Not All Plants Produce Useful Essential Oils
When you view AromaWeb's Essential Oil Profile Directory and when you patronize reputable aromatherapy retailers/suppliers, you'll notice that essential oils are not commercially available for many botanicals that you may expect to be available. Most fruits, except for citrus fruits, cannot effectively be steam distilled to produce essential oils. Citrus fruits are the exception to my generic fruit comment because citrus fruits are encased in a "rind" that houses a great deal of essential oil that can be steam distilled or cold pressed.
Let's take "apple essential oil" as an example...
There is no such thing as a commercially available, steam distilled apple fruit (pulp) essential oil or apple blossom essential oil. However, in the past, there were various claims that hyped that "green apple essential oil" was helpful for weight loss. Such claims should be discredited because no expert in essential oil usage can claim that green apple essential oil can be beneficial for weight loss since no such oil is commercially available.
Essential oils are sometimes confused with other types of oils, extracts or fluids derived from a botanical. Continuing with our apple example, it is possible to find or make natural apple extracts, tinctures, flavor oils, macerated oils, infused oils, all of varying qualities. Additionally, it's possible that Apple Seed Oil may be available as a cold pressed or solvent extracted carrier oil/vegetable oil. However, I cannot comment on the potential quality, benefits or hazards of an apple seed vegetable oil. As apple seeds contain a compound that can metabolize into cyanide, the safety of using such an oil, if available, in topical holistic aromatherapy applications, would need to be researched.
Why Are Essential Oils Not Available For So Many Aromatic Flowers, Fruits and Other Plants?
With the exception of citrus oils that can be cold pressed or steam distilled, most essential oils are produced via steam or water distillation.
However, the natural essential oil and aromatics present in many plants are not conducive to steam or water distillation methods or would require such an enormous amount of botanical material that the cost is far too excessive.
Jasmine is a good example. Jasmine flowers are especially aromatic. However, the fragile flowers cannot be effectively steam distilled. Instead, Jasmine does tolerate the solvent extraction process well, so Jasmine is readily available as Jasmine Absolute. Jasmine CO2 Extract is now also becoming more commercially available.
Is It an Authentic Essential Oil or Isn't It?
You may come across reputable vendors that do offer limited quantities of essential oils or absolutes that are rarely available. In these instances, it is usually because the amount of plant material required and/or the manpower required to produce the oil is especially costly or that there is limited demand, but that it technically can be produced. However, there are countless companies around the Web that are intentionally (or just out of stupidity) selling fragrance oils, adulterated essential oils, extracts or other liquid aromatics that are falsely labeled as pure essential oils or absolutes. It's important to be able to distinguish between a reputable seller of truly rare and precious essential oils and misleading businesses. Always confirm the method of extraction to ensure that you are clear on what you are considering purchasing. The reputable essential oil retailer/supplier of rare oils will have a solid reputation within the holistic aromatherapy industry and/or will generally eagerly describe the oils, its production and other details that can shed light to the legitimacy of the oil. (For more information, see AromaWeb's How to Buy Essential Oils article.)