Phenolic compounds are plant secondary metabolites that are relevant to the appearance, smell, taste, storage quality, and health-promoting properties of foods.  Health properties include their anti-platelet, antioxidant, anti-inflammatory, antitumoral and oestrogenic activities, which might suggest their ability to prevent coronary heart disease and cancer.   There are many factors which affect the phenolic composition of foods, including genetic, agronomic, and post harvest treatments.

The agronomic factors of note include: calcium deficiencies in apples can lead to ‘bitter pit” development during storage, boron availability affects the phenolic content of plants substantially, the occurrence of betains and Ca in soil induce phenolic metabolism and anthocyanin accumulation in grapes, and silicon deprived plants illustrate more susceptibility to fungus causing powdery mildew.  Also related are the studies finding that abiotic stress is induced by high nitrogen dosages in bean plants, and calcium chloride applications can aid in maintaining membrane integrity in some crops.

Phenolic compounds are also crucially related to the flavor of foods; their presence resulting in the bitter, sweet, pungent, or astringent taste in some foods.  Examples are the bitter phenolics present in hops and citrus fruits, the pungent, ones prevalent in hot peppers, ginger, and turmeric, and volatile ones related to aromas such as vanillin.