Enumeration and rapid identification of yeasts during extraction processes of extra virgin olive oil in Tuscany.
The aim of this study was to evaluate the occurrence of yeast populations during different olive oil extraction processes, carried out in three consecutive years in Tuscany (Italy), by analysing crushed pastes, kneaded pastes, oil from decanter and pomaces. The results showed yeast concentrations ranging between 10(3) and 10(5) CFU/g or per mL. Seventeen dominant yeast species were identified by random amplified polymorphic DNA with primer M13 and their identification was confirmed by restriction fragments length polymorphism of ribosomal internal transcribed spacer and sequencing rRNA genes. The isolation frequencies of each species in the collected samples pointed out that the occurrence of the various yeast species in olive oil extraction process was dependent not only on the yeasts contaminating the olives but also on the yeasts colonizing the plant for oil extraction. In fact, eleven dominant yeast species were detected from the washed olives, but only three of them were also found in oil samples at significant isolation frequency. On the contrary, the most abundant species in oil samples, Yamadazyma terventina, did not occur in washed olive samples. These findings suggest a phenomenon of contamination of the plant for oil extraction that selects some yeast species that could affect the quality of olive oil.
Dipartimento di Gestione dei Sistemi Agrari, Alimentari e Forestali (GESAAF), sezione di Scienze e Tecnologie Alimentari e Microbiologiche, Università degli Studi di Firenze, piazzale delle Cascine, 24, 50144, Florence, Italy.
Eleonora
E
Mari
Dipartimento di Gestione dei Sistemi Agrari, Alimentari e Forestali (GESAAF), sezione di Scienze e Tecnologie Alimentari e Microbiologiche, Università degli Studi di Firenze, piazzale delle Cascine, 24, 50144, Florence, Italy.
Simona
S
Guerrini
Dipartimento di Gestione dei Sistemi Agrari, Alimentari e Forestali (GESAAF), sezione di Scienze e Tecnologie Alimentari e Microbiologiche, Università degli Studi di Firenze, piazzale delle Cascine, 24, 50144, Florence, Italy. lisa.granchi@unifi.it.
Lisa
http://orcid.org/0000-0002-9232-2829
L
Granchi
Dipartimento di Gestione dei Sistemi Agrari, Alimentari e Forestali (GESAAF), sezione di Scienze e Tecnologie Alimentari e Microbiologiche, Università degli Studi di Firenze, piazzale delle Cascine, 24, 50144, Florence, Italy.
Massimo
M
Vincenzini
D044822:Biodiversity; D004271:DNA, Fungal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D019652:Extraction and Processing Industry; D005506:Food Contamination; D005516:Food Microbiology; D020459:Genes, rRNA / Q000235:genetics; D007558:Italy; D031658:Olea / Q000382:microbiology*; D000069463:Olive Oil / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D012150:Polymorphism, Restriction Fragment Length; D015003:Yeasts / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology
D004271:DNA, Fungal; D004275:DNA, Ribosomal; D000069463:Olive Oil; D010936:Plant Extracts
Extra virgin olive oil; Identification; Random amplified polymorphic DNA (RAPD–PCR); Yeasts