title: Ester synthesis and hydrolysis in an aqueous environment, and strain specific changes during malolactic fermentation in wine with Oenococcus oeni.
abstract: Previous work has shown that Oenococcus oeni produces esterases that are capable of hydrolysing artificial substrates. Using SPME-GCMS, this study provides evidence that purified O. oeni esterases have the ability to both synthesise and hydrolyse esters. Two purified esterases (EstA2 and EstB28) synthesised ethyl butanoate and ethyl hexanoate to varying degrees. Both purified esterases hydrolysed ethyl butanoate, ethyl hexanoate and ethyl octanoate. Once this dual activity was confirmed, malolactic fermentation (MLF) trials were conducted in wine with O. oeni strains that had been previously observed to have either high or low esterase activity against artificial substrates. Strain specific differences were observed and strains with low esterase hydrolysis activity against artificial substrates had a higher level of total esters measured after MLF. The results demonstrate the impact that O. oeni has on wine aroma and relates this to the ester hydrolysis and synthesis abilities of O. oeni strains.
authors.affiliation: School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Glen Osmond, SA 5064, Australia. krista.sumby@adelaide.edu.au
authors.forename: Krista M
authors.initials: KM
authors.lastname: Sumby
authors.forename: Vladimir
authors.initials: V
authors.lastname: Jiranek
authors.forename: Paul R
authors.initials: PR
authors.lastname: Grbin
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D004950:Esterases / Q000737:chemistry* / Q000378:metabolism; D004952:Esters / Q000737:chemistry* / Q000378:metabolism; D005285:Fermentation; D006868:Hydrolysis; D056585:Oenococcus / Q000145:classification / Q000201:enzymology* / Q000378:metabolism; D013045:Species Specificity; D014920:Wine / Q000032:analysis* / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D004952:Esters; D004950:Esterases
keywords: Ester; Esterase; Oenococcus oeni; Synthesis; Wine