ISO 7366:1987

Overview - ISO 7366:1987 in brief

ISO 7366:1987 specifies a chemical titrimetric method for the determination of 1‑monoglycerides and free glycerol in animal and vegetable fats and oils. The standard covers samples including products from interesterification of fats and fatty acids with glycerol. The procedure separates the chloroform-soluble mono‑1‑glycerides from the aqueous phase containing free glycerol, oxidizes each fraction with periodic acid, and quantifies the liberated iodine by titration with sodium thiosulfate.

Key topics and technical requirements

• Scope: Applicable to animal and vegetable fats and oils and products from interesterification; not suitable if other polyhydric substances with adjacent hydroxyls are present in the same solvent phase.
• Analytical principle:
  • Dissolve test portion in chloroform; extract free glycerol into aqueous acetic acid.
  • Oxidize mono‑1‑glycerides in the chloroform phase with excess periodic acid; add potassium iodide (KI) and titrate liberated iodine with standard sodium thiosulfate.
  • Oxidize glycerol in the aqueous phase similarly and titrate.
• Reagents (examples given in the standard):
  • Chloroform; acetic acid 5% (w/v); periodic acid solution (2.7 g/L preparation described); KI solution (150 g/L, iodine/iodate‑free); sodium thiosulfate standard (c = 0.1 mol/L); starch indicator (10 g/L).
• Apparatus: Common laboratory glassware, separatory (decanter) funnels, 500 ml conical flasks, magnetic stirrer.
• Performance and reporting:
  • Results expressed as mass percent with one decimal place.
  • Repeatability limits indicated (e.g., mono‑1‑glycerides: difference between duplicate determinations not to exceed 0.5% (m/m) at 15–25% range; free glycerol: 0.1% (m/m)).
• Sampling: Reference to ISO 5555 for sample preparation and handling.

Practical applications and users

• Quality control laboratories in the edible fats and oils industry assessing mono‑glyceride and glycerol content.
• Food and agricultural product testing labs verifying compositional changes after processing or interesterification.
• Analytical chemists validating production batches where mono‑glyceride or glycerol levels affect product specifications.
• Regulatory and conformity testing where standardized, reproducible titrimetric methods are required.

Related standards

• ISO 5555 - Sampling of animal and vegetable fats and oils (referenced for sampling procedures).
• Other ISO methods for fat and oil analyses may be used in conjunction for broader compositional profiles.

Keywords: ISO 7366:1987, animal and vegetable fats and oils, determination of 1‑monoglycerides, free glycerol, periodic acid oxidation, titration, potassium iodide, sodium thiosulfate, chloroform extraction, food lab analysis.