The PCA plot includes data from both harvest times, although it
can be problematic to compare sensory result obtained at two different
time points. The PCA bi-plot for the raw tubers is shown in
Fig. 1. In this plot, PC 1 explained 48% of the variation in the data
and PC 2 explained 26%. PC 1 primarily described differences between
harvest times. Tubers harvested in the autumn, were related
to high levels of citric acid, phenolic acids and TP, as opposed to
those from spring harvest, which were related to high levels of
malic acid. PC 2 separated the samples according to scores in
whiteness and browning, and the instrumentally measured colour
parameters a⁄, b⁄ and chroma. The sensory attribute browning was
placed near b⁄ and chroma, whereas whiteness was placed near a⁄.