Please excuse me to post a gross photograph. But if you make mochi or are given handmade mochi, it gets molded pretty quickly. The above photograph is my handmade kagamimochi and a New Year’s door decoration.
Kagamimochi looked great when it was made at the end of last year. But while it was displayed at the warm living room windowsill, the condition deteriorated quickly. By the time to take it down on January 7th, it was like the photograph above.
The Japanese used to eat molded mochi, but Just like molded bread, molded mochi should be discarded, because even if you can’t see it, the long root of mold is growing deep inside of mochi.
To keep mochi longer for your consumption, buy packaged mochi from a Japanese grocery store, and keep it in a refrigerator.
Kagamimochi could be just disposed as a garbage (I am not certain about composting molded food.), but many Japanese, including myself feel unsettled about casually discarding the item of some religious significance. In Japan, people bring New Year’s decorations to a nearby shrine on January 15th, so that they can be burnt properly.
If you don’t have any Japanese shrine in your neighborhood, the items you used for New Year’s decoration can be wrapped in paper with salt, which is believed to have purifying property. Then just toss.