2.5 g of sample were placed into a centrifuge tube, and then
30 mL of distilled water were added. The mixture was shaken for
5 min with intermittent agitation on a vortex mixer, and then centrifuged
at 5000 rpm for 10 min. The supernatant was poured into a
moisture dish of known weight. The sample was dehydrated overnight
in the oven set at 40 C. The dish was removed from the oven,
and put in the desiccators to equilibrate. Finally, the dish with dried
sample and lid were weighed. The WSI was calculated as: