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Oil Quality

Safflower is thought to be one of the highest quality vegetable oils. To understand why this is so, some understanding of oil quality is required. Oils (which are liquid at room temperature), and fats (which are solid at room temperature) are composed of chains of carbon atoms (fatty acids) of varying length, combined with glycerol. The carbon atoms that form the backbone of these fatty acids can form four chemical bonds, including bonds with other carbon atoms. Oils and fats are "saturated" if all the bonds between carbon atoms in the carbon atom chain are single bonds (C-C-C). They are "unsaturated" if one or more of the carbon atom pairs share a double bond (C-C=C-C).

Many fatty acids have names. Two of the most important ones are oleic acid and linoleic acid. Oleic acids are "monounsaturated," meaning that they have one pair of carbon atoms among the 18 making up the carbon chain that share a double bond (denominated 18:1). Linoleic acid (18:2) is "polyunsaturated," meaning that there are in this case two pairs of carbon atoms in the carbon chain that share a bond. The iodine number quantifies the degree of unsaturation of the total fatty acids in an oil. A high number means less saturation. That is why linoleic types have a higher iodine number than oleic types of safflower.

"Hydrogenated" oils become fats by the catalytic conversion of unsaturated fatty acids to saturated fatty acids through the substitution of hydrogen-carbon bonds for carbon-carbon bonds. Butter, an animal fat, is composed primarily of short chain fatty acids (less than 14 carbon atoms in a row: <C14), which are mostly saturated fatty acids. Because of the high degree of saturation, butter and other compounds with predominantly short chain fatty acids naturally are solid at most ambient temperatures. In contrast, unsaturated vegetable oils have a bend or crook in the base carbon chain where the double bond occurs (cis-unsaturated fatty acids). These bends or crooks tend to keep the fatty acid molecules from lying closely together and the compounds remain liquid at ambient temperatures. To make margarine from vegetable oils, the fatty acids have to be modified to allow them to solidify. When vegetable oils are hydrogenated, some unsaturated bonds remain, but the geometry of the unsaturated carbon-carbon bonds in the carbon chains is changed (from "cis" to "trans"). Trans fatty acids can lie parallel to each other, allowing the oils to act like fats and become solid at lower temperatures.

The only essential fatty acid in human nutrition (the one that the human body needs but cannot make from other precursors) is linoleic. Some nutritionists also believe that the omega-3 fatty acids are essential. Beyond these, the nutritional value of oils becomes a controversial and ever-changing subject1. Currently, the consumption of unsaturated oils (particularly those with oleic fatty acids) is thought to be healthier than the consumption of mostly saturated fats, particularly those that also contain some trans-unsaturated carbon-carbon bonds.

Oils for human use should not go rancid, should be clear, not murky, have desirable taste characteristics, and not have any undesirable secondary compounds. The presence in a vegetable oil of fatty acids with high degrees of unsaturation and high peroxide values leads to instability. Safflower produced in California is low in both properties. Some consumers prefer strong-flavored oils like olive and peanut, while others do not want salad or cooking oil to impart flavor. Oleic safflower has a similar composition to olive oil (though with less of the saturated fatty acids found in olive oil), but a milder taste. It has the lowest saturated fat content of any oil (similar to canola oil) but without the unpleasant cooking odor of canola. The oil content of seeds and oil quality of safflower grown in California is the highest produced anywhere in the world, because the crop is ideally suited to California's climate.

1Safflower production increased rapidly during the late 1960s in response to rising public demand based on the success of a book entitled "Calories Don't Count" (Taller, H. 1961. Simon and Schuster, NY). The author maintained that the consumption of tablets with high amounts of linoleic acid (safflower oil) together with meals would allow high caloric intake without weight gain and other adverse health effects. Sadly, these claims were found to be without merit and calories do, indeed, count.

Table 2. Comparison of percentage of major fatty acids in edible vegetable oils.
Fatty acids		Safflower		Canola*	Soybean	Corn	Sunflower	Peanut	Olive
Denomination	Name	Oleic	Linoleic
14:0	-	-	-	0.75	0.1	-	-	0.1	-
16:0	Palmitic	5	5-7	4.0	10.8	11.4	6.0-7.0	10.0	11.0
18:0	Stearic	<1	2	1.6	4.0	1.9	4.0-5.0	2.3	2.2
20:0	-	-	-	0.5	-	-	-	-	-
22:0	-	-	-	0.4	-	-	-	-	-
Total Saturated		7.0	10.4	6-9	15.1	13.3	10.8	17.8	13.5
16:1	-	-	-	0.25	0.2	-	-	0.1	0.8
18.1	Oleic	77	15	61.0	23.8	25.3	17-20	47.1	75.8
20:1	-	-	-	1.5	0.2	-	-	1.4	0.3
22:1	-	-	-	0.2	-	-	-	-	-
Total monounsaturated		77	15	61-64	24.3	25.3	20.4	48.6	77.1
18:2	Linoleic	15	77	19-26	53.3	60.7	68.8	33.6	8.3
18:3	Linolenic	-	-	8-13	7.1	0.7	-	-	0.6
Total polyunsaturated		15	77	27-35	60.6	61.4	68.8	33.6	8.8
Source: Adapted from Smith 1996; Ackman 1990; Dorrell 1978. Note: Figures are rounded or are estimates. Ranges represent various cultivars and locations. * Average of several types.

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Modified: 28 May 1999 Comments to webmaster@agric.ucdavis.edu