Reference Number: 137
Lactic Acid Bacteria: Prevalence
Flavour compounds are key elements for consumer acceptance and product identification in bread. One category of speciality breads, the sourdoughs have a fermentation process affected by a complex microflora of yeasts and lactic acid bacteria which confer specific flavour characteristics. Although yeasts have the primary leavening role, lactic acid bacteria (LAB), with trophic and non-trophic relationships, produce important flavour components. Sourdoughs are becoming important as consumers move away from pan breads towards speciality products. However, successful new product development requires an understanding of variations in carbohydrates’ metabolism, roles of endogenous enzymes and interactions of microorganisms for generation of non-volatile and volatile flavour compounds. The potential of sourdough baking remains to be developed through specifications and optimisations of process conditions and introduction of exogenous enzymes and other ingredients. With effective new product development sourdough characteristics could be matched to relate with consumer tastes.
SIGNIFICANCE OF THIS STUDY
In sourdoughs, the interactions between microbial strains and ingredients, fermentation temperature, pH and leavening time have all been shown to influence the flavour and aroma of sourdough bread. Flavour-active compounds are produced by LAB and yeasts individually and through their interactions. For example, heterofermentative LAB mainly produce ethyl acetate and certain alcohols and aldehydes, whereas homofermentative LAB synthesise diacetyl and other carbonyls. In contrast, iso-alcohols are products of yeast fermentation but may contribute little towards the final bread flavour compared to other volatile compounds. The current paper showed that the addition of fructose/glucose/maltose or citrate to the dough increases LAB contributions to volatile formation in baking and Maillard and Caramelization reactions are also responsible for flavour formation in the sourdough bread making process.