The compounds inside rice
koji
have been thoroughly investigated as an essential material in making many food-related products, including
sake
. However, these studies focused only on quantitative aspects, leaving features that can still be uncovered if seen from a new perspective. Visualization of the metabolites inside rice
koji
may as well be the new angle needed to retrieve more information regarding rice
koji
making. Here we utilized mass spectrometry imaging (MSI) to visualize the distribution of sugars, sugar alcohols, and amino acids inside rice
koji
. Imaging results revealed that several sugars alcohols and amino acids were shown to have characteristic distribution near the edges or surface of rice
koji
. Furthermore, the distribution appears to be correlated with the different structure of rice
koji
. This study is the first report of using MSI to visualize sugars, sugar alcohols, and amino acids in rice
koji
.