Novel Approaches for Elongation of Fish Oils into Very-Long-Chain Polyunsaturated Fatty Acids and Their Enzymatic Interesterification into Glycerolipids.

Elongation of the Very-Long-Chain Fatty Acids-4 (ELOVL4) enzyme that is expressed in neuronal tissues, sperm, and testes mediates biosynthesis of very-long-chain polyunsaturated fatty acids (VLC-PUFAs) from dietary long chain PUFAs (LC-PUFAs). The VLC-PUFAs are critical for neuronal and reproductive function. Therefore, mutations in ELOVL4 that affect VLC-PUFA biosynthesis contribute to retinal degenerative diseases including Autosomal Dominant Stargardt-like Macular Dystrophy (STGD3). Recent studies have also shown not only a depletion of retinal VLC-PUFAs with normal aging but also a more significant loss of VLC-PUFAs in donor eyes of patients with age-related macular degeneration (AMD). However, currently, there are no natural sources of VLC-PUFAs to be evaluated as dietary supplements for the attenuation of retinal degeneration in animal models of STGD3. Here, we report the development of a novel chemical approach for elongation of eicosapentaenoic (C20:5 n-3) and docosahexaenoic (C22:6 n-3) acids from fish oils by 6 carbon atoms to make a unique group of VLC-PUFAs, namely all-cis-hexacosa-11,14,17,20,23-pentaenoic acids (C26:5 n-3) and all-cis-octacosa-10,13,16,19,22,25-hexaenoic acids (C28:6 n-3). The three-step elongation approach that we report herein resulted in a good overall yield of up to 20.2%. This more sustainable approach also resulted in improved functional group compatibility and minimal impact on the geometrical integrity of the all-cis double bond system of the VLC-PUFAs. In addition, we also successfully used commercial deep-sea fish oil concentrate as an inexpensive material for the C6 elongation of fish oil LC-PUFAs into VLC-PUFAs, which resulted in the making of gram scales of VLC-PUFAs with an even higher isolation yield of 31.0%. The quality of fish oils and the content of oxidized lipids were key since both strongly affected the activity of the PEPPSI-IPr catalyst and ultimately the yield of coupling reactions. Downstream enzymatic interesterification was used for the first time to prepare structured glycerolipids enriched with VLC-PUFAs that could be evaluated in vivo to determine absorption and transport to target tissues relative to those of the free fatty acid forms. It turned out that in the synthesis of structured triacylglycerols and glycerophospholipids with VLC-PUFAs, the polarity of the immobilized lipase carrier and its humidity were essential.

Value-Added Squalene in Single-Cell Oil Produced with Cutaneotrichosporon oleaginosus for Food Applications.

Single-cell oil (SCO) produced by oleaginous microorganisms is potentially a more land-efficient and sustainable alternative to vegetable oil. The cost of SCO production can be reduced by value-added co-products like squalene, a highly relevant compound for the food, cosmetic, and pharmaceutical industry. For the first time, squalene in the oleaginous yeast Cutaneotrichosporon oleaginosus was analyzed, reaching 172.95 ± 61.31 mg/100 g oil in a lab-scale bioreactor. Using the squalene monooxygenase inhibitor terbinafine, cellular squalene was significantly increased to 2169 ± 262 mg/100 g SCO, while the yeast remained highly oleaginous. Further, SCO from a 1000 L scale production was chemically refined. The squalene content in the deodorizer distillate (DD) was found to be higher than that in DD from typical vegetable oils. Overall, this study demonstrates squalene as a value-added compound in SCO from C. oleaginosus for application in food and cosmetics without the use of genetic modifications.

Formation of 5α-Sitostan-3-one, 5α-Campestan-3-one, and Steroidal Hydrocarbons in Edible Oils during Catalytic Hydrogenation.

Targeted analysis confirmed the presence of new phytosterol degradation products in fully hydrogenated commercial samples. EI-MS, APCI-MS, and 1D-NMR experiments led to the identification of 10 novel markers of catalytic hydrogenation, among which 5α-sitostan-3-one and 5α-campestan-3-one, isomers of saturated and monounsaturated steroidal hydrocarbons, were reported in edible oils for the first time. Examination of the phytosterol degradation mechanism was done by the catalytic transfer deuteration technique. The mitigation strategy of potentially detrimental compounds included optimization of processing parameters. The effect of catalyst dosage (≤0.1% based on Ni basis) and temperature region (>180 °C) were the most crucial factors in phytosterol degradation control.