One way to test the validity of these
assignments is to examine mixtures of
simple homogeneous substrates as reported
by Schofield et al.(1994). These investiga-
tors used mixtures of processed cellulose
and bacterial cellulose. The gas curves
from in vitrodigestion of each individual
cellulose could be fitted using a single pool
logistic equation and the specific rate for
the bacterial cellulose was higher than that
for the processed cellulose. Gas curves
from mixtures of known composition were
analysed using a dual-pool logistic equa-
tion, and the pool sizes (faster, slower)
correlated well with sample composition.
A second, less abstract, demonstration
of the internal consistency of the logistic
model was reported by Stefanon et al.222 P. Schofield
Fig. 10.7.Data for soy hulls and wheat straw (circles, see Fig. 10.4) fitted using single- or dual-pool equations.
Log = logistic (Equation 10.5), Gr = Equation 10.7 (Groot et al., 1996). When a two-pool model was
required, the curves for the individual pools were plotted separately (the sum of these curves fits the data
points almost exactly). Numbers 1 and 2 for the individual pools (lighter lines) identify the faster and slower
digesting components respectively. The solid line tracking the data points represents the single-pool fit. For
clarity, only 20% of the experimental data points are shown.