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In this study, for the first time, polyphenols are extracted using microwave-assisted deep eutectic solvents (MW-DES) from supercritical CO2defatted date seeds under variable operating conditions. The best conditions consisted of choline chloride: formic acid (1:2 molar ratio), a solid to solvent ratio of 1/20 (g/mL) (0.75 g of dry biomass in 15 mL solvent), an extraction time of 50 s, and a microwave power of 400 W. The maximum polyphenols extraction yield was 128 g gallic acid equivalent/kg dry biomass (g GAE/kg) (which is the highest value ever reported in literature for date seeds extracts). The antioxidant activity of the optimum extracts was assessed with the DPPH and ABTS quenching capacities being equal to 27 and 145 mg trolox equivalent/g dry biomass, respectively. Mainly mannose and manno-oligosaccharides were solubilized during extraction. The highest yields were (obtained at 200 W, 120 s) 35.07 and 32.18 mg/g of dry biomass for mannose and manno-oligosaccharides, respectively. It was also observed that the total mannose (monomer and oligomer) release during the extraction increased linearly (r2= 0.9951) with respect to microwave energy applied per gram of date seeds (J/g).

Three concepts for a 3000 t/a continuous autohydrolysis plant aiming at a full fractionation of agricultural residues (wheat straw as model substrate) into streams rich in xylose, glucose, and lignin, respectively, are developed. For this purpose, two kinetic models based on batch liquid-hot water experiments (30 mL, 170–230 °C, 10–60 min) were investigated. The solid hemicellulose conversion was described with a first-order rate model. The concentration and conversion profile investigation of the solid and liquid phases using the severity factor resulted in a linear equation describing the hemicellulose solubilization: XHC= (0.5839 ∗ log(R0) − 1.7027) ± 0.06. Here, specific process parameter boarders for the maximal hemicellulose concentration and furfural formation at log(R0) = 4.0 considering the liquid phase were identified. These findings were used to propose a multi-step hydrothermal processing approach, with intermediate sugar extraction, tailored to the compositional requirements of the product streams. Seven reactor types were evaluated for its feasibility; in this regard, the screw conveyor reactor (SCR) was evaluated as most promising. For the concepts, the SCR reactors were scaled, based on the generated data. It was found that the process temperature is a major parameter determining the reactor size. It is considered more important than the number of autohydrolysis treatment steps. In brief, the fractionation of agricultural residues using a multi-step continuous plant is evaluated to be very promising for the industrial application, regarding selectivity, handling, investment, and process costs.

Natural compounds include a boundless diversity of molecules and functionalities that represent an excellent pool of materials for production of functional foods, food additives, and pharmaceuticals. Research on lignin functional and bioactive properties has recently become the center of interest for research centers worldwide, chasing for the complete valorization of products obtained in biorefining processes and unraveling the potential of this natural polymer for its use in high adding-value target industries, as the case of pharmaceutical, food, and cosmetics. This review addresses the potential applications of lignin for human consumption products, as well as the current challenges that these potential products need to overcome in the regulatory frame and consumer acceptance. Moreover, lignin structure-related mechanisms are proposed with emphasis in pharmaceutical and food applications.

In this work, the potential of lignin as a filler additive and anti-aging agent in a pressure-sensitive adhesive (PSA) based on natural rubber (NR) was investigated. Herein, different approaches to incorporate lignin into NR matrix by adaptation of a two-step compounding process were evaluated. At first, a twin-screw extruder (TSE) was utilized to prepare pre-formulations followed by the secondary finalization of adhesive mass inside a planetary roll extruder (PRE). For the industrial production of PSAs, the adhesive mass is required to have well-distributed additive materials and adequate adhesion, cohesion, and longevity. The impact of the added lignin was evaluated concerning optical appearance, compatibility between lignin and rubber/resin, adhesion performance, shear strength, thermal stability, antioxidant capability, dynamic-mechanical behavior, aging behavior at elevated temperature and under UV exposure, and filler morphology. It was found that the PSAs including aquasolv (AS) lignin after the spray-drying post-treatment exhibited excellent thermal, mechanical, and antioxidative properties. Thus, it was shown that the sustainably producible lignin can be utilized both as filler and antioxidant in natural rubber-based pressure-sensitive adhesive masses with comparable performance properties as commercially available products.