Lactic acid bacteria microbiota in faba bean sourdough fermentation

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http://urn.fi/URN:NBN:fi:hulib-201611092981
Title: Lactic acid bacteria microbiota in faba bean sourdough fermentation
Author: Kianjam, Maryam
Contributor: University of Helsinki, Faculty of Agriculture and Forestry, Department of Food and Environmental Sciences
Publisher: Helsingfors universitet
Date: 2016
Language: eng
URI: http://urn.fi/URN:NBN:fi:hulib-201611092981
http://hdl.handle.net/10138/169774
Thesis level: master's thesis
Discipline: Food Science
Food Science
Food Science
Abstract: The literature review deals with faba bean and the important effects of lactic acid bacteria (LAB) fermentation on legumes. Particularly, the information about sourdough and LAB microbiota together with the main factors affecting sourdough microbial community is presented. A brief introduction regarding the methods used for LAB identification is also given. The main aim of the experimental study was to identify LAB microbiota in faba bean sourdoughs of two different varieties during backslopping procedure. Doughs from Italian (I) and Finnish (F) faba bean flours were spontaneously fermented and propagated daily through backslopping on a laboratory scale for 14 days. Samples were taken from selected propagation times (0, 1, 2, 5, 7, and 14) for microbiological and biochemical analyses. The pH values and total titratable acidity (TTA) were monitored throughout the process. Analyses of organic acids and oligosaccharides of selected samples were carried out with HPLC methods at University of Bari, Italy. The identity of the LAB isolates was revealed by sequence analysis of 16S rDNA and the differentiation of LAB strains was analyzed by randomly amplified polymorphic DNA (RAPD)-PCR. Minor changes occurred between I and F sourdoughs based on microbiological and biochemical analyses. However, several differences were found in LAB diversity between these two sourdoughs. More variety of LAB species and higher strains diversity were found in F faba bean sourdough. Besides Pediococcus pentosaceus, Leuconostoc mesenteroides, and Weissella koreensis identified in both sourdoughs, Enterococcus casseliflavus, Enterococcus faecium, Lactobacillus sakei, Lactococcus lactis, and Weissella cibaria were only detected in F sourdough. In both sourdoughs, Pediococcus pentosaceus was predominant and persistent. Also, Leuconostoc mesenteroides was found as second frequent species in both sourdoughs. According to all analyses, the maturity of sourdoughs was achieved during 5 days of propagation. This study demonstrated the importance of flour type and composition on establishing microbial ecology of sourdough. The research study encourages exploring the potential of faba bean flour in sourdough-type fermentation and encourages further investigations on the identified isolates as starter cultures for fermented faba beans and faba bean-cereal products.
Subject: Faba bean
fermentation
sourdough
lactic acid bacteria


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