Wholly Guacamole has no preservatives in it and it sits in the case for weeks. Here is how. The ingredient list is Hass avocados, distilled vinegar, and under 2% water, jalapeno peppers, salt, dehydrated onion and granulated garlic. The vinegar is there for more than flavor. It pulls the pH down low enough that bacterial spores can't grow, and that matters because pressure doesn't kill spores. Then the sealed package goes into a vessel full of water and the water gets pressurized to a level their own site describes as putting it at the bottom of the ocean. Because the pressure comes from every direction at once, the food is not crushed, just squeezed evenly. At that pressure the proteins inside bacteria and yeast unfold and stop working, so the product gets pasteurized without ever being heated. Heat ruins fresh food. It turns avocado bitter and it cooks the fresh out of juice. Pressure kills the same bacteria and leaves the color and the flavor alone. It's called high pressure processing or HPP. A lot of the refrigerated guacamole in the case gets it, and so does cold pressed juice and a lot of the deli meat that says no preservatives on the front.