2.1. KW characteristics
KW was collected on a weekly basis from a canteen at Tsinghua
University. The major components were carbohydrates derived
from bread, cooked noodles and rice, proteins and fat. The asreceived
KW was mixed with a kitchen blender to ensure uniformity
and representation of experimental materials and stored at
4 C in a refrigerator after being crushed into particles with an
average size of 1e2 mm. Table 1 shows the basic characteristics of
KW.