Although decanal (FEMA# 2362, CAS# 112-31-2) is a vitally important contributor to the character of sweet orange peel oil, and virtually all compounded orange flavors, the aldehydic profile of this molecule used alone does not ring quite true— it is far too simplistic. The aldehydic profile it generates is distinctly too one-dimensional. Adding the other saturated aldehydes found in orange, such as octanal (FEMA# 2797, CAS# 124-13-0), creates some complexity and improves the situation a little, but much of the problem still remains. To fully solve the problem we need to look toward decanal’s unsaturated relatives.
We have already considered the helpful role that can be played by trans-2-decenal (FEMA# 2366, CAS# 3913-81-3). This molecule can certainly add interesting further complexity, but the most important and useful unsaturated derivative of decanal that is found naturally in orange oil is 4-decenal (FEMA# 3264). This chemical is commercially available in both cis (CAS# 21662-09-9) and trans (CAS# 65405- 70-1) forms. The two molecules smell undeniably similar: citrus and aldehydic, with notable power and freshness. In my opinion, the cis form has a slight edge, with a fresher, more natural profile.