Grape-specific native microbial communities influence the volatile compound profiles in fermenting grape juices

Area of Science:

• Oenology and Viticulture
• Microbiology
• Food Chemistry

Background:

• The specific contribution of native grape microbial communities to wine's unique characteristics remains unclear.
• Understanding these microbial influences is key to controlling wine's sensory profile.

Purpose of the Study:

• To investigate how distinct native grape microbial communities from Malbec (Vitis vinifera) and Isabella (Vitis labrusca) influence grape juice fermentation and volatile composition.
• To determine the role of specific non-Saccharomyces yeast species in these fermentations.

Main Methods:

• Utilized microbial communities from Malbec and Isabella grapes as starters for Malbec grape juice fermentation.
• Performed homologous and heterologous fermentation analyses.
• Quantified volatile profiles and analyzed yeast species abundance (Hanseniaspora uvarum, Hanseniaspora opuntiae, Starmerella bacillaris).
• Assessed growth parameters of isolated yeast species in different grape juices.

Main Results:

• Each Vitis-specific microbial starter distinctly influenced the volatile profiles of the fermented grape juice.
• Significant shifts in the relative abundance of key non-Saccharomyces yeasts (Hanseniaspora uvarum, Hanseniaspora opuntiae, Starmerella bacillaris) were observed.
• No significant growth differences were found for isolated yeast species between Malbec and Isabella grape juices, suggesting starter community composition is critical.

Conclusions:

• Native grape microbiota composition critically shapes the volatile profile and identity of fermented grape juice.
• Vitis-specific microbial communities are pivotal in determining fermentation outcomes and the final wine character.