Sugar Refining Process: From Cane to ICUMSA 45 for Non-Technical Buyers

Understanding where ICUMSA 45 sugar comes from — and what happens during refining — is more valuable for a procurement manager than it might initially appear. The refining process determines which quality parameters are most variable, why certain defects occur more frequently at particular steps, and what questions to ask a supplier to assess whether their production system reliably delivers the specification you need.

This guide walks through the complete journey from sugarcane in the field to ICUMSA 45 in a container, with emphasis on the quality control points that matter most for procurement.

Stage 1: Field to Mill — Sugarcane Harvesting and Crushing

Harvesting

Sugarcane is harvested either manually or by mechanical harvester. The timing and method of harvest affect the quality of sugar produced:

Fresh cane crushing: Cane crushed within 24–48 hours of harvest produces higher-sucrose, lower-dextran juice. This is the quality ideal.
Delayed crushing: Damaged or delayed cane undergoes natural sucrose inversion (sucrose → glucose + fructose) and microbial activity (Leuconostoc bacteria produce dextran). The result is lower-polarity raw sugar with elevated dextran — a problem for downstream refiners.

Procurement implication: Suppliers near their cane supply and with short crush-to-mill timelines produce better-quality raw sugar. Thai mills in major cane-growing provinces (Nakhon Sawan, Kanchanaburi, Suphanburi) have well-managed supply chains with short cane transit times.

Juice Extraction

Crushed cane yields a raw juice containing approximately 12–18% sucrose plus impurities (fiber, minerals, amino acids, coloring compounds). The fiber (bagasse) is separated and typically used to fuel the mill's boilers.

Stage 2: Raw Sugar Production at the Mill

Juice Clarification

Raw juice is heated and treated with lime (calcium hydroxide) to precipitate impurities. The limed juice is settled or filtered to remove the precipitate (called mud or press cake). Clarified juice emerges as a lighter-colored syrup.

Quality impact: Insufficient liming leaves more impurities; over-liming creates calcium salts that affect downstream crystallization. Mill liming quality affects the ash and color of the final raw sugar.

Evaporation and Crystallization

Clarified juice is evaporated in multi-stage evaporators under vacuum to produce a thick syrup (massecuite). Controlled crystallization (seeding with fine sugar crystals, then growing crystals in the supersaturated syrup) produces raw sugar crystals coated in molasses.

VHP production: Mills producing VHP (Very High Pol) sugar apply additional clarification and washing stages to produce higher-polarity, lower-color raw sugar than standard raw grade.

Centrifugation

The massecuite is spun in centrifuges, separating crystals from the residual molasses syrup (which becomes molasses byproduct). Washing the crystals with water or steam during centrifugation removes more molasses coating, increasing polarity and reducing color.

Output: Raw sugar (96–99° pol, 600–3,000 IU color, 0.5–2.5% moisture) or VHP sugar (99.0–99.5° pol, 600–1,200 IU color, 0.15–0.25% moisture).

Stage 3: Refining — Raw Sugar to ICUMSA 45

Affination (Washing)

The first stage of the refinery treats incoming raw/VHP sugar to remove the remaining molasses film:

Raw sugar is mixed with a warm sugar syrup to create a "magma"
The magma is centrifuged to remove the molasses-syrup mixture
Crystals emerge as "washed raw sugar" with reduced color and impurities

This step removes 40–60% of the color in the raw sugar before full refining begins.

Dissolution

Affined sugar is dissolved in water to produce a high-concentration liquor (approximately 60–65° Brix). At this point, all the impurities from the raw sugar are in solution and must be removed in subsequent steps.

Clarification

Two main clarification routes:

Carbonatation: CO₂ gas is bubbled into the liquor in the presence of lime. Calcium carbonate precipitates, carrying impurities to the bottom. The clarified liquor is filtered. This process is common in beet sugar refineries and in some large cane refineries; it produces very high-quality refined sugar.

Phosphatation: Phosphoric acid and lime create calcium phosphate, which floats to the surface carrying impurities (flotation process). The impurity "scum" is skimmed off; the clarified liquor proceeds to decolorization. More common in cane sugar refineries.

Decolorization

This is the most commercially sensitive stage for halal compliance (bone char issue — see Post 24). The clarified liquor passes through adsorbent beds that remove color compounds:

Granular Activated Carbon (GAC): The predominant modern method; plant-derived carbon (usually coal or coconut shell); fully halal
Ion Exchange Resin: Polymer beads with charged surfaces that bind color ions; synthetic; halal
Bone Char (bone black): Calcined animal bones; highly effective historically; not halal; largely phased out in modern refineries

After decolorization, the liquor should be near-colorless. Any residual color at this stage limits the achievable ICUMSA number.

Evaporation and Crystallization (Refinery Stage)

Decolorized, clarified liquor is again evaporated to supersaturation and crystallized under controlled conditions. The crystallization conditions — seeding rate, crystal growth temperature, cooling profile — determine grain size, crystal uniformity, and whiteness.

Centrifugation and Drying

Refined crystal massecuite is centrifuged to separate crystals from the surrounding white syrup (refined liquor, which is recycled or used for liquid sugar production). Crystals are washed with hot water or steam to maximize whiteness.

Washed crystals are dried in a rotary or fluidized-bed dryer to achieve the final moisture specification (max 0.04%).

Quality checkpoint: The moisture reading at the dryer exit is the critical control point for ICUMSA 45 moisture compliance. Over-drying produces brittle crystals (more fines); under-drying produces high-moisture product with caking risk.

Screening and Grading

Dried sugar is passed over vibrating screens to ensure uniform crystal size. Fine particles and oversized lumps are separated; commercial-grade ICUMSA 45 has a defined crystal size distribution (typically 0.3–1.2 mm mean diameter).

Packing and Storage

Refined sugar is conveyed to packing stations and loaded into 50 kg bags (or bulk), then stored in a temperature and humidity-controlled warehouse awaiting shipment.

Quality Control Checkpoints: Where Problems Enter

Understanding at which stage a quality failure can enter allows buyers to target their verification questions at the right point:

Quality Issue	Enters at Stage	Prevention/Detection
High dextran	Field → Mill (cane damage)	Specify dextran limit; verify mill's cane supply proximity
High ICUMSA color	Clarification / decolorization	Specify ICUMSA color; verify decolorizer type and regeneration frequency
Low polarity	Crystallization / poor raw sugar input	Specify minimum polarity; verify input VHP/raw sugar specification
High moisture	Drying / post-drying exposure	Specify max moisture; verify drying controls; check warehouse conditions
Caking	Post-drying storage / packaging	Specify packaging (PE-lined bags); verify warehouse humidity controls
Bone char contamination	Decolorization	Request halal certificate confirming GAC or IEX decolorization; verify certifier

What to Ask a New Sugar Supplier

Based on the above process knowledge, these are the most discriminating questions to ask a potential new supplier:

"What decolorization method does your refinery use? GAC, IEX, or bone char?"
"What is your target moisture at the dryer exit, and what is your control tolerance?"
"How frequently are your GAC or IEX beds regenerated/replaced, and what is your typical color output after decolorization?"
"What is your average dextran specification from your raw sugar suppliers?"
"Can you provide the last 6 months of production QC data showing ICUMSA color, polarity, and moisture lot averages?"

A supplier who answers these questions with specific data has the process knowledge to back their specification claims. Vague answers are a warning sign.

How MC International's Refinery Partners Are Qualified

MC International S.P.A Co., Ltd sources ICUMSA 45 from Thai refineries that we have audited for process compliance, including verification of decolorization system (GAC-based, halal-compliant), dryer maintenance schedules, and warehouse humidity controls. We do not engage refineries that use bone char or that lack documented moisture-control procedures.

Our SGS inspection certificates include all ICUMSA parameters with measured values — providing a production lot snapshot that reflects the process quality described above.

Request Our Refinery Process Documentation

Buyers performing formal supplier qualification can request our refinery process summary and quality management system documentation.

Email: sales@mcispcoltd.com

WhatsApp: +66 99 437 2193