Anonymized use case. Client, brand and supplier names are withheld, and so are the formula and process settings. This is how DyeConverter™ worked the problem. Every pick is a candidate to bench-test, not a guarantee.
The problem
A shelf-stable cocktail mixer, juice-based and hot-filled, needed to look very light yellow-green. Two things were going wrong. The color turned amber during the hot fill and kept darkening on the shelf. And nothing in the formula could hold a green: the pineapple and lime supplied yellow, and nothing supplied blue.
What we modeled
- Product: non-carbonated, juice-containing mixer, 12 months ambient, in a clear bottle under retail light.
- pH: about 2.9, with a second batch reading lower.
- Process: hot fill, with a hold of about 10 minutes near 85°C.
- What the formula brings to the color problem: vitamin C from the juices, a high sugar load, juice amino acids and strong acid.
- Market and label: United States, with a “natural” claim on the label.
Step one: fix the browning
Added color sits on top of the brown, so a blue over a browning base reads olive. Three reactions were browning this mixer:
- Vitamin C breakdown, the classic way citrus juices brown. Heat, oxygen and warm storage speed it up.
- Acid breakdown of the sugar. At pH 2.9, sucrose splits, and fructose degrades into brown compounds (via HMF) under heat.
- Maillard browning between the sugars and the amino acids in the juice concentrates.
The levers: hold no longer than validation requires, cool the bottles fast, deaerate and minimize headspace, store cool, consider UV-protective packaging, and source fresher, lighter concentrates.
Step two: build the green from blue plus the yellow already there
At pH 2.9, the strongest fit was Galdieria extract blue (21 CFR 73.167), an acid-tolerant blue from an extremophile alga that is far more acid-stable than spirulina. Jagua blue (21 CFR 73.225) came a close second: one supplier’s own beverage tests show it stable in a pH 2.2 syrup, with xanthan gum needed to prevent flocculation in a ready-to-drink at pH 3.0. Jagua also reads slightly green-blue, which helps a lime-green target.
The single biggest lever was pH. Moving from 2.9 to 3.0 to 3.2 puts both blue families inside supplier-documented ranges and opens up gardenia blue (21 CFR 73.168) as well. Getting there means slightly less lime or a little sodium citrate, which changes the tartness and must be re-confirmed by the process authority.
If the base yellow reads weak, a clear-beverage grade of beta-carotene (21 CFR 73.95) holds up in acid, and the juices’ vitamin C helps protect it. Standard emulsions cloud a clear mixer, so the grade matters.
What we ruled out, and why
- Anthocyanins (black carrot, purple sweet potato, red cabbage, elderberry): red to magenta at pH 2.9, not blue. Over the pineapple yellow they read peach or brown.
- Butterfly pea: turns purple in acid.
- Standard spirulina: breaks down in acid and in the hot-fill hold. Acid-stable grades exist, but they suit a cold-filled or HPP chilled version, not a hot fill.
- Copper chlorophyllin: US use is limited to dry citrus beverage mixes.
- Turmeric: fades quickly in a clear bottle.
The label note
FDA’s longstanding position is that added color, including color from natural sources, is generally inconsistent with a “natural” claim, and any added color must be declared. That one goes to the regulatory team before launch.
Honest limits
No supplier publishes data for a full 85°C, 10-minute hold at pH 2.9. Published studies put the genipin blues (jagua, gardenia) among the most heat-stable natural blues, and Galdieria tolerates far more acid and heat than spirulina, but its behavior in a hold this long is not published. The next step was hot-fill data from each supplier at these exact conditions, then a bench titration at pH 2.9 and 3.2 against the target photo, under retail light, after accelerated storage.
Have a color that will not hold in your process? Talk to us, or try the Color Studio.
Frequently Asked Questions
Can you make a natural green for a very acidic, hot-filled beverage?
Usually yes, by adding an acid-tolerant natural blue to the yellow the juices already supply. At pH 2.9, Galdieria extract blue and jagua blue are the strongest candidates. Spirulina is not, because it breaks down in strong acid and heat.
Why does a light green beverage turn olive or amber on the shelf?
Browning. Vitamin C breakdown, acid breakdown of sugar and Maillard reactions all darken the base. Any blue added on top of a browning base reads olive, so the browning has to be slowed first.
Does raising the pH help natural blues?
A lot. Moving from about pH 2.9 to 3.0 to 3.2 puts Galdieria, jagua and gardenia blues inside their supplier-documented ranges. Any pH change must be re-confirmed by the process authority.