Effect of bioprocessing of wheat bran in wholemeal wheat breads on the colonic SCFA production in vitro and postprandial plasma concentrations in men.

The health benefits of whole grain consumption can be partly attributed to the inclusion of the bran or outer-layers of the grain rich in dietary fibre. Fibre is fermented in the colon, leading to the production of beneficial metabolites, such as short-chain fatty acids (SCFA). The effect of five different types of bread on the SCFA production was studied in an in vitro model of human colon.

Bioprocessing of wheat bran in whole wheat bread increases the bioavailability of phenolic acids in men and exerts antiinflammatory effects ex vivo.

Whole grain consumption has been linked to a lower risk of metabolic syndrome, which is normally associated with a low-grade chronic inflammation. The benefits of whole grain are in part related to the inclusion of the bran, rich in phenolic acids and fiber. However, the phenols are poorly bioaccessible from the cereal matrix.

Crosslinking food proteins for improved functionality.

Different possibilities for protein crosslinking are examined in this review, with special emphasis on enzymatic crosslinking and its impact on food structure. Among potential enzymes for protein crosslinking are transglutaminase (TG) and various oxidative enzymes. Crosslinking enzymes can be applied in cereal, dairy, meat, and fish processing to improve the texture of the product.

Extensive dry ball milling of wheat and rye bran leads to in situ production of arabinoxylan oligosaccharides through nanoscale fragmentation.

This study investigated the potential of ball milling as a dry process for in situ production of arabinoxylan oligosaccharides (AXOS) in arabinoxylan (AX)-rich wheat and rye bran. An extensive lab-scale ball mill treatment (120 h, 50% jar volume capacity) increased the wheat bran water-extractable arabinoxylan (WE-AX) level from 4% (untreated bran) to 61% of the wheat bran AX. Extractable AX fragments had an arabinose/xylose ratio (A/X ratio) of 0.

Bioprocessing of wheat bran improves in vitro bioaccessibility and colonic metabolism of phenolic compounds.

Ferulic acid (FA) is the most abundant phenolic compound in wheat grain, mainly located in the bran. However, its bioaccessibility from the bran matrix is extremely low. Different bioprocessing techniques involving fermentation or enzymatic and fermentation treatments of wheat bran were developed aiming at improving the bioaccessibility of phenolic compounds in bran-containing breads.

Formation of protein-oligosaccharide conjugates by laccase and tyrosinase.

Proteins and certain carbohydrates contain phenolic moieties, which are potential sites for modification of the function of the biopolymers. In this study, the capability of two different fungal oxidative enzymes, laccase from Trametes hirsuta (ThL) and tyrosinase from Trichoderma reesei (TrT), to catalyze formation of hetero-cross-linking between tyrosine side chains of alpha-casein and phenolic acids of hydrolyzed oat spelt xylan (hOSX) was studied. Formation of reaction products was followed by size exclusion chromatography (SEC), fluorescence spectroscopy, and SDS-PAGE, using specific staining methods for proteins and protein-carbohydrate conjugates.

Oxidation of peptides and proteins by Trichoderma reesei and Agaricus bisporus tyrosinases.

The capability of a novel tyrosinase from Trichoderma reesei (TrTyr) to catalyse the oxidation and oxidative cross-linking of l-tyrosine (l-Y) and tyrosine side-chains in GYG and EGVYVHPV peptides, in bovine serum albumin (BSA) and beta-casein proteins as well as in proteinaceous wool fibres was studied by oxygen consumption measurement, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), reverse phase high-performance liquid chromatography (RP-HPLC), matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and fluorescence microscopy. TrTyr was compared to the well-characterised tyrosinase from Agaricus bisporus (AbTyr) in terms of oxidation and cross-linking. According to the results obtained TrTyr was capable of cross-linking peptides and proteins more efficiently than AbTyr.

Comparison of the characteristics of fungal and plant tyrosinases.

Enzymatic crosslinking provides valuable means for modifying functionality and structural properties of different polymers. Tyrosinases catalyze the hydroxylation of various monophenols to the corresponding o-diphenols, and the subsequent oxidation of o-diphenols to the corresponding quinones, which are highly reactive and can further undergo non-enzymatic reactions to produce mixed melanins and heterogeneous polymers. Tyrosinases are also capable of oxidizing protein- and peptide-bound tyrosyl residues, resulting in the formation of inter- and intra-molecular crosslinks.

Elucidating the mechanism of laccase and tyrosinase in wheat bread making.

Cross-linking enzymes generate covalent bonds in and between food biopolymers. These enzymes are interesting tools for tailoring dough and bread structures, as the characteristics of the biopolymers significantly determine the viscoelastic and fracture properties of dough and bread. In this study, the influence of oxidative cross-linking enzymes, tyrosinase from the filamentous fungus Trichoderma reesei and laccase from the white rot fungus Trametes hirsuta, on dough and bread were examined.

Expression of the Trichoderma reesei tyrosinase 2 in Pichia pastoris: isotopic labeling and physicochemical characterization.

Trichoderma reesei tyrosinase TYR2 has been demonstrated to be able to oxidize various phenolic compounds and also peptide and protein bound tyrosine, and thus is of great interest for different biotechnological applications. In order to understand the reaction mechanism of the enzyme it would be essential to solve its three dimensional structure. Pichia pastoris is a suitable expression system for the production of recombinant enzymes for NMR studies and therefore we expressed TYR2 in this host.

Production and characterization of a secreted, C-terminally processed tyrosinase from the filamentous fungus Trichoderma reesei.

A homology search of the genome database of the filamentous fungus Trichoderma reesei identified a new T. reesei tyrosinase gene tyr2, encoding a protein with a putative signal sequence. The gene was overexpressed in the native host under the strong cbh1 promoter, and the tyrosinase enzyme was secreted into the culture supernatant.