Xylanase Production by Solid-State Fermentation for the Extraction of Xylooligosaccharides from Soybean Hulls§.

Research background: The development of a novel process for the production of xylooligosaccharides (XOS) based on the 4R concept is made possible by the integration of numerous techniques, especially enzymatic modification together with the physical pretreatment of renewable materials. This study aims to integrate the use of agricultural wastes for the production of xylanase by a new strain of Penicillium sp. and value-added products, XOS. Experimental approach: For the production of xylanase, a solid-state fermentation was performed using wheat bran as substrate. To obtain the most active crude extract of xylanase, the time frame of cultivation was first adjusted. Then, the downstream process for xylanase purification was developed by combining different membrane separation units with size exclusion chromatography. Further characterisation included determination of the optimal pH and temperature, determination of the molecular mass of the purified xylanase and analysis of kinetic parameters. Subsequently, the hydrolytic ability of the partially purified xylanase in the hydrolysis of alkali-extracted hemicellulose from soybean hulls was investigated. Results and conclusions: Our results show that Penicillium rubens produced extracellular xylanase at a yield of 21 U/g during solid-state fermentation. Using two ultrafiltration membranes of 10 and 3 kDa in combination with size exclusion chromatography, a yield of 49 % and 13-fold purification of xylanase was achieved. The purified xylanase (35 kDa) cleaved linear bonds ß-(1→4) in beechwood xylan at a maximum rate of 0.64 µmol/(min·mg) and a Michaelis constant of 44 mg/mL. At pH=6 and 45 °C, the purified xylanase showed its maximum activity. The xylanase produced showed a high ability to hydrolyse the hemicellulose fraction isolated from soybean hulls, as confirmed by thin-layer chromatography. In the hydrothermally pretreated hemicellulose hydrolysate, the content of XOS with different degrees of polymerisation was detected, while in the non-pretreated hemicellulose hydrolysate, the content of xylotriose and glucose was confirmed. Novelty and scientific contribution: Future research focusing on the creation of new enzymatic pathways for use in processes to convert renewable materials into value-added products can draw on our findings.

Ultrasonication for production of nanoliposomes with encapsulated soy protein concentrate hydrolysate: Process optimization, vesicle characteristics and in vitro digestion.

This study presents the state-of-art research about the assembly of soy proteins in nanocarriers, liposomes, and its design includes different physicochemical strategies and approaches: two-step enzymatic hydrolysis of soy concentrate, hydrolysate encapsulation by using phospholipids and cholesterol, and application of ultrasonication. Achieved results revealed that ultrasonication, together with cholesterol addition into phospholipid layers, improved the stability of nanoliposomes, and a maximum EE value of 60.5 % was obtained. Average size of peptide-loaded nanoliposomes was found to be from 191.1 to 286.7 nm, with a ζ potential of -25.5 to -34.6 mV, and a polydispersity index of 0.250-0.390. Ultrasound-assisted encapsulation process did not lead to a decrease in the antioxidant activity of the trapped peptides. FTIR has indicated an effective hydrophobic interaction between phosphatidylcholine and hydrolysate peptides. TEM and SEM have confirmed the spherical nanocarrier structure and unilamelarity. Prolonged gastrointestinal release and stability of peptides have been enabled by liposome nanocarriers.