and the pH was further adjusted to 7.5 using 1 M NaOH.The digestion solution was incubated in a shaking water bath at 37 °C for another 2 h. During digestion, aliquots (1 ml) of WP digest were collected at 0, 30, 60, 120 and 180 min, and then submerged in a boiling water bath for 10 min to inactivate the pepsin and pancreatin. The aliquots were then cooled and stored at −25 °C for further analysis.