Saponification index determination

The saponification index measurement determines the amount of base (often KOH) required to saponify the esterified fatty acids contained in a fat. This measurement provides information on the average size of the fatty acid chains and is a key indicator for assessing the composition and purity of a fat .

This index, expressed in mg of KOH/g of matter , is an essential piece of data in the characterization of oils, fats, waxes and soaps . In particular, it makes it possible to differentiate natural vegetable oils from modified products , to control manufacturing quality and to ensure the conformity of finished products .

Principle and method of analysis

The analysis is based on a saponification reaction in which an excess of alkaline solution (often KOH) is added to the fatty substance to be tested. The unconsumed excess is then measured by acid titration .

The protocol, carried out according to ISO standardized methods (e.g. ISO 3657 for fatty substances of animal and vegetable origin), follows the following steps:

1. Dissolution of the fatty substance in a mixture of ethanol and potash.
2. Controlled heating until complete saponification.
3. Determination of excess alkali by acid titration (hydrochloric or sulfuric acid).
4. Calculation of the saponification index according to basic consumption.

The method can be coupled with a spectrophotometric measurement for more precise control of neutralization reactions, particularly in complex matrices.

This analysis thus makes it possible to obtain information on:

• the average length of fatty acids (the higher the index, the shorter the chains),
• the triglyceride composition ,
• and the purity of oils or fats .

Industrial applications

The saponification index dosage is widely used in several fields:

• Food industry : quality control of vegetable oils and animal fats used in the formulation of processed products.
• Cosmetics : evaluation of the composition and stability of oils, vegetable butters, waxes, soaps and moisturizing creams.
• Nutraceuticals : verification of the purity of functional or enriched oils (omega-3, fish oils, linseed oils, etc.).
• Animal nutrition : control of fats and oils added to food formulas.
• Plants and natural extracts : characterization of essential oils or lipid extracts in botanical formulations.

Monitoring this index is essential to guarantee the quality of raw materials and the conformity of manufacturing processes .

Further analyses recommended

For a complete characterization of fatty substances, YesWeLab recommends combining this analysis with:

• Acid value determination : measurement of the degree of hydrolysis and rancidity.
• Peroxide value determination : evaluation of primary oxidation of oils.
• Fatty acid profile analysis (GC-FID) : qualitative and quantitative identification of fatty acids.
• Determination of smoke point : measurement of the thermal stability of fatty substances.
• Melting point measurement : assessment of the purity and thermal behavior of fats.

These combined analyses allow complete traceability of lipid quality , from production to packaging of the finished product.

YesWeLab Services

YesWeLab relies on a European network of ISO 17025 and/or COFRAC accredited partner laboratories , specialized in analytical chemistry, spectrophotometry and titrimetry applied to fatty substances .
Our experts select the most suitable analytical protocol according to your matrices (oils, extracts, soaps, waxes, butters) and your regulatory requirements (ISO, pharmacopoeia, Ecocert) .

Thanks to the YesWeLab digital platform , you can centralize your analysis requests , track your samples in real time and consult your results reports directly online.
Since 2020, YesWeLab has been supporting cosmetics, food and nutraceutical manufacturers in the characterization and quality control of their fatty raw materials .

For any specific requests or quotes, contact our scientific team today.