OENO IVAS 2019 banner
IVES 9 IVES Conference Series 9 OENO IVAS 9 OENO IVAS 2019 9 Analysis and composition of grapes, wines, wine spirits 9 Trials with machine harvested sauvignon blanc: the importance of grape transport time and temperature

Trials with machine harvested sauvignon blanc: the importance of grape transport time and temperature

Abstract

It is well known that free varietal thiols, in particular 3-mercaptohexanol (3MH) and 3-mercaptohexyl ace-tate (3MHA), are important constituents to the aroma of New Zealand Sauvignon blanc wines. This along with the popular practice of machine harvesting in New Zealand were the motivation for the following two pilot studies.
Firstly, it was examined if the presence of 3MH and 3MHA could be influenced by a change in transporta-tion time of machine harvested grapes. This came about as it was noticed that some Marlborough wineries process grapes incoming from multiple growing regions. Here, the thiol precursor contents, Glut-3MH and Cys-3MH, of 21 lab scale wines were examined after experiencing different simulated transportation times (0, 1.5, 3 and 4.5 h).

Results suggested that significant (p < 0.05) increases in the amount of Cys-3MH and Glut-3MH for some of the treatments associated to longer transportation times was possible. However, after fermentation while some of the experimental wines did not display any significant difference between the transportation times trialled, others displayed an opposite (downward) trend for the presence of 3MH and 3MHA across the increasing time points.

Secondly, as machine harvesting can occur throughout the day and night, of which atmospheric changes in temperature are anticipated, it was hypothesised that the skin contact taking place due to the nature of the machine harvesting can occur at different temperatures. For this study a holding period of 2h was chosen to represent the transport time of harvested grapes to a processing winery while the grape holding tempera-tures investigated were 6, 15 and 24 °C. Cys-3MH and Glut-3MH were quantified both before and after the different temperature treatments of the machine harvested grapes. ANOVA and Tukey HSD did not reveal any significant (p > 0.05) differences in thiol precursor levels before the 2h holding period. However, after this time a significant difference (p < 0.05) between the 6 and 15°C for both Cys-3MH and Glut-3MH was established. Following fermentation, the levels of 3MH and 3MHA were also quantified and revealed similar levels of these thiols between all of the experimental wines with no significant differences (p > 0.05) detec-ted between the holding temperatures investigated.

DOI:

Publication date: June 10, 2020

Issue: OENO IVAS 2019

Type: Article

Authors

Katie Parish-Virtue 1, Mandy Herbst-Johnstone 1, Flo Bouda 2, Rebecca Deed 1, and Bruno Fedrizzi 1, Claire Grose 3, Mandy Herbst-Johnstone 1, Damian Martin 3

1) Wine Science Programme, School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand
2) Delegat Limited, 172 Hepburn Rd, Henderson, Auckland, New Zealand
3) Viticulture and Oenology Group, The New Zealand Institute for Plant and Food Research Ltd, Blenheim, New Zealand

Keywords

Transport time, Temperature, Machine harvesting, Thiols, Sauvignon blanc 

Tags

IVES Conference Series | OENO IVAS 2019

Citation

Related articles…

Texas terroir: gis characterization of the texas high plains ava

The Texas High Plains AVA is one of eight officially recognized wine regions in Texas, established in 1993. Six local wineries, including the second-largest in Texas, are supported by approximately 50 vineyards, which are also major suppliers of grapes to Texas wineries outside the region.

The Shield4Grape project to improve the sustainability of European viticulture

Grapevine (vitis spp.) Is one of the major and most economically important fruit crops worldwide. Unlike other cropping systems, viticulture has ancient historical connections with the development of human culture and with the socio-cultural background of grape-growing areas. The vitis genus is characterised by high levels of genetic diversity, as result of natural genetic mutations, which are common in grapevines and further assisted by ongoing vegetative propagation.

Correlation between agronomic performance and resistance gene in PIWi varieties in the field

Today’s viticulture faces a considerable challenge dealing with fungal diseases and limitations on the use of plant protection products (PPP) have increased the pressure to find more sustainable alternatives. One strategy may be the development and cultivation of disease-resistant grapevine varieties (PIWI) that could maintain crop productivity and quality while reducing dependence on PPP. In this work a set of 9 PIWI varieties (5 white and 4 red) deploying genes for resistance to powdery and downy mildew were evaluated in two consecutive years in Valdegón, La Rioja, with Tempranillo and Viura as controls. The objective was to correlate agronomic performance and disease incidence with the presence of disease resistance genes in two different seasons: with (2023) and without disease pressure (2022).

Impact of yeast derivatives to increase the phenolic maturity and aroma intensity of wine

Using viticultural and enological techniques to increase aromatics in white wine is a prized yet challenging technique for commercial wine producers. Equally difficult are challenges encountered in hastening phenolic maturity and thereby increasing color intensity in red wines. The ability to alter organoleptic and visual properties of wines plays a decisive role in vintages in which grapes are not able to reach full maturity, which is seen increasingly more often as a result of climate change. A new, yeast-based product on the viticultural market may give the opportunity to increase sensory properties of finished wines. Manufacturer packaging claims these yeast derivatives intensify wine aromas of white grape varieties, as well as improve phenolic ripeness of red varieties, but the effects of this application have been little researched until now. The current study applied the yeast derivative, according to the manufacture’s instructions, to the leaves of both neutral and aromatic white wine varieties, as well as on structured red wine varieties. Chemical parameters and volatile aromatics were analyzed in grape musts and finished wines, and all wines were subjected to sensory analysis by a tasting panel. Collective results of all analyses showed that the application of the yeast derivative in the vineyard showed no effect across all varieties examined, and did not intensify white wine aromatics, nor improve phenolic ripeness and color intensity in red wine.

Red wine astringency: evolution of tribological parameters during different harvest dates

Astringency is a specific oral sensation dominated by dryness and puckering feeling and is one of the leading quality factors for red wines, as well as some fruit products