude that 87Sr/86Sr value of wasabi allowed us to distinguish the production area clearly.
On the other hand, the 87Sr/86Sr values of crops cultivated in the field are considered to be partly affected by precipitation and fertilizer. Therefore we conducted field survey and planter test for potato in Shizuoka. Field survey was conducted at Mishima, in eastern part of Shizuoka prefecture, and at Mikatahara, in western part of it, and 87Sr/86Sr of potato and soil exchangeable fraction were compared. As a result, there was a correlation between potato and soil in 87Sr/86Sr, although the effects of precipitation and fertilizer were observed. The planter test suggests that the influence of fertilizer on 87Sr/86Sr varies depending on the amount of exchangeable Sr contained in the original soil.