How cereal flours, starters, enzymes, and process parameters affect the in vitro digestibility of sourdough bread.

Digestibility of leavened baked goods relies on multiple factors: starch bioavailability and protein hydrolysis during food processing and digestion, presence of antinutritional factors, and satiety and gastrointestinal symptoms after intake. Several studies highlighted that bread digestibility might be positively affected by long-time sourdough fermentation. Nevertheless, most research is focused on single factors and their effect on digestibility, excluding the potential complementary effects of more than one factor. In this work, a multitude of factors influencing the the in vitro starch and protein digestibility and predicted glycemic index were assessed simultaneously. Forty-six different breads made with various raw material/ingredients (flour, enzymes, lactic acid bacteria cytoplasmic extracts and gluten), type of sourdoughs (fresh or commercial liquid or dried), strains of lactic acid bacteria and yeasts, and time and temperature of fermentation, were preliminarily investigated. Further selection of optimal conditions was based on statistical analysis and final breads were further characterized for their peptide profiles, total free amino acids and quality indexes of the digestible protein fraction. Among the factors considered, results identified a claimed in vitro digestibility for breads made with whole wheat, spelt, and rye flours, obtained with lactic acid bacteria strains selected for the peptidase activity, added of fungal proteases, and fermented at the optimal temperature of 37 °C.

Commercial Organic Versus Conventional Whole Rye and Wheat Flours for Making Sourdough Bread: Safety, Nutritional, and Sensory Implications.

Organic farming is gaining a broad recognition as sustainable system, and consumer demand for organic products has increased dramatically in the recent past. Whether organic agriculture delivers overall advantages over conventional agriculture is, however, contentious. Here, the safety, nutritional, and sensory implications of using commercial organic rye, soft, and durum wheat flours rather than conventional-made sourdough bread have been investigated. Culture-dependent and culture-independent approaches were used to explore the microbial architecture of flours and to study their dynamics during sourdough propagation. Besides biochemical features, the main nutritional (amino acid content, asparagine level, and antioxidant activity) characteristics of sourdoughs were investigated, and their effect on the structural, nutritional, and sensory profiles of breads assessed. Overall, the organic farming system led to flours characterized by lower content of asparagine and cell density of Enterobacteriaceae while showing higher concentration of total free amino acids. Differences of the flours mirrored those of sourdoughs and breads. The use of sourdough fermentation guaranteed a further improvement of the flour characteristics; however, a microbial and sensory profile simplification as well as a slight decrease of the biochemical parameters was observed between breads with sourdough after one-cycle fermentation and 10 days of propagation.

Sourdough Fermented Breads are More Digestible than Those Started with Baker's Yeast Alone: An In Vivo Challenge Dissecting Distinct Gastrointestinal Responses.

As a staple food, bread digestibility deserves a marked nutritional interest. Combining wide-spectrum characterization of breads, in vitro nutritional indices, and in vivo postprandial markers of gastrointestinal function, we aimed at comparing the digestibility of sourdough and baker's yeast breads. Microbiological and biochemical data showed the representativeness of the baker´s yeast bread (BYB) and the two sourdough breads (SB and t-SB, mainly differing for the time of fermentation) manufactured at semi-industrial level. All in vitro nutritional indices had the highest scores for sourdough breads. Thirty-six healthy volunteers underwent an in vivo challenge in response to bread ingestion, while monitoring gallbladder, stomach, and oro-cecal motility. SB, made with moderate sourdough acidification, stimulated more appetite and induced lower satiety. t-SB, having the most intense acidic taste, induced the highest fullness perception in the shortest time. Gallbladder response did not differ among breads, while gastric emptying was faster with sourdough breads. Oro-cecal transit was prolonged for BYB and faster for sourdough breads, especially when made with traditional and long-time fermentation (t-SB), whose transit lasted ca. 20 min less than BYB. Differences in carbohydrate digestibility and absorption determined different post-prandial glycaemia responses. Sourdough breads had the lowest values. After ingesting sourdough breads, which had a concentration of total free amino acids markedly higher than that of BYB, the levels in blood plasma were maintained at constantly high levels for extended time.