Evaluating Quality Indices of Pickled Garlic Based on Electrical Properties

Abstract

The detection of quality indices of pickled garlic, including its titratable acidity content, pH value, moisture and salt content is a complex, destructive and time-consuming endeavor. In effort to remedy this, a quality-testing method based on measurement of electrical properties was established in this study, which uses a parallel-plate system connected to an impedance analyzer. Electrical parameters of garlic during pickling were gathered and analyzed in nondestructive combinations of frequency points (100 Hz, 1 kHz, 10 kHz and 1 MHz) and input voltage levels at 200 mV. Impedance (Z) and resistance (R) both showed obvious linear correlations with quality indices of pickled garlic because of ionic conductance under the action of an alternating electric field. The most favorable estimations were characterized by R2 values of 0.9883 (moisture content and R at 1 kHz) and 0.9739 (salt content and Z at 100 Hz). Results facilitate a successful, alternative application for rapid assessment of quality indices of pickled vegetable products. Practical Applications The parallel-plate electrode technique is widely used to evaluate physicochemical properties of agricultural products, favored because of its high precision, convenience and nondestructiveness. In our research, electrical parameters such as impedance, equivalent capacitance, admittance, quality factors and resistance were rapidly detected by this technique for the evaluation of physicochemical properties and quality indices of pickled garlic. Obvious linear correlations between impedance, resistance and quality indices were observed, as they relate to ionic conductance on the influence of alternating electric fields over the frequency range from 100 Hz to 1 MHz at 200 mV. The results demonstrate promising potential application of this method to the general quality assessment of pickled vegetable products.