Prevalent lactic acid bacteria in cider cellars and efficiency of Oenococcus oeni strains Ainoa Sánchez a , Monika Coton b , Emmanuel Coton b , Mónica Herrero a, * , Luis A. García a , Mario Díaz a a Department of Chemical Engineering and Environmental Technology, University of Oviedo, Spain b ADRIA Normandie, Bd du 13 juin 1944,14310 Villers-Bocage, France article info Article history: Received 6 August 2011 Received in revised form 19 December 2011 Accepted 14 February 2012 Available online 5 March 2012 Keywords: Cider Malolactic fermentation Starter cultures Food safety Indigenous strains Industrial abstract Malolactic fermentation (MLF) is an important step in cider production in order to allowing for improvement of microbiological stability and organoleptic characteristics of cider. Induction of this fermentation by using starter cultures enables a better control over this bioprocess, but although it is a common practice in winemaking, starters specifically focussed for cider MLF are not yet commercially available. Proper starter cultures need to present the ability to degrade L-malic acid conferring pleasing sensory characteristics while avoiding toxicological risks. In this work, lactic acid bacteria (LAB) were first isolated from MLF industrial cider samples, obtained in a cellar in the main cider-producing region of Spain, Asturias. Isolates, identified by molecular tools, belonged to the Lactobacillus brevis and Oenococcus oeni species. After a phylogenetic analysis, representative strains of both identified species were evalu- ated in order to determine their fermentation capacity, showing O. oeni the best behaviour in this cider fermentation, as previously demonstrated for wine in the literature. Consequently, and with the aim to test the influence at strain level, selection of O. oeni isolates as starters for cider fermentation has been undergone. In order to check the influence of geography over biodiversity, O. oeni strains from six different industrial cellars representing the distinct producing areas in the region (located in a ratio of 30 km) were analyzed by using a specific RAPD method. In this way, isolates were typed in five distinct groups, mainly corresponding to each producing area. All strains isolated from the same cellar showed the same RAPD profile revealing the significance of geographical origin in the indigenous cider LAB. Molecular tools were applied to reject those isolates exhibiting presence of genes related to organoleptic spoilage (exopolysaccharides and acrolein production) or food safety (biogenic amine production), as key selection criteria. Representative strains of each of the five O. oeni RAPD groups were tested as pure cultures to evaluate their technological utility for cider production. Experimental data of malic acid degradation and cell concentration obtained were fitted to previously selected kinetic models aimed to optimization and prediction of bioprocess performance. Four strains revealed as suitable potential starter cultures for conducting MLF in cider production. Ó 2012 Published by Elsevier Ltd. 1. Introduction The food industry is expected to produce safe, healthy and nutritious products of high quality. For many food products, fermentation with starter cultures containing LAB is an essential part of the production process (Smid et al., 2005). Cider production in Asturias (a north-western region in Spain) is made via a sponta- neous fermentation, interactions between microorganisms are not controlled during the process, and completing MLF by indigenous microbiota may take several months or it may occur in some tanks but not in others. Induction of the MLF using selected bacterial starter cultures is becoming the best option at industrial level. However, the application of starter cultures for the MLF has not been employed yet in cider production, due to the lack of adapted cultures (Xu et al., 2005) commercially available to conduct this fermenta- tion. Asturias manufactures 80% of the total cider production in the country, which meant around 50,000 tons in 2009. In winemaking, as a result of natural selection, Oenococcus oeni becomes the dominant species among those triggering MLF (Bon et al., 2009). Consequently, winemaking practices involve inocula- tion of wine with commercially prepared strains of O. oeni * Corresponding author. Department of Chemical Engineering and Environmental Technology, Faculty of Chemistry, University of Oviedo, C/ Julián Clavería s/n., 33071, Oviedo, Spain, Tel.: þ34 985 103439; fax: þ34 985 103434. E-mail address: herreromonica@uniovi.es (M. Herrero). Contents lists available at SciVerse ScienceDirect Food Microbiology journal homepage: www.elsevier.com/locate/fm 0740-0020/$ e see front matter Ó 2012 Published by Elsevier Ltd. doi:10.1016/j.fm.2012.02.008 Food Microbiology 32 (2012) 32e37