Use of a QCM electronic nose to evaluate the aromatic quality in apples

Abstract

The “Libra Nose” electronic nose has eight Quartz Microbalance Sensors. When gas molecules are adsorbed onto the quartz crystal surface, the oscillation frequency changes in proportion to the amount of mass. The response of sensors depends on numerous factors that may be difficult to control, such as the temperature and the humidity of the carrier gas. All these factors cause changes in the selectivity of sensors which affect the reproducibility of measurements. In this paper additive and multiplicative corrections are proposed to be applied to the raw sensors´s signal in order to eliminate sources of variation. After these corrections, the sensors´ response gives useful information to distinguish between batches of apples with different ripeness stage.