Integrated biorefinery for xylooligosaccharides, pectin, and bioenergy production from orange waste

Abstract

Orange waste is one of the most underutilized biowastes. It accounts for 50% of the fruit weight after juice extraction, presenting an environmental problem due to inappropriate disposal. Industrial waste exploitation is a sustainable way to obtain bioproducts and bioenergy. However, the efficiency of chemical treatments and enzymatic cocktails is still a bottleneck in these processes. One potential route to reduce costs is to design consecutive extraction and hydrolysis stages to yield more products from different fractions of the same feedstock, reducing the use of time and bulk materials. This study assessed the economic performance of an orange processing waste (OPW) biorefinery for xylooligosaccharides (XOS), pectin, and bioenergy, involving three aspects: (1) experimental procedures, (2) a simulation approach, and (3) optimization tools. The optimization of hydrothermal treatment for pectin extraction decreased material costs by more than 60% and preserved the xylan content for xylooligosaccharide production by enzymatic hydrolysis. This study analyzed different biorefinery capacities, and solid waste exploitation for heat and steam generation, improving sustainability. The production cost per kg of high‐purity pectin and xylooligosaccharides is 3.67 $ with an efficient solvent recovery and self‐sufficiency for standard power usage. These results proved the economic feasibility and low environmental impact of the OPW biorefinery.

Transforming orange waste with yeasts: bioprocess prospects

“…In this case, the hydrolysis of this last polysaccharide becomes predominant in enabling the desired biotransformation (Scapini et al, 2023c). Still, it is important to highlight that the enzymatic hydrolysis of xylan present in orange residues can be harnessed to generate Xylooligosaccharides, molecules with great potential as functional food ingredients (Ávila et al, 2020;Martins and Goldbeck, 2023). In this context, for example, Martins and Goldbeck (2023) demonstrated that the integration of pectin production, Xylooligosaccharides, and bioenergy (with biogas production from free sugars and cellulose) could be an alternative to achieve the economic viability of orange waste-based biorefineries (see section 4).…”

“…Oligosaccharides can be derived from the hydrolysis of the hemicellulose structure present in orange waste. Similarly to what has been described above for POSs, these hemicellulose-derived oligosaccharides are prebiotics of significant interest in the food industry and can be prepared through autohydrolysis, acid hydrolysis, or enzymatic hydrolysis of the hemicellulose-rich fraction (Cho et al, 2020;Martins and Goldbeck, 2023). Therefore, following the extraction of pectin, it is feasible to explore this conversion route.…”

“…The hydrothermal process for extracting the pectin structure has been previously reported to preserve 60% of the xylan content, enabling enzymatic conversion to xylooligosaccharides (XOS). This process also facilitates the conversion of solid waste into energy, allowing for the design of a self-sufficient plant in accordance with the principles of the circular economy and biorefineries (Martins and Goldbeck, 2023).…”