The physicochemical properties, total phenolic, antioxidant activities, and phenolic profile of fermented olive cake

Fermentation of olive cake during 60 days by evaluating the physicochemical properties, total phenolic, antioxidant activities and phenolic profile was investigated. The chemical composition showed that olive cake is rich in crude fiber and carbohydrates (Nitrogen free extract) and contains moderate amounts of crude protein, fat and ash. Total phenolics which are determined by the folin–ciocalteuic method were decreased during fermentation while no change was observed in antioxidant activities and nitrogen and carbon percentages. On the other hand olive cake samples contain little amounts of antioxidants. The HPLC profiles for olive cake extracts contain the highest amount of caffeic acid followed by vanillic acid, gallic acid, and catechin, respectively also phenolic acids and compounds decreased during fermentation. It can be concluded that olive cake fermentation is considered a good procedure to reduce phenolic compounds which could be harmful in using olive cake “as is” for animal feeding or plant fertilizers.