Fruit morphological and nutritional quality features of goji berry (Lycium barbarum L.) during fruit development

•Goji berry fruit development was studied at three growth phases, divided into two key time points.•Sugar content increased from the young to red fruit stage during development.•Total sugar and polysaccharide content were identified as the main evaluation factors for the nutritional quality of different cultivars.•Morphological and nutritional quality of ‘Ningqi 7’ was better than that of the other cultivars.