Neutralization Number
An indication of the acidity or basicity (alkalinity) of an oil. The neutralization number is expressed in milligrams of potassium hydroxide or hydrochloric acid needed to neutralize any acid or base in one gram of oil. The Acid Number (AN) test uses potassium hydroxide as the neutralizing agent, and the Base Number (BN) test uses hydrochloric acid as the neutralizing agent.