The present study was concerned with the development of selective electrical measurements for the determination of free acidity in virgin olive oil. This will provide a simple and fast method to test the VOO quality, that can be easily implemented as a low-cost portable electronic system. The electrical measurements were carried out using an experimental set-up built with benchtop instrumentation. The sensor, hosting the sample under test, features a couple of stainless steel electrodes and is incubated in a WTC Binder thermal chamber at 20°C. The sample was electrically characterized in the frequency range 20 Hz – 2 MHz using a Agilent E4980A LCR meter, controlled by a PC Laptop system via USB interface. The PC system acquires the measured data, calculates the electrical parameters and stores the measured data. The electrical conductance was found to correlate with the free acidity of olive oil measured according to EC regulation no. 2568/91. Up to 100 fresh and old virgin olive oils, purchase from local markets as well as Italian oil mills, with different percentage of free acidity, were tested. Samples featuring higher acidity were characterized also by higher electrical conductance. A conductance threshold could be used to discriminate between extra virgin olive oils and olive oils that presented a lower quality. The experimental conditions, including the electrochemical technique, choice of solvent, as well as the dilution factor of VOO extract, were investigated.
Virgin Olive Oil Free Acidity: An Electrochemical Determination
DI LECCE, GIUSEPPE;GROSSI, MARCO;RICCO', BRUNO;GALLINA TOSCHI, TULLIA
2013
Abstract
The present study was concerned with the development of selective electrical measurements for the determination of free acidity in virgin olive oil. This will provide a simple and fast method to test the VOO quality, that can be easily implemented as a low-cost portable electronic system. The electrical measurements were carried out using an experimental set-up built with benchtop instrumentation. The sensor, hosting the sample under test, features a couple of stainless steel electrodes and is incubated in a WTC Binder thermal chamber at 20°C. The sample was electrically characterized in the frequency range 20 Hz – 2 MHz using a Agilent E4980A LCR meter, controlled by a PC Laptop system via USB interface. The PC system acquires the measured data, calculates the electrical parameters and stores the measured data. The electrical conductance was found to correlate with the free acidity of olive oil measured according to EC regulation no. 2568/91. Up to 100 fresh and old virgin olive oils, purchase from local markets as well as Italian oil mills, with different percentage of free acidity, were tested. Samples featuring higher acidity were characterized also by higher electrical conductance. A conductance threshold could be used to discriminate between extra virgin olive oils and olive oils that presented a lower quality. The experimental conditions, including the electrochemical technique, choice of solvent, as well as the dilution factor of VOO extract, were investigated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
