Phenolic profiles and antioxidant capacities of mulberry (Morus atropurpurea Roxb.) juices from different cultivars

Abstract

Two hundred and seventy six mulberry juice samples were analyzed by high-performance liquid chromatography with diode-array detection quadrupole time-of-flight tandem mass spectrometry to identify the major polyphenols in the representative mulberry fruit cultivar Da10. Using FRAP, ABTS, and DPPH assays, total phenolic contents and antioxidant capacities of 276 mulberry juice samples from four provinces in China were found to be within the following ranges: 412.55–1471.86 mg/L gallic acid equivalent, 37.90–361.75 mmol/mL ferrous sulfate equivalent, 46.12–342.13 mmol/mL Trolox equivalent, and 7.30–216.41 mmol/mL ascorbic acid equivalent. Cluster analysis separated the cultivars into two groups. One group consisted of samples from Guangdong, Guangxi, and Hainan Provinces, which had high phenolic contents and antioxidant capacities. The other group consisted of samples from Xinjiang Province, which had low phenolic contents and antioxidant capacities. Antioxidant activity and phenolic content were correlated. Flavonoids were the main polyphenols of “Da10”. In addition to free phenolic compounds, various bound phenolic compounds were identified. This work provides a large dataset characterizing different mulberry cultivars for deeper research. “45–7”, “qianshan3” and “guoxuan04-129” were superior cultivars based on their high phenolic contents and antioxidant capacities. The results of this study support further research into mulberry use in human food and healthcare industries.

Keywords

• mulberry juice
• bound polyphenols
• free polyphenols
• antioxidant capacity
• hplc-dad-q-tof-ms/ms