Citral is an unsaturated aldehyde in the terpene class. Citral is one of the fragrances in perfume that must be declared.
http://www.biosite.dk/leksikon/citral.htm Citral is a natural component of the orange peel and is included as a fragrance in essential oils. In the future, the content of citral must - like 25 other substances - be declared on all skin care and cosmetic products when the amount exceeds 10 ppm (i.e. parts per million, for example 10 mg per kg). https://www.netspiren.dk/b/Hvad-er-aeteriske-olier/