*Review* **Strategies to Increase the Value of Pomaces with Fermentation**

**Paulo E. S. Munekata <sup>1</sup> , Rubén Domínguez <sup>1</sup> , Mirian Pateiro <sup>1</sup> , Asad Nawaz 2,3, Christophe Hano <sup>4</sup> , Noman Walayat <sup>5</sup> and José M. Lorenzo 1,6,\***


**Abstract:** The generation of pomaces from juice and olive oil industries is a major environmental issue. This review aims to provide an overview of the strategies to increase the value of pomaces by fermentation/biotransformation and explore the different aspects reported in scientific studies. Fermentation is an interesting solution to improve the value of pomaces (especially from grape, apple, and olive) and produce high-added value compounds. In terms of animal production, a shift in the fermentation process during silage production seems to happen (favoring ethanol production rather than lactic acid), but it can be controlled with starter cultures. The subsequent use of silage with pomace in animal production slightly reduces growth performance but improves animal health status. One of the potential applications in the industrial context is the production of enzymes (current challenges involve purification and scaling up the process) and organic acids. Other emerging applications are the production of odor-active compounds to improve the aroma of foods as well as the release of bound polyphenols and the synthesis of bioactive compounds for functional food production.

**Keywords:** pressing residue; grape; apple; silage; animal production; enzyme production; polyphenols
