title: Production of 4-ethylphenol in alperujo by Lactobacillus pentosus.
abstract: BACKGROUND
  Alperujo is the paste generated from the two-phase extraction system of olive oil. This wet pomace must be stored for several months and, during this period, the formation of 4-ethyphenol provokes a strong off-odour. The aim of this work was to identify the microorganisms able to produce this volatile phenol.
  
  
  RESULTS
  Yeast and bacterial strains were isolated from stored alperujo and tested for their ability to metabolize p-coumaric acid and form 4-ethylphenol. Among them, Lactobacillus pentosus was the microorganism that both in synthetic medium and alperujo gave rise to 4-ethylphenol formation. This microorganism did not grow in alperujo acidified to pH 2, thereby confirming that acidification as the best method to control odour emissions during alperujo storage.
  
  
  CONCLUSIONS
  Lactic acid bacteria, particularly Lactobacillus pentosus, can be responsible for the formation of the off-odour caused by 4-ethylphenol during the storage of alperujo. This odour can be prevented by acidifying the alperujo.
authors.affiliation: Instituto de la Grasa IG-CSIC, 41012-, Seville, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: de Castro
authors.affiliation: Instituto de la Grasa IG-CSIC, 41012-, Seville, Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Asencio
authors.affiliation: Instituto de la Grasa IG-CSIC, 41012-, Seville, Spain.
authors.forename: Maria Victoria
authors.initials: MV
authors.lastname: Ruiz-Méndez
authors.affiliation: Instituto de la Grasa IG-CSIC, 41012-, Seville, Spain.
authors.forename: Concepción
authors.initials: C
authors.lastname: Romero
authors.affiliation: Instituto de la Grasa IG-CSIC, 41012-, Seville, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Brenes
mesh_terms: D003373:Coumaric Acids / Q000378:metabolism; D005285:Fermentation; D005516:Food Microbiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007778:Lactobacillus / Q000254:growth & development / Q000378:metabolism*; D009812:Odorants / Q000032:analysis / Q000517:prevention & control*; D031658:Olea; D010636:Phenols / Q000378:metabolism*; D011422:Propionates
chemical_list: D003373:Coumaric Acids; D007220:Industrial Waste; D010636:Phenols; D011422:Propionates; C042291:4-ethylphenol; C495469:p-coumaric acid
keywords: 4-ethylphenol; Dekkera bruxellensis; alperujo; olive; storage