The physical and nutritional properties of plant oils were governed by the FA composition in TGs. Various contents of saturated and unsaturated FAs in TG mixtures resulted in their different melting points at room temperature (oils vs fats), oxidation stability, digestion, or relation to the harmful low-density lipoprotein cholesterol. The average composition of FAs was expressed by average parameters calculated from the TG composition in individual samples (Table 5.2). Values of calculated average parameters were compared with values of the relevant parameters of FAs — i.e., ECN = 16, CN = 18, and DB = 1 for oleic acid (C18:1), etc. For example, average ECN (aECN) = 15.88, aCN = 17.76, and aDB = 0.94 for olive oil corresponded to the high content of oleic acid with 18 carbon atoms and 1 double bond; in fact, with the total content of oleic acid (73.85%). As an example, the aECN = 14.21, aCN = 17.82, and aDB = 1.81 for evening primrose oil corresponded to the high content of linoleic acid with 18 carbon atoms and 2 double bonds; in fact, with the total content of linoleic acid (67.49%). Average ECN values of analyzed samples ranged from 14 to 16, with several exceptions. Coconut oil (aECN = 12.10) was typical, with its high content of short-chain FAs with a low ECN value. Lower aECN values for linseed (aECN = 13.68), redcurrant (13.82), and blackcurrant (13.91) oils were caused by a high content of linolenic acid (ECN = 12), or linolenic and gamma-linolenic (ECN = 12) acids in the case of blackcurrant and redcurrant oils. In contrast, the higher value for cocoa butter (aECN = 16.72) resulted from the high content of stearic acid with ECN = 18. Plant oils were composed predominantly of FAs with 18 carbon atoms, which also corresponded to an average number of carbon atoms ranging from 17.40 to 18.00 in plant oils. Exceptions were found for coconut oil (aCN = 12.10), with its high content of short-chain FAs; palm oil (aCN = 17.07), with its high content of palmitic acid; and peanut oil (aCN = 18.05), with its higher content of long-chain FAs from C20 to C24. The content of saturated and unsaturated FAs in samples was a valuable nutritional parameter in the human diet. In analyzed samples, aDB ranged from 0.9 to 1.9, apart from in the highly saturated coconut (aDB = 0.13), cacao butter (0.37), and palm (0.61) oils, or the highly unsaturated blackcurrant (1.94), redcurrant (2.00), and linseed (2.09) oils.
Other important nutritional parameters of plant oils were expressed by the sums of essential, saturated, monounsaturated, and polyunsaturated FAs (Table 5.2). FAs with double bonds at positions D12 and D15 (u3 and u6 FAs) are essential for humans, and have to be obtained by food; therefore, their content in plant oils correlates with the nutritional value of these oils.
The sum of essential FAs in most samples was found to range from 10 to 70%, apart from in cacao butter (1.89%), coconut oil (2.21%), olive oil (9.3%), and highly essential safflower oil (73.96%). The sum of saturated FAs in analyzed plant oils ranged from 10 to 25% in common plant oils, apart from redcurrant (7.73%) and rapeseed (9.07%) oils, and the highly saturated oils (48.10% of saturated FAs in palm oil, 63.53% in cocoa butter, and 87.06% in coconut oil). In analyzed samples, the sum of monounsaturated FAs ranged from 15 to 65%, except for evening primrose oil (7.99%), coconut oil (10.73%), avocado oil (67.71%), hazelnut oil (68.39%), and olive oil (75.37%). The sum of polyunsaturated FAs ranged from 10 to 70% in samples, except for cocoa butter (1.89%), coconut oil (2.21%), olive oil (9.30%), redcurrant oil (70.98%), blackcurrant oil (71.00%), safflower oil (74.00%), and evening primrose oil (80.57%).
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