Blending at such high speeds created a layer of foam, as air bubbles were introduced. The blended slurry was vacuum filtered through a 70 μm (nylon) cell strainer (VWR, USA). The filtered slurry solution was then poured into disposable conical-bottom 50 mL centrifuge tubes (VWR, USA). The tubes were centrifuged at 10,000 rpm at 4°C for 10 min in an Avanti J-26 XPI centrifuge (Beckman Coulter, USA). The slurry was washed 3 times with MilliQ water, and a pellet of fine granules was collected at the bottom of the tube when the water was aspirated.