Characterization of fatty acid composition from five perilla seed oils in China and its relationship to annual growth temperature

Omega-3 fatty acids have been shown to reduce inflammation and may help prevent chronic diseases like heart disease and arthritis. Alpha-linolenic acid is a type of w-3 fatty acids and has been reported with a remarkably high content (>50%) only in seeds of several plant species, for example, Perilla and Linum usitatissimum L. It is a valuable compound obtained from plants which can provide health benefits similar to those derived from fish oil. In this study, five seed samples from five varieties of the monotypic genus Perilla collected from five provinces in China were analyzed to determine their fatty acid composition. The seed oils were extracted using Soxhlet, and oil contents of these samples ranged from 33.25 to 42.58% (wt/wt). Fatty acid compositions were then analyzed using gas chromatography-mass spectrometry (GC-MS). Saturated, monounsaturated and polyunsaturated fatty acids accounted for 9.16 to 10.49, 13.78 to 20.93 and 63.12 to 73.45% of their totals, respectively, in which the content of the unsaturated fatty acids was over 90% on average. Moreover, a-linolenic acid was dominant (52.58 to 61.98%) in all the oil samples, and it comprised 65.67 to 68.37% of the total unsaturated fatty acids and 83.30 to 84.38% of the polyunsaturated acids, respectively. However, contents of the w-6 linoleic acid in the five samples were only 10.54 to 15.87%, and the ratio of w-6 to w-3 fatty acids was as low as 0.2 to 0.26. The results indicate that Perilla oil is presently the best quality oil derived from plant sources and hence it could be developed into commercial products to serve as a valuable alternative vegetable oil. Furthermore, oil from seeds obtained in regions with lower average growth temperature has relatively higher percentage of unsaturated fatty acids.   Key words: Annual growth temperature, gas chromatography-mass spectrometry (GC-MS),w-3 a-linolenic acid, w-6 linoleic acid, Perilla, seed oil, variety.