Natural blue in acidic beverages
Last checked: October 31, 2026By OTHER Natural Flavors, a service of Xponent21 Inc
Which natural blues FDA allows in beverages, and what the published evidence says about each one in acid.
The short answer
- Below pH 4, galdieria extract blue is the only approved natural blue with a published low-pH figure, and that figure comes from a supplier.
- Spirulina is approved for beverages but precipitates in acid. It suits neutral drinks, not most sodas or ades.
- Gardenia blue is approved for several acidic beverage types, but the published stability study stops at pH 5. Ask suppliers for data at your pH.
- Butterfly pea turns purple or pink in acid.
- Ask every supplier for stability data at your exact pH, process and shelf life, in writing, before you commit.
Four options compared
| Option | Approved beverage uses | In acid | Heat and light | Confidence | Sources |
|---|---|---|---|---|---|
| Galdieria extract blue | Approved for nonalcoholic beverages and bases, juices, fruit drinks, smoothies and dairy drinks (21 CFR 73.167). | The supplier says it "can withstand a pH as low as 2.8" (self-reported). This is the only natural blue we found with a published low-pH figure. | Not published in the sources we found. Ask for heat and light data at your pH. | Medium | |
| Gardenia (genipin) blue | Approved for sport drinks, flavored noncarbonated water, fruit drinks and ades, and ready-to-drink teas (21 CFR 73.168). Not listed for carbonated soft drinks. | A 2001 study found the pigment more stable at alkaline pH than at neutral or acidic pH. It tested pH 5 to 9, so it does not show performance below pH 5. Not verified below pH 5. | Held color after 10 hours at 60 to 90 °C (pH 5 to 9) and under 5,000 to 20,000 lux in the same study. | Medium | |
| Spirulina extract (phycocyanin) | Approved for nonalcoholic beverages, beverage mixes and alcoholic beverages under 20% alcohol (21 CFR 73.530). | Works best near neutral. A 2021 review puts its best range at pH 5.5 to 6.0 and reports protein precipitation at pH 3 and 4. A supplier says it "normally precipitates at pH 4.0" (self-reported). | Stable to about 45 °C; breaks down faster from about 47 to 69 °C and above 70 °C. Light-sensitive: about 20% loss in 36 hours under continuous light in one test. | High | |
| Butterfly pea flower extract | Approved for sodas, sports and energy drinks, flavored and sparkling water, juices, teas and alcoholic beverages (21 CFR 73.69). | Changes color with pH. Acid, such as lemon or lime juice, shifts it toward pink or purple, so it is not a blue option in most acidic drinks. Useful when you want purple. | Not published in the sources we found. | Medium |
- Option
- Galdieria extract blue
- Approved beverage uses
- Approved for nonalcoholic beverages and bases, juices, fruit drinks, smoothies and dairy drinks (21 CFR 73.167).
- In acid
- The supplier says it "can withstand a pH as low as 2.8" (self-reported). This is the only natural blue we found with a published low-pH figure.
- Heat and light
- Not published in the sources we found. Ask for heat and light data at your pH.
- Confidence
- Medium
- Option
- Gardenia (genipin) blue
- Approved beverage uses
- Approved for sport drinks, flavored noncarbonated water, fruit drinks and ades, and ready-to-drink teas (21 CFR 73.168). Not listed for carbonated soft drinks.
- In acid
- A 2001 study found the pigment more stable at alkaline pH than at neutral or acidic pH. It tested pH 5 to 9, so it does not show performance below pH 5. Not verified below pH 5.
- Heat and light
- Held color after 10 hours at 60 to 90 °C (pH 5 to 9) and under 5,000 to 20,000 lux in the same study.
- Confidence
- Medium
- Option
- Spirulina extract (phycocyanin)
- Approved beverage uses
- Approved for nonalcoholic beverages, beverage mixes and alcoholic beverages under 20% alcohol (21 CFR 73.530).
- In acid
- Works best near neutral. A 2021 review puts its best range at pH 5.5 to 6.0 and reports protein precipitation at pH 3 and 4. A supplier says it "normally precipitates at pH 4.0" (self-reported).
- Heat and light
- Stable to about 45 °C; breaks down faster from about 47 to 69 °C and above 70 °C. Light-sensitive: about 20% loss in 36 hours under continuous light in one test.
- Confidence
- High
- Option
- Butterfly pea flower extract
- Approved beverage uses
- Approved for sodas, sports and energy drinks, flavored and sparkling water, juices, teas and alcoholic beverages (21 CFR 73.69).
- In acid
- Changes color with pH. Acid, such as lemon or lime juice, shifts it toward pink or purple, so it is not a blue option in most acidic drinks. Useful when you want purple.
- Heat and light
- Not published in the sources we found.
- Confidence
- Medium
Why blue is hard in acid
Many sodas, sports drinks and ades are acidic. The approved natural blues come from an alga, a cyanobacterium, a flower and a fruit, and acid changes or precipitates some of them. That is why a blue that works in ice cream can fail in a lemonade.
How to read the confidence column
- High
- A primary source (FDA, Federal Register, a statute) or two or more independent sources that agree.
- Medium
- One named source: trade press, a company statement or a supplier. Supplier figures are self-reported.
- Low
- A figure we found without a named source, or a single estimate we could not trace.
What we have not verified
We found no independent published study that tests gardenia blue or galdieria extract blue below pH 4 in a finished beverage. The low-pH figure for galdieria comes from a supplier. If you have stability data you can share, contact us.
Approval dates and every permitted use are on Natural colors FDA has approved since 2025.
InfoOTHER Natural Flavors is a service of Xponent21 Inc. We share public information and introductions. We do not give legal or regulatory advice and do not guarantee that any color or flavor will perform in your product. Confirm regulatory status with counsel and test every formulation. Sources and the date we last checked them are listed on each page.