Original Research ArticleEstablishing compositional differences between fresh and black garlic by a metabolomics approach based on LC-QTOF MS/MS analysis

- The compositional profiles of fresh and black garlic were studied and compared.
- Differences in composition were established among three fresh garlic varieties.
- The effect of heat treatment on composition as a function of the variety was evaluated.
- Amino acids and organosulfur compound were drastically affected by heat treatment.

Despite the increasing popularity of black garlic as a food ingredient, few studies have been devoted to in-depth profiling characterization of this product from fresh garlic. In this research polar extracts from fresh and black garlic of three garlic varieties cultivated in the South of Spain were characterized using liquid chromatography with tandem mass spectrometry in high resolution mode with a QTOF analyzer. Ninety-eight compounds were tentatively identified and classified as a function of the given family: amino acids and derivatives, organosulfur compounds, saccharides and derivatives, lipids and derivatives, and others. The composition of the three garlic varieties was compared and the differences among them evaluated. Then, fresh and black garlic were compared to determine the compounds that are exclusive of each one and also the compounds with levels significantly different among them. The heat treatment changes significantly the composition in garlic of the amino acids family, followed by organosulfur compounds.