Overview
ISO 22994:2021 specifies a routine laboratory method - the sea sand method - for determining the dry matter content of liquid or pasty coffee extracts. Intended for quality control and analytical laboratories, the standard defines sample preparation, required apparatus and reagents, the drying procedure in a vacuum oven, calculation of results and reporting requirements.
Key Topics and Requirements
- Scope: Applicable to liquid and pasty coffee extracts; designed as a routine method for dry matter determination.
- Principle: Mix the sample with acid‑cleaned, annealed sea sand and dry to constant weight in a vacuum oven (70 ± 2 °C for 16 h, ~131 mbar). Determine dry residue by mass loss.
- Apparatus & reagents:
- Analytical balance (accuracy 0.1 mg)
- Vacuum oven, low weighing vessels with lids or metal trays, desiccator, stirring rod
- Sea sand (analytical grade) and grade 1 water (ISO 3696) if needed for mixing
- Sample preparation: Use a representative, homogenized sample. Frozen extracts are typically defrosted and mixed so insoluble dry components at room temperature are included.
- Procedure parameters: Typical sea sand mass 25–30 g per vessel; weigh a test portion such that the dry matter corresponds to 0.1–1.0 g; avoid lumps/crusts; cool in desiccator before weighing.
- Calculation & reporting: Dry matter reported as mass fraction (g/100 g) with specified rounding (single determinations to 0.01 %). Test reports should follow ISO/IEC 17025 reporting principles and include sample ID, method reference (ISO 22994:2021), test dates and any deviations.
- Repeatability: The standard sets minimum repeatability expectations - e.g., the method can statistically differentiate two samples (10–60 % dry matter) differing by 0.5 % at P = 95 % (≈ ±0.25 % variation).
Applications and Who Uses It
- Coffee processors and extract manufacturers for product specification and batch control.
- Quality control and testing laboratories performing routine compositional analysis of coffee extracts.
- R&D teams evaluating extraction efficiency and formulation changes.
- Regulatory agencies and contract testing bodies requiring standardized, comparable dry matter results.
Keywords: ISO 22994:2021, coffee extracts, dry matter content, sea sand method, vacuum oven, laboratory method, liquid coffee extracts, pasty coffee extracts.
Related Standards
- ISO 3696 - Water for analytical laboratory use (referenced for grade 1 water).
- ISO/IEC 17025 - General requirements for competence of testing and calibration laboratories (reporting and laboratory competence).
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