flavonoid compounds diminished in the control mushrooms during
storage. However, essential oil fumigation induced a lower rate of
decrement in phenolic content, and cinnamaldehyde fumigation
even stimulated flavonoid accumulation in the mushroom compared
with the other treatments at the end of storage. This is similar
to the findings by Wang et al. (2008) in blueberries.
Accumulation of secondary metabolites such as flavonoids and
phenolics is one of the common responses of plants to many biotic
and abiotic stresses (Dong, Zhang, Lu, Sun, & Xu, 2012). For example,
UV-C irradiation and ozone fumigation have been reported to
stimulate flavonoid accumulation in shiitake mushroom and plant
cells (Jiang, Muhammad, Jiang, Lu, & Ying, 2010; Xu et al., 2011). It
is hypothesised that essential oils would act as ‘‘signalling compounds’’
that trigger a signal that resembles a mild stress to the
fruit. As a defense response, fruit produces additional phenolic
compounds and flavonoids and increases their antioxidant activities
(Sharma & Tripathi, 2006). Some studies have shown that
the accumulation of phenols and anthocyanins paralleled the
increase in phenylalanine ammonialyase (PAL) activity in Chinese
bayberry (Wang et al., 2009).