Centre Projects
Influence of sample preparation on release of thiol precursors and methoxypyrazines
Brief:The composition of grapes is not uniform. For example the rachides (bunch stems) are reported to have high concentrations of methozypyrazines, while the flesh has very low concentrations.
As a result of the differences in relative concentrations
between skin, flesh and rachides, fruit processing methods
can have a marked influence on the flavour and aroma
profiles in the juice and, in turn, on the wine. For
example, machine management and operation, and transport
time to the winery from the vineyard, could have a significant
impact on the concentrations of flavour and aroma compounds
largely found in the skin, whereas little effect might
be expected on the concentrations predominantly in the
flesh.
Pressing pressure might also be expected to influence
the release of various components. The concentrations
in juice of skin-dominant flavour components (IBMP and
P-3MH) may be expected to increase as press pressure
increases, with free-run juice having the lowest concentration
and final pressing the highest. The impact of fruit
processing protocols on the release of flavour and aroma
compounds into the juice will be studied.
