Fermentation as a Strategy to Valorize Olive Pomace, a By-Product of the Olive Oil Industry

In the Mediterranean region, where olive oil is mostly produced, high amounts of olive oil by-products are generated, which creates an ecological concern, due to their phytotoxic phenolic components (e.g., oleuropein, hydroxytyrosol, tyrosol). However, these compounds also represent a relevant source of antioxidants for health and well-being. The food and beverage, cosmetic, and pharmaceutical industries can all greatly benefit from the treatment and proper exploitation of olive oil by-products for their health-promoting benefits in various fields. Additionally, recovery and treatment procedures can support effective waste management, which in turn can increase the sustainability of the olive oil sector and result in worthwhile economic advantages. Due to their high phenolic content, olive pomace could be viewed as a good matrix or primary supply of molecules with high added value. The purpose of this review was to give a thorough overview on how the primary solid olive oil by-products, particularly olive pomace, are currently valued through fermentation, emphasizing their applications in several industries-ethanol production, enzyme production, animal feeding, and human nutrition. It was possible to conclude that the olive pomace has a microbiota profile that allows spontaneous fermentation, a process that can increase its value. In addition, its phenolic content and antioxidant activity are relevant to human health; thus, further studies should be carried out in order to implement this process using olive pomace as the main substrate.