Determination of highly volatile compounds in fresh onion (Allium cepa L.) by room‐temperature enrichment headspace‐trap coupled to cryotrapping GC–MS

Abstract

Conventional headspace‐based analysis is not suitable for identifying volatile compounds in fresh onion (Allium cepa L.) because large amounts of water vapor could affect the determination of target compounds. A headspace‐trap was introduced to remove water vapor and keep the analytes in the trap tube. Additionally, the headspace‐trap method based on room‐temperature enrichment could prevent enzyme‐sensitive samples from denaturing to maintain the original flavor compositions of the samples. Moreover, the highly volatile compounds were poorly separated after headspace extraction. By using a cryotrapping device, these compounds were well separated. Therefore, a room‐temperature enrichment headspace‐trap cryotrapping gas chromatography with mass spectrometric method was established for the determination of volatile compounds in fresh onion. With this method, a total of 73 volatile compounds were identified by mass spectral search and retention index. Among them, 29 highly volatile compounds were successfully separated before the retention time of 5 min, and these compounds contributed significantly to the smell of onion. The volatile compounds were dominated by dipropyl disulfide (35.42%), 1,2‐dithiolane (15.82%), 1‐propanethiol (11.74%) and propanal (11.23%). The results indicated that the proposed method was an effective tool for analyzing volatile compounds in high‐water‐content fresh onion samples.

Comparison of Organosulfur and Amino Acid Composition between Triploid Onion Allium cornutum Clementi ex Visiani, 1842, and Common Onion Allium cepa L., and Evidences for Antiproliferative Activity of Their Extracts

“…18). Besides dipropyl disulfide (35.45%), which was the most dominate sulfur compound identified in fresh onion, Liu et al (2018) [32] also reported a certain amount of 1-propanethiol, which was found to be abundant in A. cornutum (14.1%) and A. cepa L. in the current study. The second major compound present in A. cornutum (Table 1) was diisopropyl trisulfide, which was also reported to be the second most prominent compound present in A. cepa L., according to Ndoye Foe et al (2016) [17] and Teshika et al (2018) [33].…”

In-Vitro Evaluation of the Antioxidant and Anti-Inflammatory Activity of Volatile Compounds and Minerals in Five Different Onion Varieties

“…On the other hand, some compounds were in lower values or not detected such as 3,3-Thiobis-1-propene, and Dimethyl disulfide. Liu et al [38] reported that 1-propanethiol was the most abundant volatile compound in onion (14.1%) which was in agreement with the current study. The amount composition of volatile compounds is responsible for the biological activity and flavor [18,24].…”

Generation of Meaty Aroma from Onion (Allium cepa L.) with Polyporus umbellatus: Fermentation System, Sensory Profile, and Aroma Characterization

“…33 Odorants identified in the blank were previously described in onions and mostly belonged to the following chemical classes: aldehydes, sulfur compounds, alcohols, ketones, and pyrazines. 22,34,35 The aldehydes mainly imparted a fatty, deep-fried, and green odor note, such as (E,E)-2,4-decadienal (No. 47, Table 1), whereas the sulfur compounds had alliaceous impressions, such as methyl propyl trisulfide (No.…”