Bilberry Extract 25% Anthocyanins: Why a UV Assay Is Not Enough

Bilberry (Vaccinium myrtillus) extract is one of the best-selling berry ingredients in Europe, the US and Japan, usually sold as "25% anthocyanins". It is also one of the most adulterated botanicals on the market, because a cheap red-purple material can be made to pass a simple colour test.

In short: a 25% figure measured by a single-wavelength UV method can't tell bilberry anthocyanins from food dyes or anthocyanins from cheaper plants. Only an HPLC fingerprint showing bilberry's own anthocyanin pattern proves you are buying bilberry.

What bilberry extract is

Bilberry is the small wild blue berry of Northern and Eastern Europe, a close relative of the cultivated blueberry. Unlike blueberry, its flesh is purple all the way through, which is why it is so rich in anthocyanins. Standardised extracts are made from the fresh or frozen fruit, purified so that anthocyanins make up about a quarter to a third of the dry powder.

Bilberry fruit naturally contains 15 different anthocyanins: five anthocyanidins (delphinidin, cyanidin, petunidin, peonidin and malvidin), each bound to glucose, galactose or arabinose. That pattern is a fingerprint. Blueberry, black rice and elderberry all contain anthocyanins, but in a different mix.

25% vs 36%: reading the label

So a "36%" product is not necessarily stronger than a "25%" one. Always ask which compounds were counted, which reference standard was used and which method gave the number. Our guide to extract ratios and standardisation explains the general principle.

How bilberry extract is adulterated

Genuine 25% bilberry extract is expensive, so the price gap invites fraud. Published cases include:

• Synthetic dye. A 2006 study found an extract that met its 25% claim by UV, but HPLC showed only 9% anthocyanins; the rest of the colour came from the azo dye amaranth (E123).
• Cheaper anthocyanin sources. Extracts of black rice, black soybean hulls, mulberry and other berries have been sold as bilberry. They give the right colour and a 25% UV result, but the wrong anthocyanin pattern.
• Blends. A little real bilberry mixed with a cheaper extract, which a total-anthocyanin test can't detect.

Surveys have found the problem is common: in one Italian study about half of the commercial extracts tested differed significantly from reference bilberry. See our wider guide to adulteration and identity testing.

Tests that catch it

• HPLC-DAD fingerprint of the 15 anthocyanins, compared with a bilberry reference. This is the key test.
• HPTLC, which also separates the dye amaranth from real anthocyanins.
• A simple pH check: anthocyanins turn from red to blue as pH rises; a dye that stays red is a warning sign.
• Pharmacopoeia methods: the European Pharmacopoeia has a monograph for refined and standardised fresh bilberry fruit dry extract, assayed by HPLC.
• Contaminants: heavy metals, pesticides, residual solvents and microbiology, like any extract. Our guide on how to read a COA covers these.

Rules by market

• USA: sold as a dietary supplement; label claims must be structure and function claims, and the facility must follow FDA dietary supplement GMP (21 CFR 111), including identity testing.
• EU and UK: sold as a food supplement. Eye-health claims for bilberry are not authorised; botanical claims remain on hold, so check national rules. See our guide to EU health claims for botanicals.
• Japan: bilberry is a popular food ingredient; Foods with Function Claims need notified scientific evidence.

Buyer checklist

• Botanical name Vaccinium myrtillus and fruit as the plant part
• Anthocyanin content with method (HPLC preferred) and what was counted
• HPLC fingerprint compared with a bilberry reference, per batch
• Statement that no synthetic colours are added
• Heavy metals, pesticides, solvents and microbiology results
• Carrier or excipient declared (for example maltodextrin)

Colour is cheap. Bilberry's 15-anthocyanin fingerprint is not.

Bilberry from Arizone

Arizone International LLP makes bilberry capsules for private label brands outside India. Tell us your anthocyanin target, test method and market, and we'll confirm the extract specification and identity testing before you order.

Sources: Penman et al.: bilberry adulteration using the food dye amaranth; SupplySide: identifying the real standardised bilberry extract; NutraIngredients: AHPA bilberry test methods; Journal of Spectroscopy (2018): screening commercial bilberry extracts; ABC-AHP-NCNPR Botanical Adulterants Prevention Program.