Biotechnological Treatments of Gluten and Gluten-Free Flours to Improve Dough Texture Properties and Aroma Profiles of the Product

This project is focused on the improvement of gluten and gluten-free bakery products using a new biotechnological process based on the combined use of a protein cross-linking enzyme, microbial transglutaminase from Streptoverticillum mobaraense and, a selected microbial consortium of lactic acid bacteria and yeasts (i. e. selected strains of Lactobacillus sanfrancisciensis and Candida milleri). The transglutaminase enzyme is studied for its ability to organize and create protein networks allowing an improvement of the structure and texture of the dough made from different flours. The microbial consortium is selected for its capacity to produce interesting metabolites which leads effect on the sensory, rheological and shelf-life features of the final product. The novelty behind the rational plan is the evaluation of the consequence of the two biological agents in combination, exploiting the beneficial and technological effects of both. Even the use of different plant sources as a substrates, belong to cereals, pseudo-cereals and legumes allowing us to well understand significant effects in the process. At molecular level, the proteins rearrangement after enzymatic treatment, was investigated by sodium dodecyl sulphate-poly acrylamide gel electrophoresis and biochemical colorimetric tests. The microbiological analysis was conducted in order to study the adaptability of the microbial consortium to sourdough prepared from unconventional flours. Bacteriological cultures and microbiological methods were used. In order to evaluate the sourdough metabolic activity and the fermentation process, volatile compounds were detected and analysed by Gas Chromatography–Mass Spectrometry coupled with solid-phase micro-extraction technique. Moreover, the synergic combination of transglutaminase and sourdough fermentation has been evaluated in order to define their effects on the technological properties. Rheological properties and crumb grain features were measured by Texture profile analysis (TPA), stress relaxation tests and Image analysis. Finally, allergenic potential of the processed product was determined by immunological analysis

New bread formulation with improved rheological properties and longer shelf-life by the combined use of transglutaminase and sourdough

The combined use of the protein reticulating enzyme transglutaminase (TGase) and a selected microbial consortium of Lactobacillus sanfranciscensis and Candida milleri for improving the rheological properties, aroma, and shelf-life of a bakery product was evaluated. A microbial TGase, showing the highest activity over a wide temperature range on different protein substrates, was selected among different types. Results showed that this TGase was able to produce isodipeptide bonds, especially in the gluten fraction, leading to the formation of protein aggregates, which improved the structure of a sourdough bakery product. The microbial TGase in combination with sourdough exhibited a positive synergistic effect allowing the production of flavor-enriched bread, with rheological properties similar to those of standard bread

Combination of transglutaminase and sourdough on gluten-free flours to improve dough structure

The aim of this work was to evaluate the effects of microbial transglutaminase (mTG) and sourdough on gluten-free (GF) flours. Besides deamidation and incorporation of amines, mTG catalyses protein cross-links, modifying dough structure. Sourdough from lactic acid bacteria (LAB) and yeast modifies dough protein composition, determining proteolysis, which induce the formation of aroma precursor metabolites. The chemical-physical interactions of volatile molecules with various constituents of the matrix affect the retention of aroma compounds. Here, the effect on volatile molecule profiles and on protein networks formation after mTG treatment in sourdoughs obtained with four GF flours belonging to cereals, pseudo-cereals and legumes (rice, corn, amaranth and lentil) was investigated. Sourdough was prepared with a two-step fermentation using Lactobacillus sanfrancisciensis (LSCE1) and Candida milleri (PFL44), then mTG was added after 21\ua0h of fermentation at increasing levels. The results showed that mTG had the capacity to modify GF flour proteins and improve protein networks formation, involving mainly the prolamin protein fraction. This is particularly relevant for the production of GF backed goods generally lacking of technological, structural and sensorial features compared with products obtained with wheat flour sourdough fermentation. Interestingly, mTG treatment of sourdough affected also the volatile composition and indeed possibly the final organoleptic properties of the products

Immunoreactivity of Gluten-Sensitized Sera Toward Wheat, Rice, Corn, and Amaranth Flour Proteins Treated With Microbial Transglutaminase

The aim of this study was to analyze the effects of microbial transglutaminase (mTG) on the immunoreactivity of wheat and gluten-free cereals flours to the sera of patients with celiac disease (CD) and non-celiac gluten sensitivity (NCGS). Both doughs and sourdoughs, the latter prepared by a two-step fermentation with Lactobacillus sanfranciscensis and Candida milleri, were studied. In order to evaluate the IgG-binding capacity toward the proteins of the studied flours, total protein as well as protein fractions enriched in albumins/globulins, prolamins and glutelins, were analyzed by SDS-PAGE and enzyme-linked immunosorbent assay (ELISA). Results showed that while mTG modified both gluten and gluten-free flour by increasing the amount of cross-linked proteins, it did not affect the serum's immune-recognition. In fact, no significant differences were observed in the immunoreactivity of sera from CD and NCGS patients toward wheat and gluten-free protein extracts after enzyme treatment, nor did this biotechnological treatment affect the immunoreactivity of control samples or the sera of healthy patients. These results suggest that mTG may be used as a tool to create innovative gluten and gluten-free products with improved structural properties, without increasing the immune-reactivity toward proteins present either in doughs or in sourdoughs.(VLID)356938