Pulled deli ham from the fridge and noticed a rainbow-like shine on the slices. Is that normal?

It’s important to note that this iridescence is not an indicator of spoilage. Instead, it is a natural occurrence that results from the meat’s structure and how it interacts with light. In fact, this phenomenon is often observed in various other types of sliced meats, such as roast beef and turkey.

The iridescent effect on meat surfaces is primarily due to the diffraction of light. When light hits the surface of the meat, it is scattered by the muscle fibers, which act like tiny prisms. This scattering causes the light to split into its component colors, much like a prism separates white light into a rainbow.

Additionally, the cut of the meat plays a significant role in this process. When meat is sliced very thinly, the uniformity and alignment of the muscle fibers enhance the light diffraction, making the iridescent effect more pronounced. This is why thinner slices of deli meats are more likely to exhibit this colorful sheen.