According to the method of Martin et al., the bioaccessibility of UA in digested samples was determined (Martin et al., 2016). Bioaccessibility was determined as the fraction of each compound available for intestinal absorption, that is, included in the MP. UA content in MP was determined by High Performance Liquid Chromatography (HPLC). An Alliance Model 2695 liquid chromatography system equipped with a quaternary solvent delivery system, an autosampler, and a diode array detector (DAD) was used at 210 nm. The temperature of the column (YMC-Pack ODS-A, 250 × 4.60 mm) and the autosampler was set at 30 (±5) ◦C. The mobile phase was HPLC grade methanol:0.1% phosphoric acid solution (92.5:7.5, v/v) at a flow rate of 1 mL/min, and the injection volume was 20 μL. Each sample was analyzed at least three times. A series of UA standard products (0.5, 1, 2, 4 and 8 μg/mL) were prepared. The standard curve of UA was drawn with UA concentration as abscissa and peak area as ordinate. The linear regression equation and the bioaccessibility formula of UA were obtained as follows.Where y is the peak area of UA (mV⋅s) and × is the UA concentration (μg/mL). The correlation coefficient (R2) is 0.9999. Then CMicelle is the concentration of UA in the micellar fraction and CDigesta is the concentration of UA in the whole sample after the pH-stat experiment.