Ester value
The ester value is the number of mg of potassium hydroxide required to saponify the esters in 1.0 g of the substance.[1]
Contents
Wax esters
Wax esters are oxoesters of long-chain fatty acids esterified with long-chain alcohols. The ester value shows the amount alkali consumed in the saponification of the esters[2] and is possible identify and differentiate the waxes with this value; for example beeswax ester value is 72 to 79 mg KOH/ g, candelilla wax ester value is 31 to 43 mg KOH/g and carnauba wax ester value is 74 to 78 mg KOH/g.
Method
In ester value determination, the sample is hydrolysed to alcohol and using excess of standar potassium hydroxide solution. The excess of alkali is back titrated. USP-NF monographs presents a general procedure of ester value apply to fats, fixed oils and waxes.
USP 401
.[1]