In recent years, concerns about a good-quality diet have increased. Food supplements such as prebiotics have great nutritional and health benefits. Within the diverse range of prebiotics, xylooligosaccharides (XOs) show high potential, presenting exceptional properties for the prevention of systemic disorders. XOs can be found in different natural sources; however, their production is limited. Lignocellulosic biomasses present a high potential as a source of raw material for the production of XOs, making the agro-industrial by-products the perfect candidates for production on an industrial scale. However, these biomasses require the application of physicochemical pretreatments to obtain XOs. Different pretreatment methodologies are discussed in terms of increasing the production of XOs and limiting the coproduction of toxic compounds. The advance in new technologies for XOs production could decrease their real cost (USD 25–50/kg) on an industrial scale and would increase the volume of market transactions in the prebiotic sector (USD 4.5 billion). In this sense, new patents and innovations are being strategically developed to expand the use of XOs as daily prebiotics.

Renewable energy sources, such as biofuels, represent promising alternatives to reduce dependence on fossil fuels and mitigate climate change. Their production through enzymatic hydrolysis has gained relevance by converting agro-industrial waste into fermentable sugars and residual oils, which are essential for the generation of bioethanol and biodiesel. The fungus Aspergillus stands out as a key source of enzymes, including cellulases, xylanases, amylases, and lipases, which are crucial for the breakdown of biomass and oils to produce bioethanol and fatty acid methyl esters (FAME). This review examines the current state of these technologies, highlighting the significance of Aspergillus in the conversion of energy-rich waste materials. While the process holds significant potential, it faces challenges such as the high costs associated with enzymatic production and final processing stages. Agro-industrial waste is proposed as an energy resource to support a circular economy, thereby eliminating reliance on non-renewable resources in these processes. Furthermore, advanced pretreatment technologies—including biological, physical, and physicochemical methods, as well as the use of ionic liquids—are explored to enhance process efficiency. Innovative technologies, such as genetic engineering of Aspergillus strains and enzyme encapsulation, promise to optimize sustainable biofuel production by addressing key challenges and advancing this technology towards large-scale implementation.

The present work aimed to use cocoa pod husk (CPH) and its extracted pectin as a potential substrate for the production of pectinase and to test the enzyme produced in the clarification process of apple juice. CPH with a particle size of <0.84 mm was employed for pectinase production by a selected strain of Aspergillus niger NRRL 2270. The optimization of the physicochemical conditions of the production medium led to an enzymatic activity of 602.03 U/g dry CPH, which was obtained under the following conditions: 110.25 g/L of CPH, 5% w/v pectin extract, 0.05 g/L of yeast extract, incubation at 28 °C, and pH 4, representing a 176% increase in enzymatic activity under the evaluated conditions. The production kinetics of pectinase showed maximum enzymatic activity at 96 h. Subsequently, the enzymatic extract was precipitated, microfiltered, and ultrafiltrated, resulting in 4852.50 U/mg of specific activity. The enzymatic activity after recovery and purification processes corresponded to 819 U/g dry CPH. Finally, a clarification stage of apple juice was carried out, in which the produced pectinase (CauPec) showed turbidity of 448.89 NTU compared to 417.89 NTU for the commercial enzyme and a viscosity of 1.86 cP, CauPec, and 1.19 cP, commercial pectinase, as well as soluble solids of 8.0 for commercial pectinase and 8.73 for CauPec. Therefore, it can be concluded that CPH and its pectin extract were excellent substrates for the production of pectinases, whose formulation is highly stable and can be applied in the clarification of apple juice.

Second-generation (2G) bioplastics are emerging as a new potential source to supply the global plastics market. Differently to the first generation, 2G bioplastics are produced from non-edible, bio-based sources. Lignocellulosic biomass and non-edible vegetable oils are the main carbon sources for the production of 2G bioplastics, avoiding competition with the food industry for the same raw material source. Lignocellulosic biomass is the most promising and widely distributed source for the sustainable production of 2G bioplastics. However, the rich composition in polymers (carbohydrates and lignin) make the lignocellulosic biomass recalcitrant. For this reason, it is necessary to apply pretreatment methods for the destructuring of lignocellulosic biomass and to improve the release of fermentable sugars and phenolic monomers. Then, these monomers are used through biotechnological and chemical processes to produce 2G bioplastics. Depending on the applied chemical or fermentative route, biodegradable or non-biodegradable 2G bioplastics can be obtained with the same properties as traditional plastic. The use of lignocellulosic biomass generates great prospects for sustainable production of 2G bioplastic. In addition, the application of circular bioeconomy concepts and the implementation of lignocellulosic biorefineries would make industrial-scale production viable, increasing the reuse and valorization of agro-industrial by-products.