The study of the microbiotas of 19 Italian sourdoughs used for the manufacture of traditional/typical breads allowed the identification, through a culture-dependent approach, of 20 and 4 species of lactic acid bacteria (LAB) and yeasts, respectively. Numerically, the most frequent LAB isolates were Lactobacillus sanfranciscensis (ca. 28% of the total LAB isolates), Lactobacillus plantarum (ca. 16%), and Lactobacillus paralimentarius (ca. 14%). Saccharomyces cerevisiae was identified in 16 sourdoughs. Candida humilis, Kazachstania barnettii, and Kazachstania exigua were also identified. As shown by principal component analysis (PCA), a correlation was found between the ingredients, especially the type of flour, the microbial community, and the biochemical features of sourdoughs. Triticum durum flours were characterized by the high level of maltose, glucose, fructose, and free amino acids (FAA) correlated with the sole or main presence of obligately heterofermentative LAB, the lowest number of facultatively heterofermentative strains, and the low cell density of yeasts in the mature sourdoughs. This study highlighted, through a comprehensive and comparative approach, the dominant microbiotas of 19 Italian sourdoughs, which determined some of the peculiarities of the resulting traditional/typical Italian breads. During the last decades, European and worldwide consumers have come ever more to appreciate traditional and typical foods. Traditional is the definition used for foods that historically are part of the cultural heritage of people living in a certain geographical area (29a). Typical is the attribute used for a food produced using one or more ingredients having characteristics strictly depending on the geographical area it comes from (9). Mainly due to the long history of regional political division, about 200 different types of bread are manufactured throughout Italy with large differences of recipes and traditions (24). Some breads have already received the Protected Designation of Origin (PDO) (Pane di Altamura and Pagnotta del Dittaino) or the Protected Geographical Indication (PGI) (Pane di Matera, Pane Casareccio di Genzano, and Coppia Ferrarese). In spite of the differences, almost all traditional/typical Italian breads use sourdough as the natural starter. Sourdough represents a very complex biological ecosystem (19) where yeasts and, especially, lactic acid bacteria (LAB) largely determine the sensory, technology, nutritional, and functional features of the resulting baked goods (20). In mature sourdoughs, LAB occur in numbers Ͼ10 8 CFU g Ϫ1 , whereas the number of yeasts is at least one order of magnitude lower (19). The microbial composition of the sourdough was subjected to numerous studies which have revealed a large species diversity (for reviews, see references 15, 16, 22, and 43). Overall, Lactobacillus brevis, Lactobacillus paralimentarius, Lactobacillus plantarum, Lactobacillus rossiae, and Lactobacillus sanfranciscensis dominate sourdough processes that are characterized by low incubation t...

This work was aimed at decreasing the glycaemic index (GI) of white wheat bread. Breads made with wheat flour (WF) or wholemeal flour (WMF) and fermented with baker's yeast had similar values of resistant starch (RS; 1·4 -1·7 %, starch basis). Sourdough Lactobacillus plantarum P1 and Lactobacillus brevis P2 favoured the highest formation of RS (approximately 5 %) when fermented with WF and WMF. The mixture (1:1) of WF and WMF (WF/WMF) was selected. The effect of dietary fibres, chemical or sourdough acidification on the hydrolysis index (HI) of WF/WMF bread was determined. Among fibres, only the addition of oat fibre (5 %) decreased the HI to 90·84 %. Lactic acid determined the lowest HI, and the effect was related to the decrease of pH. For the same decrease of pH, breads fermented with L. plantarum P1 and L. brevis P2 (sourdough WF/ WMF) showed values of HI lower than chemical acidification. The glucose response and GI of WF bread or sourdough WF/WMF bread enriched with oat fibre was determined by using fifteen healthy volunteers. Anhydrous glucose was used as reference. The area under the glucose response curve and the value of GI (72 %) of WF bread were significantly (P, 0·05) higher than sourdough WF/WMF bread enriched with oat fibre (GI ¼ 53·7 %). The decrease of GI of the sourdough WF/WMF bread may be due to both fibre content and decreased pH. Compared to WMF bread, sourdough WF/WMF bread, enriched with oat fibre, had higher specific volume, better cell crumb structure and more appreciated acidulous smell, taste and aroma.Glycaemic index: White wheat bread: Lactobacilli: Oat fibreThe glycaemic index (GI) is the measure of the power of food to raise the concentration of B-glucose in the blood after a meal. GI is defined as the ratio between the incremental area under the B-glucose response curve of the tested meal containing 50 g digestible carbohydrates and the incremental area under the B-glucose response curve of the standard food, i.e. 50 g pure glucose. Overall, carbohydrates that break down quickly during digestion have a high GI since their B-glucose response is fast and high. Carbohydrates that break down slowly have a low GI 1 .Several large-scale, observational studies from Harvard University (Cambridge, MA, USA) indicate that long-term consumption of a diet with high glycaemic load (GI £ dietary carbohydrate content) is a significant independent predictor of the risk of developing type 2 diabetes 2,3 and CVD 4 . More recently, evidence has been accumulating that a low-GI diet might protect against development of obesity 5 , colon cancer and breast cancer 6 . The mechanisms of protection of the low-GI diet may derive from: (1) the slow release of carbohydrates in the upper gastrointestinal tract; (2) the lowering of the insulin demand 7 ; and (3) the generally high concentration of indigestible carbohydrates such as dietary fibre and resistance starch (RS), which, in turn, increase the fermentative activity at the colon level. This latter fermentative activity increases the synthesis of propioni...

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