Docosahexaenoic Acid Is Naturally Concentrated at the sn-2 Position in Triacylglycerols of the Australian Thraustochytrid Aurantiochytrium sp. Strain TC 20.

The Labyrinthulomycetes or Labyrinthulea are a class of protists that produce a network of filaments that enable the cells to glide along and absorb nutrients. One of the main two Labyrinthulea groups is the thraustochytrids, which are becoming an increasingly recognised and commercially used alternate source of long-chain (LC, ≥C20) omega-3 containing oils. This study demonstrates, to our knowledge for the first time, the regiospecificity of the triacylglycerol (TAG) fraction derived from Australian thraustochytrid Aurantiochytrium sp. strain TC 20 obtained using 13C nuclear magnetic resonance spectroscopy (13C NMR) analysis. The DHA present in the TC 20 TAG fraction was determined to be concentrated in the sn-2 position, with TAG (16:0/22:6/16:0) identified as the main species present. The sn-2 preference is similar to that found in salmon and tuna oil, and differs to seal oil containing largely sn-1,3 LC-PUFA. A higher concentration of sn-2 DHA occurred in the thraustochytrid TC 20 oil compared to that of tuna oil.

Microwave pre-treatment of canola seeds and flaked seeds for increased hot expeller oil yield.

Microwave (MW) pre-treatment of canola seeds or flaked seeds was found to be a superior alternative to the conventional thermal pre-treatment (steam). Flaked seeds were "cooked" (heat-treated) with steam or using microwave treatments in the temperature range of 62-130 °C prior to expeller pressing. Microwave cooking at 100 °C resulted in the highest increase in the pressed oil yield, which is an increase of 3.7% (w/w) on a pressed oil basis or 9.0% (oil in seed basis) compared with steam cooking. Whole canola seeds conditioning was conducted with microwaves or steam, in the temperature range of 40-75 °C, followed by microwave or steam cooking at 100 °C to evaluate the effect of MW treatment during conditioning on the expeller oil yield. The use of a continuous microwave process for combined conditioning of whole seeds at 55 °C and subsequent cooking of flaked seeds at 100 °C resulted in a 4.0% increase in expeller oil yield, compared with steam conditioning and cooking. The influence of dry basis (db %) moisture contents of 5%, 11.5%, and 16.5% on oil yield after steam or MW treatments of seeds and flaked seeds was also studied. The moisture content of 11.5% (db %) yielded the highest net oil yield for both MW and steam at best conditioning and cooking temperatures of 55 °C and 100 °C, respectively. No significant impact of MW cooking was seen on oil quality compared with conventional steam cooking.