Assessment of bruise volumes in apples using X-ray computed tomography

•X-ray CT images have been used to detect and quantify bruise volumes in apples.•The developed methodology was applied on ‘Jonagold’, ‘Joly Red’ and ‘Kanzi’ apples.•3D visualisation of the bruises showed that they can be highly irregularly shaped.•Destructive bruise volume measurements were carried out for comparison. A non-destructive methodology was developed to automatically detect and quantify bruise volumes in the equatorial region of apples, using X-ray CT images. Grey level threshold values were calculated to segment bruises in ‘Jonagold’, ‘Joly Red’ and ‘Kanzi’ apple fruit using the multi-level Otsu’s threshold method. Comparisons were made between the CT-based bruise volume estimates and bruise volume estimates that were based on destructive measurements in combination with simple geometric assumptions. Visualisation of the bruises in both 2 and 3D showed that bruises, resulting from a pendulum impact with a spherical impactor, can be highly irregularly shaped which implies that the bruise volume estimations based on simple geometric assumptions cannot deliver accurate results.