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.

Lytic bacteriophages affect the population dynamics of multi-strain microbial communities.

Background: Lytic bacteriophages infect and lyse bacteria and, as a by-product, may affect diversity in microbial communities through selective predation on abundant bacterial strains. We used a complex dairy starter named Ur to investigate population dynamics of Lactococcus lactis, Lactococcus cremoris and Leuconostoc mesenteroides strains in terms of constant-diversity and periodic selection models. Methods: To mimic the starter Ur, we designed blends of 24 strains representing all eight previously identified genetic lineages in the starter culture. The blends were propagated by daily transfers in milk for over 500 generations in the presence or absence of a cocktail of lytic bacteriophages. The relative abundance of genetic lineages of L. lactis, L. cremoris and Lc. mesenteroides strains present in the complex blend, as well as phage presence, were monitored. Results: Control blends without phage predation showed decreased strain diversity, leading to a stable state due to the domination of the fittest strain(s) of a particular lineage according to periodic selection dynamics. However, in phage-challenged blends, predation caused a large shift in the microbial composition by killing the fittest and sensitive strains. Conclusion: It was demonstrated that phage-challenged blends maintained their diversity at the level of genetic lineages, thus providing experimental support for the constant-diversity dynamics model in a complex microbial community.

Fortification of Yellow Alkaline Noodles with Wheat Bran and the Impact on Physical and Sensorial Properties.

Food fortification is a commonly-used method to increase nutritional value of food products in order to reduce the risks of Non-Communicable Diseases (NCDs). Noodles are a versatile and popular staple food, especially in Asia, that can be nutritionally enriched using various types of ingredients and one of them is wheat bran that is rich in dietary fiber. This study aimed to determine effect of fortification of fresh yellow alkaline noodles with wheat bran on its physical and sensorial properties. Addition of wheat bran was varied in concentration (0-20%) and physical properties of fortified yellow alkaline noodles were assessed. Additionally, 9-point hedonic scale and 'Just About Right' scale were employed to assess sensory properties of the fortified noodles, using 40 non-trained panelists. Noodles fortified with the highest amount of wheat bran exhibited the highest cooking loss (4.61%) compared to the non-fortified one (2.78%), indicating weak structural integrity, presumably due to the impaired gluten network. On contrary, noodles fortified with various amount of wheat bran did not demonstrate significant alteration of textural properties in terms of springiness, cohesiveness, and resilience. Sensorially, noodles fortified with 10% of wheat bran had the highest preference among the panelist based on general appearance, overall acceptability, color suitability, hardness suitability, and smoothness. Proximate analysis showed noodles supplemented with 10% of wheat bran met regulatory criteria for claim as a high-fiber food, with its dietary fiber content of 5.40 g/100 g of noodles. Conclusively, fortification of yellow alkaline noodles with wheat bran could improve its product properties.