Why Does Vacuum-Sealed Meat Smell Different When Opened?

Vacuum packaging keeps oxygen out, which is the main mechanism that helps meat last longer. The meat’s own enzymes keep working without oxygen, and harmless bacteria that live in oxygen-free conditions also produce some acid and odor compounds. Because these compounds have nowhere to escape, they build up in the package. The meat’s color also changes in this environment: without contact with oxygen, it looks dark red with a purplish tint, a color that is often mistaken for spoilage.

The color of vacuum-packed meat may change after opening; however, a smell that fades or a brighter color does not prove that the meat is safe. Do not rinse raw meat; splashing water can spread bacteria to the sink and counter. Follow cold-storage conditions and the label’s consumption instructions. Do not eat meat with an odor, stickiness, or slime suggesting spoilage; do not assume that leaving questionable meat on the counter or rinsing it makes it safe.

Spoilage gives different signs, and they do not dissipate in air: a sharp, ammonia-like, or sweet, rotten smell; a slimy, sticky film on the surface that leaves a mark on your finger; a gray or greenish color; or a swollen package. If any of these signs are present, do not rinse or wait for the meat; do not use it. A swollen package in particular should be taken seriously because it indicates gas-producing activity inside, and that warning applies regardless of the date on the package.

A few details can make opening the package easier. Open it in the sink and inside a deep bowl, because liquid from the package can spread across the counter and cause cross-contamination. The red liquid from the meat is not blood; it is a mixture of water and protein from the muscle, and discarding it is not a loss. If the opened meat will not be used right away, store it in a sealed container on the refrigerator’s bottom shelf, because the long date on the vacuum package is no longer valid once the vacuum seal is broken. Do not leave the empty package on the counter; throw it away immediately and wash your hands with soap.

The period after opening the vacuum seal is short. Meat that stayed in the package for weeks should be treated like ordinary raw meat after opening and cooked within a few days; freeze it if it will not be cooked. The vacuum bag itself can be used for freezing, but if it has a hole or is loose, wrap it in a second layer. For cooking, this meat is no different from other meat: bring whole cuts to 63 °C / 145 °F and let them rest for 3 minutes; bring ground meat to 71 °C / 160 °F.