Foss Soxtec™ ST 243 Fat Extractor Unit

Solvent Extraction System – 6-Position Soxhlet Apparatus Capacity | 0.1–100% Fat Range

The Problem with Traditional Soxhlet Extraction

If your lab still relies on traditional Soxhlet extraction, you already know the frustrations: extraction cycles that run 6 to 24 hours, excessive solvent consumption that inflates operating costs, and the ever-present safety risk of heating flammable solvents on open hot plates. These limitations don’t just slow down your workflow — they create a bottleneck that affects every decision downstream, from quality release to production scheduling.

The Foss Soxtec™ ST 243 Fat Extractor Unit is the modern answer to these challenges. It is a semi-automatic, 6-position solvent extraction system that delivers the same accuracy as classical Soxhlet methods — fully compliant with AOAC and ISO standards — while completing a full batch in just 40 to 60 minutes. Designed for food, feed, dairy, and agricultural laboratories, it dramatically reduces analysis time, cuts solvent use by up to 80%, and incorporates built-in safety features that protect your operators and your facility.

Whether you are testing meat, cereals, instant noodles, milk powder, pet food, or animal feed, this system handles it all with a reproducibility of ±1% relative across its full measuring range of 0.1% to 100% fat.

Why Laboratories Are Moving to the Soxtec™ ST 243

Extraction in Minutes, Not Hours

The single biggest advantage of this system is speed. A classical Soxhlet apparatus requires 6 to 24 hours to complete one extraction cycle. The ST 243 finishes the same work — for a batch of six samples — in 40 to 60 minutes. That is a five-fold acceleration at minimum. In practical terms, this means your lab can process 30 to 36 samples in a single working day instead of waiting overnight for results. For quality control labs where production hold times depend on fat analysis, this speed translates directly into faster product release and reduced inventory costs.

Drastic Reduction in Solvent Consumption

Traditional Soxhlet extraction is notoriously solvent-intensive, often requiring 150 to 300 mL of petroleum ether or hexane per sample. The ST 243 uses only approximately 40 to 50 mL per batch of six — not per sample, per batch. On top of that, the integrated solvent recovery system reclaims roughly 80% of the solvent used, condensing it back for reuse. This means your annual solvent procurement costs drop significantly, your hazardous waste disposal volume shrinks, and your lab’s environmental footprint improves — all without any compromise in extraction efficiency.

Built-In Safety for Flammable Solvent Handling

Working with petroleum ether and hexane always carries risk. The ST 243 mitigates this with a spark-proof hot plate and dual temperature sensors that continuously monitor heating conditions. The system is designed to never reach the ignition point of the solvent in use. Combined with an efficient condenser that contains solvent vapors and the requirement to operate within a fume hood (minimum airflow of 0.5 m/s), this unit provides a fundamentally safer working environment compared to open Soxhlet setups with heating mantles.

Reproducible Results with Minimal Operator Variability

Semi-automatic operation means the system controls the critical phases — boiling, rinsing, and solvent recovery — automatically and consistently. The operator handles sample loading, solvent filling, and final gravimetric weighing, but the extraction process itself is standardized from run to run. Dedicated batch handling tools for cups and thimbles reduce direct contact with hot glassware and minimize the risk of accidental sample loss or contamination. The result is tighter reproducibility and greater confidence in your reported values.

Full Regulatory Compliance and Method Approval

In regulated industries, analytical results are only as good as the method behind them. The Soxtec™ ST 243 is approved and validated for a range of internationally recognized official methods, including AOAC 2003.05 and 2003.06 (total fat in foods), AOAC 991.36 (fat in meat and meat products), ISO 1444:1996 (meat and meat products — determination of free fat), ISO 11085:2008 (cereals, cereal-based products, and animal feeding stuffs), and ISO 6492:1999 (animal feeding stuffs — determination of fat content).

This means results generated on the ST 243 are defensible during audits by SGS, BSTI, national food safety authorities, the Islamic Foundation (for Halal certification), and international buyers. Installation Qualification (IQ) and Operational Qualification (OQ) documentation is available from the supplier to support GLP, GMP, and ISO 17025 accreditation requirements.

Versatile Application Across Sample Types

The system is designed to handle a wide range of sample matrices encountered in food, feed, and agricultural testing. Typical applications include raw and processed meat products, dairy products such as milk powder (using Celite 545 as a filter aid per standard dairy fat protocols), cereals, grains, and flour, instant noodles and fried snack products, animal feed and pet food, oilseeds and oil-bearing raw materials, and environmental samples such as soil and sludge for oil and grease determination.

The recommended sample size is 0.5 to 3 grams, with 0.5 to 2 grams being typical for total fat determination. The sample should not exceed one-third to one-half of the 40 mL thimble capacity to ensure optimal solvent circulation and complete extraction.

How the System Works

The Soxtec™ ST 243 operates through a controlled three-phase extraction cycle.

In the boiling phase, the thimble containing the weighed sample is immersed directly in the boiling solvent. This direct contact between sample and hot solvent provides rapid and aggressive initial extraction, dissolving the bulk of the fat content in the first few minutes.

During the rinsing phase, the thimble is raised above the solvent level. Fresh, condensed solvent continuously drips through the sample from above, rinsing out residual fat — similar to the classical Soxhlet principle but significantly faster due to the prior boiling step.

In the recovery phase, the solvent is evaporated from the extraction cup and condensed back into a collection vessel for reuse. The fat remains in the cup. After a brief drying step, the cup is weighed to determine the fat content gravimetrically.

This three-phase approach is what allows the ST 243 to match the thoroughness of traditional Soxhlet extraction while compressing the total cycle time to under one hour.

Detailed Technical Specifications

What’s Included in the System

The Soxtec™ ST 243 is supplied as a complete, ready-to-run package. The delivery includes the extraction unit (6-position), the control unit for parameter setting and process management, extraction cups, extraction thimbles, seals and gaskets, and batch handling tools for safe manipulation of hot cups and thimbles. This means your lab can begin running samples immediately after installation and qualification, with no additional equipment purchases required to get started.

Consumables and Annual Operating Requirements

For routine operation, the following consumables are needed on a recurring basis: extraction thimbles (reusable 10 to 20 times with proper care), solvents such as petroleum ether or n-hexane, replacement seals and gaskets, and filter papers. Spare parts that may be needed depending on usage intensity include heating elements and condenser tubing. A recirculating chiller is recommended — though not strictly required — in regions where tap water temperature exceeds 20°C during summer months, as elevated water temperature can reduce condensation efficiency and solvent recovery rates.

Frequently Asked Questions

Can fat be extracted from milk powder using this system?
Yes. The ST 243 is fully suitable for fat extraction from milk powder when used with Celite 545 as a filter aid, following standard AOAC or ISO dairy fat protocols.

What solvent should be used for instant noodles?
Petroleum ether or n-hexane are the recommended solvents for extracting fat from instant noodles and similar fried products, as specified by standard food fat extraction methods. Extraction time for noodles with approximately 16% fat is typically 40 to 60 minutes.

Is the system fully automatic?
The ST 243 is semi-automatic. The boiling, rinsing, and solvent recovery phases are controlled automatically. Sample preparation, loading, solvent filling, and final weighing are performed manually by the operator.

Is tap water sufficient for cooling, or is a chiller needed?
Under normal laboratory conditions, tap water at 1 to 2 liters per minute is sufficient. In warmer climates or during summer, a recirculating chiller is recommended to maintain consistent condensation performance.

How many times can thimbles be reused?
With proper cleaning, drying, and careful handling, thimbles can typically be reused 10 to 20 times. Reuse frequency depends on the sample type and whether the thimble sustains any physical damage during extraction.

Is this system accepted during third-party audits?
Yes. The Soxtec™ ST 243 is widely recognized and accepted by auditors from SGS, BSTI, national food safety regulators, the Islamic Foundation, and international buyers, provided the system is operated according to validated standard methods with proper documentation.

What warranty is provided?
The system comes with a standard 12-month warranty covering manufacturing defects, with access to technical support, spare parts supply, and optional annual maintenance service contracts.

Can this system be used for environmental testing?
Yes. Beyond food and feed applications, the ST 243 can be used for extracting oils and fats from environmental matrices such as soil and sludge, using appropriate validated extraction methods.

Upgrade Your Fat Analysis Workflow

The Foss Soxtec™ ST 243 is not just an incremental improvement over traditional Soxhlet — it is a fundamental upgrade in how your laboratory performs fat extraction. Faster results, lower costs, safer operation, and full compliance with international standards make it the definitive choice for any lab serious about efficient and reliable crude or total fat determination.

Contact our team today to request a quotation, schedule a live demonstration, or discuss how the Soxtec™ ST 243 can be configured to meet your specific testing requirements.