Simultaneous microwave-assisted extraction of bioactive compounds from aged garlic

In this work, the simultaneous extraction of bioactives (organosulfur compounds, such as S-allyl-L-cysteine (SAC), carbohydrates, such as neokestose and neonystose, and total phenolic compounds) from aged garlic has been optimized for the first time to obtain multifunctional extracts for further application as food ingredients. Analytical methods using liquid chromatography coupled to mass spectrometry (HPLC-MS) and by hydrophilic interaction liquid chromatography with evaporative light scattering detection (HILIC-ELSD) were also previously optimized. High sensitivity (limits of detection between 0.013 and 0.77 µg mL^-1) and appropriate repeatability (< 12%) and accuracy (> 92%) for the analysis of bioactives were achieved. After selecting water as the extraction solvent and microwave-assisted extraction (MAE) as the most efficient technique, operation conditions were optimized using a Box-Behnken experimental design (60 min; 120 °C; 0.05 g mL^-1; 1 cycle) to maximize the content of bioactives from different aged garlic samples. Regarding organosulfur compounds, only SAC (traces-2.32 mg g^-1 dry sample) and cycloalliin (1.23-3.01 mg g^-1 dry sample) were detected in all samples, while amino acids such as arginine (0.24-3.45 mg g^-1 dry sample) and proline (0.43-3.91 mg g^-1 dry sample) were, in general, the most abundant. Bioactive carbohydrates (from trisaccharides to nonasaccharides) were only detected in fresh garlic and aged garlic processed under mild conditions, whereas all garlic extracts showed antioxidant activity. The developed MAE methodology is shown as a successful alternative to other procedures for the simultaneous extraction of aged garlic bioactives intended by the food and nutraceutical industries, among others.