title: Diversity of the lactic acid bacterium and yeast microbiota in the switch from firm- to liquid-sourdough fermentation.
abstract: Four traditional type I sourdoughs were comparatively propagated (28 days) under firm (dough yield, 160) and liquid (dough yield, 280) conditions to mimic the alternative technology options frequently used for making baked goods. After 28 days of propagation, liquid sourdoughs had the lowest pH and total titratable acidity (TTA), the lowest concentrations of lactic and acetic acids and free amino acids, and the most stable density of presumptive lactic acid bacteria. The cell density of yeasts was the highest in liquid sourdoughs. Liquid sourdoughs showed simplified microbial diversity and harbored a low number of strains, which were persistent. Lactobacillus plantarum dominated firm sourdoughs over time. Leuconostoc lactis and Lactobacillus brevis dominated only some firm sourdoughs, and Lactobacillus sanfranciscensis persisted for some time only in some firm sourdoughs. Leuconostoc citreum persisted in all firm and liquid sourdoughs, and it was the only species detected in liquid sourdoughs at all times; it was flanked by Leuconostoc mesenteroides in some sourdoughs. Saccharomyces cerevisiae, Candida humilis, Saccharomyces servazzii, Saccharomyces bayanus-Kazachstania sp., and Torulaspora delbrueckii were variously identified in firm and liquid sourdoughs. A total of 197 volatile components were identified through purge and trap-/solid-phase microextraction-gas chromatography-mass spectrometry (PT-/SPME-GC-MS). Aldehydes, several alcohols, and some esters were at the highest levels in liquid sourdoughs. Firm sourdoughs mainly contained ethyl acetate, acetic acid, some sulfur compounds, and terpenes. The use of liquid fermentation would change the main microbial and biochemical features of traditional baked goods, which have been manufactured under firm conditions for a long time.
authors.affiliation: Department of Soil, Plant and Food Sciences, University of Bari A. Moro, Bari, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Di Cagno
authors.forename: Erica
authors.initials: E
authors.lastname: Pontonio
authors.forename: Solange
authors.initials: S
authors.lastname: Buchin
authors.forename: Maria
authors.initials: M
authors.lastname: De Angelis
authors.forename: Anna
authors.initials: A
authors.lastname: Lattanzi
authors.forename: Francesca
authors.initials: F
authors.lastname: Valerio
authors.forename: Marco
authors.initials: M
authors.lastname: Gobbetti
authors.forename: Maria
authors.initials: M
authors.lastname: Calasso
mesh_terms: D044822:Biodiversity; D001939:Bread / Q000032:analysis / Q000382:microbiology*; D005285:Fermentation; D005511:Food Handling; D019344:Lactic Acid / Q000032:analysis / Q000378:metabolism; D007778:Lactobacillus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D064307:Microbiota; D014908:Triticum / Q000382:microbiology*; D015003:Yeasts / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D019344:Lactic Acid