CONICET | Buscador de Institutos y Recursos Humanos

The use of modern two-phase processing techniques for olive oil production, with no water addition, generates a new by-product that is a combination of liquid and solid waste, called alperujo. In Argentina, the alperujo is at present usually disposed on the ground in the field, leading to a loss of soil quality. This is due to the olive biophenols that are mainly retained in this waste. It is known that phenolic compounds are both antimicrobial and phytotoxic. This fact makes the alperujo difficult to be biologically degraded. The recovery of phenols by liquid-liquid extraction with ethyl acetate is presented in this work. A sample of alperujo obtained from a local factory (Arbequina variety) was used for this purpose. The effects of extraction temperature and time, solvent volume and pH of the aqueous phase before extraction were studied using a 24 two-level factorial design and measuring total phenol content with Folin-Ciocalteu reagent. The aqueous extract from the alperujo was characterized as follows: 22.9 kg/m3 of total solids (2540B APHA Method), 20.1 kg/m3 of volatile solids (2540E APHA Method), 0.13 % m/m of oil, pH = 5.3, COD = 32.2 kg/m3 (5220D APHA Method), 5 days-BOD = 16.1 kg/m3 (5210B APHA method) and 0.90 g/L of total phenols. The best recovery of phenols (> 25 %) was attained using one extraction step under the following conditions: solvent to aqueous extract ratio = 3:1 v/v, 20 °C, 120 min and pH = 2. The percentage of recovered phenols was increased by repeated extractions. In conclusion, the biophenols from alperujo can be recovered by liquid/liquid extraction. This has two beneficial consequences: the former is the recovery of valuable materials with applications as natural antioxidants in food and pharmaceutical industries; the latter is the drop of the environmental impact of the waste stream arising from the reduction of phenols content in the alperujo.