Investigation of Volatiles Emitted from Freshly Cut Onions (Allium cepa L.) by Real Time Proton-Transfer Reaction-Mass Spectrometry (PTR-MS)

Abstract

Volatile organic compounds (VOCs) in cut onions (Allium cepa L.) were continuously measured by PTR-MS during the first 120 min after cutting. The headspace composition changed rapidly due to the very reactive volatile sulfurous compounds emitted from onion tissue after cell disruption. Mass spectral signals corresponding to propanethial S-oxide (the lachrymatory factor) and breakdown products of this compound dominated 0–10 min after cutting. Subsequently, propanethiol and dipropyl disulfide predominantly appeared, together with traces of thiosulfinates. The concentrations of these compounds reached a maximum at 60 min after cutting. Propanethiol was present in highest concentrations and had an odor activity value 20 times higher than dipropyl disulfide. Thus, propanethiol is suggested to be the main source of the characteristic onion odor. Monitoring the rapid changes of VOCs in the headspace of cut onion necessitates a high time resolution, and PTR-MS is demonstrated to be a very suitable method for monitoring the headspace of freshly cut onions directly after cutting without extraction or pre-concentration.

Combination of Cymbopogon citratus and Allium cepa essential oils increased antibacterial activity in leafy vegetables

“…The compound found in the highest proportion was dipropyl trisulfide (30.52%), followed by dipropyl disulfide (25.96%), methyl propyl disulfide (4.73%) and dimethyl trisulfide (2.3%). Sulfur compounds are synthesized during the degradation of alk(en)yl cysteine sulfoxides by the enzyme alliinase; moreover, during EO extraction by steam water, these compounds are transformed to alkyl sulfides . Previous studies have identified methyl propyl trisulfide, dipropyl trisulfide and dipropyl tetrasulfide in onion EOs as being responsible for their odor, taste and antibacterial capacity …”

“…Sulfur compounds are synthesized during the degradation of alk(en)yl cysteine sulfoxides by the enzyme alliinase; moreover, during EO extraction by steam water, these compounds are transformed to alkyl sulfides. 17,18 Previous studies have identified methyl propyl trisulfide, dipropyl trisulfide and dipropyl tetrasulfide in onion EOs as being responsible for their odor, taste and antibacterial capacity. 18,19 Antibacterial effect of individual EOs Table 1 shows the antibacterial activity of C. citratus and A. cepa EOs.…”

“…17,18 Previous studies have identified methyl propyl trisulfide, dipropyl trisulfide and dipropyl tetrasulfide in onion EOs as being responsible for their odor, taste and antibacterial capacity. 18,19 Antibacterial effect of individual EOs Table 1 shows the antibacterial activity of C. citratus and A. cepa EOs. Both oils showed activity against all tested bacteria.…”

Stability and extraction of bioactive sulfur compounds from Allium genus processed by traditional and innovative technologies

“…Thiosulfinates are relatively unstable and capable of decomposing/rearranging into polysulfides, thiosulfonates, and other OSCs (Løkke et al, 2012). Various parameters can affect and alter the rates of such reactions, including temperature and pH.…”

The characteristic Performace of Quantitative Flowering Characters and Metabolomic Profile of Shallot (Allium cepa var. aggregatum) Induced by Vernalization

“…Tanaman yang divernalisasi pada stadia ini juga mengandung organosulfur dan sumber nitrogen seperti nitrogen oxide, propylene sulfide, 2,benzyl cyanide, dan tetradecanamideSenyawa organik ini termasuk dalam kelompok senyawa thiol, yang merupakan cairan tak berwarna dan memiliki aroma yang kuat. Lokke et al (2012) melaporkan bahwa umbi bawang memiliki senyawa propanethiol konsentrasi tertinggi dengan aktifitas aroma 20 kali lebih tinggi dari pada dipropyl disulfide.…”