Crush a fresh clove of garlic and you release 2.5 to 4.5 mg of allicin per gram of fresh weight, drawn from an alliin reserve of 6 to 14 mg per gram, and it starts breaking down within hours of existing. It is already leaving. A compound that can't hold still for a day makes a terrible batch marker, which is why serious labels in this category measure something else entirely.
Allicin refuses to sit still
Alliin and the enzyme alliinase live in separate compartments inside the clove, and crushing is what introduces them. Allicin forms within seconds. Give it hours and it has turned into a family of other sulfur compounds, none of them allicin anymore. Heat is harsher still. In one widely cited study, microwave cooking of unpeeled, uncrushed garlic destroyed alliinase activity completely, which ends production before it starts. The same logic runs through your kitchen. Cook crushed garlic hard and the enzyme is gone; let minced garlic sit overnight and the allicin it made is gone soon after.
This instability has a label consequence. Powdered products sold to a USP standard contain no allicin at all. Makers quote an allicin potential, a yield figure, instead, obtained by dissolving the powder in water at room temperature and reading how much formed after 30 minutes. It is a ceiling achieved under ideal conditions, not a promise about what you swallow or what survives digestion.
What the aging builds instead
Sliced raw cloves held in aqueous ethanol at room temperature for 10 to 20 months go through a slow transformation. The harsh, unstable compounds convert, and what remains is water soluble and stable, headed by S-allyl cysteine, known as SAC. The result is aged garlic extract, and SAC is its standardisation marker, measured directly by high performance liquid chromatography rather than estimated from a precursor.
Stability is the entire point. SAC holds up in solution, in storage, and through the digestive tract, so the amount printed on the label can be verified batch after batch. The duration is not decoration; it is the process. Shortcuts at higher temperatures exist, and they produce a different profile, which is why an extract that names its aging time is telling you something checkable. You give up the pungency of the raw clove and get a compound that can actually be measured. For label purposes, measurable wins every time. The payoff is an extract that behaves the same way every time you test it, which is the property any analytical method depends on.
What a standardised figure actually promises
A figure in mg of SAC is a measurement claim. It says this batch contains this much of a named compound, verified by an analytical method. That buys you comparability. You can compare one batch to the next from the same maker, and one brand to another, on a like for like basis.
What it doesn't buy you is a promise about outcomes. The published trials of this extract used daily doses from 600 mg to 2,400 mg, and SAC standardisation is what let those trials be reproduced with equivalent material. Between one harvest and the next, alliin content varies with variety, soil, and storage, which is true of any plant and is exactly why the standardised figure exists. Comparability between batches is a different claim from an effect in you, and the label only ever makes the first one. Anyone who reads the second one into it has gone past what the number says.
How to use this at the shelf
Weight alone tells you little. A capsule saying 500 mg of extract has told you a mass and nothing about content. Look for a named compound with a number: mg of SAC per serving, or per gram of extract. Treat those yield figures as theoretical maxima, because that is how the assay defines them. If a maker measures their material, they tend to say so plainly, and the number appears next to the compound rather than the plant. Ask one question of any label that quotes a compound: who measured it, with what method, and is the aging time stated. Answers to those questions separate a measured product from a merely weighed one. When you compare two labels, the one quoting measured compounds gives you something you can check. The one quoting only weights is asking you to take the powder on faith.
Frequently asked questions
What is S-allyl cysteine?Show answerHide answer
A stable, water soluble sulphur compound formed during the aging of garlic.
Why not measure allicin?Show answerHide answer
Allicin is unstable and breaks down quickly, so it is a poor batch marker.
Does a standardised figure guarantee effect?Show answerHide answer
No. It guarantees comparability between batches, which is a different claim.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
