Abstract: The invention relates to a method for determination of a quality property of a piece of meat. A light reflection measurement probe is inserted into a muscle of the piece of meat, while the muscle is undergoing the conversion process from living tissue in a newly slaughtered animal to cooled edible meat. The light reflectivity of the muscle is measured by means of a probe in several, different wavelengths or wavelength bands. The probe remains in the muscle for a period of time after this measurement series, while the conversion process in the muscle is proceeding. The light reflectivity of the muscle is measured again in the same wavelengths. The measurement data, possibly after processing, are inserted in an algorithm which expresses the quality property on the basis of changes between the data of the measurement series, and the quality property is automatically calculated in a calculation unit. The probe is removed from the muscle.