Free fatty acids (FFA) are produced by the hydrolysis of oils and fats. The level of FFA depends on time, temperature and moisture content because the oils and fats are exposed to various environments such as storage, processing, heating or frying. Since FFA are less stable than neutral oil, they are more prone to oxidation and to turning rancid. Thus, FFA is a key feature linked with the quality and commercial value of oils and fats. The American Oil Chemists' Society (AOCS), the Association of Official Analytical Chemists (AOAC) and the European Commission (EC) Regulations have established almost identical standard methods for the assessment of FFA. These methods are based on titration, where oils or fats need to be dissolved in hot neutralized ethanol or ethanol/diethyl ether using phenolphthalein as an end point indicator. Titrimetric procedures are, however, laborious and need large amounts of chemicals and solvents. The cost of chemicals and environmental issues further limit these procedures. In addition, accurate detection of end points, especially for highly colored crude oil using a colorimetric indicator, is a difficult task. Despite these disadvantages, the titration method is unfortunately still being used in most of the edible-oil industries for the determination of FFA. Because of a lack of any comprehensive review on this very important topic, we have made an attempt to present a review in order to discuss the various methods available with special emphasis on the instrumental methods because of their high sensitivity, accuracy and rapidity.

Analytical approaches for the assessment of free fatty acids in oils and fats

A test kit for testing acidity of a lubricant in a climate control system containing a naphthalimide dye contains an aqueous solution having a salt and a known amount of hydroxide and an organic solution containing an alcohol and an organic solvent having a flash point of at least 130° F. When a lubricant is added to a combination of the aqueous solution and the organic solution, the color of the bottom layer indicates the acid content of the lubricant.

Method and apparatus for testing the acidity of a lubricant in a climate control system

Applications of Metrology, Chemometrics and Quality Assurance in Analytical Chemistry

pH-Metric determination of acid values in oilseeds without titration

A reagent for pH-metric acid number determination in a petroleum oil with low acid numbers (AN≦003 mg KOH/g oil) includes a salt of a strong base and a weak acid, and, an alkali in a mixture of water and an alcohol The salt of a strong base and a weak is, preferably, sodium benzoate in a concentration of 002 to 01 M The alcohol is, preferably, isopropanol in a concentration of from 50% to 80% by volume The alkali is, preferably, an hydroxide and, most preferably, potassium hydroxide The alkali should be adjusted to provide a pH′o, which is the pH of an equivalence-point on a titration curve of a strong acid added to a test portion of sodium benzoate, water and isopropanol

Reagent for the PH-metric determination of low acid numbers in petroleum oils

A reagent for the acid value determination in oils. The reagent contains a tertiary amine, such as triethanolamine, in a water-alcohol mixture as solvent. Preferred is isopropanol/water. The reagent allows determinations of acid values in oils in a two phase system. The use of the reagent is based on a pH-metric technique with conditional pH-measurement before and after the addition of an oil sample to the reagent.

Reagent for the determination of acids in oils

The acid value (AV) of vegetable oils is determined without titration by using a new reagent consisting of triethanolamine in a solution of water and isopropyl alcohol. When the oil sample is mixed with the reagent in the pH-metric cell, free fatty acids from the sample are extracted into the reagent (3-4 min). The initial pH, called conditional pH'1, is measured, a standard acid (HCl) is added, and the final pH, pH'2, is measured. AV is calculated from the difference between pH'1 and pH'2. The method is applicable for quality control of vegetable oils during their production, trade, and use.

pH-metric determination of the acid value of vegetable oils without titration.

A method for determining the acid value of oilseeds. A reagent kit for the rapid extraction of the free fatty acids from oilseeds which consists of reagents: "A" and "B". Reagent "A" contains a tertiary amine (such as triethanolamine) in water and an alcohol--hydrocarbon mixture as solvent. Preferred is water/isopropanol/heptane. Reagent "A" allows rapid (1-2 min) solid-liquid extraction of the free fatty acids and some other acids from oilseeds. Reagent "B" contains a strong acid and an inorganic salt in water. Reagent "B" enables the rextraction (liquid-liquid; about 5 min) of the free fatty acids only into a separate hydrocarbon phase, which can be used for the acid value determination.

Determination of acid values in oil seeds

La presente invention concerne un procede pour la determination de la valeur acide d'oleagineux. Selon l'invention, le procede comprend les etapes suivantes : secher un oleagineux pulverise, introduire l'echantillon d'oleagineux pulverise dans le reactif A comprenant une amine tertiaire, de l'eau, un alcool et un hydrocarbure, et agiter ce melange pendant quelques minutes, ajouter au melange le reactif B, qui comprend un acide fort et un sel inorganique dans de l'eau, et agiter le melange, en transferant ainsi les acides gras libres dans la phase superieure d'hydrocarbure, retirer une aliquote a partir de la phase superieure et determiner la valeur acide par des moyens usuels dans ladite aliquote.

Berezin Oleg Y

Papers

Reagent for the determination of acids in oils

pH-metric determination of the acid value of vegetable oils without titration.

Reagent for the PH-metric determination of low acid numbers in petroleum oils

Determination of acid values in oil seeds

Procede pour la determination de la valeur acide d'oleagineux et jeu de reactifs utilisable dans ce procede.