*2.3.1. Nutritional and antioxidant properties*

Phenolic compounds are natural antioxidants that are present in food or in the body, to delay or stop the oxidation of that substance. The main advantages of these natural antioxidant are (1) they are readily acceptable by the consumers; (2) they are considered to be safe; (3) no safety tests are required by legislation; and (4) this natural antioxidant is identical to the food which people have taken over a hundred years or have been mixing with food. Phenolic compounds are associated with nutritional and organoleptic qualities of foods from plant origin [24, 26]. Phenolic compounds at low concentration protect foods from autoxidation, but at high concentration, they can cause undesirable discoloration as a result of their interaction with the carbohydrate or protein components.

Among naturally found phenolic compounds, phenolic acids are of high interest due to their potential biological properties [27, 28]. Many phenolic acids are known to be potent antioxidants through their radical scavenging activity, and due to their chemical structure, the reactivity of phenolic acids increases as the number of hydroxyl and methoxyl groups increases [29]. The consumption of fruits, vegetables, and soft drinks such as tea and coffee, which contain phenolic compounds, has been linked to lower risk of some diseases, such as cancer and CVD [30, 31]. However, the use of phenolic acids as natural antioxidants in foods and nutraceutical supplements has the limitation of low solubility in oil-based media. Nevertheless, lipase-catalyzed reactions of lipids with phenolic acids could produce structured lipids with phenolic moieties, which would have health benefits and improved solubility characteristics [32–35].
