Rubbing cheese wheels with oils, particularly olive oil (sometimes combined with smoked pepper or cocoa powder or other flavor enhancements), is a technique used to help develop and protect rinds during aging. This method enhances flavor development while protecting against microbial growth. It adds a beautiful patina to the cheese rind, and helps to regulate drying of the cheese while it ages.
Initially after salting and drying when the firm but not fully developed rind forms, apply oil regularly (e.g., daily or every other day) for about two weeks to encourage proper development of the outer layer.
Afterwards, to maintain the rind continue applying olive oil as needed, typically once per week depending on environmental conditions and cheese type. For example, in less humid environments, you may need to apply oils more frequently if the rinds begin to appear dry.
Use a sufficient amount of olive oil (or preferred oil blend with flavorings) each time to ensure thorough coverage over the entire surface area. When adding extras to the oil, for example in Ibores cheese, mix crushed and powdered smoked paprika into the olive oil before applying it.
Gently rub or brush onto rinds using clean hands, cloth, or appropriate tools like soft brushes. The whole cheese may be oiled, or it can be pulled out of its aging space and flipped over, and then oil applied everywhere but the bottom before putting it back if you wish to avoid getting excessive oil on the aging boards.
Oiling the rind helps provide protection against microbial growth, creating a protective barrier against some mold development and cheese mites while allowing proper aging processes to occur beneath the surface. Oiled rinds can breathe well, but they help limit moisture loss which allows a cheese to age for a longer time before it dries out too much.
Oiled rinds add depth of flavor through oil absorption over time. Especially combined with common additions such as smoked pepper or cocoa powder it can add distinctive taste profiles.
Even though oiled rinds can slow moisture loss, it's still importain to maintain proper temperature and relative humidity levels in aging areas. High relative humidity (greater than 90%) will encourage runaway mold growth even on an oiled rind.
For certain cheeses like traditional Manchego, allow molds to grow naturally then rub them into the rind with oil. Over time, this process can result in distinctive blackened rinds due to continuous oiling with the molds dying or maturing inside the oiled rind.
Check that your relative humidity is high enough in your aging space. For most cheeses, a relative humidity between 80-90% is desirable, even with an oiled rind. As the cheese ages, the relative humidity can be on the lower side. Oiling more frequently at first can help to limit moisture loss otherwise.