Effects of laccase and xylanase on the chemical and rheological properties of oat and wheat doughs.

The effects of Trametes hirsuta laccase and Pentopan Mono BG xylanase and their combination on oat, wheat, and mixed oat-wheat doughs and the corresponding breads were investigated. Laccase treatment decreased the content of water-extractable arabinoxylan (WEAX) in oat dough due to oxidative cross-linking of feruloylated arabinoxylans. Laccase treatment also increased the proportion of water-soluble polysaccharides (WSNSP) apparently due to the beta-glucanase side activity present in the laccase preparation.

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.

Effect of protein structure on laccase-catalyzed protein oligomerization.

Laccase-catalyzed oligomerization of proteins was studied using Trametes hirsuta laccase (ThL) and coactosin as a model system. The reaction mechanism was elucidated using free amino acids and the tripeptide Gly-Leu-Tyr as substrates. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and high-performance liquid chromatography (HPLC) as well as oxygen consumption measurements and SDS-PAGE were used to study the reactions.

Dietary carbohydrate modification enhances insulin secretion in persons with the metabolic syndrome.

Background: The metabolic syndrome markedly increases the risk of type 2 diabetes and cardiovascular disease, but the influence of dietary modification on insulin and glucose metabolism independent of weight loss is still poorly understood.

Objective: Our aim was to test whether carbohydrate dietary modifications improve insulin sensitivity and secretion and glucose tolerance in overweight or obese persons with the metabolic syndrome, even in the absence of weight loss.

Design: We assessed the effect of carbohydrate modification on insulin and glucose metabolism in 72 overweight or obese men and women with the metabolic syndrome, as determined according to the National Cholesterol Education Program criteria.

Kinetics of transglutaminase-induced cross-linking of wheat proteins in dough.

The effects of TGase in dough after 15, 30, 45, and 60 min of resting time after mixing were studied with a Kieffer test. The resistance to stretching of control dough did not change greatly during the 60 min time period after mixing. In dough, TGase decreased extensibility and increased resistance to stretching and this change was already observed after the first 15 min (first measurement).

Structural differences between rye and wheat breads but not total fiber content may explain the lower postprandial insulin response to rye bread.

Background: Rye bread has a beneficial effect on the postprandial insulin response in healthy subjects. The role of rye fiber in insulin and glucose metabolism is not known.

Objective: The aim of the study was to determine the effect of the content of rye fiber in rye breads on postprandial insulin and glucose responses.