What is the iridescent sheen on deli meat?

The iridescent sheen you see on deli meat is actually a thin layer of fat that has been crystallized during the curing process.

Here's a breakdown of why it happens:

* Curing: Deli meats are often cured with salt, sugar, and sometimes nitrates. The salt draws moisture out of the meat, and the sugar helps to create a flavorful, preserved product.

* Fat Crystallization: The curing process also alters the structure of the fat in the meat. The fat molecules are forced closer together and start to crystallize.

* Iridescent Sheen: When light hits these tiny fat crystals, it scatters in different directions, creating the iridescent sheen you see.

In short: It's a completely natural and harmless result of the curing process. It can actually be a sign of a good-quality deli meat, as it indicates that the meat has been properly cured.