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…

Addition of glutathione-rich inactivated yeasts to white musts: effects on wine composition and sensory quality

Glutathione plays a key role in preventing some oxidative processes during winemaking. This molecule limits the must enzymatic oxidation, reacts with caffeic acid and generates a colourless compound that prevents subsequent browning. It also has a protective effect on wine aroma, preventing the oxidation of the volatile compounds with a high sensory impact.

Free and bound terpene profile of recovered minority white grape varieties by GC × GC-TOFMS

Climate change presents a significant challenge for actual viticulture. In this context, recovering minority grape varieties can be a crucial strategy to ensure resilience, particularly those capable of maintaining quality and aromatic complexity under water stress.

Do natural wines differ from conventionally-produced wines?

In recent years, consumer awareness for consuming healthy and environmental sustainability products has considerably increased [1]. In an ever-changing and highly competitive environment such as the wine sector, production of wines without sulfites, or biodynamic, organic or vegan wines, has experienced an important increase to meet the new needs of consumers [2,3]. Beyond these categories of regulated products, a new concept has emerged: natural wines (NW), for which there is not an established definition or legal regulation. Rather, producers have a personal idea of naturalness under the premise of applying minimal intervention from grape to wine production [4]. In this context, it is hypothesized that self-defined natural wines are different from conventional wines (CW) in their sensory and chemical profile. The predicament of natural wine is based on anecdotic declarations and assumes that minimal intervention guarantees the production of wines with organoleptic properties able to express the “terroir” and thus promote wine diversity, plurality and sensory typicity against the risk of standardization of CW.

Genome wide association mapping of phenology related traits in Vitis vinifera L

Climate change, with rise in temperatures, is leading to an advance in the dates of phenological stages, with a loss in quality of the grape final product. Therefore, the understanding of the genetic determinants driving the phenological stages of flowering, veraison and the interval between them, represents a target for the development of grapevine’s cultivar adapted to the changing environment.
Here we conducted a GWA study to identify SNPs significantly associated to flowering time, veraison time and to the interval among them. A germplasm collection (CREA-VE in Susegana, Treviso, Italy) including 649 grapevine’s cultivar representing 365 unique genotypes was considered.

History of inorganic and isotopic signatures in Champagne over the last century: lessons

The notion of «terroir» refers to the link between the composition, quality and taste of a wine, on the one hand, and its place of origin, on the other. It involves, among other things, the signature of soil elements, as well as the influence of climatic conditions and plant material used. The composition of the wine is also influenced by the winemaking, storage and bottling processes. We were lucky enough to have a time series of the same champagne, from the end of the first world war to the present. On this exceptional time series, we followed, with the most advanced methods, all the elemental signatures by isotopic multi-dilution, the evolution of the isotopic ratios of heavy elements with very high precision of Sr, Pb, B and Cu.