Optimization of the preparation of high-purity ellagic acid from blueberry pomace through an antisolvent precipitation method

Due to the low purity of natural ellagic acid, its clinical application has been less reported. Currently, blueberry pomace is discarded as processing waste. However, it is rich in ellagic acid and a good raw material for producing high-purity ellagic acid. Therefore, this study aimed to investigate an optimal horizontal combination scheme for producing of high-purity ellagic acid by antisolvent precipitation using crude ellagic acid extracted from blueberry pomace. Solvent screening results indicated that n-methylpyrrolidone had the highest ellagic acid solubility. Single-factor analysis showed that the oscillation speed, reaction time, crystallization temperature and antisolvent-to-solvent ratio had significantly affected ellagic acid purity, but solid-liquid ratio had little effect. A Box-Behnken-Centre combined design was used to determine the optimal combined scheme. The results showed that at a solvent concentration of 20 mg/mL, the optimal parameters were crystallization temperature 21.1 °C, reaction time 11.2 min, volume ratio of 15.6:1 antisolvent to solvent and oscillation speed of 144 r/min. Under these conditions, ellagic acid purity was 96.63%, relative standard deviation (RSD) was 1.20%, and recovery rate was 69.60%. Fourier transform infrared analysis showed that the spectral peak of purified ellagic acid matched that of the standard. In summary, the antisolvent precipitation method greatly improved the purity of ellagic acid extracted from blueberry pomace, which is not only conducive to the resource recycling, but also provides a theoretical basis for the production of high-purity ellagic acid and the possibility of expanding the application scope of ellagic acid in pharmaceuticals and nutraceuticals.