The insoluble materials were removed by centrifugation at 3,000 rpm×5min. The supernatant was
filtered (Whatman filter paper no. 1) and the excess waterwas evaporated using a rotary evaporator (Hei-Vap
Plug and Play Value 1, Heidolph, Germany), and freezedried (Freezone 6 Plus, Labconco, USA). The solid extract
(OligoPKE) was stored in capped containers at−80◦C. The above process was repeated until sufficient
OligoPKE for the study was obtained.