Reference Number: 29
Year: 1997
Link: Link to original paper
Lactic Acid Bacteria: Heterofermentative | Homofermentative | Prevalence
Yeast: Saccharomyces cerevisiae | Saccharomyces exiguous (Torulopsis holmii)
Summary
Summary
Lactobacillus sanfrancisco, named after the city from where the sourdough micro- organism was first isolated, is an obligatory heterofermentative Lactobacillus with phylo- genetic relationship to the Lactobacillis casei. It was first isolated by Kline and Sugihara (1971) and subsequently revised by Weiss and Schillinger (1984) for inclusion in Approved List of Bacterial Names. Lb. sanfrancisco growth is very fastidious: it requires fresh yeast extractives, unsatu- rated fatty acids (mainly oleic acid) and it preferentially ferments maltose rather than glucose. Occasionally, strains that ferment sucrose, ribose, gluconate, galactose, raffinose or fructose have been identified. Lb. sanfrancisco has been widely isolated from rye and wheat sourdoughs of several bread-producing areas and from sourdoughs used to make Panettone.
SIGNIFICANCE OF THIS STUDY
In this paper, research on Lactobacillus sanfrancisco, a key sourdough lactic acid bacterium is reviewed. Marco Gobbetti and others have found that the association between Lb. sanfrancisco and Saccharomyces exiguus is typical in the production of breads such as the San Francisco French bread and Panettone. The association between Lb. sanfrancisco and Saccharomyces cerevisiae has been studied in sourdoughs from different countries and research has shown that both the bacterial and yeast species share a relationship based on nutritional exchange. For example, the consumption of soluble carbohydrates and the subsequent energy yield of Lb. sanfrancisco are greatly influenced by the associated yeasts and vary according to the type of sugars present in the flour mixture. The current paper provides a comprehensive understanding of the type of relationship shared by Lb. sanfrancisco and the different yeast species which is key in understanding the dynamics of the sourdough process and the conditions that determine the final flavour and texture of your sourdough bakes.