Brix (°Bx)

Detailed Explanation

In confectionery, Brix (°Bx) is the common language of recipe and process control. By definition it expresses the sucrose-equivalent total dissolved solids percentage in 100 g of solution. In practice not only sucrose but also glucose syrup, fructose, dextrose, sorbitol, and other soluble solids contribute to the Brix reading.

Measurement methods: • Refractometer — refractive index → Brix conversion; handheld field tool or inline sensor • Hydrometer — specific gravity → Brix conversion; low accuracy, used for quick checks • Density meter (inline measurement instrument type) — high accuracy (±0.02 °Bx), laboratory standard • Polarimeter — for pure sucrose solutions

Typical Brix bands: • Syrup: 65–80 °Bx • Jam/marmalade: 65–70 °Bx • Hard candy (drops): 96–98 °Bx • Jelly/jellybean mass: 78–82 °Bx (at mogul depositing stage) • Marshmallow: 75–78 °Bx • Fondant: 88–92 °Bx

Brix has a direct inverse correlation with water activity (aw); this relationship underlies storage stability and microbiological safety in confectionery.

Why It Matters

Brix is critical in confectionery production for four primary reasons:

1. Cooking end-point — water evaporation during cooking raises the dissolved solids ratio; cooking must stop once the target Brix is reached. Under-cooking = low viscosity + weak gel structure; over-cooking = colour darkening, Maillard by-products, hard texture. 2. Microbiological safety — high Brix → low aw → suppression of mould, yeast, and bacterial growth. Below 65 °Bx, jam becomes microbiologically at risk. 3. Rheological behaviour — depositors/fillers operate within a tight viscosity window. A jelly mogul depositing line targets 80 ± 1 °Bx; deviation causes filling errors. 4. Shelf life — Brix is directly linked to Equilibrium Relative Humidity (ERH); when storage RH > ERH the product picks up moisture (cap, tack), and otherwise it dries. For 80 °Bx jelly, ERH ≈ 68%; storage should be at around 55% RH.

In mogul processes, Brix deviation upsets starch moisture balance: lower Brix → wetter mass → starch absorbs excess moisture → tray bed becomes tacky → shape distorts. So Brix control is a precondition not only for the cooking station but for entire line yield.

Brix–aw–ERH Relationship

Approximate aw equation for a sucrose solution (Norrish model):

aw = xwater × exp(−K × x²)

x: mole fraction of dissolved solids (for sucrose x = nsuk / (nsuk + nwater)) xwater: mole fraction of water (1 − x) K: Norrish constant (6.47 for sucrose)

ERH (%) = aw × 100

Practical conversions (sucrose solution, 25°C): • 60 °Bx → aw 0.90 → ERH 90% • 70 °Bx → aw 0.82 → ERH 82% • 75 °Bx → aw 0.77 → ERH 77% • 80 °Bx → aw 0.68 → ERH 68% • 85 °Bx → aw 0.55 → ERH 55%

(Norrish calculation; because sucrose is supersaturated above ≈ 67 °Bx at 25°C, the high-Brix rows are model values.) In the presence of glucose syrup, values shift by 3–8% (molecular-weight correction).

Storage design criterion: RHambient = ERHproduct − safety margin (typically 10–15%)

Engineering Note

Field engineering notes for Brix management:

• Temperature correction — refractometers are calibrated at 20°C; ATC (automatic temperature compensation) is required for hot syrup readings. A raw 78 °Bx read at 80°C may actually be 80 °Bx. • Inline measurement — an inline refractometer at the cooker outlet feeds Brix into a PID loop; cook time / steam flow are auto-adjusted. • Blend balance — the glucose-syrup-to-sucrose ratio determines graining risk; typical jelly recipes use 30–40% glucose syrup to prevent saturation. • Process water management — high-mineral source water shifts refractometer readings; pre-treatment (demineralised or reverse osmosis) is recommended. • Storage link — finished-product storage and packing area RH must be 10–15% below product ERH; otherwise jelly surfaces absorb moisture and become tacky. The mogul stove room, being a drying stage, runs at a much lower RH (e.g. 32°C / 25% RH). In a correctly configured system, ambient RH and dew point are held steady through closed-loop PID.

Calibration: refractometers should be verified weekly with pure water (0 °Bx) and a certified 60 °Bx reference solution.

NKT Application Link

For this application NKT – Nem Kontrol Teknolojileri supplies TFT ADP series silica gel rotor dehumidifiers. It supports unit selection with capacity calculation and technology matching based on space conditions, target temperature and RH (or dew point) and moisture load, and provides technical service and spare parts. Design, installation and commissioning remain within the scope of the facility's designer and contractor.