Macrowine 2021
IVES 9 IVES Conference Series 9 Whole bunch fermentation: adding complexity, or just making ‘green’ wine?

Whole bunch fermentation: adding complexity, or just making ‘green’ wine?

Abstract

AIM: Certain grape varieties contain negligible levels of isobutyl methoxypyrazine (IBMP) in grapes. However, it has long been known that grape stems may have a high concentration of IBMP. The study aimed to discover the extent to which whole bunch addition during fermentation contributes to ‘capsicum’ (green) flavour and aroma in wine by imparting IBMP. It was also of interest to determine whether additional tannin could be extracted from stem contact, which was expected to impact wine astringency.  

METHODS: Pinot noir and Shiraz grapes were either fermented either completely crushed, or as 100% whole bunches. Other treatments had proportional whole bunch addition at 25%, 50% or 75%. Wines were put through descriptive sensory analysis after 10 months and multiple volatile and non-volatile compounds were analysed at the same time.  

RESULTS:  For both varieties, the sensory scores for ‘green capsicum’ and the concentration of IBMP were highly correlated with the proportion of whole bunches in the ferment. Volatile compounds other than IBMP were increased by whole bunch fermentations, and were α-terpineol, β-citronellol and E-2-hexenol. For Shiraz, the wood-derived volatiles guaiacol and vanillin increased with whole-bunch inclusion, while for Pinot noir ethyl cinnamate increased, possibly reflecting that some carbonic maceration occurred. In Shiraz wines, the concentration of tannin and the perception of astringency increased with the inclusion of whole bunches, but this was not observed for Pinot noir. Whole-bunch ferments from both grape varieties had lower levels of polysaccharide in the finished wine, primarily due to a lower contribution of pectic material.     

CONCLUSIONS: This study showed that winemakers can substantially alter wine volatile and non-volatile composition through whole bunch fermentation. The results will be discussed in terms of potential wine style outcomes for the respective grape varieties, whether whole bunch inclusion might improve the complexity of a wine, or simply introduce unwanted ‘green capsicum’ attributes.

DOI:

Publication date: September 10, 2021

Issue: Macrowine 2021

Type: Article

Authors

Keren Bindon (1), Martin Day (1), Dimitra Capone (2), Stella Kassara (1), Eleanor Bilogrevic (1), Damian Espinase-Nandorfy (1), Flynn Watson (1), Leigh Francis (1)

(1) The Australian Wine Research Institute, Research, Adelaide, Australia
(2) Arc Training Centre For Innovative Wine Production, The University Of Adelaide, Adelaide, Australia

Contact the author

Citation

Related articles…

Potential of new genetic resources to improve drought adaptation of grapevine rootstocks

Grapevines are grown mainly as grafts worldwide, but the rootstocks most commonly used were selected between the late 19th and early 20th centuries and are based on reduced genetic diversity[1]. In the context of climate change, it is indeed urgent to diversify the range of rootstocks with genotypes much more adapted to drier environments, than the existing ones[2]. The aim of this study was to evaluate the potential of new genetic resources for grapevine rootstock breeding programs. For this purpose, 12 American and Asian wild Vitis species (3 to 5 accessions per species = 50 accessions) were evaluated for their rooting ability and drought response.

Read More

Development of a semi-controlled setup for manipulating drought and heat stress in open field trials

Drought and heat stress will pose challenges for the future of viticulture and wine quality, as grapevine biological processes are pushed beyond their optimum conditions. Efforts are increasing to study and predict the effects of drought spells and heatwaves on grapevine physiology and resulting harvest quality. This calls for the development of adequate systems to induce and manipulate the required stress, especially in open field trials where conditions are more difficult to control. We present a semi-controlled system for studying drought and heat stress in grapevine in the field.

Read More

Bioprotective effect of a Torulaspora delbrueckii/Lachancea thermotolerans mixed inoculum and its impact on wines made.

SO2 is an additive widely used as antimicrobial in winemaking industry. However, this compound can negatively affect health, so the search for alternatives is currently a line of research of great interest. One of the proposed alternatives to SO2 as an antimicrobial is the use of bioprotection yeasts, which colonize the medium preventing the proliferation of undesirable microorganisms.

Read More

Développer des outils simples pour accompagner les viticulteurs dans leurs changements de pratiques et répondre aux enjeux du siècle à venir

French viticulture is currently facing major challenges as it enters the new century: climate change, the need to reduce inputs, societal issues, changing consumer habits, labor shortages …. Vinopôle bordeaux-aquitaine, to which the teams from the chambre d’agriculture de la gironde belong, supports winegrowers of the gironde and bergerac-duras regions in the gradual evolution of their practices.

Read More

Monitoring arthropods diversity in the “Costières de Nîmes” viticulture landscape

Biodiversity loss in agrosystems is partly due to landscape simplification (field enlargement, hedgerows removal…) that led to a loss of heterogeneity of the overall landscape.

Read More