You can press it many times but its best only done once if you want authentic virgin olive oil. I was doing some research for someone and found this info which I think will be useful .
I knew I remembered reading something on cold-pressed olive oil and I just found it
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What should "
Cold-Pressed"
really mean?
When you go to the health food store and look in the oils section, you may see a lot of oils labeled as cold-pressed. But most, if not all, of those oils are not really cold-pressed. Cold-pressed should mean that the oil was extracted in such a way that it was not subjected to heat, and additionally, that heat was not generated in the process of the oil being extracted. If a little heat is generated, it should be below the temperature at which the value of the oil is destroyed. Genuinely cold pressed oils have all their nutritional value intact, including enzymes, Omega 3's and 6's, and other known and unknown factors. These oils must be refrigerated to preserve their freshness.
In practice, what does Cold-Pressed mean?
Most cold-pressed oils have been heat treated. Seeds that are going to be mechanically pressed are usually cooked first to increase their yield. This means they are heated to 248 F for up to two hours. This process cracks the seed, exposing the oils to air and light, which cause oxidation. The oil is then extracted by squeezing the cooked seeds with screw presses, which generated heat again (approximately 185 to 203 F). These oils are sold as unrefined, but, as you can see, they have gone through at least two heat processes, which destroyed their nutritional value. Such heated oils are detrimental to your health because most of their fatty acids have been converted from the natural cis fatty acid form (present in unheated oil) to trans fatty acids, which are toxic and have been implicated as a causative factor in heart disease and cancer.