Chemometric Optimisation Of Pressurised Liquid Extraction For The Determination Of Alliin And S-Allyl-Cysteine In Giant Garlic (Allium Ampeloprasum L.) By Liquid Chromatography Tandem Mass Spectrometry

Introduction Giant garlic is a functional food that contains different kinds of bioactive molecules with beneficial effects on chronic noncommunicable diseases like diabetes and cardiovascular conditions. Considering biosynthesis pathways, abundance, and biological activity, alliin and S-allyl-cysteine were used as chemical markers of organosulphur compounds present in giant garlic.Objective To establish a chemometric optimisation of pressurised liquid extraction for the determination of alliin and S-allyl-cysteine in giant garlic by liquid chromatography tandem mass spectrometry (LC-MS/MS).Methodology Samples were blanched (ca. 90 degrees C for 10 min) to inactivate alliinase and gamma-glutamyl transpeptidase enzymes and then freeze-dried. Chemometric optimisation was performed via response surface methodology based on central composite design (CCD). Organosulphur compound yields were determined applying a validated LC-MS/MS method in multiple reaction monitoring (MRM) mode using the following transitions: for alliin m/z 178 -> 74 and for S-allyl-cysteine m/z 162 -> 41.Results According to CCD results, under constant conditions of pressure (1500 psi) and time (20 min), the optimal conditions for pressurised liquid extraction of alliin and S-allyl-cysteine were 70.75 and 68.97% v/v of ethanol in extraction solvent and 76.45 and 98.88 degrees C as extraction temperature, respectively. Multiple response optimisation for the simultaneous extraction of both organosulphur compounds was established via desirability function. Under these conditions, 2.70 +/- 0.27 mg g(-1) dry weight (DW) of alliin and 2.79 +/- 0.22 mg g(-1) DW of S-allyl-cysteine were extracted.Conclusions These results clearly demonstrated that pressurised liquid extraction is an efficient green technique to extract bioactive organosulphur compounds from giant garlic. Extraction yields were significantly (p < 0.05) higher than those obtained with conventional ultra-turrax extraction.