Novel approach for the determination of volatile compounds in processed onion by headspace gas chromatography–mass spectrometry (HS GC–MS)

Evaluation of aroma profile differences between sué, sautéed, and pan-fried onions using an innovative olfactometric approach

“…However, 2,4-dimethylfuran which is mainly detected in the three onion preparations and 2-methylfuran have never been reported in either cooked or raw onions and their origin remains unclear. 2-Pentylfuran, previously reported in processed onions [4,7], could originate from thermal degradation of lipids [47] but could also originate from the thermal interaction of 2,4-decadienal with either cysteine or glutathione [37]. Hydrocarbons were also found in the volatile composition of the three cooked onion samples and, to our knowledge, only dodecane and tetradecane were previously detected in cooked onions [46].…”

“…Alk(en)yl mono-, di-, and tri-sulfides were detected in large numbers in the headspace of each sample and were all previously identified in raw [6,[33][34][35][36]42] and/or cooked onions [4][5][6][7][8]13]. These compounds were previously found to be the major volatile components in onion oil obtained by steam distillation [9,10].…”

“…Most of them were previously reported in raw [6,[33][34][35][36] and/or heated onions [4][5][6][7][8]13]. The TPA of sulfur compounds detected is between three and five times higher in the pan-fried onion preparation than in sautéed and sué onion preparations, respectively.…”

“…Alkanethiols could be derived from interactions of Maillard reactions and lipids [37]. Methanethiol and propanethiol were previously found in raw [6,34,42] and cooked onions [4][5][6][7][8]13], but to our knowledge, pentanethiol has never been reported in onions. However, this compound has already been identified in the volatile composition of chive (Allium schoenoprasum L.) [38].…”

“…Some publications deal with the effect of cooking such as boiling, baking, frying, sterilization, and microwave treatments on the onion gas chromatography (GC) profile. As reported in these publications, the major compounds found in heated onions remain sulfur compounds such as mono-, di, tri-, tetrasulfides, thiophenes, and thiols but aldehydes, carboxylic acids, ketones, hydrocarbons, furans, pyrroles, and alcohols were also identified [4][5][6][7][8]. However, the contribution of these compounds in the perceived aroma of cooked onions was less investigated.…”