Saponification value (or "saponification number", also referred to as "sap" in short) represents the number of milligrams of potassium hydroxide or sodium hydroxide required to saponify 1g of fat under the conditions specified. It is a measure of the average molecular weight (or chain length) of all the fatty acids present. As most of the mass of a fat/triester is in the 3 fatty acids, it allows for comparison of the average fatty acid chain length. If there are more moles of potassium hydroxide (KOH) used for 1 gram of fat then there are more moles of the fat. Therefore the chain lengths are smaller, due to the equation: The chemical compound potassium hydroxide, (KOH) sometimes known as caustic potash, potassa, potash lye, and potassium hydrate, is a metallic base. ... Sodium hydroxide (NaOH), also known as lye or caustic soda, is a caustic metallic base. ... Saponification of a lipid with potassium hydroxide. ... Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. ...

Number of moles = mass of oil/relative atomic mass.

The relative atomic mass would be smaller with smaller fatty acid chains, meaning more moles. The higher the saponification value the smaller the chain lengths.

Handmade Soapmakers who aim for bar soap use NaOH sap values, which are derived from the saponification value calculated by laboratories (KOH sap value). To convert one to the other, multiply or divide by 56.11/40 (the ratio of the molecular weights). Soapmaking is the process of creating soap from raw ingredients such as fats, oils and lye. ...

Standard methods for analysis are for example: ASTM D 94 (for petroleum) and DIN 51559. ASTM International is an international voluntary standards organization that develops and produces technical standards for materials, products, systems and services. ... Look up din in Wiktionary, the free dictionary. ...

The calculated saponification value is not applicable to fats and oils containing high amounts of unsaponifiable material, free fatty acids (>0.1%), or mono- and diacylglycerols (>0.1%).

See also

• acid number
• EN 14214
• iodine number
• saponification

The acid number in chemistry is the mass of potassium hydroxide in milligrams that is required to neutralize one gram of chemical substance. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The iodine number in chemistry is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. ... Saponification of a lipid with potassium hydroxide. ...

External links

• Therese Lott's Saponification Calculator - Standalone spreadsheet for calculating saponification values in handmade soapmaking.