Technological aspects and stability of polyphenols

Nowadays, more and more dietary supplements containing polyphenols and polyphenol-rich food products are developed in the health food markets to meet the needs of the people who cannot consume adequate amounts of vegetables and fruits all over the world. Technically, the dietary beneficial compounds are extracted, purified, and concentrated from natural plant food resources using different techniques and processes and processed into tablets or capsules for public consumption. However, the polyphenols are unstable and highly prone to degradation and/or reaction with some factors (e.g., oxygen and metal ions) changing their structures during processing and storage, which result to the decrease of polyphenols’ biological activities. To this line, this chapter discusses the stability of polyphenols under different factors such as pH, temperature, light, oxygen, enzymes, proteins, and metal ions as well as interaction with other food constituents.