Overview
ISO 3093:2009 specifies the Hagberg‑Perten falling number (FN) method for estimating alpha‑amylase activity in cereals. It applies to wheat, rye and their flours, durum wheat and durum wheat semolina, and expresses results as a falling number (seconds). The method measures starch liquefaction caused by alpha‑amylase using a precision viscometer tube and stirrer and is widely used in cereal quality testing. Note: the method is not applicable for determination of very low alpha‑amylase activity.
Key topics and technical requirements
- Principle: gelatinize a suspension of sample + water, boil, and record the time for a viscometer stirrer to fall - the falling number (FN) in seconds reflects enzyme activity and starch liquefaction.
- Measured values: Falling number (FN); conversion to Liquefaction Number (LN) is described so LN values (which are additive) can be used to estimate mixture composition.
- Sample types: whole grain (ground to specified particle size), flour and semolina (lumps removed or reground to meet particle size requirements).
- Sample preparation: control of moisture content (results referenced to ~15% moisture); specific test portion masses adjusted for sample moisture to keep dry matter constant.
- Apparatus: FN apparatus (water bath with cooling, precision viscometer tubes and metallic stirrer, stoppers), automatic pipette/dispener, analytical balance, laboratory mill and sieves. FN tubes have defined dimensions and a specifically designed viscometer stirrer is required.
- Quality and precision: includes procedures for duplicate determinations, moisture determination (ISO 712), particle size checks, and documented precision (repeatability/reproducibility) from interlaboratory tests.
- Corrections & annexes: altitude correction equations for FN (Annex A) and interlaboratory results (Annex B).
- Intellectual property: the commercially common Falling Number apparatus (Perten) is subject to patent rights; ISO notes licensing availability.
Applications and who uses the standard
- Millers and flour manufacturers: assess enzyme activity affecting dough and baking performance.
- Grain buyers, traders and quality control labs: evaluate sprout damage and decide grade or handling.
- Cereal testing laboratories and research: standardized FN results for comparison and breeding trials.
- Regulatory bodies and food industry QA: specification compliance, contract testing and dispute resolution.
- Useful when estimating blend formulations by converting FN to LN to predict the FN of mixtures.
Related standards
Keywords: ISO 3093:2009, falling number, Hagberg‑Perten, alpha‑amylase, wheat testing, rye testing, durum semolina, FN, liquefaction number, cereal quality testing.