The oil refining process gives corn oil an excellent frying quality and resistance to smoking or discolouration. Corn oil is valued for its high energy value. Energy value of 100 gm corn oil is 884 kcal as against 86 kcal in case of equal amount of corn meal. Quality of cooking oil is usually associated with proportion of unsaturated to saturated fatty acids. Higher proportion of unsaturated fatty acids in oil represents better quality of oil. Standard method to measure quality of corn oil is ratio of unsaturated linoleic acid to other major saturated fatty acids, and iodine number. Refined corn oil contains 95% triglycerides. Corn belt corn typically has 60% linoleic acid (18:2), 20% oleic acid (18:1), 18% palmitic acid (16:0), 2% steric acid (18:0), small amounts of linoleic acid (18:3), and trace amounts of other fatty acids. Comparison of nutrient content of edible vegetable oils shows that corn oil has highest proportion of unsaturated fatty acids (58.7%) and significantly low proportion of saturated fatty acids (12.7%) (Table 2). Proportion of monosaturated fatty acids is very low in corn oil as compared to other edible oils. Ratio of unsaturated linoleic acid to other major saturated fatty acids for normal corn is about 1.67, 2.31 for sunflower, 1.36 for soybean and 0.12 for palm oil, which contains large amounts of saturated fatty acids. Iodine number, a measure of degree of unsaturation of corn oil, has a negative correlation with total oil concentration.

The negative association between oil percentage and iodine number results from a decrease in linoleic and an increase in oleic fatty acids. It has been found that two factors affect fatty acid composition of corn oil. These are genotype and environment. Changes in the inbreds of corn hybrids influence the fatty acid composition of commercial corn hybrids. Oil quality and quantity are found to vary over years and locations. The fatty acid composition of corn oil is affected by position of kernels on the ear. Palmitic and linoleic acid content of the oil increases for kernels from the base to the tip of the ear. On the other hand, oleic fatty acid content of the kernels decreases from base to tip. Sampling of kernels in the central portion of the ear is recommended for samples to be analyzed for fatty acid composition. Presence of significant amount of phytosterols (968 mg/100 g) in corn oil improves its quality significantly by reducing the amount of cholesterol absorption from food. Corn oil also provides a good source of vitamin E (21.11 mg ATE/100 g) and tocopherol (14.3 mg/100 g). These are responsible for increased shelflife of corn oil. Four isomers of tocopherols are found in corn, viz. α-, β-, γ-, and δ-. Out of these α-tocopherol is most common.