Folic acid (FA) is an important B vitamin made up of 2-amino-4-hydroxyl-6-methylpterin, para-amino benzoic acid, and glutamic acid. FA exists in a large variety of foods including green leafy vegetables, fruits, meat products, beans, fermented dairy products, and cereals, but the content of FA in natural foods is not high, which dissatisfies with demands of the human body. FA deficiency has been associated with a number of health disorders such as mental confusion, diarrhea, irritability, behavior disorder, and headache or nerve damage. Besides, insufficient intake of FA can lead to neural tube defects in developing embryos, elevated plasma homocysteine, different types of cancer, Alzheimer, etc. The daily recommended intake (DRI) as approved in European Union (EU) is 400 μg day−1 for adults; higher intake (600 μg day−1) is recommended for women before and during pregnancy. FA has special importance for pregnant women and infants, and FA supplementation is particularly important in those edible foods. Therefore, monitoring FA content is necessary to guarantee the quality of functional foods.