The key aroma components and (furan) fatty acids in fresh red goji berries were determined and their variations after hot-air drying were investigated to understand the impacts of drying. 22 of the 46 detected aroma components were found to be the key aroma components in fresh red goji berries, including (E)-β-damascenone, 1-octen-3-one, and trans-4,5-epoxy-(E)-2-decenal, which elicited the cooked apple-like, mushroom-like, and metallic odor impressions. Linoleic acid, oleic acid, and palmitic acid were the predominant fatty acids. Furan fatty acid (FuFA) in fresh red goji berries was measured for the first time and 11-(3,4-dimethyl-5-pentylfuran-2-yl)-undecanoic acid (11D5) was the only FuFA. The subsequent analysis of hot-air-dried red goji berries at 50 °C caused the increment in the contents of fatty acids. A remarkable decrease was found in lipid-derived aroma components and FuFA, especially aldehydes, ketones, and 11D5. In addition, the rare 9-(5-pentylfuran-2-yl)-nonanoic acid (9F5) was detected in red goji berries after drying.

Red goji berries, reputed worldwide as “superfruit”, are commonly marketed after natural drying or hot-air drying. A sensomics approach was applied to the aroma analysis of red goji berries under two drying methods. Fifty-two aroma-active compounds were screened and identified by aroma extract dilution analysis (AEDA) coupled with gas chromatography with olfactometry (GC/O). The contents and the odor activity values (OAVs) of 49 aroma-active compounds were determined. Acetic acid was the predominant aroma compounds in both berries. Meanwhile, the key aroma compounds in both berries were (E)-2-nonenal, (Z)-4-heptenal, 3-methyl-2,4-nonanedione, hexanal, etc., which were lipid derivatives. Natural drying promoted the formation of some aldehydes that exhibited green and fatty notes. Hot-air drying facilitated the production of ketones with hay-like and cooked apple-like odor attributes due to the thermal reaction. The fatty acid patterns between naturally dried and hot-air-dried red goji berries differed not significantly and were dominated by linoleic acid, oleic acid, palmitic acid, etc. The knowledge of the impacts of different drying processes on the aroma quality in red goji berries is beneficial for the quality control and optimization of dried red goji berries.

Furan fatty acids (FuFAs) are lipophilic antioxidants that occur in small amounts (≤1% of the total fatty acids) in plants and animals. They are characterised by a furan substructure within an otherwise saturated acyl chain. Although FuFAs are valuable dietary components due to their beneficial effects, research is hampered by the unavailability of standard substances such as α'-propyl-substituted FuFAs, which are particularly common in fish oils. Here we succeeded in isolating 11-(3,4-dimethyl-5-propylfuran-2-yl)-undecanoic acid ethyl ester (11D3-EE) from gram-amounts of an eicosapentaenoic acid ethyl ester (EPA-EE) oil. After an initial enrichment by hydrogenation and urea complexation, the concentrated FuFA-EE fraction was separated by countercurrent chromatography (CCC) in two-dimensional heart-cut mode using the biphasic solvent system n-hexane/benzotrifluoride/acetonitrile (20:7:13, v/v/v). Comparative investigations showed that the head-to-tail mode was better suited than the tail-to-head mode. With the help of the ProMISE2 software, two time-shifted injections were carried out in one run with in total four heart-cuts. As a result, 1.2 mg of 11D3-EE with a purity of 95% (recovery: ∼2.5%), 11.3 mg 11D3-EE with a purity of 90% (recovery: ∼23.6%), and 1.2 mg of the trace compound 9D3-EE (95% purity; recovery not determinable) were isolated from the sample initially enriched by hydrogenation and urea complexation.

Furan fatty acids (FuFAs) are excellent antioxidants but rather unexplored because of their high instability and low contributions to the total lipids of food and biota samples. Therefore, the use of internal standards (IS) is essential for the correct determination of FuFAs in food. However, suitable IS, such as isotope‐labeled FuFAs, are currently unavailable, and alternative solutions have to be considered. Since degradation of FuFAs occurs in the furan moiety, the IS must not necessarily carry a carboxyl group. Therefore, one monomethylated (M‐11‐5) and one dimethylated (D‐11‐5) 1,4‐ O ‐bridged‐1,3‐diene (oxaDE) were synthesized and applied in the GC/MS analysis of β‐methyl substituted (M‐FuFAs) and β,β'‐dimethyl substituted FuFAs (D‐FuFAs). GC/MS measurements verified a similar fragmentation as for FuFA methyl esters (FuFA‐MEs), along with favorable low quantification limits (0.8–0.9 pg). Transesterification of two FuFA‐EE (9M5, 11D5) along with two oxaDEs (M‐11‐5, D‐11‐5) enabled monitoring the recovery of FuFAs and verified the lower stability of D‐FuFAs compared to M‐FuFAs. Problems caused by unstable reagents in the transesterification step could be identified and solved with the newly introduced IS. The final application of the method to six fish oils enabled the detection of eight FuFAs with amounts up to 1.2 g/100 g fish oil.