ORAC, DPPH and FRAP: interesting numbers that do not belong on a purchase specification

An ORAC value is a marketing number that acquired a decimal point. As a purchasing control it fails on the two things a specification has to do: it does not identify the material, and it does not reliably detect a bad batch.

What these assays actually measure

ORAC, DPPH, FRAP and TEAC are all test-tube measurements of how a sample behaves toward a particular radical or oxidant under particular conditions. They measure chemistry in a cuvette. They are not interchangeable with each other, they use different reference standards, and a sample can rank differently depending on which one you run.

The US Department of Agriculture withdrew its ORAC database in 2012, citing the routine misuse of the values. That withdrawal is the clearest statement available on how much weight the number should carry.

Why they fail as a quality control

• They are not specific. A high value tells you something in the sample is reducing, not what. Adding a cheap reducing agent such as ascorbic acid raises the number without adding any of the material you are paying for.
• They are not reproducible between labs. Inter-laboratory variation on the same sample is routinely large enough to swallow any difference you were trying to detect.
• They do not track the actives. Two batches with the same assay value can have materially different marker compound content, which is the thing that actually defines the extract.

What to specify instead

For any extract sold on its phytochemical content, the control is the marker compound, quantified by a separation method:

• A named marker assayed by HPLC or UPLC — total polyphenols as gallic acid equivalents, anthocyanins, proanthocyanidins, or whatever the material is genuinely characterised by, with the method stated.
• A chromatographic fingerprint, compared against a reference batch. This is the single most effective adulteration check available for botanical extracts.
• Identity confirmation — TLC or HPTLC at minimum, DNA barcoding for raw herbs where species substitution is a known risk.
• The usual purity set — heavy metals, pesticides, microbiology, residual solvents.

If your customer wants an ORAC figure anyway

Plenty of finished-product brands still ask for one, and there is no harm in supplying it as supporting information. Put it on the CoA as an informational parameter, clearly separated from the release specification. What it should never be is the number that decides whether a batch is accepted.