Effects of Three Extraction Methods on Avocado Oil Lipid Compounds Analyzed via UPLC-TOF-MS/MS with OPLS-DA

Abstract

Avocado oil is excellent functional oil. Effects of three extraction methods (squeezing extraction, supercritical carbon dioxide extraction, and aqueous extraction) on the species, composition, and contents of lipids in avocado oil were analyzed via ultra-performance liquid chromatography–time-of-flight tandem mass spectrometry (UPLC-TOF-MS/MS), and the differential components of lipids were revealed by OrthogonalPartialLeast Squares-DiscriminantAnalysis (OPLS-DA), S-plot combined with variable importance in the projection (VIP). The results showed that the fatty acid composition of avocado oil mainly consisted of oleic acid (36–42%), palmitic acid (25–26%), linoleic acid (14–18%), and palmitoleic acid (10–12%). A total of 134 lipids were identified first from avocado oil, including 122 glycerides and 12 phospholipids, and the total number of carbon atoms contained in the fatty acid side chains of the lipids was 32–68, and the number of double bonds was 0–9. Forty-eight differential lipid compounds with significant effects of the three extraction methods on the lipid composition of avocado oil were excavated, among which the differences in triglycerides (TG), phosphatidylethanol (PEtOH), and phosphatidylmethanol (PMeOH) contents were highly significant, which provided basic data to support the subsequent guidance of avocado oil processing, quality evaluation, and functional studies.

Looking into the lipid profile of avocado and byproducts: Using lipidomics to explore value‐added compounds

“…Either reversed-phase (RP) and normal phase HPLC-MS approaches have been used in the analysis of lipid extracts from avocado (as summarized in Tables 3, 4, and 6), allowing the separation of the lipid extracts based on the fatty acyl chains (hydrophobicity; length; number and position of double bonds) or based on the polar head groups, respectively (Liu et al, 2023;Pacetti et al, 2007;Shen et al, 2014;Takenaga et al, 2008). However, TA B L E 3 Lipidomics studies reporting the analysis of acylglycerols and polar lipids from avocado pulp extracts using mass spectrometry (MS)-based approaches.…”

“…Regarding the analysis of complex lipid classes found in the lipid extracts from avocado portions and oils (Ge, Zang, et al., 2021; Liu et al., 2023) (Tables 3, 5, and 7), its identification has been done either by direct infusion shotgun MS in targeted approaches (Vaikkinen et al., 2013) or by HPLC–MS in (un)targeted approaches, both using soft ionization techniques (Ge, Zang, et al., 2021; Jakab et al., 2002; Pacetti et al., 2007; Rodríguez‐López et al., 2017; Züge et al., 2017), namely, electrospray ionization (ESI) and atmospheric pressure chemical ionization (Tables 3, 5, and 7). Although less reported, matrix‐assisted laser desorption ionization coupled to MS (Shen et al., 2014) or MS imaging (Horn et al., 2013) was also used for the analysis of lipids (polar and nonpolar) from avocado pulp (Tables 3 and 7).…”

“…Very recently, Liu et al. (2023), in addition to TAG, also reported for the first time 14 oxidized TAG (OxTAG), 12 DAG, ether‐linked DAG and TAG (3 EtherDAG and 2 EtherTAG) in pulp oil using HPLC‐time‐of‐flight‐MS. As far as we know, the same authors also depict, for the first time, the polar lipid composition of pulp oil (Table 4).…”

“…Higher content of TAG containing MUFA 18:1 ω − 9 and PUFA C18:2 ω − 6 (in one, two, or all the three fatty acyl moieties) was reported using SCO 2 (Tan et al., 2018b). The PEtOH and PMeOH lipid species with these FA were found to be more abundant in pulp oil obtained by SCO 2 , whereas the long extraction process by UAAE and the long air contact time resulted in higher OxTAG content (Liu et al., 2023). This reinforces not only the SCO 2 as the technique of choice for obtaining high nutritional quality oils from pulp, but also the need of comparative studies on this topic using high‐throughput lipidomic platforms based on HPLC coupled to high‐resolution‐mass spectrometers (as Orbitrap).…”

Changes of Volatile Organic Compounds of Different Flesh Texture Pears during Shelf Life Based on Headspace Solid-Phase Microextraction with Gas Chromatography–Mass Spectrometry

“…Group 1 consisted of Nanguoli, group 2 consisted of Ruanerli, group 3 consisted of Louis and Cure, group 4 consisted of Korla pear, group 5 consisted of Jingbaili, and group 6 consisted of Yali and Hanhongli, to achieve the effective differentiation between the crisp-flesh pear and soft-flesh pear samples, indicating significant differences in the composition of VOCs between crispy and soft-flesh pears. After 200 replacement tests, the replacement test model R2 was 0.55, Q2 was −0.842, and the intersection point of the Q2 regression line and the vertical axis was less than 0 (Figure 4C), indicating that the discriminant model had a good explanatory ability and did not overfit, and the model validation was effective [38]. Variable importance in projection (VIP) in OPLS-DA represents the effect of differences between the corresponding metabolites on the classification and identification of each group of samples in the model, and it is generally accepted that there are significant differences in metabolites with VIP > 1 and p < 0.05 [39].…”