Continuous production of pectic oligosaccharides from sugar beet pulp in a cross flow continuous enzyme membrane reactor.

Sugar beet pulp pectin is an attractive source for the production of pectic oligosaccharides, an emerging class of potential prebiotics. The main aim of the present work was to investigate a new process allowing to produce pectic oligosaccharides in a continuous way by means of a cross flow enzyme membrane reactor while using a low-cost crude enzyme mixture (viscozyme). Preliminary experiments in batch and semi-continuous setups allowed to identify suitable enzyme concentrations and assessing filtration suitability. Then, in continuous experiments in the enzyme membrane reactor, residence time and substrate loading were further optimized. The composition of the obtained oligosaccharide mixtures was assessed at the molecular level for the most promising conditions and was shown to be dominated by condition-specific arabinans, rhamnogalacturonans, and galacturonans. A continuous and stable production was performed for 28.5 h at the optimized conditions, obtaining an average pectic oligosaccharide yield of 82.9 ± 9.9% (w/w), a volumetric productivity of 17.5 ± 2.1 g/L/h, and a specific productivity of 8.0 ± 1.0 g/g E/h. This work demonstrated for the first time the continuous and stable production of oligosaccharide mixtures from sugar beet pulp using enzyme membrane reactor technology in a setup suitable for upscaling.

Desorption electrospray ionization high-resolution mass spectrometry for the fast investigation of natural polysaccharide interactions with a model drug in controlled release systems.

RATIONALE: The control of drug release involves gaining an understanding of the complex interaction networks among drug-excipients-matrix-biological fluids. Thus, novel analytical methods that will lead to a better understanding of these interaction networks are urgently required. METHODS: Desorption electrospray ionization high-resolution mass spectrometry (DESI-HRMS) was used to evaluate the behaviour of four biocompatible polysaccharides (chondroitin sulfate, chitosan, sodium alginate and λ-carrageenan) in the release of atenolol (ATN) from drug tablets. An aqueous solution at three different pH values (pH 7.4, 4.5 and 1.2) was electrosprayed onto the tablets, allowing direct, fast, sensitive detection of atenolol as the protonated molecule in positive ion mode. Information about the desorption mechanism was obtained by analyzing the ATN [M+H](+) ion signal as a function of time. ATN-polymer interactions in the drug/polymer mixtures were also studied by Horizontal Attenuated Total Reflectance (HATR) Fourier transform infrared (FTIR) spectroscopy. RESULTS: The DESI-MS results revealed statistically different ATN desorption trends as a function of the polysaccharide investigated and the pH of the desorbing solution. Different release kinetics were ascribed to the drug-polymer interactions, and to the diffusion process of the drug through the hydrated polymer mesh. In particular, the alginate and λ-carrageenan matrices were able to sustain drug release from the tablet even for a highly soluble drug. The HATR results confirmed the presence of ATN-polymer interactions that, depending on the polymer-drug-solvent combination used, might affect ATN diffusion. CONCLUSIONS: These results suggest that DESI-MS has a potential role for the micro-environmental analysis of drug diffusion and surface distribution in polymeric matrices.

Continuous production of pectic oligosaccharides from onion skins with an enzyme membrane reactor.

The aim of this research was to valorize onion skins, an under-utilized agricultural by-product, into pectic oligosaccharides (POS), compounds with potential health benefits. To achieve high hydrolysis performance with the multi-activity enzyme Viscozyme L, an innovative approach was investigated based on a cross-flow continuous membrane enzyme bioreactor (EMR). The influence of the various process conditions (residence time, enzyme concentration, substrate concentration) was investigated on productivity and yield. The composition of the POS mixtures in terms of mono- and oligosaccharides was assessed at the molecular level. At optimized conditions, a stable POS production with 22.0g/L/h volumetric productivity and 4.5g/g POS/monosaccharides was achieved. Compared to previous results obtained in batch for the enzyme Viscozyme L, EMR provided a 3-5× higher volumetric productivity for the smallest POS. Moreover, it gave competitive results even when compared to batch production with a pure endo-galacturonase enzyme, demonstrating its feasibility for efficient POS production.

Composition of black soldier fly prepupae and systematic approaches for extraction and fractionation of proteins, lipids and chitin.

Black soldier fly (BSF, Hermetia illucens) constitutes an economic way to convert residual biomasses into a valuable source of biomolecules, such as proteins, lipids and chitin. The present investigation was undertaken to evaluate the feasibility of applying different extraction protocols, either chemical extractions or enzymatic assisted extraction, to recover pure fat, protein and chitin fractions. First, exact proximate composition, total amino acids, fatty acids profile, and N-acetylglucosamine content of the prepupae samples were determined. BSF prepupae biomass contained, expressed on dry weight, 32% proteins, 37% lipids, 19% minerals, 9% chitin. The lipid fraction was easily recovered by organic solvents, while the most challenging issue was the separation of protein from chitin. The best separation was obtained by alkali extraction of proteins (96% of protein recovered) albeit with loss in their integrity as indicated by the measurement of the degree of hydrolysis with the o-phthaldialdehyde method. To avoid protein damage in alkali media, a stepwise protein extraction adopting milder conditions was also explored based on Osborne fractionation method, allowing the recovery of >85% of BSF high purity and high quality proteins, and the obtainment of chitin-enriched fraction as well. The possibility of using an enzymatic assisted extraction of proteins was also explored, obtaining a maximum nitrogen solubilisation in the best case (with Bacillus licheniformis protease) of about 60%. In this latter case, the chitin fraction obtained also had a significant residual protein content.

Pectin oligosaccharides from sugar beet pulp: molecular characterization and potential prebiotic activity.

Pectin oligosaccharides (POS) have been indicated as a new class of potential prebiotic compounds, which can be produced from pectin-rich food byproducts. In the present study, different technological means of POS production were explored to produce tailor-made POS mixtures starting from sugar beet pulp. The overall POS production process consisted of two steps: the extraction of pectin and the hydrolysis of pectin to tailored POS by combined hydrolysis/fractionation approaches. Different extraction as well as hydrolysis and fractionation methodologies were applied. The obtained POS were characterized for their total galacturonic acid content and, at a deeper level, using a HILIC-ESI/MS methodology, for the POS structure and composition. The composition of POS fractions was studied as a function of the technology used to obtain them. Finally, the potential prebiotic properties of the POS mixtures obtained were thoroughly explored by several in vitro experiments aimed at detecting lactic acid bacteria (LAB) stimulation by POS fractions. Several fractions were very efficient in stimulation, in a species-dependent manner. The overall best fractions were in general those rich in arabinans having a low degree of polymerization, obtained from the enzymatic extraction of biomass and subsequent fractionation with low-medium molecular weight cut-off. Quite interestingly, no POS fraction was able to stimulate pathogenic E. coli strains. The data reported here clearly indicate the possibility to obtain diverse fractions with different prebiotic properties starting from the same biomass, and outline clear potential for POS obtained from sugar beet pulp with the appropriate technology to act as prebiotic compounds.

Enzymatic production of pectic oligosaccharides from onion skins.

Onion skins are evaluated as a new raw material for the enzymatic production of pectic oligosaccharides (POS) with a targeted degree of polymerization (DP). The process is based on a two-stage process consisting of a chelator-based crude pectin extraction followed by a controlled enzymatic hydrolysis. Treatment of the extracted crude onion skin's pectin with various enzymes (EPG-M2, Viscozyme and Pectinase) shows that EPG-M2 is the most appropriate enzyme for tailored POS production. The experiments reveal that the highest amount of DP2 and DP3 is obtained at a time scale of 75-90min with an EPG-M2 concentration of 26IU/mL. At these conditions the production amounts 2.5-3.0% (w/w) d.m for DP2 and 5.5-5.6% (w/w) d.m for DP3 respectively. In contrast, maximum DP4 production of 5.2-5.5% (w/w) d.m. is obtained with 5.2IU/mL at a time scale of 15-30min. Detailed LC-MS analysis reveals the presence of more methylated oligomers compared to acetylated forms in the digests.