> Gradual permeation of gas through the clay barrier allows oxygen to enter the container, keeping the grapes alive, while the elevated concentration of carbon

> Gradual permeation of gas through the clay barrier allows oxygen to enter the container, keeping the grapes alive, while the elevated concentration of carbon dioxide inside the package inhibits the grapes' metabolism and prevents the growth of fungus. The grapes are prevented from drying out, and the mud absorbs liquid which would otherwise lead to bacterial and fungal growth. Pretty incredible that this works. I wonder how much trial and error went into perfecting the process nearly a millennium ago.