Optimum aqueous extraction conditions for preparation of a phenolic-enriched Davidson's plum (Davidsonia pruriens F. Muell) extract

This study aimed to optimise aqueous extraction conditions for total phenolic compounds (TPC) from Davidson's plum (Davidsonia pruriens F. Muell) and to assess the physicochemical and antioxidant properties of the phenolic-enriched extract. The results showed that temperature, time and ratio significantly affected the extraction of TPC. Optimization of extraction conditions was performed using response surface methodology (RSM) utilising a Box-Behnken design. Optimal extraction conditions were determined to be temperature: 90 °C, extraction time: 30 min and solvent to mass ratio: 20:1 mL g^-1. The extracted solid obtained under these conditions had low-moisture content, high water solubility and contained 45 mg GAE g^-1 of TPC, 22 mg RUE g^-1 of flavonoids, 3.2 mg CAE g^-1 of proanthocyanidins, 2 mg CGE g^-1 of anthocyanidins and 56 mg ACE g^-1 vitamin C. The extract possessed potent antioxidant capacity, but was comparatively lower than those of vitamin E and BHT. Thus, Davidson's plum should be further investigated for its potential health promoting benefits and utilisation in the nutraceutical and food industries.