Perhaps the etymology of the word will help with the connection to the taste. In Dutch (another Germanic language) mealy = 'melig', which is close to 'meel' (: flour). There you have the connection to the sawdust-taste. Sawdust and flour, i think, taste pretty much the same.

In German it's "mehlig", and it's exactly the adjective to "Mehl" (flour).

But I wouldn't call it a taste, it's texture: "how it feels in the mouth".

Although this state goes hand in hand with a stale taste.

Or for that matter, the English word cornmeal.

It's more a texture than a taste.