Overview
ISO 13965:1998 specifies an enzymatic method for the quantitative determination of water‑free starch and glucose contents in all kinds of meat and meat products (including poultry). The method is suitable down to 0.30% (m/m) and explicitly excludes chemically modified starches and their derivatives. ISO 13965:1998 describes sample preparation, enzymatic hydrolysis, spectrometric measurement and calculation conventions for reliable starch determination and glucose determination in meat matrices.
Key topics and technical requirements
- Scope and limits
- Applicable to raw and processed meat products; detection limit 0.30% (m/m).
- Not applicable for chemically modified starches.
- Principle (enzymatic reactions)
- Solubilize starch and partially hydrolyse with α‑amylase.
- Convert starch to glucose with amyloglucosidase (AGS) (omitted when measuring glucose only).
- Phosphorylate glucose using hexokinase (HK) and ATP to glucose‑6‑phosphate.
- Oxidize glucose‑6‑phosphate via glucose‑6‑phosphate dehydrogenase (G‑6‑PDH) with NADP+, producing NADPH.
- Measure NADPH spectrophotometrically (primary wavelength 340 nm; alternatives 365 nm or 334 nm with adjusted coefficients).
- Reagents & apparatus
- Enzymes: α‑amylase (heat‑stable), amyloglucosidase, HK/G‑6‑PDH mixes.
- Cofactors: NADP, ATP; buffers (acetate, citrate, triethanolamine).
- Equipment: homogenizer/mincer, pH‑meter, water bath (60 ±2 °C), spectrometer (340 nm), quartz cuvettes (10 mm path), analytical balance.
- Sample handling
- Homogenize sample and analyse within 24 h; extract maltose/glucose with 40% ethanol if maltose is present (maltose interferes because AGS hydrolyzes it to glucose).
- Calculations & precision
- Detailed absorbance difference formulas and conversion to % (m/m) are provided using NADPH molar absorption coefficient.
- Repeatability and reproducibility performance limits are specified for given concentration ranges.
Applications and users
- Food testing and analytical laboratories validating ingredient declarations.
- Meat processors and QC teams monitoring added starch levels for formulation control.
- Regulatory and compliance agencies verifying labeling and adulteration.
- Research labs studying carbohydrate content in meat formulations.
Practical uses include ingredient verification, nutritional labelling, detection of undeclared extenders and process control.
Related standards
- ISO 3696:1987 - Water for analytical laboratory use (reagent water quality referenced).
- ISO 3100‑1 - Recommended sampling methods for food (sampling guidance referenced).
Keywords: ISO 13965, starch determination, glucose determination, enzymatic method, meat products, amyloglucosidase, hexokinase, NADPH, spectrometric measurement, analytical method.