Ian M. O'HAra

This study develops an integrated thermodynamic and exergoeconomic framework to identify efficiency losses and cost bottlenecks in sugarcane bagasse biorefineries co-producing polylactic acid (PLA) with electricity and value-added coproducts such as succinic acid, xylitol, and lignin-based adhesive. Four process configurations were modelled in SuperPro Designer (v13) and evaluated through exergy, cost, and unit operation-level diagnostics. Across all configurations, overall exergy efficiencies ranged from 47-55%, while functional exergy efficiencies spanned 27-48%, demonstrating strong sensitivity to coproduct integration and energy-recovery strategy. Pretreatment, fermentation, polymerisation, and lactic-acid purification exhibited high thermodynamic performance, whereas PLA purification and electricity generation were identified as the dominant exergy-loss hotspots. Exergoeconomic analysis showed that downstream separations govern cost formation, with purification steps exhibiting the highest costs and the strongest coupling between irreversibility and economic penalty. Coproduct upgrading, particularly lignin-based adhesive production, delivered improved exergy utilisation but required substantially higher capital intensity, revealing a clear trade-off between thermodynamic gains and investment burden. Cost-formation patterns further indicated that purification units are predominantly destruction cost-dominated, whereas adhesive production stages are capital-dominated, underscoring the differing economic drivers across process blocks. Priority improvement opportunities include reducing heat and utility demand in PLA and coproduct separations, enhancing solvent and energy recovery, and rationalising capital allocation in adhesive-production stages. The integrated framework presented here provides a robust basis for selecting scalable, efficient PLA biorefineries and highlights the critical influence of coproduct strategy on both thermodynamic and economic performance. These insights support the development of more efficient, cost-competitive, and resource-optimised biorefinery systems based on agricultural residues.

Sustainable and environmentally friendly extraction methods for natural bioactive compounds are gaining significant attention in the food, beverage, and nutraceutical industries. Among these bioactive compounds, anthocyanins, which are potent antioxidants, have garnered particular interest due to their health-promoting properties. Banana inflorescence, an underutilized agricultural by-product, is a rich source of bioactive compounds. However, the extraction of bioactive compounds is often energy-intensive, which raises concerns about environmental sustainability. Accelerated solvent extraction (ASE) has emerged as an efficient and less energy-consuming method for isolating these compounds. This study investigates the optimization of ASE for the extraction of phenolic compounds, including anthocyanins, from fresh banana inflorescence. The effect of extraction parameters, including temperature (60, 80, and 100 °C), solvent type (water, ethanol, methanol), and solvent composition (50% ethanol + 50% water, 75% ethanol + 25% water, 100% ethanol, 50% methanol + 50% water, 75% methanol + 25% water, 100% methanol, water), on the extraction efficiency was evaluated. The results showed that the most effective extraction conditions were 75% methanol + 25% water at 100 °C, yielding the highest concentrations of total phenolics (1239.58 ± 20.83 mg/100 g), antioxidant activity (2.21 ± 0.03 mg/mL), and anthocyanins (22.82 mg ± 1.91/100 g). LC-UV-MS analysis revealed three primary anthocyanidins: cyanidin-3-rutinoside, delphinidin-3-rutinoside, and petunidin-3-rutinoside. These findings suggest that banana inflorescence, an agricultural waste product, can be efficiently utilized as a source of bioactive compounds using ASE, contributing to sustainable practices in the food and nutraceutical industries. The optimized extraction process provides a promising approach for the valorization of banana inflorescence, enhancing its potential as a functional ingredient in food products.

Anthocyanin is an important flavonoid with antioxidant, anticancer, and anti-inflammatory properties. This research investigates the anthocyanin content of Cavendish banana inflorescence, a by-product often discarded as agricultural waste. The study employs two drying methods, namely oven-drying and freeze-drying, followed by accelerated solvent extraction using acidified water and methanol. Liquid chromatography-mass spectroscopy (LC-MS) results confirm banana inflorescence as a rich source of anthocyanins. According to LC-MS analysis, freeze-dried banana inflorescence extracted in methanol at 80 °C exhibits the highest anthocyanin content (130.01 mg/100 g). This sample also demonstrates superior characteristics, including a chroma value of 40.02 ± 0.01, a redness value of 38.09 ± 0.16, 18.46 ± 0.02 °Brix, a total phenolic content of 42.5 ± 1.00 mg/g, expressed as gallic acid equivalents, and a total antioxidant activity of 71.33 ± 0.08% when assessed with the DPPH method. Furthermore, the study identifies the predominant anthocyanin as cyanidin, along with the presence of other anthocyanins such as delphinidin (Dp), malvidin (Mv), petunidin (Pt), pelargonidin (Pg), and peonidin (Pn). Interestingly, the extracted anthocyanins demonstrate pH sensitivity, changing from red to brown as pH increases. These findings highlight the potential of utilizing Cavendish banana inflorescence for anthocyanin extraction, offering sustainable waste valorization methods with promising applications in biomimetics and bioinspiration fields.

Plant-derived foods with therapeutic potential have strong connection with both the pharmaceutical and nutraceutical industries. The effectiveness of these therapeutic properties is heavily influenced by the thermal treatment during drying and extraction methods. Traditional convective drying is a very energy incentive and lengthy process. Although some advanced and hybrid drying methods have been developed, these have not been applied in drying of banana inflorescence. In this study, we investigated the effects of freeze-drying (FD) and intermittent microwave convective drying (IMCD), as well as traditional convective oven drying (CD), on the polyphenol profile of banana inflorescence when extracted using the energy-efficient Accelerated Solvent Extraction method (ASE). Our findings revealed that the freeze-dried banana inflorescence powder exhibited the highest extraction of bioactive compounds when using 75% methanol at 100 °C as a solvent. It recovered 2906.3 ± 20.83 mg/100 g of the phenolic compounds and 63.12 ± 0.25% antioxidant activity under the optimal extraction conditions. While IMCD was found to be the second-best drying method in terms of preserving bioactive compounds, its operational time and cost were significantly lower compared to freeze-drying. Furthermore, our study confirmed the presence of medicinal compounds such as gallic acid, protocatechuic acid, caffeic acid, coumaric acid, catechin, ferulic acid, kaempferol, and quercetin in banana inflorescence. The development of innovative functional foods and pharmaceutical ingredients through green extraction methods and optimal drying conditions holds significant potential to save energy in the process, enhance human health, and promote environmental sustainability and circular economy processes. These efforts align with supporting Sustainable Development Goals (SDGs) 3 and 12.

The bioeconomy holds promise in reducing dependence on fossil fuels, addressing climate change, and promoting resource efficiency, thereby stimulating economic growth, innovation, and improving food security. In 2020, the International Advisory Council on Global Bioeconomy (IACGB) released a comprehensive report that analyzed the progress of bioeconomy policies across the globe up until that year. This study builds on that report, analyzing bioeconomy policy trends between 2020 and 2024. The study aims to contribute valuable insights for policymakers, researchers, and other stakeholders involved in shaping the evolving bioeconomy landscape.

Background: Sugarcane bagasse is a major source of lignocellulosic biomass, yet its economic potential is not fully realised. To add value to bagasse, processing is needed to gain access to the embodied recalcitrant biomaterials. When bagasse is stored in piles in the open for long periods it is colonised by microbes originating from the sugarcane, the soil nearby or spores in the environment. For these microorganisms to proliferate they must digest the bagasse to access carbon for growth. The microbial community in bagasse piles is thus a potential resource for the discovery of useful and novel microbes and industrial enzymes. We used culturing and metabarcoding to understand the diversity of microorganisms found in a uniquely undisturbed bagasse storage pile and screened the cultured organisms for fibre-degrading enzymes.Results: Samples collected from 60 to 80 cm deep in the bagasse pile showed hemicellulose and partial lignin degradation. One hundred and four microbes were cultured from different layers and included a high proportion of oleaginous yeast and biomass-degrading fungi. Overall, 70, 67, 70 and 57% of the microbes showed carboxy-methyl cellulase, xylanase, laccase and peroxidase activity, respectively. These percentages were higher in microbes selectively cultured from deep layers, with all four activities found for 44% of these organisms. Culturing and amplicon sequencing showed that there was less diversity and therefore more selection in the deeper layers, which were dominated by thermophiles and acid tolerant organisms, compared with the top of pile. Amplicon sequencing indicated that novel fungi were present in the pile.Conclusions: A combination of culture-dependent and independent methods was successful in exploring the diversity in the bagasse pile. The variety of species that was found and that are known for biomass degradation shows that the bagasse pile was a valuable selective environment for the identification of new microbes and enzymes with biotechnological potential. In particular, lignin-modifying activities have not been reported previously for many of the species that were identified, suggesting future studies are warranted.