Automated flow pH-method for the determination of total free fatty acids content in edible oils

摘要

An automated flow pH-method for the determination of titratable acidity (TA) in edible oil without titra-tion is proposed, based on pH measurements on an oil sample emulsion in a suitable reagent. The developed flow pH system involves two constant rate flows: the flow of oils samples and the flow of reagent: triethanolamine + KNO_3 + H_2O + i-PrOH, in which oils is insoluble. The flows are mixed in the mixer forming the emulsion in which the free fatty acids (FFA) extraction is started. Then, the emulsion is passed to the coil for completion of FFA extraction and thermostation and then forwarded to pH-cell for pH measurement. Using pH values and linear dependence of pH vs. log (TA) allows the TA determination. The optimum parameters for the automated flow pH-system have been found, i.e., volumes of the mixer and the coils, the rate of sample and reagent, pH and TA ranges. The results of the TA determination in the edible oils were statistically compared with the standard titration method.