Quantification of morphochemical changes during in situ enzymatic hydrolysis of individual biomass particles based on autofluorescence imaging.

Enzymatic hydrolysis of biomass is an established method for producing biofuels. Lignocellulosic biomass such as corn stover is very inhomogeneous material with big variation on conversion rates between individual particles therefore leading to variable recalcitrance results. In this study, we used noninvasive optical microscopy techniques, such as two-photon microscopy and fluorescence lifetime imaging microscopy, to visualize and analyze morphological and chemical changes of individual corn stover particles pretreated with sulfuric acid during hydrolysis.

Biomass Pretreatment and Enzymatic Hydrolysis Dynamics Analysis Based on Particle Size Imaging.

Parameters such as pretreatment method, enzyme type and concentration, determine the conversion efficiency of biomass' cellulose and hemicellulose to glucose and mainly xylose in biomass-based fuel production. Chemical quantification of these processes offers no information on the effect of enzymatic hydrolysis (EH) on particle morphology. We report on the development of a microscopy method for imaging pretreated biomass particles at different EH stages.

The two Rasamsonia emersonii α-glucuronidases, ReGH67 and ReGH115, show a different mode-of-action towards glucuronoxylan and glucuronoxylo-oligosaccharides.

Background: The production of biofuels and biochemicals from grass-type plant biomass requires a complete utilisation of the plant cellulose and hemicellulosic xylan via enzymatic degradation to their constituent monosaccharides. Generally, physical and/or thermochemical pretreatments are performed to enable access for the subsequent added carbohydrate-degrading enzymes. Nevertheless, partly substituted xylan structures remain after pretreatment, in particular the ones substituted with (4-O-methyl-)glucuronic acids (UAme).

Enzyme resistant feruloylated xylooligomer analogues from thermochemically treated corn fiber contain large side chains, ethyl glycosides and novel sites of acetylation.

In order to use corn fiber as a source for bioethanol production the enzymatic hydrolysis of the complex glucuronoarabinoxylans present has to be improved. Several oligosaccharides present in the supernatant of mild acid pretreated and enzymatically saccharified corn fiber that resist the current available enzymes were (semi)purified for structural analysis by NMR or ESI-MS(n). The structural features of 21 recalcitrant oligosaccharides are presented.

Fast and robust method to determine phenoyl and acetyl esters of polysaccharides by quantitative ¹H NMR.

The acetyl (AcE), feruloyl (FE), and p-coumaroyl (pCE) ester contents of different cereal and grass polysaccharides were determined by a quantitative ¹H NMR-based method. The repeatability and the robustness of the method were demonstrated by analyzing different plant polysaccharide preparations. Good sensitivity and selectivity for AcE, FE, and pCE were observed.

Characterization of oligomeric xylan structures from corn fiber resistant to pretreatment and simultaneous saccharification and fermentation.

Corn fiber, a byproduct from the corn industry, would be a good source for bioethanol production if the hemicellulose, consisting of polymeric glucoronoarabinoxylans, can be degraded into fermentable sugars. Structural knowledge of the hemicellulose is needed to improve the enzymatic hydrolyses of corn fiber. Oligosaccharides that resisted a mild acid pretreatment and subsequent enzymatic hydrolysis, representing 50% of the starting material, were fractionated on reversed phase and size exclusion material and characterized.

Some phenolic compounds increase the nitric oxide level in endothelial cells in vitro.

The vasorelaxing properties of chocolate and wine might relate to the presence of phenolic compounds. One of the potential mechanisms involved is stimulation of endothelial nitric oxide (NO) production, as NO is a major regulator of vasodilatation. This study aimed to develop an in vitro assay using the hybrid human endothelial cell line EA.

Combined normal-phase and reversed-phase liquid chromatography/ESI-MS as a tool to determine the molecular diversity of A-type procyanidins in peanut skins.

Peanut skins, a byproduct of the peanut butter industry, are a rich source of proanthocyanidins, which might be used in food supplements. Data on the molecular diversity of proanthocyanidins in peanut skins is limited and conflicting with respect to the ratio of double- (A-type) versus single-linked (B-type) flavan-3-ol units. NP- and RP-HPLC-MS were used as tools to analyze the molecular diversity of proanthocyanidins in a 20% (v/v) methanol extract of peanut skins.

Procyanidin dimers A1, A2, and B2 are absorbed without conjugation or methylation from the small intestine of rats.

Intervention studies with procyanidin (PC)-rich extracts and products such as cocoa and wine suggest protective effects of PC against cardiovascular diseases. However, there is no consensus on the absorption and metabolism of PC dimers. Interestingly, nothing is known about the absorption of A-type PC.

Procyanidin dimers are metabolized by human microbiota with 2-(3,4-dihydroxyphenyl)acetic acid and 5-(3,4-dihydroxyphenyl)-gamma-valerolactone as the major metabolites.

Procyanidins (PCs) are highly abundant phenolic compounds in the human diet and might be responsible for the health effects of chocolate and wine. Due to low absorption of intact PCs, microbial metabolism might play an important role. So far, only a few studies, with crude extracts rich in PCs but also containing a multitude of other phenolic compounds, have been performed to reveal human microbial PC metabolites.