Valorisation of Citrus Processing Waste for Bacterial Cellulose Production through an Integrated Biorefinery Approach

Abstract

Citrus Processing Industry (CPI) for juice and concentrate, generates substantial amounts of by-products given that only 50% of the fruit’s mass is used during the production process. The worldwide production of citrus fruits accounts for 143 x 106 t per year, resulting in industrial generation of citrus peel waste (CPW) which exceeds 24 x 106 t (FAO, 2017) and mainly consists of peels, pulp, seeds and segment membranes (Marín et al., 2007). Although traditional management practices include the use of CPW as animal feed or organic fertilizer (Lopez et al., 2010), various studies have been conducted towards exploitation of CPW for the production of high value-added products including essential oils, pectin, succinic acid (Patsalou et al., 2017), bacterial cellulose (Andritsou et al., 2018), ethanol and methane (Patsalou et al., 2019). An additional burden of CPIs concerns the significant amounts of wastewater disposed, which constitutes mainly water used for factory cleaning, juice concentration, cooling water and water produced by essential oil extraction. Wastewater of CPIs comprises large variability of organic loads, suspended and settling solids, colloidal and settleable suspended solids and other soluble or insoluble compounds, such as sugars, phenolic compounds, essential oils and organic acids (Zema et al., 2019). These molecules include valuable compounds which can be either isolated for food and pharmaceutical applications or further treated for the production of high-added value commodities. Bacterial Cellulose (BC) constitutes a biopolymer of tremendous industrial importance owing to its numerus unique properties including high …