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…

Contribution of very high resolution satellite remote sensing to the mapping of harvest zones in the Maipo Valley (Chile)

Les images de très haute résolution spatiale sont utilisées depuis peu en viticulture comme une aide à la cartographie des zones de vendanges. A partir d’images multispectrales de très haute résolution spatiale IKONOS (résolution 4 m) et SPOT-5 en supermode (résolution 2.5 m), on propose ici une démarche de segmentation d’une région de vignoble en zones de vendanges.

Read More

Freeze-thaw temperature oscillations promote increased differential gene expression during grapevine bud dormancy

In northern cold climate conditions, chilling requirement fulfillment in dormant grapevine buds is slowed or stopped by subzero temperatures impacting the transcriptional processes needed to complete chilling requirement. Cabernet Franc and Reisling in Geneva, NY were used to determine the impact of natural oscillating temperatures on grapevine bud transcriptional activity during light and dark periods of a two-week period in January with fluctuating diurnal winter temperatures. Cabernet Franc and Reisling bud samples were collected at 32 time points during the natural vineyard temperature cycle at 6:00 (dark), 14:00 (light) and 18:00 (dark) hours) to monitor gene expression in consecutive freezing and non-freezing temperature oscillations. Genotype, light and dark, and temperature oscillations conditions were explored.

Read More

Improvement of non-Saccharomyces yeast dominance during must fermentation by using spontaneous mutants resistant to SO2, EtOH and high pressure of CO2

AIM: A genetic study of four wine T. delbrueckii strains was done. Spore clones free of possible recessive growth‐retarding alleles with enhanced resistance to winemaking stressing conditions were obtained from these yeasts. METHODS: The genetic marker of resistance to cycloheximide (cyhR) allows easy monitoring of the new mutants obtained from these yeasts.

Read More

Developmental stage-specific effects of high temperature on aroma accumulation in ‘Marselan’ grapes from the Helan Mountain region

The aroma of wine grapes is influenced by a complex metabolic network, with terroir factors, especially high temperatures, playing a critical role during berry development.

Read More

Impact of moderate water deficit on grape quality potential on Pinot Noir in Champagne (France)

Environmental factors like soil and climate influence grape quality potential. Their impact is often mediated through vine water and nitrogen status. Depending on the color of the grapes (red or white) and the type of wine produced, the desired level of vine water and nitrogen status for optimum wine quality is different. Little investigation has been carried out concerning these factors and their potential influence on sparkling wine quality on two vintages. In this study vine water and nitrogen status were assessed at a very high density and related to grape composition and berry weight. Through statistical analyses, the major factors driving grape quality potential on Pinot noir in Champagne were highlighted.

Read More