The third test was frozen bread at − 20 °C.
From our hypothesis, it was expected that this test would give the best results, however analysis only showed 24 tags out of 42 (57.1%).
Even if the results are similar to the fresh meat test, the distribution of read tags was very different (Fig. 3c).
In this case, all tags were read at the front of the container, gradually fading to where no tag was read in the last two rows of the load.
The tags up top were read slightly further towards the back of the container than the tags at the bottom of the pallets, which is explained by the position of the antenna (at the top of the front wall, therefore closer to those tags).