Abstract
Sourdough is the oldest form of leavened bread used as early as 2000 BC by the ancient Egyptians. It may have been discovered by accident when wild yeast drifted into dough that had been left out resulting in fermentation of good microorganisms, which made bread with better flavour and texture. The discovery was continued where sourdough was produced as a means of reducing wastage with little known (at that point of time) beneficial effects to health. With the progress and advent of science and technology in nutrition, sourdough fermentation is now known to possess many desirable attributes in terms of health benefits. It has become the focus of attention and practice in modern healthy eating lifestyles when linked to the secret of good health. The sourdough starter is an excellent habitat where natural and wild yeast plus beneficial bacteria grow by ingesting only water and flour. As each sourdough starter is unique, with different activities, populations and interactions of yeast and bacteria due to different ingredients, environment, fermentation time and its carbohydrate fermentation pattern, there is no exact elucidation on the complete make-up of the sourdough microbiome. Some lactic acid bacteria (LAB) strains that are part of the sourdough starter are considered as probiotics which have great potential for improving gastrointestinal health. Hence, from a wide literature surveyed, this paper gives an overview of microbial communities found in different sourdough starters. This review also provides a systematic analysis that identifies, categorises and compares these microbes in the effort of linking them to specific functions, particularly to unlock their health benefits.
Highlights
In the study of Rizzello et al [64], all sourdough starters were harboured with Leuconostoc citreum, Lactobacillus plantarum and Lactococcus lactis, which are almost similar to the microbial profiles of dough prior to fermentation
Aided by the enzyme fructose-1,6-diphosphate aldolase, facultatively heterofermentative lactic acid bacteria (LAB) sometimes fall under the homofermentative group as they digest carbohydrates using the same pathway, i.e., Embden–Meyerhof–Parnas (EMP) as obligately homofermentative LAB, instead of phosphoketolase pathway for obligately heterofermentative LAB [1,71,105]. Both the obligately homofermentative and facultatively heterofermentative LAB dominate the sourdough microbiota when fermentation temperature is above 30 ◦ C, but when the sourdough starter is kept at temperature below 30 ◦ C, it comprises primarily obligately heterofermentative LAB [93]
The dynamics and diversity of microbiomes in sourdough are known to give many benefits to bread and mankind. These are wholesome nutrients and distinctive functions and benefits for health. This provides solutions to a large population whose lifestyle is inclined to eating bread as staple food, as conventional breads are laden with carbohydrate, highly starch-based and contain gluten which may have adverse effects on health
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Scientists have started to discover that the variability in number and type of microbiota in dough depends not just on the native microbial flora of the baker’s environment and hands, and other factors like choice of flour, when and how often the starter is fed, dough hydration level and type of cereal used, leavening temperature, fermentation time and sourdough maintenance temperature [12,13,14]. Each microbial community has the ability to produce unique flavour profile as some yield yoghurt-like flavour from lactic acid while others produce sharper, more vinegary note with acetic acid (https://truesourdough.com/18-ways-tomake-sourdough-bread-more-or-less-sour/, accessed 21 March 2021) [16]. Microbiome in sourdough is affected by various components in different types of flours and dough hydration level, backslopping time, fermentation time and temperature. Improvedproperties properties of Improved ofbread bread (a) Extend shelf life (b) Improve flavour (a)(c)Extend shelf life
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