Analysis of Volatile Compounds Produced by 2 Strains of Lactococcus lactis Isolated from Leben (Tunisian Fermented Milk) Using Solid-Phase Microextraction-Gas Chromatography |
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| Authors: | M Ziadi JP Wathelet M Marlier M Hamdi P Thonart |
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| Affiliation: | Authors Ziadi and Hamdi are with LETMI (Laboratoire d'Ecologie et de Technologie Microbienne) Inst. Natl. des Sciences Appliquées et de Technologie (INSAT), BP 876, 1080 Tunis, Tunisia. Authors Wathelet and Marlier are with Unitéde Chimie Générale et Organique and author Thonart is with Centre Wallon de Biologie Industrielle (CWBI), FacultéUniv. des Sciences Agronomiques de Gembloux (FUSAGX), Passage des Déportés, 2, 5030 Gembloux, Belgium. Direct inquiries to author Hamdi (E-mail: ). |
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| Abstract: | ABSTRACT: The volatile compounds that characterize Leben during fermentation with 2 Lactococcus lactis strains (SLT6 and SLT10) in flasks, in a 100-L fermentor, and during storage at 4 °C, were investigated and compared to those from commercial Leben. Volatile compounds from Leben were concentrated by a Carboxen–PDMS fiber and analyzed by GC-MS. These compounds include acids, alcohols, aldehydes, ketones, sulfur compounds, and hydrocarbons. Commercial Leben presented a poor volatile profile compared to the laboratory-made Leben. The mixed culture of 2 Lactococcus lactis strains resulted in higher volatile compound formation than the single strain culture. The GC volatile profiles of Leben produced in flask and in the 100-L fermentor were similar. Changes in volatile compounds were observed during storage at 4 °C. The effect of culture conditions on production of volatiles by SLT6 strain was studied. Aeration (0.1 mL/min) and agitation enhanced the production of diacetyl, acetoin, 3-methylbutanal, and 3-methylbutanol. Fermentation at pH 5 had no effect on volatile production. |
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| Keywords: | Lactococcus Leben quantification solid-phase microextraction (SPME) volatiles |
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