Brix and Acidity in Fruit Juice Concentrate: What They Mean and How to Specify Them

What does Brix measure?

Degrees Brix (°Bx) express the mass of dissolved solids in 100 g of liquid, read as the sucrose-equivalent on a refractometer, normally at 20 °C. In fruit juice most of those solids are sugars, but organic acids, minerals and other soluble compounds contribute as well. That is why Brix tracks sugar closely without being the same thing as a sugar analysis.

Two practical consequences for buyers:

• Brix is a mass ratio. A 50°Bx concentrate contains roughly 50 kg of soluble solids per 100 kg of product. Do formulation maths in kilograms; a 50°Bx concentrate weighs about 1.23 kg per litre, so litre-based calculations drift.
• Very acidic concentrates need a clear reading convention. Acids raise the refractometer reading differently from sugar. For high-acid fruit such as passion fruit, ask whether the Brix on the specification and COA is the direct reading or corrected for acidity, and keep the same convention for every lot.

Does 50°Bx mean sugar was added?

No. A concentrate is made by removing water, usually by evaporation. The solids stay, so the Brix rises. Single-strength passion fruit juice reconstitutes at around 12°Bx under the Codex standard; evaporating about three-quarters of the juice’s weight as water brings it to about 50°Bx without a gram of added sugar.

Added sugar is a question of recipe and authenticity, not of the Brix figure:

• the ingredient declaration and the supplier’s specification must state any added sugar;
• authenticity can be checked analytically, for example through the sugar profile, and through stable isotope methods that detect cane or corn sugar in fruit juice;
• industry reference guidelines such as the AIJN Code of Practice give typical composition ranges that laboratories compare against.

If a claim such as “100% juice” or “no added sugar” will appear on your finished product, ask for the recipe statement and keep the authenticity evidence with the lot documents.

Why do Brix and acidity belong in the same specification?

Brix tells you how much fruit solids you are buying. Acidity — usually titratable acidity expressed as citric acid — tells you how sour those solids are. The ratio between the two (the Brix/acid ratio) drives the sweet-sour balance, and it moves with fruit maturity, variety and season.

Two concentrates at the same Brix can therefore behave differently in a recipe:

• a higher-acid lot needs more sugar or less concentrate to reach the same taste;
• a lower-acid lot can taste flat at the dosage the recipe was built on;
• colour, aroma, viscosity and pulp vary independently of both.

For a beverage manufacturer, the useful specification is Brix with a tolerance, acidity with a tolerance, and a sensory reference, all reported on each lot COA and checked against the approved sample.

How much concentrate does a recipe need?

Juice content is calculated from the Brix at which the fruit’s juice is considered single strength. The Codex standard for fruit juices (CXS 247-2005) sets minimum Brix levels for reconstituted juice, among them:

Codex marks the passion fruit and pineapple values as acid-corrected, and for pineapple it accepts juice of lower natural Brix from some origins (not below 10°Bx) provided authenticity is demonstrated. National rules can set their own references, so confirm the one your market uses before you print a juice percentage.

The dosage then follows from a mass balance using the juice share by mass. If market labelling rules require a juice percentage by volume, convert using the appropriate juice and finished-drink densities; a mass fraction is not automatically the same as a volume fraction:

concentrate (kg) = finished quantity (kg) × juice share by mass × reconstitution Brix ÷ concentrate Brix

For example, 1000 kg of a drink formulated to contain 10% passion fruit juice by mass, made from a 50°Bx concentrate reconstituted at 12.0°Bx, needs 1000 × 0.10 × 12.0 ÷ 50 = 24 kg of concentrate. The same calculation shows why a lot delivered at 48°Bx instead of 50°Bx changes the dosage by about 4%: a Brix tolerance is a cost and consistency parameter, not a formality.

How do mango, pineapple and passion fruit concentrates compare?

Mango, pineapple and passion fruit concentrates should not be compared on Brix alone: the fruits differ in acidity, aroma and body, and mango’s viscosity limits how far it can be concentrated.

Our published working values for each product are in the table further down. Application cost depends on how much of each concentrate a recipe needs to reach its taste and juice-content targets, not on the Brix figure by itself.

Can the Brix be customised?

Within the process capability of the producing factory, often yes. Before asking for a non-standard Brix, weigh three effects:

1. Stability. A lower Brix means more water and higher water activity, which makes the product more dependent on aseptic filling, chilling or freezing.
2. Quality in storage. Very high Brix inhibits many microorganisms, but does not by itself guarantee stability; validated processing, packaging and storage are still required. Such concentrates can darken and lose fresh aroma faster in warm storage.
3. Freight. Removing water raises Brix and reduces the weight shipped for the same quantity of fruit solids. Higher Brix is usually cheaper per kilogram of fruit solids delivered.

State the target and the tolerance (for example 50 ± 1°Bx), the measuring convention and the acidity range you expect with it.

What to specify and test before approving a concentrate

Approve a concentrate on a written specification and on a trial in your own recipe. The specification should cover at least these points:

• fruit, variety where it matters, and single-strength or concentrate format;
• Brix target and tolerance, measuring temperature and acid-correction convention;
• titratable acidity and pH ranges;
• pulp content, and for passion fruit whether seeded or seedless material is acceptable;
• colour, aroma and taste reference, held as a retained sample;
• microbiological criteria appropriate to the pack format;
• pack format and storage temperature (aseptic, chilled or frozen), and the shelf-life statement that applies to that route;
• the COA parameters to be reported for every lot.

Then test the approved sample in your own recipe: a bench trial followed by a pilot run shows dosage, taste and stability far better than a specification sheet can. Our guide to aseptic concentrate packaging and storage covers drums, shelf life and shipping temperature, and passion fruit concentrate in beverages covers separation and dosage in ready-to-drink products.