Effect of the cleaning and disinfection methods on the hygienic conditions of fermentation tanks of table olives (Olea europaea L.) Negrinha de Freixo cultivar
The authors are grateful to the Foundation for Science and Technology
(FCT, Portugal) for financial support through national funds
FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/
2020) and SusTEC (LA/P/0007/2021). The authors are also grateful to
the Project OLIVECOA—Centenarian olive trees of Cˆoa Valley region:
rediscovering the past to valorize the future, ref. COA/BRB/0035/2019.
F´atima Martins acknowledges the financial support to the project
“OleaChain: Competencies for sustainability and innovation in the
traditional olive grove value chain in the North Interior of Portugal”
(NORTE-06-3559-FSE-000188). Nuno Rodrigues thanks to National
funding by FCT - Foundation for Science and Technology, P.I., through
the institutional scientific employment program-contract. The authors
also thank the table olive producers who generously provided their facilities
for sampling.
This study aimed to evaluate and identify the microbial community attached to the surfaces of fermenter tanks
used in table olive Negrinha de Freixo cultivar processing through molecular analysis and verify if the cleaning/
disinfection was done correctly. Four fermentation tanks previously used in table olive processing were sampled
at three different inside areas: upper, middle, and lower. Before sampling, four cleaning/disinfection methods
were applied to the tanks, including (i) pressurised water; (ii) a disinfectant product used to clean bowls
(Vasiloxe); (iii) 10% sodium hydroxide solution (caustic soda liquid); and (iv) a disinfectant product used by the
wine industry (Hosbit). For each sample collected, mesophilic aerobic bacteria, yeast and moulds (YMC), lactic
acid bacteria (LAB), as well as total coliforms (TC) and Pseudomonas aeruginosa were evaluated. The results
showed significant differences between the different cleaning/disinfection methods applied. The fermenter
sanitised with only pressurised water showed a greater abundance of microorganisms than the others. Mesophilic
aerobic bacteria were the predominant population, with counts ranging between 2.63 and 5.56 log10 CFU/100
cm2, followed by the moulds (3.11–5.03 log10 CFU/100 cm2) and yeasts (2.42–5.12 log10 CFU/100 cm2). High
diversity of microbial communities was observed between the different fermenter tanks. The most abundant
species belonged to Aureobasidium, Bacillaceae, Cladosporium, and Rhodotorula genera. LAB, TC, and P. aeruginosa
were not detected. This study hopes to improve hygienic conditions and increase the quality assurance and safety
of the final product.
