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.