"our high-fat salami had gone rancid"

Amundsen had encountered the same thing when he reached his first Barrier depot:

We reached the depot, and found everything in order. The heat here must have been very powerful; our lofty, solid depot was melted by the sun into a rather low mound of snow. The pemmican rations that had been exposed to the direct action of the sun’s rays had assumed the strangest forms, and of course, they had become rancid.