Lipid, fatty acid and sterol content analysis of New Zealand Undaria pinnatifida
Marine algae, usually called seaweed, are common aquatic plants found in the oceans (Vazhiyil Venugopal, 2008). They have been used for centuries as food, pharmaceuticals and fertilizers. In many cultures, especially in Asian countries such as Japan, Korea, China, Vietnam, Indonesia and Taiwan seaweeds are a significant part of the diet (Besada et al., 2009. Seaweed is also used in the manufacture of industrial hydrocolloids such as agar, carrageenan and alginates.
The brown seaweed U. pinnatifida was accidentally introduced to Wellington harbour by ships from Asia in the late 1980’s. Since then, it has spread very quickly around the coast because of two important factors: suitable growth conditions in New Zealand and its strong invasiveness (M. D. Stuart, 2004). However, until 2010 the law in New Zealand did not allow people to harvest or culture U. pinnatifida as it was defined as an “unwanted organism” by MAF Biosecurity. In 2010 the government reviewed this policy and have subsequently allowed greater freedom for the marine industry to use this seaweed commercially (MAF.Biochemistry, 2010).
As a species of marine algae, geography and temperature are the two major parameters that determine its growth and nutritional content (Nelson, Phleger, & Nichols, 2002). For example, It has been shown that the total lipid contents of green and red seaweeds may increase at lower temperature (5-10 oC) (Nelson et al., 2002).
In general, the lipid content of marine algae is lower than other plant species but the lipids are rich in polyunsaturated fatty acids (PUPAs) which are important for human health (Dawczynski, Schubert, & Jahreis, 2007; Norziah & Ching, 2000). Since it is hard for humans to synthesize the long chain n-3 polyunsaturated fatty acids (LC-PUFAs) found in fish oil, sources such as Undaria pinnatifida have gained more attention recently, because not only it contain abundant n-3 PUFAs but also the cost of cultivation is relatively low (Kumari, Kumar, Gupta, Reddy, & Jha, 2010).
The public still have little knowledge on the Undaria pinnatifida. They do not realise how valuable the Undaria pinnatifida can be. As a result, this project will focus on the lipid and fatty acid content of Undaria pinnatifida, which because of the high proportion of PUFAs is of considerable commercial interest.
Results of this research show that the main lipid classes found in Undaria are the non-polar lipids, followed by phospholipids and glycolipids. The sporophyll contains 2.34% total lipid by weight, while the blade is 1.53% total lipid by weight.
LC-MS analysis of the lipid extracts showed the presence of many phytochemical compounds and lipids especially glycerophospholipids. This suggests that further analysis is likely to produce more interesting compounds.
The fatty acids determined in this project confirmed pervious research, but with some differences. Polyunsaturated fatty acids and saturated fatty acids are the two major fatty acid classes found in Undaria, of which palmitic and henicosanoic are the major saturated fatty acids, while gamma-linolenic and dihomo-g-linolenic are the principal polyunsaturated fatty acids. The sporophyll contains more fatty acids (12.46 mg/g) than the blade (10.85 mg/g).
Analysis of thye non-saponifiable lipids showed that commercially interesting fucosterol is the major sterol found in Undaria and the concentration is 0.323 mg/g