Novel insights into different kefir grains usefulness as valuable multiple starter cultures to achieve bioactive gluten-free sourdoughs

Plant-Based Antioxidants in Gluten-Free Bread Production: Sources, Technological and Sensory Aspects, Enhancing Strategies and Constraints

The recognized contribution of antioxidant compounds to overall health maintenance and spotted deficiencies in celiac patients' diets has driven more intensive research regarding antioxidant compounds' inclusion in gluten-free bread (GFB) production during the last decade. The presented review gathered information that provided insights into plant-based antioxidant sources which are applicable in GFB production through the resulting changes in the technological, sensory, and nutritional quality of the resulting antioxidant-enriched GFB. The influence of the bread-making process on the antioxidant compounds' content alteration and applied methods for their quantification in GFB matrices were also discussed, together with strategies for enhancing the antioxidant compounds' content, their bioaccessibility, and their bioavailability, highlighting the existing contradictions and constraints. The addition of plant-based antioxidant compounds generally improved the antioxidant content and activity of GFB, without a profound detrimental effect on its technological quality and sensory acceptability, and with the extent of the improvement being dependent on the source richness and the amount added. The determination of a pertinent amount and source of plant-based antioxidant material that will result in the production of GFB with desirable nutritional, sensory, and technological quality, as well as biological activity, remains a challenge to be combated by elucidation of the potential mechanism of action and by the standardization of quantification methods for antioxidant compounds.

Multi-omics characterization of the microbial populations and chemical space composition of a water kefir fermentation

In recent years, the popularity of fermented foods has strongly increased based on their proven health benefits and the adoption of new trends among consumers. One of these health-promoting products is water kefir, which is a fermented sugary beverage based on kefir grains (symbiotic colonies of yeast, lactic acid and acetic acid bacteria). According to previous knowledge and the uniqueness of each water kefir fermentation, the following project aimed to explore the microbial and chemical composition of a water kefir fermentation and its microbial consortium, through the integration of culture-dependent methods, compositional metagenomics, and untargeted metabolomics. These methods were applied in two types of samples: fermentation grains (inoculum) and fermentation samples collected at different time points. A strains culture collection of ∼90 strains was established by means of culture-dependent methods, mainly consisting of individuals of Pichia membranifaciens, Acetobacter orientalis, Lentilactobacillus hilgardii, Lacticaseibacillus paracasei, Acetobacter pomorum, Lentilactobacillus buchneri, Pichia kudriavzevii, Acetobacter pasteurianus, Schleiferilactobacillus harbinensis, and Kazachstania exigua, which can be further studied for their use in synthetic consortia formulation. In addition, metabarcoding of each fermentation time was done by 16S and ITS sequencing for bacteria and yeast, respectively. The results show strong population shifts of the microbial community during the fermentation time course, with an enrichment of microbial groups after 72 h of fermentation. Metataxonomics results revealed Lactobacillus and Acetobacter as the dominant genera for lactic acid and acetic acid bacteria, whereas, for yeast, P. membranifaciens was the dominant species. In addition, correlation and systematic analyses of microbial growth patterns and metabolite richness allowed the recognition of metabolic enrichment points between 72 and 96 h and correlation between microbial groups and metabolite abundance (e.g., Bile acid conjugates and Acetobacter tropicalis). Metabolomic analysis also evidenced the production of bioactive compounds in this fermented matrix, which have been associated with biological activities, including antimicrobial and antioxidant. Interestingly, the chemical family of Isoschaftosides (C-glycosyl flavonoids) was also found, representing an important finding since this compound, with hepatoprotective and anti-inflammatory activity, had not been previously reported in this matrix. We conclude that the integration of microbial biodiversity, cultured species, and chemical data enables the identification of relevant microbial population patterns and the detection of specific points of enrichment during the fermentation process of a food matrix, which enables the future design of synthetic microbial consortia, which can be used as targeted probiotics for digestive and metabolic health.

Optimizing postbiotic production through solid-state fermentation with Bacillus amyloliquefaciens J and Lactiplantibacillus plantarum SN4 enhances antibacterial, antioxidant, and anti-inflammatory activities

Background

Postbiotics are an emerging research interest in recent years and are fairly advanced compared to prebiotics and probiotics. The composition and function of postbiotics are closely related to fermentation conditions.

Methods

In this study, we developed a solid-state fermentation preparation method for postbiotics with antimicrobial, antioxidant, and anti-inflammatory activities. The antibacterial activity was improved 3.62 times compared to initial fermentation conditions by using optimization techniques such as single factor experiments, Plackett-Burman design (PBD), steepest ascent method (SAM), and central composite design (CCD) methods. The optimized conditions were carried out with an initial water content of 50% for 8 days at 37°C and fermentation strains of Bacillus amyloliquefaciens J and Lactiplantibacillus plantarum SN4 at a ratio of 1:1 with a total inoculum size of 8%. The optimized SSF medium content ratios of peptide powder, wheat bran, corn flour, and soybean meal were 4, 37.4, 30, and 28.6%, respectively.

Results

Under these optimized conditions, postbiotics with a concentration of 25 mg/mL showed significant broad-spectrum antibacterial capabilities against Escherichia coli, Salmonella, and Staphylococcus aureus and strong antioxidant activity against ABTS, DPPH, and OH radicals. Moreover, the optimized postbiotics exhibited good anti-inflammatory ability for reducing nitric oxide (NO) secretion in RAW 264.7 macrophage cells in response to LPS-induced inflammation. Furthermore, the postbiotics significantly improved intestinal epithelial wound healing capabilities after mechanical injury, such as cell scratches in IPEC-J2 cells (p < 0.05).

Conclusion

In brief, we developed postbiotics through optimized solid-state fermentation with potential benefits for gut health. Therefore, our findings suggested that the novel postbiotics could be used as potential functional food products for improving body health.

Preparation of Sourdoughs Fermented with Isolated Lactic Acid Bacteria and Characterization of Their Antifungal Properties

Traditional sourdough is obtained using a mixture of flour and water stored at room temperature until acidification. Therefore, adding lactic acid bacteria (LAB) can improve the quality and safety of sourdough bread. Faced with this problem, four drying techniques-freeze-drying, spray-drying, low-temperature drying, and drying at low humidity-have been applied. Our goals were to isolate LAB strains with antifungal potential against Aspergillus and Penicillium fungi. The antifungal capacity was evaluated with agar diffusion, co-culture in overlay agar, and a microdilution susceptibility assay. In addition, the antifungal compounds generated in sourdough were analyzed. As a result, dried sourdoughs were prepared with Lactiplantibacillus plantarum TN10, Lactiplantibacillus plantarum TF2, Pediococcus pentosaceus TF8, Pediococcus acidilactici TE4, and Pediococcus pentosaceus TI6. The minimum fungicidal concentrations ranged from 25 g/L versus P. verrucosum and 100 g/L against A. flavus. A total of 27 volatile organic compounds were produced. Moreover, the lactic acid content reached 26 g/kg of dry product, and the phenyllactic concentration was significantly higher than the control. The P. pentosaceus TI6 exhibited a higher antifungal capacity in vitro and demonstrated a higher production of antifungal compounds compared to the other strains; therefore, further studies will evaluate the impact of this sourdough in bread manufacture.

Exploiting the Native Microorganisms from Different Food Matrices to Formulate Starter Cultures for Sourdough Bread Production

The use of sourdough for bread production involves fermentation, which is dominated by lactic acid bacteria (LAB) and yeast. Sourdough can be inoculated with a starter culture or through a food matrix containing microorganisms to initiate sourdough fermentation. Sourdough is used as leavening agent for bread making, and metabolites produced by LAB and yeast confer a specific aroma and flavor profile to bread, thus improving its sensory attributes. However, few publications report the effect of microorganisms from different food products and by-products on sourdough fermentation. This review focuses on using different starter cultures from various food sources, from wheat flour to starter cultures. Additionally, included are the types of sourdough, the sourdough fermentation process, and the biochemical transformations that take place during the sourdough fermentation process.

Effect of the Addition of Soybean Residue (Okara) on the Physicochemical, Tribological, Instrumental, and Sensory Texture Properties of Extruded Snacks

An extrusion process was used to improve the physical and textural characteristics of an extruded snack supplemented with soybean residue (okara). An extreme vertices mixture design with a constraint for okara flour (0−50%), mung bean flour (20−70%), and rice flour (20−80%) resulted in the production of eleven formulations. The color, radial expansion index (REI), bulk density, tribological behavior, and instrumental and sensory texture of the extruded snacks were evaluated. Increasing the quantity of okara resulted in an extrudate with a darker, redder color, decreased REI, increased bulk density, and decreased crispness. The tribological pattern of the snack was determined by its dominant composition (protein, starch, or fiber) in the flour mixture, which contributed to the stability of the lubricating film under rotational shear. A principal component analysis of sensory data captured a total of 81.9% variations in the first two dimensions. Texture appeal was inversely related to tooth packing (r = −0.646, p < 0.05). The optimized formulation for texture preference had an okara content of 19%, which was 104% crispier and 168% tougher than an okara content of 40%. This by-product of soybean milk processing can thus be used to develop gluten-free snacks with desirable physical characteristics and texture.