These 3M test strips check whether a cooking oil is safe or degraded. In good condition the first square turns blue or green; if it turns yellow, the oil is not in good shape. The strips are meant to be used at around 150°C, but they still show the state of an oil at lower temperatures.

Test something that already smells rancid and the strip does turn yellow; with a badly degraded oil, two squares or more go yellow. So they do work.



Now look at Cheng Chi fried shallots: the first square is green and the rest are blue — the reading you would expect from fresh oil.

We want to make the best in the world, so we have no objection at all to you sending it for testing yourself.

If it fails, we will pay for the test. Everyone should be checking. Fresh enough to say so out loud.