Valorization of orange peel waste through mixotrophiccultivation of Nannochloropsis oculata

The orange citrus fruit is one of top-five fruit commodities that dominate the global fruit market. According to FAO, global orange production reached 68 million tons representing 8.5% of the total fruit production [1]. Approximately, 40-60% of oranges are processed for juice production, of which 50-60% ends up as waste including seed, peel, and segment membrane. Among these wastes, peel is the major constituent accounting for approximately 44% of the weight fruit mass. The disposal of orange waste requires specific procedures and, consequently, represents a cost for the agro-industry. Orange waste disposal by bioconversion may be quite difficult, because of the presence of several antimicrobial compounds (e.g. essential oils) as well as the high chemical complexity of the macromolecular content. Ideally, orange waste disposal could be coupled to a bioprocess for the production of high-value added compounds to obtain an economically relevant integrated process. In this study, we propose a bioconversion process in which orange waste is used as a low-cost organic substrate for cultivation of Nannochloropsis oculata to produce biomass and oils, which can be used for biofuels and/or PUFAs production [2, 3].