Characterization of coconut oil in different varieties in Sri Lanka. (205)
Keywords:Autoxidation, average molecular weight, coconut oil, degree of saturation, fatty acids, free fatty acids, peroxide value
AbstractIdentification and characterization of morphological/physical properties of different varieties of coconut are very important in breeding programs and the quality parameters of oil, such as degree of saturation, free fatty acids and average molecular weight of fatty acids are vital for selecting a type of oil for human consumption. The aim of the study was to test the effect of variety on oil concentration and oil quality properties of thirteen different coconut varieties (San Raman, Nawasi Thembili, Ran Thembili, Dwarf Yellow, Dwarf Green, Dwarf Brown, King Coconut, CRIC 65, Dikiri, Kapruwana, CRIC 60, Sri Lanka Tall and Nawasi Pol) grown in Sri Lanka and to evaluate morphological/physical properties in the varieties. The degree of saturation and average molecular weight of the fatty acids were studied using the parameters of iodine and saponification values respectively. Furthermore, free fatty acids and peroxide value of oils were also studied. The evaluation of morphological/ physical characters revealed that Dikiri and San Raman were the best varieties for oil extraction. The lowest performances were observed in Nawasi Thembili, Dwarf Green, King Coconut and CRIC 60 varieties. Further, Ran Thembili, Dwarf Yellow, Dwarf Brown, CRIC 65, Kapruwana and Sri Lanka Tall varieties showed the intermediate characters. Among the tested varieties, the highest saturated fatty acid contents were observed in Nawasi Thembili and the highest unsaturated contents were observed in Dwarf Green, Dwarf Yellow and Dwarf Brown varieties. The highest average molecular as indicated by the highest saponification value was shown by Ran Thembili and Dikiri varieties, while Nawasi Thembili and Dwarf Yellow were the lowest. Ran Thembili variety showed the maximum initial free fatty acids content and the lowest content was observed in the Sri Lanka Tall variety. Autoxidation was not observed in any sample immediately after oil extraction. Dwarf Green, Dikiri and Sri Lanka Tall varieties showed the highest moisture contents and Nawasi Thembili, the lowest. It is concluded from the results that Dwarf Green, Dwarf Yellow, San Raman and Nawasi Thembili are the best varieties for quality oil extraction for human consumption.