3.2. Effects of processing on chemi

3.2. Effects of processing on chemical classes
There is no published information about the effect of heat and
HPP treatment on volatile components of pennywort juice. The total
concentration of volatile compounds in fresh juice was higher
than in processed juice (p < 0.05) and there was a non-significant
trend in the order sterilised juice > HPP juice > pasteurised juice,
respectively. Reductions in the concentration of acyclic alcohols,
aldehydes, oxygenated monoterpenes, sesquiterpene hydrocarbons,
and oxygenated sesquiterpenes were detected after some
of the processing operations, whereas ketones increased significantly
(Table 2). Aldehydes and oxygenated sesquiterpenes were
present at higher concentration in fresh juice than in other samples
(p < 0.05), monoterpene hydrocarbons were also found in high concentrations
but there was no significant difference between HPP
and heat-treated samples (p > 0.05). In addition, there was no
significant difference between fresh and HPP juice (p > 0.05) in the
total content of alcohols, ketones and oxygenated monoterpenoids.
Moreover, there was no significant difference between HPP and
processed juice (p > 0.05) in the content of acyclic alcohols, aldehydes,
oxygenated monoterpenes, sesquiterpene hydrocarbons,
oxygenated sesquiterpenes, miscellaneous compounds and total
volatiles as shown in Table 2. However, HPP caused more flavour
volatiles in the acyclic alcohols class to be retained, with a trend
to greater retention of aldehydes and oxygenated monoterpenoids
(p > 0.05) than pasteurisation and sterilisation.