Search

CRUE-CSIC (Acuerdos Transformativos 2021), Furfural comes from lignocellulosic biomass that, together with its derived products, has many useful applications in several industries. Furfural is usually obtained via pentose dehydration using a biphasic reactor to extract furfural in situ from its reaction medium. However, the conventional solvents used so far, mainly toluene and methyl isobutyl ketone (MIBK), are harmful to health and the environment. Therefore, hydrophobic natural solvents have been successfully tested in this work to improve the performance of the process from a sustainable point of view. First, 30 natural solvents were screened using the conductor-like screening model for real solvents (COSMO-RS) method to select solvents with high affinity to furfural. From the results obtained in the screening, 14 natural and 2 conventional solvents were selected for experimentation, including thymol, eugenol, toluene, MIBK, and several hydrophobic eutectic solvents formed by thymol. Then, the liquid−liquid extraction of furfural was carried out both in vials and in a reactor, simulating the usual temperature and pH conditions for obtaining furfural. Thymol and eugenol showed extraction yields of 95 and 91%, significantly higher than those of conventional solvents MIBK and toluene, which were 85 and 81%, respectively. Finally, the in situ reaction and extraction of furfural from xylose were performed using the natural solvents eugenol and thymol and the conventional solvent MIBK. Under operating conditions, namely, microwave heating to 443.2 K, 10 min of reaction, and a solvent-to-feed ratio of 1.00, xylose conversion of 96.7%, furfural selectivity of 75.3%, and a furfural production yield of 72.8% from xylose were obtained using eugenol as the organic solvent, with improved outcomes over MIBK and thymol cases, pointing an adequate approach to improve both the effectiveness and the sustainability of the process., Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Depto. de Ingeniería Química y de Materiales, Fac. de Ciencias Químicas, TRUE, pub

Pectic oligosaccharides (POS) derived from industrial byproducts, such as lemon peels (LP) and sugar beet pulp (SBP), have been reported to be non-digestible oligosaccharides an catalogued as promising candidates as prebiotics. This work has evaluated the selective fermentation of POS by potential probiotic Lactobacillus and Bifidobacterium strains. POS were fully characterized based on molecular weight and proportion of neutral and acidic oligosaccharides. All the tested probiotic strains reached better growth results when SBP POS were added to the growth media than LP POS. On the other hand, while Lactobacillus rhamnosus GG showed poor growth with LP POS-2, Bifidobacterium lactis Bb-12 was the only strain able to ferment these compounds. Lactic, acetic and formic acids were the main organic acids derived from POS fermentation by the assayed strains. The cocultures with Bacteroides fragilis did not modify the fermentation capability of the probiotic bacteria. This study has demonstrated that complex POS derived from lemon and sugar beet byproducts could be used as carbohydrate source by lactobacilli and bifidobacteria, showing the low-molecular-weight LP POS-2 a specific bifidogenic effect towards B. lactis. Results are promising for the development of synbiotic supplements.

In this work, dilute sulphuric acid prehydrolysis of residual empty pods of Moringa oleifera fruits was investigated as pretreatment for enzymatic hydrolysis of cellulose. In experiments performed at 130–190 °C for 10–30 min, corresponding to a severity range between log Ro = 1.9 and log Ro = 4.2, the effect of pretreatment conditions on the recovery of polysaccharides and on the enzymatic convertibility of cellulose was evaluated. Overall cellulose recovery was above 95% in the pretreatments performed at 130 and 160 °C, and between 87 and 90% in the pretreatments at 190 °C, while xylan recovery in the most severe pretreatments was only 24.7–50.2%. The highest sugar concentration in the acid prehydrolysates (15.0 g/L) was obtained in the pretreatment performed at 160 °C and 20 min. The formation of degradation products was low at mild pretreatment conditions, but it increased with the severity. Furfural concentration reached 4.04 g/L at log Ro = 3.1 and decreased again with a further increase of the pretreatment severity. HMF, formic acid and levulinic acid were formed only in the most severe pretreatments. The pretreatment was effective for improving the enzymatic hydrolysis of cellulose, and the highest conversion (84.3%) was achieved in the material pretreated at mid severity (log Ro = 3.1).