Taggiasca extra virgin olive oil colonization by yeasts during the extraction process.

Area of Science:

• Food microbiology
• Oenology
• Agricultural science

Background:

• Newly produced olive oil's opalescence stems from trapped microorganisms in vegetation water and solid particles.
• The microbiota of fresh olive oil is dominated by yeasts and molds, with bacteria largely eliminated during malaxation.

Purpose of the Study:

• To investigate the yeast populations in Taggiasca extra virgin olive oil throughout the production and storage process.
• To identify specific yeast species present in wash water, kneaded paste, and fresh and stored olive oil.

Main Methods:

• Sampling of wash water, kneaded paste, and fresh/stored olive oil from Taggiasca variety olives in Liguria.
• Physiological characterization and identification of yeast groups and predominant species.
• Analysis of yeast survival and diversity during six months of olive oil storage.

Main Results:

• Six distinct yeast groups were identified in wash water, kneaded paste, and fresh Taggiasca olive oil.
• Key species identified include Kluyveromyces marxianus, Candida oleophila, Candida diddensiae, Candida norvegica, Wickerhamomyces anomalus, and Debaryomyces hansenii.
• Only Wickerhamomyces anomalus survived and remained dominant in the oil after six months of storage, indicating strong selective pressure.

Conclusions:

• The yeast composition of fresh olive oil is directly influenced by the olive carposphere microbiota.
• Olive oil storage imposes significant selective pressure, drastically reducing yeast diversity.
• Wickerhamomyces anomalus demonstrates remarkable resilience and adaptability to the extra virgin olive oil environment during storage.