Various cold storage-backslopping cycles show the robustness of Limosilactobacillus fermentum IMDO 130101 as starter culture for Type 3 sourdough production.

Type 3 sourdoughs, which are starter culture-initiated and subsequently backslopped, are less studied than other sourdough types. Yet, they can serve as a model to assess how competitive starter culture strains for sourdough production are and how the microbial composition of such sourdoughs may evolve over time. In the present study, Limosilactobacillus fermentum IMDO 130101 was used to produce Type 3 sourdoughs, prepared from wheat and wholemeal wheat flours. Therefore, an initial fermentation of the flour-water mixture was performed at 30 °C for 48 h. This was followed by cold storage-backslopping cycles, consisting of refreshments (50 %, v/v), fermentation steps of 16 h, and storage at 4 °C each week, every three weeks, and every six weeks. The microbial dynamics (culture-dependent and -independent approaches) and metabolite dynamics were measured. In all sourdoughs produced, starter culture strain monitoring, following an amplicon sequence variant approach, showed that Liml. fermentum IMDO 130101 prevailed during one month when the sourdoughs were refreshed each week, during 24 weeks when the sourdoughs were refreshed every three weeks, and during 12 weeks when the sourdoughs were refreshed every six weeks. This suggested the competitiveness and robustness of Liml. fermentum IMDO 130101 for a considerable duration but also showed that the strain is prone to microbial interference. For instance, Levilactobacillus brevis and Pediococcus spp. prevailed upon further cold storage and backslopping. Also, although no yeasts were inoculated into the flour-water mixtures, Kazachstania unispora, Torulaspora delbrueckii, and Wickerhamomyces anomalus were the main yeast species found. They appeared after several weeks of storage and backslopping, which however indicated the importance of an interplay between LAB and yeast species in sourdoughs. The main differences among the mature sourdoughs obtained could be explained by the different flours used, the refreshment conditions applied, and the sampling time (before and after backslopping). Finally, the metabolite quantifications revealed continued metabolite production during the cold storage periods, which may impact the sourdough properties and those of the breads made thereof.

Wholemeal wheat flours drive the microbiome and functional features of wheat sourdoughs.

This study aimed to evaluate the effect of soft (Triticum aestivum) and durum (Triticum durum) wheat flours at different extraction rate (type 00, 0, 1 and 2) and wholemeal flours on the microbial composition and functionality of type I sourdough. Enterobacteriaceae constituted the main component of the microbiome of refined soft and durum wheat flours. On the contrary, wholemeal durum wheat flour harboured mainly Xanthomonadaceae. Differences were also found between the soft and durum wheat flours. After 8 h of fermentation (1 day), a different behaviour of the microbiome components was observed. All the mature sourdoughs harboured a core microbiome constituted by 4 species (Pediococcus pentosaceus, Lactobacillus brantae, Pediococcus argentinicus and Weissella cibaria). Based on the type of flour, the relative abundance of each core species differed among sourdoughs. In addition, other dominant lactic acid bacteria species were variously detected in sourdoughs. Mature sourdoughs showed marked variations for the concentrations of glucose, fructose, maltose, lactic and acetic acids, ethanol and free amino acids (FAA). Specific correlations (r > 0.7; FDR < 0.05) were found between the microbiome and total phenols, fibres and metabolome of mature sourdoughs. Breads made by using wholemeal soft wheat or durum wheat doughs started by wholemeal wheat flour-based sourdoughs were characterized by the highest total amount of free cations (Ca2+, Zn2+, Fe2+, Mg2+), antioxidant activity and improved sensory traits.

Mechanism of action and interactions between xanthine oxidase inhibitors derived from natural sources of chlorogenic and ferulic acids.

The aim of this study was to estimate the phenolic composition and xanthine oxidase (XO) inhibitory activity of green coffee beans (GCB) and wholemeal wheat flour (WF). Additionally, the type and strength of interaction (expressed as the combination index, CI) and mode of XO inhibition were analyzed. The major phenolic in GCB was 5-caffeoylquinic acid (39.92mg/g dw). The main phenolic acids in WF were trans- and cis-ferulic acids (257 and 165.57mg/100g dw, respectively). Both ferulic and chlorogenic acids individually inhibited XO, and for their combination moderate synergism was found. Buffer extractable compounds from GCB and WF demonstrated slight synergism (CI=0.92), while potentially bioaccessible and bioavailable compounds acted synergistically (CI=0.43 and 0.54, respectively). Buffer-extractable and potentially bioavailable phytochemicals from GCB acted uncompetitively, whereas potentially bioaccessible compounds acted as noncompetitive XO inhibitors. The addition of 3-5% of GCB to wheat bread significantly increased XO-inhibitory activity.

Phytase activity of lactic acid bacteria and their impact on the solubility of minerals from wholemeal wheat bread.

The objective of this study was to determinate phytase activity of bacteriocins producing lactic acid bacteria previously isolated from spontaneous rye sourdough. The results show that the highest extracellular phytase activity produces Pediococcus pentosaceus KTU05-8 and KTU05-9 strains with a volumetric phytase activity of 32 and 54 U/ml, respectively, under conditions similar to leavening of bread dough (pH 5.5 and 30 °C). In vitro studies in simulated gastrointestinal tract media pH provide that bioproducts prepared with P. pentosaceus strains used in wholemeal wheat bread preparation increase solubility of iron, zinc, manganese, calcium and phosphorus average 30%. Therefore, P. pentosaceus KTU05-9 and KTU05-8 strains could be recommended to use as a starter for sourdough preparation for increasing of mineral bioavailability from wholemeal wheat bread.