A portable device for the quality control of vegetal products comprising a power supply (7) intended for powering a circular crown of lighting lamps (41) at the centre of which there is arranged the receiving objective of a spectrometer (45) provided with means (431) adapted for resting on the product to be checked, said spectrometer (45) being associated to a microprocessor (11) which provides the measurement data on display means (12); according to the invention, the lamps (41) are permanently powered, and in stand-by, at a reduced voltage (70), lower than the nominal voltage (71) delivered by the power supply (7), and instantaneously at the nominal voltage (71 supplied by the power supply (7) through a power circuit (8) whose activation is commanded and controlled by the microprocessor (11) in response to an activation signal generated by a button (10).