Abstract
Monoterpenes are responsible for the distinctive flavour of grape cultivars such as Gewiirztraminer, Riesling and several muscat cultivars. These components are present as odour-active free volatile terpenes (FVT) and as potentially volatile terpenes (PVT), i.e. glycosides and polyols capable of releasing FVT by temperature-, pH-, or enzyme induced hydrolysis. Our first work focused on the impact of fruit exposure on terpene concentrations in Gewiirztraminer. Fully-exposed fruit consistently displayed higher FVT and PVT than partially-exposed and fully-shaded fruit. This knowledge was utilised to investigate effects of cultural practices. Hedging and basal leaf removal (BLR) increased FVT and PVT levels, while multi-site experiments also indicated that hedging and BLR could increase FVT and PVT in berries and musts of early-season cultivars such as Bacchus, Pearl of Csaba, Gewiirztraminer, Schonburger and Siegerrebe. Canopy division, BLR and increased vine spacing also increased FVT and PVT concentrations in Riesling fruit. Low-heat unit sites appear to promote accumulation of monoterpenes in Vitis vinifera more than warmer sites, when compared at equal growing degree days. Prefermentation practices such as delayed harvest, prolonged pressing and skin contact were also shown to increase must terpene content. In many cases, these differences in terpene concentrations in the berries and musts were organoleptically detectable in wines. Our conclusions to date are: (1) PVT are more responsive to viticultural and enological practices than FVT; (2) FVT and PVT are rarely correlated with soluble solids, titratable acidity or pH, and thus cannot be predicted by standard harvest indices; (3) Losses in FVT and PVT can occur between the berry and juice stages, hence the desirability of skin contact; (4) FVT and PVT concentrations can, in some cases, be related to wine-tasting results.
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Claims 18
Claim · model-written summary
Fully exposed Gewiirztraminer fruit had higher FVT and PVT than partially exposed or shaded fruit.
Verbatim
e0“Fully-exposed fruit consistently displayed higher FVT and PVT than partially-exposed and fully-shaded fruit.”
e1“fruit exposure on terpene concentrations in Gewiirztraminer”
t0“Grape”
Claim · model-written summary
Hedging increased FVT and PVT levels.
Not reportedComparator
Verbatim
e0“Hedging and basal leaf removal (BLR) increased FVT and PVT levels”
t0“Grape”
Claim · model-written summary
Basal leaf removal increased FVT and PVT levels.
Not reportedComparator
Verbatim
e0“Hedging and basal leaf removal (BLR) increased FVT and PVT levels”
t0“Grape”
Claim · model-written summary
Multi-site experiments indicated hedging could increase FVT and PVT in early cultivar berries and musts.
- Taxon
- Grapet0
- Organ / stage
- berries and mustse0
- Treatment
- hedginge0
- Outcome
- FVT and PVTe0
- Direction
- increasee0
- Qualifier
- early-season cultivars such as Bacchus, Pearl of Csaba, Gewiirztraminer, Schonburger and Siegerrebee0
Not reportedComparator
Verbatim
e0“multi-site experiments also indicated that hedging and BLR could increase FVT and PVT in berries and musts of early-season cultivars such as Bacchus, Pearl of Csaba, Gewiirztraminer, Schonburger and Siegerrebe.”
t0“Grape”
Claim · model-written summary
Multi-site experiments indicated BLR could increase FVT and PVT in early cultivar berries and musts.
- Taxon
- Grapet0
- Organ / stage
- berries and mustse0
- Treatment
- BLRe0
- Outcome
- FVT and PVTe0
- Direction
- increasee0
- Qualifier
- early-season cultivars such as Bacchus, Pearl of Csaba, Gewiirztraminer, Schonburger and Siegerrebee0
Not reportedComparator
Verbatim
e0“multi-site experiments also indicated that hedging and BLR could increase FVT and PVT in berries and musts of early-season cultivars such as Bacchus, Pearl of Csaba, Gewiirztraminer, Schonburger and Siegerrebe.”
t0“Grape”
Claim · model-written summary
Canopy division increased Riesling fruit FVT and PVT concentrations.
- Taxon
- Grapet0
- Material
- Rieslinge0
- Treatment
- Canopy divisione0
- Outcome
- FVT and PVT concentrationse0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“Canopy division, BLR and increased vine spacing also increased FVT and PVT concentrations in Riesling fruit.”
t0“Grape”
Claim · model-written summary
BLR increased Riesling fruit FVT and PVT concentrations.
Not reportedComparator
Verbatim
e0“Canopy division, BLR and increased vine spacing also increased FVT and PVT concentrations in Riesling fruit.”
t0“Grape”
Claim · model-written summary
Increased vine spacing increased Riesling fruit FVT and PVT concentrations.
- Taxon
- Grapet0
- Material
- Rieslinge0
- Treatment
- increased vine spacinge0
- Outcome
- FVT and PVT concentrationse0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“Canopy division, BLR and increased vine spacing also increased FVT and PVT concentrations in Riesling fruit.”
t0“Grape”
Claim · model-written summary
Low heat unit sites appear to promote Vitis vinifera monoterpene accumulation more than warmer sites at equal growing degree days.
- Taxon
- Vitis vinifera
Vitis viniferae0 - Outcome
- accumulation of monoterpenese0
- Direction
- moree0
- Qualifier
- equal growing degree dayse0
- Comparator
- warmer sitese0
- Setting
- Low-heat unit sitese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low-heat unit sites appear to promote accumulation of monoterpenes in Vitis vinifera more than warmer sites, when compared at equal growing degree days.”
Claim · model-written summary
Delayed harvest increased must terpene content.
Not reportedComparator
Verbatim
e0“Prefermentation practices such as delayed harvest, prolonged pressing and skin contact were also shown to increase must terpene content.”
t0“Grape”
Claim · model-written summary
Prolonged pressing increased must terpene content.
Not reportedComparator
Verbatim
e0“Prefermentation practices such as delayed harvest, prolonged pressing and skin contact were also shown to increase must terpene content.”
t0“Grape”
Claim · model-written summary
Skin contact increased must terpene content.
Not reportedComparator
Verbatim
e0“Prefermentation practices such as delayed harvest, prolonged pressing and skin contact were also shown to increase must terpene content.”
t0“Grape”
Claim · model-written summary
Terpene concentration differences were often detectable in wine sensory assessment.
Verbatim
e0“In many cases, these differences in terpene concentrations in the berries and musts were organoleptically detectable in wines.”
t0“Grape”
Claim · model-written summary
PVT were more responsive to viticultural and enological practices than FVT.
Verbatim
e0“PVT are more responsive to viticultural and enological practices than FVT”
t0“Grape”
Claim · model-written summary
FVT and PVT rarely correlated with soluble solids, titratable acidity or pH and could not be predicted by standard harvest indices.
- Taxon
- Grapet0
- Compound
- soluble solids, titratable acidity or pHe0
- Outcome
- FVT and PVTe0
- Qualifier
- rarely correlatede0
Not reportedDirection
Verbatim
e0“FVT and PVT are rarely correlated with soluble solids, titratable acidity or pH, and thus cannot be predicted by standard harvest indices”
t0“Grape”
Claim · model-written summary
FVT and PVT losses can occur between berry and juice stages.
Verbatim
e0“Losses in FVT and PVT can occur between the berry and juice stages”
t0“Grape”
Claim · model-written summary
The authors favor skin contact because of terpene losses during juice preparation.
Verbatim
e0“hence the desirability of skin contact”
t0“Grape”
Claim · model-written summary
FVT and PVT concentrations can sometimes relate to wine tasting results.
- Taxon
- Grapet0
- Outcome
- FVT and PVT concentrationse0
- Qualifier
- in some casese0
- Comparator
- wine-tasting resultse0
Not reportedDirection
Verbatim
e0“FVT and PVT concentrations can, in some cases, be related to wine-tasting results.”
t0“Grape”
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