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Practical limitations in determining vegetable oil acid values by a novel pH‐metric method
Author(s) -
Berezin O. Yu,
Tur’yan Ya I.,
Kogan L.,
Kuselman I.,
Shenhar A.
Publication year - 1997
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-997-0067-3
Subject(s) - triethanolamine , chemistry , titration , reagent , acid value , oleic acid , base (topology) , chromatography , hydrolysis , soybean oil , organic chemistry , analytical chemistry (journal) , mathematics , food science , biochemistry , mathematical analysis
A novel pH‐metric method is described for the determination of acid values (AV) in vegetable oils without titration. The method is based on a reagent containing triethanolamine, isopropanol, and water to which an oil sample is added before measuring pH. Oil samples with AV in the range 0.006–0.107 mg KOH/g oil were prepared from commercial soybean oil by treatment with a strong‐base anion exchanger in OH − form and addition of oleic acid. Compared to the standard titrimetric method, significantly greater AV were obtained at less then 0.02 mg KOH/g oil. This was due to the influence of triethanolamine hydrolysis on the acid‐base equilibrium in the mixture “oil‐reagent.” Thus, the AV 0.02 mg KOH/g oil is accepted as the limit of quantitation. Because refined oils usually have AV of 0.05 mg KOH/g oil or more, this method should be suitable for practical oil analyses.