*4.2. Determination of Contents of Anthocyanins Components and Total Flavonoids*

The frozen petal tissue (0.5 g) was added to 1.5 mL of 2 M HCl in methanol solution for grinding and homogenization, and low-temperature ultrasound for 15 min was followed by centrifugation [49]. The supernatant was used for anthocyanin extract. The contents and components of anthocyanins in the four samples were determined by high-performance liquid chromatography (HPLC), and chromatograms were mapped by chromatographic workstation software (LC-WS100) [50]. The total flavonoid content in each sample was measured by UV spectrophotometry [51]. The results are expressed as mg quercetin equivalent per g of dry weight (QE mg/g DW).
