Solid-phase micro extraction coupled with GC–MS for determination of the metabolite profile of newly isolated strains of Lactobacillus delbrueckii ssp. bulgaricus

Abstract

The biological and organoleptic properties of Bulgarian yogurt are largely determined by the metabolic activity of the selected strains of Lactobacillus delbrueckii ssp. bulgaricus. The HS-SPME-GC-MS technique was used to analyze the volatile compounds produced by the following strains: Lactobacillus delbrueckii ssp. bulgaricus MG1, MG2, MG3 MG4, MG5 MG6, MG7 and Lactobacillus delbrueckii ssp. bulgaricus MG8. A study to optimize the conditions of SPME was performed. The optimum extraction of the aromatic components was obtained at an extraction temperature of 50 °C and a process duration of 50 minutes. In total, 49 volatile flavor compounds, forming the aromatic profile of the obtained fermented milk, were identified. The production of acetaldehyde, 2,3-butanedione, 2-acetylfuran, 2-nonanone, 2-heptanone and 2-undecanone, pentanoic and octanoic acid, 3-carnene, undecane, dodecane, tridecane and tetradecane was detected for all strains. The only strain that produced acetoin was Lactobacillus delbrueckii ssp. bulgaricus MG7.