Live resin CBD: what freezing the plant really changes

The word "live" names the starting material, whatever the method. The plant is cut and frozen straight away, and the frozen material is what gets extracted. Two products use the word, and each is made in its own way.

Gas extraction is described in the review by Lazarjani and co-authors, published in 2021 in the Journal of Cannabis Research. Butane or propane is liquefied by cold or pressure, passed through the plant, then evaporated. The authors flag two risks: flammable gases under pressure are dangerous, and the gases are often industrial grade, carrying impurities into the extract. Residues of the solvent itself can also remain. For CO2 they give the critical point, 31.06 °C and 73.83 bar; beyond it the gas turns "supercritical" and dissolves cannabinoids. That process has its own article on supercritical CO2 extraction.

For live rosin, the plant is first washed in ice water to make a hash, the ice-o-lator method, and that hash is pressed between two heated plates. The same review points to a limit of pressing: a press cannot pair very high pressure with low temperature, and this caps how much terpene content is retained. The press is described in our article on rosin, and the textures of solvent extracts in the one on wax concentrates.

The term belongs to the trade. A search of PubMed, the US National Library of Medicine database, for the phrase "live resin" finds no study of this product (search of 23 September 2026). No peer-reviewed paper has yet measured what freezing adds to the finished product.

Live resin is sold on one idea: drying drives terpenes off. The published measurements are less clear-cut, and the answer varies with the variety and with the way the plant is dried.

A figure circulates widely, "31% of terpenes lost in a week", attributed to a 1996 study. The abstract of that study by Ross and ElSohly contains no percentage. It reports that drying left the qualitative make-up of the volatile oil unchanged, and that people who knew the smell still recognised it. We therefore do not repeat the figure.

The nearest data were published by Wanas and co-authors in 2020 in Natural Product Communications. Mature buds of three varieties were split into two batches, one distilled fresh and the other after a week of air-drying at room temperature. For the CBD variety, the monoterpene share of the volatile oil went from 58.7% to 46.5%, and myrcene, the dominant terpene, from 27.5% to 17.1%. The THC variety dropped too, from 33.7% to 25.5%, while the intermediate variety hardly changed.

Read these figures with two cautions. They are relative shares of the volatile oil and do not give milligrams lost per gram of plant; the monoterpene share also shrinks when other compounds increase. The paper is also inconsistent: its abstract reports no notable change for the CBD variety, yet its tables show the drop.

Birenboim and co-authors, in a study published in 2024 in Plants, dried two varieties at 15 °C for six to fifteen days, depending on the method. Total terpene content in the THC-rich variety rose by 25 to 30% during drying: as the plant loses water, everything left in it becomes more concentrated. Myrcene dropped by 3 to 20% in that variety and by 16 to 30% in the other. The authors confirm that monoterpenes are more sensitive than the heavier sesquiterpenes.

Taken together, the studies show that slow, cool drying lowers the most volatile monoterpenes, sometimes markedly, while leaving plenty in the plant. Freezing avoids that step, and the losses that come later still happen. Those steps are described in our article on drying and curing flowers, and terpene chemistry in the one on the role of terpenes.

For a buyer, the most useful finding concerns what happens during storage. In 2020, in Frontiers in Plant Science, Milay and co-authors kept dried and cured flowers for a year at −80 °C, −30 °C, 4 °C and 25 °C. After four months, average terpenoid concentration had dropped by more than 50% at every temperature, and the decline was generally steepest at −80 °C. Cannabinoids fell by 26% over twelve months, with the largest change at 25 °C. Ground flowers lost their terpenes faster than whole buds.

The authors report an unexpected result: monoterpenes and sesquiterpenes followed similar trends even though their volatilities differ widely. The study covers flowers only, and we found no equivalent published measurement for an extract.

In practice, any aromatic edge live resin has counts during the first months. If concentrates behave like flowers, an extract kept for a few months has lost much of what justified its price, whatever was done to the plant. Cool storage mainly protects the cannabinoids, and the study found no terpene benefit from deep cold. Keep it in a closed container away from light; our guide to storing rosin, wax and crumble sets out the rules.

A live resin made with butane or propane should go through a residual solvent test. The usual reference is the ICH Q3C guideline, adopted by the European Pharmacopoeia, which puts solvents into three classes:

Butane and propane, the two gases most often used for this kind of extract, are in none of these tables, so no pharmacopoeia limit applies to them. These standards also govern medicines, and a hemp extract sold in France has no legal obligation to meet them. A careful laboratory still uses them as the reference for interpreting a result.

On the certificate of analysis, find a "residual solvents" line naming butane and propane, with the laboratory's limit of quantification and a batch number that matches the product. A certificate covering cannabinoids alone tells you nothing about solvents. Each line is explained in our article on solvents in hash and our guide to reading a certificate of analysis, and the laboratory page describes the methods.

Whatever the extraction method, section III of article 1 of the order of 30 December 2021 caps Δ⁹-THC at 0.30% in hemp extracts and in the products containing them. The cap applies to the live resin itself as well as to the plant it came from. A concentrate gathers the cannabinoids of a large amount of plant material into a few grams. THC concentrates along with CBD, and only a batch analysis can check the threshold.

A concentrate sold as "CBD" may also contain an added semi-synthetic cannabinoid. In France, HHC, H4CBD and THCP are classified as narcotics, and our article on the H4CBD ban gives the timeline. You vaporise a concentrate instead of smoking it; our dab guide gives the temperatures. Resins from the catalogue are listed under CBD resins and hash.