A methodological approach to screen diverse cheese-related bacteria for their ability to produce aroma compounds

Tomislav Pogacic (1) , Marie-Bernadette Maillard (1) , Aurélie Leclerc (2) , Christophe Hervé (2) , Victoria Chuat (1) , Florence Valence (1) , Anne Thierry (1)

1 STLO - Science et Technologie du Lait et de l'Oeuf
2 Laboratoires Standa

Microorganisms play an important role in the development of cheese flavour, producing a variety of aroma compounds for which lactose/citric acid, proteins and fat are precursors. There is a demand from cheese producers to diversify the flavour of semi-hard cheeses. A large screening is required to identify strains of interest among the diversity of cheese-related bacterial species and strains. This step cannot be bypassed and is time-consuming. Our aim was to develop a methodological approach to facilitate and expedite the screening of various cheese-related bacteria for their ability to produce aroma compounds. Our strategy was to combine: (i) the use of a curd-based broth medium incubated under conditions mimicking cheese manufacturing and ripening, ii) a powerful method of extraction of volatiles, headspace trap, coupled to gas chromatography-mass spectrometry, and iii) a metabolomicsbased method of data processing using the XCMS package of R software and multivariate analysis. This approach was applied to eleven species: lactic acid bacteria (Leuconostoc lactis, Lactobacillus sakei, Lb. paracasei, Lb. fermentum, and Lb. helveticus), surface bacteria (Brachybacterium articum, Brachybacterium tyrofermentans, Brevibacterium aurantiacum, Microbacterium gubbeenense), Propionibacterium freudenreichii and Hafnia alvei. All the strains grew, with maximal populations ranging from 7.4 to 9.2 log CFU/g. In total, 53 volatile compounds were identified, of which 50 varied significantly in abundance between bacteria. Principal component analysis of volatile profiles differentiated species on their ability to produce ethyl esters (associated with Brachybacterium), sulfur compounds and branched-chain alcohols (H. alvei), branched-chain acids (H. alvei, P. freudenreichii and Lb. paracasei), diacetyl and related carbonyl compounds (M. gubbeenense and Lb. paracasei), among others. The present approach was then successfully applied to screen collections of lactic and propionic acid bacteria. The metabolomics-based method of data processing can be widely applied in the field of food flavour chemistry.

Mots clés: fromage; composé volatil; bactérie lactique; screening; caractérisation de souche; volatilome

Domaines: Ingénierie des aliments; Alimentation et Nutrition; Microbiologie et Parasitologie

Tomislav Pogacic, Marie-Bernadette Maillard, Aurélie Leclerc, Christophe Hervé, Victoria Chuat, et al.. A methodological approach to screen diverse cheese-related bacteria for their ability to produce aroma compounds. 24.International ICFMH conference, Food Micro 2014, Sep 2014, Nantes, France. , 2014. ⟨hal-01209695⟩