抄録
無洗米の環境効果を明らかにするため,無洗米と普通米について,精米工程から炊飯工程開始までのLC-CO_2評価を行った。無洗米には,4種類の製造方法があるが,製造時の燃料消費量が明確に公表されているBG(Bran Grind)精米製法の場合について考察した。その結果,共通である精米工程を除いた場合,米1kgあたりのCO_2排出量は,普通米の0.078kgに対し,無洗米は0.016kgであり,普通米の約20%であることがわかった。普通精米をBG無洗米に替えることは,とぎ洗いの手間や時間も省け,CO_2排出量削減効果の高い有効な手段といえる。また,無洗米製造の副産物である肌ヌカを水稲栽培の肥料に利用した場合は,化学肥料のみを使用する場合に比べ,米1kgあたり,0.0l7kg-CO_2増加した。
The carbon dioxide output (LC-CO_2) was analyzed for both no-wash rice and conventional rice from the beginning of the polishing process up to the start of cooking in order to assess the environment benefit of no-wash rice. Of the four different methods for producing no-wash rice, we focused on the bran grind (BG) process for which fuel-consumption data is publicly available. After excluding those processing steps which are common to the production of both no-wash and conventional rice, we found that BG no-wash rice produced 0.016kg of CO_2/kg of rice compared to 0.078kg of CO_2/kg of conventional rice. Hence, the BG production method yields a 20% reduction in CO_2 emissions compared to conventional rice production. In addition to the savings in labor, water and time afforded by no-wash rice, which needs no washing before cooking, we conclude that using BG no-wash rice instead of conventional rice is an effective way to reduce CO_2 emissions.
