Characterization of volatile compounds and triacylglycerol profiles of nut oils using SPME‐GC‐MS and MALDI‐TOF‐MS

Abstract

Several nut oil varieties mainly used as culinary and overall healthy food ingredients were subject of the present study. Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry was employed in order to determine the qualitative composition of volatile compounds. Furthermore, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used in order to assess the profiles and relative composition of the prevalent triacylglycerols (TAG) within the oils. The headspace of the majority of oil samples was dominated by high contents of acetic acid (up to 42%) and hexanal (up to 32%). As nut oils are typically gained by cold-pressing from previously roasted nuts, characteristic pyrazine derivatives as well as degradation products of long-chain fatty acids were detected. TAG analysis of these oils revealed a quite homogeneous composition dominated by components of the C 52 and C 54 group composed mainly of oleic (18:1), linoleic (18:2), stearic (18:0) and palmitic (16:0) acid residues representing together between 65 and 95% of the investigated nut oils. The TAG profiles showed characteristic patterns which can be used as 'fingerprints' of the genuine oils. Nut oils exhibiting quite similar fatty acid composition (e.g. hazelnut, pistachio and beech oil) could be clearly discriminated based on TAG showing significant differences between the oils.

Characterization of Aroma Volatiles in Camellia Seed Oils (<i>Camellia oleifera</i> Abel.) by HS-SPME/GC/MS and Electronic Nose Combined with Multivariate Analysis

“…2-Heptanone with sweet, fruity and cinnamon aroma was presented with the concentration varied from 9.33 μg/kg to 292 μg/kg in oils. 2-Nonanone was also detected in beech oil exhibited nutty, fatty and roasted flavor (Bail et al, 2009). …”

“…Limonene with mild, citrus, sweet, orange, and lemon aroma was found in various oils. It may come from the rearrangement of sterols or squalene or their oxidation products (Kao et al, 1998), and could play a very important role in the fragrance of the oil (Bail et al, 2009;Zunin et al, 2005). In this work, limonene was detected in CO21 (88.0 μg/kg) and CO27…”

Influence of roasting of shea kernels on their fat content and some quality characteristics of shea butter

“…Compounds in relatively high concentrations were 2-octene (0.1-9.2%), furfural (0.6-7.1%), acetic acid (1.4-6.7%), 5-methyl 2-furancarboxaldehyde (0.5-4.7%) and hexanal (0.3-2.6%) ( Table 4). Most compounds were also detected by Krist et al (2006) and Bail et al (2009a) in shea butter from different regions, and by Bail et al (2009b) in several nut oils mainly used as food ingredients. Most of the identified compounds were generated by the roasting of the kernels, as apparent from the comparison of volatile components of shea butter from unroasted and roasted kernels: furans, ketones, pyrazines, esters, and phenols were absent in shea butter from unroasted kernels and consequently were generated during the roasting process (Jung et al, 1999).…”

Virgin almond oil: Extraction methods and composition

“…The advantage of using a triglyceride analysis, in comparison to the fatty acid profile, is that a stereospecific distribution of fatty acids in the glycerol molecule is genetically controlled and, as a result, the information content of intact triglycerides is generally higher (Aparicio and Aparicio-Ruiz, 2000;Bail et al, 2009). Pasini et al (2013), established a lipid classification, in which unsaponifiable fraction and complex lipids (phospholipids and glycolipids) appear.…”