Bacterial community dynamics in spontaneous sourdoughs made from wheat, spelt, and rye wholemeal flour

Sourdough fermentation is a traditional process that is used to improve bread quality. A spontaneous sourdough ecosystem consists of a mixture of flour and water that is fermented by endogenous lactic acid bacteria (LAB) and yeasts. The aim of this study was to identify bacterial diversity during backslopping of spontaneous sourdoughs prepared from wheat, spelt, or rye wholemeal flour. Culture-dependent analyses showed that the number of LAB (10⁹  CFU/ml) was higher by three orders of magnitude than the number of yeasts (10⁶  CFU/ml), irrespective of the flour type. These results were complemented by next-generation sequencing of the 16S rDNA V3 and V4 variable regions. The dominant phylum in all sourdough samples was Firmicutes, which was represented exclusively by the Lactobacillales order. The two remaining and less abundant phyla were Proteobacteria and Bacteroidetes. The culture-independent approach allowed us to detect changes in microbial ecology during the 72-hr fermentation period. Weissella sp. was the most abundant genus after 24 hr of fermentation of the rye sourdough, but as the process progressed, its abundance decreased in favor of the Lactobacillus genus similarly as in wheat and spelt sourdoughs. The Lactobacillus genus was dominant in all sourdoughs after 72 hr, which was consistent with our results obtained using culture-dependent analyses. This work was carried out to determine the microbial biodiversity of sourdoughs that are made from wheat, spelt, and rye wholemeal flour and can be used as a source of strains for specific starter cultures to produce functional bread.

Developing lactic acid bacteria starter cultures for wholemeal rye flour bread with improved functionality, nutritional value, taste, appearance and safety

Starter cultures composed of lactic acid bacteria (LAB) were developed based on the genotypic and phenotypic characterisation of isolates belonging to dominant groups of bacteria in spontaneous rye wholemeal sourdoughs. Combinations of strains have been evaluated on an industrial scale in the sourdough fermentation process. Wholemeal rye bread was prepared using sourdoughs obtained with 3 new starter cultures, and compared to bread made using the commercial culture (LV2). All newly developed cultures used for the preparation of wholemeal rye bread allowed to obtain better quality products as compared to the LV2 based bread. The best results were obtained when the culture containing Lactiplantibacillus plantarum 2MI8 and exopolysaccharide (EPS)-producing Weissella confusa/cibaria 6PI3 strains was applied. The addition of yeast during sourdough breads production, especially the one prepared from mentioned above starter culture, significantly improved their organoleptic properties, their volume and crumb moisture was increased, and also the crumb acidity and hardness was reduced. Fermentation of rye wholemeal dough, especially without the yeast addition, resulted in a significant reduction in the content of higher inositol phosphates as compared to the applied flour, which is associated with improved bioavailability of minerals. The results of this study prove that the investigated new starter cultures can be successfully applied in wholemeal rye bread production.

Oat raw materials and bakery products - amino acid composition and celiac immunoreactivity

BACKGROUND

The aim of this study was to compare the biochemical and immunochemical properties of avenins in some special oat raw materials and additionally the possibility of using them as a raw material for the gluten-free bakery products.

METHODS

The compared oat raw materials were - oat flakes, commercial oat flours (including gluten-free oat flour) and residual oat flour, which is by-product of β-glucan preparation. Biochemical characteristic included amino acid compositions and SDS-PAGE profiles of extracted avenins. The immunochemical reactivity with polyclonal anti-gluten and monoclonal anti-gliadin antibodies was evaluated qualitatively and quantitatively by immunoblotting and ELISA methods. Additionally, experimental bakery products made of examined raw materials were assessed according to their suitability for the celiac patients' diet.

RESULTS

The highest protein content was measured in the β-glucan preparation "Betaven" and gluten-free oat flour. Proteins of all materials are rich in glutamic and aspartic acid, leucine and arginine. Proportions of amino acids in avenins extracted from most of oat raw materials are similar, excluding gluten-free oat flour, which has a very low avenin content and proportions of individual amino acids are different. The SDS-PAGE protein pattern consisted of proteins with molecular weight of about 25-35 kDa. Polyclonal anti-gluten anti-body recognized all protein fractions of molecular weight higher than 20 kDa. Quantitative ELISA analysis shows that the majority of samples has a gliadin-like protein content within the range of 80-260 mg/kg, excluding gluten-free flours and corresponding bakery products. Altogether, β-glucan preparation has extremely high level of gliadin-like proteins.

CONCLUSIONS

In the examined oat raw materials and foods the contents of immunoreactive amino acid sequences exceeded the limit of 20 mg/kg (considered as gluten-free) except for gluten-free flours (oat and  the prepared mixture) and the bakery products based on gluten-free flours. Unfortunately, the rest of oat raw materials and products cannot be considered gluten-free.

ATTEMPT TO APPLY STABILIZED WHEAT GERM FOR BREAD SUPPLEMENTATION

The increased interest in rational nutrition causes, that from many years is observed a growing consumption of bread, and novel food supplemented with health promoting components. For the bread production in Poland mainly wheat and rye cake flours are used, depleted of a many valuable nutrients such as protein, dietary fibre, minerals and vitamins. Because of their unique chemical composition wheat germs are a particularly valuable resource, both for direct consumption and to enhance the nutritional value of food products. The aim of the study was to prepare wheat bread with a 10% addition of commercial stabilized wheat germs. Based on the obtained results, it was found that wheat germs, due to their unique chemical composition, were a particularly valuable resource to supplement the nutritional value of bread. However, germs had detrimental effect on mechanical properties of dough, and on bread quality. Texture of bread crumb and its chemical composition were analysed. It was shown, that germs subjected to fermentation process could be used in wheat bread production as dietary fibre and mineral compound supplement.

Quality- and Health-Promoting Compounds of Whole Wheat Bread with the Addition of Stale Bread, Cornmeal, and Apple Pomace

The aim of this study was to evaluate the effect of extruded preparations on the bioactive and nutritional properties, vitamin B content, volatile compound profile, and quality of whole wheat bread. Extruded preparations based on stale bread (secondary raw materials) and apple pomace (byproducts) were used as bread additives. It was found that the preparations did not enrich the bread in protein but in health-promoting compounds, especially gallic acid, protocatechuic acid, caffeic acid, p-coumaric acid, rutin, quercetin, and B vitamins. Extruded preparations had a positive effect on the quality of the bread produced, such as yield and cohesiveness, and gave it a pleasant aroma. It was shown that among all the examined bread samples with added extruded preparations of stale bread, the cornmeal and apple pomace bread samples with 15% extruded preparation (containing 55% cornmeal, 30% stale bread, and 15% apple pomace) had sufficient nutritional value, the highest amounts of gallic acid, protocatechuic acid, p-coumaric acid, caffeic acid, rutin, and quercetin; medium amounts of ellagic acid; high antioxidant activity determined in vitro using four methods (by DPPH, ABTS, power (FRAP), and Fe(II) chelating assays); adequate quality; and significant amounts of vitamins, especially B1, B2, and B3. This type of extruded preparation should utilize apple pomace, which is a byproduct, and stale bread, which is a secondary waste. Such a combination is an excellent low-cost, easy, and prospective solution for the baking industry that could be applied to obtain bread with elevated nutritional value and enhanced health potential, as proven in this publication.

ATTEMPT TO REDUCE ACRYLAMIDE CONTENT IN ROASTED CHICORY

The aim of this study was to reduce the formation of acrylamide during roasting of chicory roots by soaking the fresh roots in a solution of calcium chloride, by the use of different temperature and time of roasting of dried roots, as well as by the addition of the enzyme (asparaginase) during roasting of dried roots. It was shown, that with increasing roasting temperature of chicory roots from 100 - 175 ° C the acrylamide content also increased, while at a temperature of 210 ° C the growth was inhibited. Increasing roasting time from 10 - 25 minutes resulted in an increased acrylamide content. Soaking the roots in the CaCl2 solution for 20 minutes reduced the formation of acrylamide during the roasting approximately by 40%, similarly as the application of asparaginase to the dried roots during the roasting process.

The Influence of Fermentation Technology on the Functional and Sensory Properties of Hemp Bread

In this work, the type of fermentation and baking technology used to make hemp bread was investigated. The physicochemical composition of flour and bread, the protein nutritional quality, fatty acids profile, texture, consumer acceptance, analysis of volatile compounds using an electronic nose and chemical compounds using an electronic tongue were determined. Differences in protein and total dietary fiber content were observed in the obtained breads. The use of sourdoughs had a minor effect on the physical properties of the bread tested (the volume and mass of the loaves, color, or crumb texture). There was no clear effect of the tested sourdoughs on the parameters of the crumb texture and its moisture, assessed physically, both on the day of baking and during storage. In this bread, the limiting amino acid was lysine (amino acid score from 56.22% to 57.63%), but the breads did not differ significantly in the value of this indicator. The n-6/n-3 ratio in breads containing hemp flour (from 3.73 to 4.48) may have a beneficial effect on human health. The best-rated bread was the HB4 with a score of 6.09. The acceptance of remaining breads were in the range from 3.91 for HB1 to 4.91 for HB2.