Untargeted and targeted metabolomics analyses of blackberries - Understanding postharvest red drupelet disorder

Red drupelet is a postharvest disorder of blackberries with several drupelets turning back to red. This affects visual quality and thus marketability and consumers' acceptance. However, the cause of this disorder as well as metabolite changes during color reversion have not been fully understood. Anthocyanins, cyanidin 3-glucoside, cyanidin 3-malonylglucoside, cyanidin 3-dioxalylglucoside, and total anthocyanin, were significantly lower in red drupelets than in black drupelets after 7 days of storage. Sugars and organic acids, lipids, and free amino acids also changed with storage and by color reversion. The untargeted metabolomics analyses indicated that red drupelets were generally differentiated from berries at harvest or black drupelets at metabolite level. The results of this study help better understand the red drupelet disorder. To our knowledge, this is the first study investigating red drupelet disorder by comparing black and red drupelets at metabolite level.