Chemical Analysis
Amylose content (AC) was determined by iodine colorimetry
at 620 nm after adding ethanol, NaOH, and acetic acid using a
rice starch as standard. Gel consistency (GC) was determined
by the method of Cagampang et al. (1973). The term “head
rice” denotes kernels 3/4 or more the original kernel length
(Abud-Archila et al. 2000). Head rice yield (HRY) is defined
as percent weight of milled head rice kernels as compared with
the total weight of milled rice.
Statistical Analysis
Data for Analysis
In electronic tongue, four points of each cycle (Fig. 2a) which
were related to the concentration and diffusion coefficients of
the charged and electroactive compounds in the solution were
extracted, resulting in 40 characteristic data for each working
electrode. So, there were 240 (40×6) characteristic data for
each sample.
In electronic nose, the ratio of conductance (G/G0) of each
sensor increased gradually, and stabilized after approximately
150 s. The sensor signals at 180 s were used for subsequent
statistical analysis, i.e., there were ten values for each sample
(Fig. 2b).
For the combination of tongue and nose, the data for
each sample (six values) were sequentially arranged by
three dimensions from electronic tongue and nose reduced
by PCA/LLE.
Theory of PCA
PCA has been widely used in modeling the statistics of a set of
multidimensional data (Wall et al. 2003). It can decompose a
dataset (Y) into two matrices, one is score matrix (T) and the
other one is loading matrix (L).
Y ¼ T L:
This linear feature extraction technique reduces dimension
of data with a minimum loss of information. In this study, we
decomposed the data from electronic tongue and nose into T