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Use of sourdough is of expanding interest for improvement of flavour, structure and stability of baked goods. Cereal fermentations also show significant potential in improvement and design of the nutritional quality and health effects of foods and ingredients. In addition to improving the sensory quality of whole grain, fibre-rich or gluten-free products, sourdough can also actively retard starch digestibility leading to low glycemic responses, modulate levels and bioaccessibility of bioactive compounds, and improve mineral bioavailability. Cereal fermentation may produce non-digestible polysaccharides, or modify accessibility of the grain fibre complex to gut microbiota. It has also been suggested that degradation of gluten may render bread better suitable for celiac persons. The changes in cereal matrix potentially leading to improved nutritional quality are numerous. They include acid production, suggested to retard starch digestibility, and to adjust pH to a range which favours the action of certain endogenous enzymes, thus changing the bioavailability pattern of minerals and phytochemicals. This is especially beneficial in products rich in bran to deliver minerals and potentially protective compounds in the blood circulation. The action of enzymes during fermentation also causes hydrolysis and solubilisation of grain macromolecules, such as proteins and cell wall polysaccharides. This changes product texture, which may affect nutrient and non-nutrient absorption. New bioactive compounds, such as prebiotic oligosaccharides or other metabolites, may also be formed in cereal fermentations.

Abstract: The aim of this work was to study the effects of sourdough fermentation of wheat flour with Lactobacillus plantarum, on the quality attributes of mixed oat-wheat bread (51 g whole grain oat flour and 49 g/100 g white wheat flour). Emphasis was laid both on β-glucan stability as well as bread structure and sensory quality. The variables of the sourdough process were: dough yield (DY), fermentation time, fermentation temperature, and amount of sourdough added to the bread dough. The sourdough process was shown to be a feasible method for mixed oat-wheat bread, and, when optimized, provided bread quality equal to straight dough baking. A small amount (10g/100 g dough) of slack sourdough fermented at high temperature for a long time resulted in the most optimal sourdough bread with the highest specific volume (3.5 cm3/g), the lowest firmness after 3 days storage (0.31 kg), and low sensory sourness with high intensity of the crumb flavour. Wheat sourdough parameters did not affect the content of oat β-glucan in the bread. Additionally, both straight dough and sourdough bread contained 1.4–1.6 g β-glucan/100 g fresh bread. The average molecular weight of β-glucan was 5.5 × 105 in both types of bread, while that of oat flour was 10 × 105. This indicates that a slight degradation of β-glucan occurred during proofing and baking, and it was not affected by variation in the acidity of the bread between pH 4.9–5.8. [ABSTRACT FROM AUTHOR]

Sourdough fermentation has a well-established role in improving flavour and structure of bread. However, the significant potential of sourdough fermentation to improve the nutritional properties of rye, oat and wheat products has gained much less attention, although the interest is at present increasing. Sourdough fermentation can modify healthiness of cereals in a number of ways: it can improve texture and palatability of whole grain, fibre-rich or gluten-free products, stabilise or increase levels of various bioactive compounds, retard starch bioavailability (low glyceamic index products) and improve mineral bioavailability. Many new interesting applications for sourdough remain still to be explored, such as the use of prebiotic starter cultures or production of totally new types of bioactive compounds. [Copyright &y& Elsevier]