Definition
A confectionery process in which sugar, chocolate, or cocoa-based coatings are applied in thin layers to a centre product inside rotating, tilted drums (panning drums), gradually building a dried and thickened shell. Hard panning uses a sugar syrup, soft panning uses powdered sugar plus a binder, and chocolate panning uses melted chocolate. Between each layer, a flow of low-dew-point air is critical for a glossy, homogeneous shell.
Detailed Explanation
Panning is a batch coating process that gradually builds a pearl-like soft or hard shell on the centre product. It is carried out in tilted (30–45°) rotating copper or stainless steel pans; pans rotate at 8–18 rpm with the centre product (almond, hazelnut, coffee bean, jellybean, gum tablet, pharmaceutical tablet) tumbling inside.
Three main panning types:
1. Hard panning — sugar syrup is applied in thin layers and each layer is dried with dry air; the cycle is repeated many times and coating takes hours. 2. Soft panning — powdered sugar + binder syrup are applied alternately; faster, but the shell is softer and less glossy. 3. Chocolate panning — molten chocolate is applied and set with cold air (pre-tempered or not, depending on the process). Nut centres are first sealed with gum arabic or syrup; polishing is applied over the chocolate shell as the final stage.
Coating quality depends heavily on process-air dew point: • Chocolate coating: typically 10–12°C / 40–50% RH; this air has a dew point of −3…+2°C (critical to prevent sugar bloom and sticking). • Polishing: warmer and drier, typically 18–22°C / 30–40% RH. • For hard and soft sugar panning, the target dew point is set per product and recipe.
Air flow into the pan is set by pan size and layer stage, usually modulated by a VFD-driven fan.
Why It Matters
Panning is a critical step shaping both the visual identity and physical performance of premium confectionery and pharmaceutical products:
1. Visual quality — a glossy, uniform, crack-free shell shapes brand perception; a matte, blotchy shell lowers consumer preference. 2. Structural durability — the shell protects the centre from mechanical and moisture-driven impacts; shelf life depends on coating quality. 3. Barrier — a well-sealed sugar or chocolate shell protects the centre from ambient moisture and oil migration. 4. Flavour profile — the shell-to-centre ratio defines the consumer's taste experience. 5. Production efficiency — at the correct dew point, layers dry or set faster, coating time shortens and the summer-winter gap closes.
Without humidity control: high dew point → layers cannot dry or moisture condenses on the surface → the next layer fails to adhere, sugar bloom forms and dragees stick together in the pan. Lower-than-required dew point → too-fast drying, dust and static. The correct band is a dew-point setpoint chosen per product and stage, held steady by the air-handling system.
Practical Example
Illustrative calculation: a chocolate panning line is to receive 5,000 m³/h of fresh air at 11°C / 45% RH (w ≈ 3.6 g/kg, dew point ≈ −0.5°C).
• At the summer design condition outdoor air is ≈ 17 g/kg (Istanbul order of magnitude). Moisture load = 5,000 × 1.2 × (17 − 3.6) / 1,000 ≈ 80 kg/h. • In winter outdoor air is ≈ 4 g/kg: load ≈ 5,000 × 1.2 × (4 − 3.6) / 1,000 ≈ 2 kg/h. This is why a unit sized for winter falls short in summer. • If a pre-cooling coil brings the air to a +9°C dew point (≈ 7.1 g/kg), about 59 kg/h is removed at the coil and the remaining ≈ 21 kg/h by the silica gel rotor. Because the target dew point is below +5°C, the final stage is the silica gel rotor. • The rotor heats the air as it removes moisture, so a post-cooling coil brings the air back to 11°C. • 5,000 m³/h falls within the TFT AD 3000-6500 range (3,000–6,500 m³/h); final selection depends on the safety margin (15–25%) and the reactivation energy source available on site.
Engineering Note
Engineering criteria for panning-line air handling:
• Per-pan airflow — set by pan size and manufacturer data; total airflow is the basis for silica gel rotor unit selection. • Stage-specific setpoints — chocolate coating 10–12°C / 40–50% RH (dew point −3…+2°C), polishing 18–22°C / 30–40% RH; a recipe-driven setpoint table on the PLC is recommended. • Summer design load — sizing uses the site's summer dehumidification design data plus a 15–25% (typically 20%) safety margin. • Reactivation energy — steam or natural gas typically cuts operating cost by 40–60% versus electric reactivation; waste heat can pre-heat the reactivation air. • Filter selection — pan return air may carry sugar, cocoa and nut dust; proper filtration protects rotor life. • Hygienic design — stainless inner casing and easy-clean filter cassette; cleaning records should be kept.
NKT Application Link
For this application NKT – Nem Kontrol Teknolojileri supplies TFT AD series silica gel rotor dehumidifiers and 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.
