ISO 5943:2006

Overview

ISO 5943:2006 (also published as IDF 88:2006) specifies a potentiometric titration method for determining the chloride content of cheeses and processed cheese products. The method applies to all cheese types and processed cheeses containing more than 0.2% (mass fraction) chloride ion. It is a standardized laboratory procedure used to quantify chloride (as Cl−) or express results as NaCl, KCl, etc.

Key topics and technical requirements

• Principle: Suspension of a weighed cheese sample in water, acidification with nitric acid, and potentiometric titration of chloride ions with a standardized silver nitrate (AgNO3) solution.
• Reagents:
  • Standard AgNO3 solution, c ≈ 0.08–0.12 mol·L−1 (calibrated by dried NaCl), concentration expressed to four decimals.
  • Nitric acid, approximately 4 mol·L−1.
  • High-purity water and analytical-grade reagents.
• Apparatus:
  • Potentiometer with an appropriate silver measuring electrode and a reference electrode.
  • Analytical balance (±0.001 g), mixer, burette (or automatic burette), graduated cylinders, and appropriate titration vessels.
• Sample preparation:
  • Remove rind or spoiled surface; grind or grate to a representative homogenized sample.
  • Typical test: 2–5 g sample suspended in ~30 mL water at ~55 °C.
  • Add 2–3 mL HNO3, then titrate with AgNO3 while monitoring potential to detect the endpoint.
• Calculations and results:
  • Result computed from titrant volumes (sample and blank), AgNO3 concentration, sample mass and the chosen molar mass (e.g., 35.5 for Cl, 58.4 for NaCl).
  • Results expressed with two decimal places.
• Fidelity:
  • Repeatability: difference ≤ 0.02 g Cl per 100 g in >95% of cases.
  • Reproducibility: difference ≤ 0.06 g Cl per 100 g in >95% of cases.

Applications and users

• Who uses it: dairy testing laboratories, quality assurance and control teams in cheese manufacturing, regulatory authorities, research labs and product development teams.
• Practical uses:
  • Verifying salt content for flavor, shelf-life and texture control.
  • Compliance testing for labeling and regulatory requirements.
  • Process monitoring (brining consistency, salt distribution) and comparative product analysis.
  • Research into salt reduction strategies while maintaining product quality.

Related standards

• ISO 707 / FIL 50 - sampling guidelines for milk and dairy products (sampling not part of ISO 5943).
• ISO 5725 series - accuracy, repeatability and reproducibility principles (used for fidelity assessment).
• ISO 5943 is published jointly by ISO and the International Dairy Federation (IDF 88).

Keywords: ISO 5943:2006, potentiometric titration method, chloride determination, cheese chloride analysis, AgNO3 titration, dairy testing standard, salt content in cheese.