|Tipo di tesi||Tesi di laurea magistrale|
|Autore||DI TANA, SILVIA|
|Titolo||caratterizzazione molecolare e microbiologica di una comunità microbica di un impasto acido senza glutine e valutazione della produzione di esopolisaccaridi.|
|Titolo in inglese||molecular and microbiological characterization of a microbial community of a gluten-free sourdough and evaluation of the production of exopolysaccharides.|
|Struttura||Dipartimento di Scienze della Vita|
|Corso di studi||CONTROLLO E SICUREZZA DEGLI ALIMENTI (D.M.270/04) (RE)|
|Data inizio appello||2021-04-15|
|Disponibilità||Accessibile via web (tutti i file della tesi sono accessibili)|
L’uso del lievito naturale per la produzione di prodotti da forno, risale fin dall’antichità ai tempi degli egizi. Nonostante sia stato sostituito dal lievito di birra, negli ultimi anni si sta riscoprendo il suo uso poiché migliora non solo la qualità fisica e sensoriale del prodotto da forno tradizionale ma anche la qualità dei prodotti da forno senza glutine che in commercio si presentano insipidi, privi di volume e con scarsa consistenza.
The use of sourdough for the production of bakery products dates back to ancient times to the times of the Egyptians. Although it has been replaced by yeast, in recent years it is being rediscovered its use because it improves not only the physical and sensory quality of the traditional baked product but also the quality of gluten-free bakery products which are on the market tasteless, lacking in volume and lacking in consistency. Three are the different sourdoughs and the first is the one that is most frequently used in production processes to obtain a unique and high-quality product. Exogenous factors (temperature, redox potential, water content and duration of the fermentation process) and endogenous factors (chemical and enzymatic composition of flour) greatly affect the stability and balance of the microflora of sourdough. Among microorganisms, lactic bacteria (LAB) are one of the most dominant species of microflora and, thanks to their characteristics, positively influence the quality of the product. In fact, they have several roles including: contributing to acidifying the medium, reducing the concentration of anti-nutrient factors such as phytic acid and characterizing the sensory profile of the product. Not only that, they also have antimicrobial activity, anifungal activity and especially the ability to produce exopolysaccharides that are natural hydrocolloids that thanks to their structure contribute to strengthen the gluten network or to replace it in a gluten-free product. This experimental study is part of a larger project divided into two parts. In the first part, the microflora of a gluten-free sourdough based on rice flour was investigated, proceeding first with a chemical-physical analysis and continuing with a characterization both phenotypic and molecular in order to identify and characterize the dominant strains of the microbiota. Instead, my thesis work was done on the second part consisting of two objectives. The first was to carry out a screening of lactic bacteria previously identified to identify the best strains producing exoplisaccharides. While the second goal was to always carry out a screening of the same lactic bacteria to evaluate antifungal activity against Aspergillus Niger, Penicillium paneum, Aspergillus flavus and Fusarium graminearum are the main fungi found in contaminated bakery products.