Identification of Anthocyanins and Optimization of Their Extraction from Rabbiteye Blueberry Fruits in Nanjing

Blueberries are rich in bioactive anthocyanins, which are associated with health benefits contributing to reducing the risk of diabetes and cardiovascular diseases. The objective of this study was to improve the yield of anthocyanins extracted from rabbiteye blueberry (Vaccinium ashei) fruits cultivated in Nanjing using ultrasound-assisted extraction and to identify the individual anthocyanins present in the extract. The extraction conditions of blueberry anthocyanins were optimized using response surface methodology. The Box–Behnken test was designed to investigate the effect of extraction using different ethanol concentrations, extraction time, and liquid-to-solid ratios. The optimum conditions of the extraction derived from the model were as follows: extraction time 24 h at 30°C using 72.50% ethanol which contains 0.02% v/v hydrochloric acid as a solvent and liquid-to-solid ratio 20 : 1 v/w. The extraction yield was 16.21 ± 0.44 mg/g under these optimum conditions. The 13 peaks of the anthocyanin extract from rabbiteye blueberry fruits in Nanjing were tentatively identified using high-performance liquid chromatography (HPLC) and high-performance liquid chromatography-electrospray ionization interface-mass spectrometer (HPLC-ESI-MS), which are the derivatives of delphinidin, cyanidin, petunidin, peonidin, and malvidin that were glycosylated by glucose, galactose, or arabinose. This research provides a reliable scientific basis for efficacious extraction and identification of anthocyanins from blueberry fruits, which would be helpful for further investigation of the function and application of blueberry anthocyanins extract to human health.