Resinoid

The crude resin is ground or broken up and stirred with solvent, often warm. The extract is settled and filtered to remove sand, bark and insoluble gum. The solvent is distilled off under vacuum. What remains is the resinoid.

The choice of solvent changes the product. Ethanol dissolves more of the polar fraction, so an ethanol resinoid tends to keep more resinous matter. Hexane draws out the less polar part. Two labdanum resinoids from the same lot of gum can therefore differ in colour, viscosity and scent.

ISO 9235 keeps these names apart. A natural oleoresin is an exudate of resin plus volatile matter, pine oleoresin for instance. An extracted oleoresin is a spice extract such as pepper or ginger, and ISO notes the two are different. A gum oleoresin is an exudate with resin, gum and volatiles, with myrrh, olibanum and galbanum as examples. A balsam is an oleoresin rich in benzoic or cinnamic derivatives: Peru, Tolu, benzoin, styrax.

A resin absolute is an absolute made from a resinoid: the resinoid is washed with ethanol, chilled, filtered and concentrated. ISO 9235 lists the resinoid as one of four valid sources of an absolute. When benzoin is steeped in ethanol and the ethanol is kept, the result is a non-concentrated extract, close to a tincture.

Pure benzoin resinoid is almost solid at room temperature. To make it weighable and mixable, producers pre-dilute it in an odourless carrier. Biolandes and Firmenich both sell Siam benzoin as 50% in dipropylene glycol (DPG).

When calculating a formula or an IFRA limit, multiply by the dilution. A 50% resinoid delivers half as much resinoid. If the carrier is benzyl benzoate, the carrier itself counts towards benzyl benzoate limits and allergen labelling.

Crude Peru balsam is prohibited by IFRA as a fragrance ingredient in any product; the first standard dates from 1974. Its extracts and distillates, meaning oil, absolute and anhydrol, are allowed with limits, for example 0.41% in fine fragrance (Category 4).

Crude styrax gums from Liquidambar styraciflua var. macrophylla or Liquidambar orientalis are also prohibited. Only extracts or distillates (resinoids, absolutes, oils) may be used, at up to 0.64% in Category 4. Opopanax is restricted to 0.43% in Category 4. Styrax and opopanax oils made by pyrolysis must be rectified and checked for polycyclic aromatic hydrocarbons.

Benzoin has no IFRA Standard of its own. Its benzyl benzoate and benzyl cinnamate count towards those substances' limits.

Figures follow IFRA Standards published at Amendment 49 (2020) and are unchanged in the 51st Amendment (2023). Check the current amendment.