An optimization approach on the determination of volatile composition, bioactive compounds and sensory properties of Lben: Effect of fermentation conditions, starter system and substrate composition

In order to optimize the quality of Lben, a Moroccan fermented milk, the impact of starter, fermentation conditions and substrate composition on its organoleptic and technological characteristics was studied using response surface methodology. Using autochthonous bacterial strains (three strains of Lactococcus lactis subsp. lactis and one Leuconostoc mesenteroides subsp. mesenteroides), the effect of independent factors including temperature (25-35 degrees C), inoculum rate (0.4-1.2%) and milk fat concentration (0.1-3.0%) on the acidifying performance, texture, proteolysis, sensory properties, some aroma-active compounds including butanoic acid, ethanol, acetoin, acetaldehyde and diacetyl, and biological activities (ACE-i and GABA) was evaluated. According to central composite design, an optimized model for Lben production was developed based on fermentation time, Lben sensory quality and its biological activities, including ACE-i activity and gamma-aminobutyric acid content. The optimal condition was obtained with 863.86 min fermentation time, 0.97% fat level, 1.2% inoculum rate corresponding to 8.08 log10 cfu/mL at 26.75 degrees C fermentation temperature.