Optimization of stir bar sorptive extraction (SBSE) and multi-stir bar sorptive extraction (mSBSE) to improve must volatile compounds extraction

The aromatic compounds present in grapes are found in very low concentrations, since, for their determination, a previous step of selective extraction is necessary. In this work we optimize and compare, for the first time, the techniques of extraction by stir bar sorption (SBSE) and multi-stir bar sportive extraction (mSBSE), with the aim of analyzing the must volatile composition. For this purpose, two randomized factorial designs were carried out in which the following factors and levels were combined and optimized: for SBSE, extraction mode (headspace (HS), direct immersion (DI), and both at the same time), extraction speed (500/1000 rpm), extraction time (1/3/6 h), extraction temperature (20/40/60 °C) and NaCl addition (with and without NaCl, and sequential); and for mSBSE: extraction speed (500/1000 rpm), extraction time (1/3/6 h), extraction temperature (20/40/60 °C), and NaCl addition (with and without). The results showed that SBSE technique provided a higher extraction of volatile compounds than mSBSE. After performing principal component analysis (PCA) and analysis of variance (ANOVA) multifactorial, it was concluded that the best conditions for SBSE were: HS, 500 rpm, 6 h, 60 °C and adding NaCl (sequential); and for mSBSE were: 500 rpm, 6 h, 60 °C and without NaCl.