After UHP treatment, the mushroom foot proteins were sus- pended in deionized water (5%, w/v) containing alkaline proteases (enzyme: substrate = 1:20, based on a preliminary experiment), and the pH was maintained at 8.5 with 0.1 M NaOH at 55 °C for2 h (Zheng, Shen, Bu, & Luo, 2008). The enzymatic reactions were stopped by heating at 90 °C for 10 min to denature the enzymes. Then, the pH of the solution was adjusted to pH 7 with 0.1 M HCl to maintain the peptide activity for subsequent experiments (Yu et al., 2013). Subsequently, the supernatant was collected via centrifugation at 4000 rpm for 10 min, and the supernatant was freeze-dried and stored at 20 °C for further analysis.