Overview
ISO/TS 12788:2022 - "Rapeseed - Determination of glucosinolate content - Spectrometric method for total glucosinolates by glucose release" specifies an analytical procedure to estimate total glucosinolate content in rapeseed (colza) by measuring the glucose released after enzymatic hydrolysis. The method uses visible spectrometry and enzymatic glucose assays rather than chromatographic separation, providing a complementary approach to the chromatographic reference method (ISO 9167). ISO/TS 12788:2022 is published as a Technical Specification.
Key topics and technical requirements
- Scope and principle: Total glucosinolates are quantified by hydrolysing glucosinolates with myrosinase, collecting the released glucose and determining glucose concentration enzymatically. Results are expressed as micromoles of glucose per gram of seed.
- Sample preparation and sampling: Requirements reference standard oilseed laboratory practices for reduction to test sample, moisture determination and grinding to a laboratory sample (see ISO 664, ISO 665).
- Reagents and buffers: The specification lists required reagents (e.g., phenol tungstate reagent, sodium phosphate buffer, myrosinase solution) and guidance on preparing calibration glucose standards.
- Glucose assays: Two validated enzymatic assay routes are provided:
- Glucose oxidase / peroxidase colorimetric assay (visible spectrometry)
- Glucose hexokinase / glucose-6-phosphate dehydrogenase assay (spectrophotometric NADPH measurement)
- Procedure steps: Extraction of glucosinolates, enzymatic hydrolysis, glucose collection (column chromatography steps described), glucose determination, and calculation of total glucosinolate content.
- Quality and precision: The document includes guidance on calculation, expression of results, repeatability/reproducibility considerations and reports results of an interlaboratory study (Annex C). Annexes also cover myrosinase extraction from Sinapis alba and recovery determination.
Applications and users
ISO/TS 12788:2022 is practical for:
- Seed testing and quality control laboratories measuring glucosinolate levels in rapeseed/canola
- Oilseed breeders and research labs screening lines for low-glucosinolate traits
- Commercial grading and acceptance testing where rapid, non-chromatographic estimation is required
- Feed and food safety analysts monitoring antinutritional and flavor-related glucosinolate content
The method is useful when chromatographic equipment is unavailable or when a rapid total-glucosinolate screening is needed.
Related standards
- ISO 9167 - Reference chromatographic methods for glucosinolates
- ISO 664 - Oilseeds - Reduction of laboratory sample to test sample
- ISO 665 - Oilseeds - Determination of moisture and volatile matter content
- ISO 3696 - Water for analytical laboratory use
Keywords: ISO/TS 12788:2022, glucosinolate content, rapeseed, spectrometric method, glucose release, myrosinase, glucose assay, canola, oilseeds, analytical method.