How to spot the muddy sediment defect in unfiltered oils

Unfiltered EVOO looks rustic, but those tiny suspended bits of olive pulp and fruit water come with a ticking clock. Over a few months, gravity forces them to settle into a thick layer of sludge at the bottom of the bottle.

Because this happens in an oxygen-free environment, it triggers anaerobic fermentation meaning the fruit particles literally rot inside the oil, creating a defect professionals call borre (muddy sediment).

To spot it, check the bottom of the bottle under a bright light for a caked, dark brown or gray layer. If you pour it, the fresh, grassy aroma will be completely gone, replaced by a smell like sweaty socks or stagnant mud, leaving a greasy, flat aftertaste.

If you love unfiltered oil, skip the giant jugs and stick to smaller bottles you can finish within three to six months. If you see a heavy layer starting to settle out, decant the clean oil off the top into a fresh container immediately to leave the sludge behind before it ruins the batch.