Polyphenols in food processing wastewaters: A review on their identification and recovery

Polyphenols are strong natural antioxidants, associated with anti-inflammatory, disease prevention and anti-microbial effects. Due to their water solubility, these molecules are at least partially transferred to process waters during processing of foods and crops which contain them. As wastewater components, polyphenols can impart toxicity and impact microbial treatment. Their recovery can contribute not only to wastewater treatment and reuse, but also to reducing economic and nutritional losses. Although olive mill wastewater has been the most thoroughly studied effluent for polyphenol recovery, other wastewaters also deserve attention. This paper reviews wastewaters containing polyphenol and their generating processes, and reports on identified polyphenols and quantities, as well as studied recovery methods. It sheds light on the state of the art and existing research gaps and highlights the need for pilot and industrial scale studies, as well as for economic evaluation of proposed technologies, ultimately providing support to the enhancement of circular economy in food industry.