Overview
ISO 2911:2004 - “Sweetened condensed milk - Determination of sucrose content - Polarimetric method” - is an ISO/IDF method for measuring unaltered sucrose (saccharose) in sweetened condensed milk. The standard applies to products made from whole, partially skimmed or skimmed milk and sucrose only, and specifies a polarimetric procedure based on optical rotation changes after controlled inversion of sucrose.
Key topics and technical requirements
- Principle: equilibrate lactose mutarotation with ammonium hydroxide, clarify the sample (zinc acetate + potassium hexacyanoferrate(II)), measure optical rotation, then induce inversion (Clerget acid hydrolysis) and re-measure. The sucrose content is calculated from the change in optical rotation.
- Sample scope: intended for normal sweetened condensed milk containing only sucrose as added sugar (no altered sucrose).
- Reagents & chemicals: zinc acetate, potassium hexacyanoferrate(II), dilute hydrochloric acid, ammonium hydroxide, dilute acetic acid and purified water (analytical grade).
- Apparatus: polarimeter or saccharimeter (2 dm tube recommended), class A volumetric glassware, pipettes, filters and controlled water baths (≈40 °C and 60 °C).
- Procedure controls: specified temperatures, dilution volumes, inversion time (60 °C, 15 min), clarification and filtration steps, and avoidance of air bubbles during dilution.
- Calculations & corrections: sucrose mass fraction is derived from polarimeter readings before and after inversion using the standard’s equations; corrections account for precipitate volume and sample fat/protein content. Temperature correction and inversion division factor (Q) are included.
- Verification: a prescribed check test (milk + known sucrose) ensures reagents and apparatus perform correctly.
- Documentation: the standard includes repeatability guidance and required test-report elements.
Applications and who uses it
- Quality control and laboratory analysis in dairy processing plants and analytical laboratories.
- Regulatory testing and product specification verification for manufacturers of sweetened condensed milk.
- Food analysts and dairy chemists assessing sucrose levels for labeling accuracy, formulation control, shelf-life studies, and compliance with standards.
- Useful in research settings comparing analytical methods for sugar quantification in milk products.
Related standards
- ISO 648 - One‑mark pipettes
- ISO 1042 - Volumetric flasks
- ISO 1737 - Fat determination in evaporated and sweetened condensed milk
- ISO 707 - Recommended sampling for milk products
Keywords: ISO 2911, sweetened condensed milk, sucrose content, polarimetric method, polarimeter, Clerget inversion, food analysis, dairy quality control.
