Exploring aqueous extraction of oleosomes from canola seed, hull and kernel

Conventional industrial oil extraction from canola seeds involves a sequential approach: expeller pressing followed by hexane extraction. However, this method is energy-intensive and further fractionation presents greater challenges.

Canola seed contains lipid-rich organelles called oleosomes, present in the cytoplasm of plant seeds. These oil bodies act as storage for lipids, encased in a phospholipid monolayer with embedded proteins. This study explores an alternative approach for canola seed processing by using water to extract oleosomes from kernels, hulls and whole seeds by blending, filtering and centrifuging.

It has long been known that canola seed oils contain low levels of the asclepic acid (cis 18:1 n-7), an uncommon fatty acid known for its biological activity. This fatty acid makes up to 5% of the canola oil fatty acid profile. Proton and carbon 13 NMR analyses were performed on the oil from oleosomes recovered from canola hulls, kernels, and whole seeds to determine fatty acid distribution and profiles. The NMR analyses showed that oleosomes derived from hull samples had high concentrations of asclepic acid, with a total content of 20.5%. Whole seeds had an Emulsion Mass Yield of 87% and an Extraction Yield of 95%. Kernels demonstrate much higher yields, with an Emulsion Mass Yield of 97.69% and an Extraction Yield of 102%. This notable increase shows that dehulling boosts the efficiency of extraction. This study highlights the distribution of bioactive compounds within canola seed and shows the effectiveness of fractionation and aqueous extraction processes. It is the first demonstration of canola hull oleosomes documenting presence of asclepic acid. The high concentrations of asclepic acid in hull oleosomes suggest that these fractions have potential applications as precursors for functional foods.