Poka-yoke is a simple, inexpensive measure that catches an error at its source, and it comes in two kinds: shutdown, which stops the process when something is placed wrongly, and warning, which flags the abnormal by colour, light or sound. Training and instructions remind a person; a physical setup works regardless of shift, tiredness or new starters.
A setup made durable by physical safeguards is built on the cold chain basics.
The cold chain already has both kinds. On GEBHARDT plates the closure colour shows the melting point (red -3, yellow -14, green -18, blue -21 °C), so a wrong plate is caught by eye: that is a warning. The freezing rack guarantees the air gap between plates by its construction and does not allow them to be packed together: that is a shutdown. The safety bracket on the container's plate shelf also stops plates from falling out.
For your own errors, list the deviations of the last three months and ask of each: how does this mistake become physically impossible? The answer is often cheap: a colour, a raised edge, a divided rack. For steps that need a human decision, such as how long the lid stayed open, make the error visible with a counter and a record instead of a block.