Chiara Nadai

This study investigated kombucha as an innovative functional starter for sourdough breadmaking. A kombucha‐based sourdough was prepared and reached technological maturity in just 5 days, significantly faster than conventional spontaneous fermentation. Its performance was compared against a traditional artisanal sourdough control. Bread quality was comprehensively evaluated through physicochemical, structural, and sensory assessments. Results demonstrate that kombucha breads exhibit specific volume, crumb structure, texture, and staling behavior comparable to traditional sourdough bread. Sensory analysis confirmed high overall acceptability and similarity between the products. Notably, kombucha breads displayed significantly higher total phenolic content and antioxidant capacity with respect to the traditional artisanal sourdough bread. These findings highlight kombucha as a highly promising alternative starter capable of accelerating sourdough production while enhancing the potential functional and nutritional properties of bread.

Kombucha is a fermented beverage widely produced at household level through backslopping and appreciated for its functional properties. Limited information is available on how repeated backslopping affects microbial dynamics, biochemical composition, and product safety over time. This study investigated the impact of twelve consecutive backslopping cycles mimicking controlled homemade conditions on green and black kombucha. Physicochemical analyses, bioactive components, antioxidant activity assays, and metabarcoding analyses were carried out to evaluate fermentation performance, safety-related parameters, functional compounds, and microbial community dynamics. Partial least squares (PLS) modelling was applied to identify key variables influenced by fermentation cycles. Both green and black kombucha maintained acetic acid and ethanol concentrations within recommended safety limits throughout all fermentation cycles, supporting the safety of homemade backslopping. Repeated fermentation cycles were associated with increased microbial activity, reflected by enhanced sugar consumption and reduced gluconic acid production, without inducing critical pH shifts nor excess of ethanol production. Functional profiling revealed variability in phenolic composition; however, antioxidant activity remained stable, suggesting a compensatory role of microbial metabolites. PLS analysis of metabarcoding data highlighted shifts within Amplicon Sequence Variants of acetic acid bacteria, with a decreasing trend along the fermentation cycles in Acetobacter in favour of Komagataeibacter . This study provides new insights into long-term backslopping effects and supports process optimization to ensure kombucha functionality and safety.

The increasing consumer attention toward plant‐based products having health‐promoting benefits has drawn attention to medicinal herbs such as Calendula officinalis and Echinacea purpurea , that are abundant in bioactive compounds exhibiting anti‐inflammatory, antimicrobial and antioxidant properties. In this work, four bacterial strains, Lactiplantibacillus plantarum 299 V, Pediococcus acidilactici IRZ12B, Lacticaseibacillus rhamnosus GG, and Bacillus subtilis natto, were used to ferment aqueous extracts of C. officinalis and E. purpurea . All tested strains exhibited robust growth in the herbal substrates, resulting in a marked drop in pH and increased microbial counts. Fermentation enhanced sugar utilization, stimulated organic acid synthesis, and reduced antinutritional compounds such as tannins, while improving the availability of certain minerals. After fermentation, extracts showed an increased total phenolic level, stronger antioxidant activity, and increased antimicrobial effects relative to unfermented controls. These findings indicate that bacterial fermentation, especially performed by lactic acid bacteria, can substantially augment the functional and phytochemical characteristics of C . officinalis and E. purpurea extracts. This approach supports the development of innovative plant‐based fermented nutraceuticals with therapeutic potential. Moreover, the optimized fermentation process offers a strategy for incorporating fermented C . officinalis and E . purpurea extracts into plant‐based food products, satisfying the increasing interest of consumers for nutrient‐rich, health‐oriented foods.

Kombucha, a fermented tea beverage, is gaining popularity due to its rich content of bioactive compounds and associated health benefits. Kombucha fermentation involves a complex microbial consortium, including acetic acid bacteria, lactic acid bacteria, and yeasts, that works synergistically to enhance its nutritional and functional properties. Key compounds produced during fermentation provide antioxidant, anti-inflammatory, and antimicrobial benefits. Despite its well-documented health-promoting properties, limited research exists on how human digestion influences the stability and functionality of kombucha bioactive components. This study investigated how digestion impacts kombucha made from green and black teas, focusing on free amino acid content, antioxidant activity, antimicrobial potential, and microbiota viability. Results showed that digestion significantly increased free amino acids, as fermentation released peptides suitable for gastrointestinal digestion. However, L-theanine, a beneficial tea compound, was no longer detectable after fermentation and digestion, suggesting limited bioaccessibility. Digested kombucha exhibited higher antioxidant activity and stronger antimicrobial effects compared to undigested tea. Moreover, culture-dependent and PMA-based sequencing confirmed the survival of viable microbial strains through simulated gastrointestinal conditions, suggesting the potential of kombucha as a source of live, functional microbes. These findings support the role of kombucha as a natural functional beverage whose health benefits not only persist but may be enhanced after digestion.

This study investigates the fermentation of Malva sylvestris aerial parts using three lactic acid bacteria: Lactiplantibacillus plantarum 299V, Pediococcus acidilactici IRZ12B, and Lacticaseibacillus rhamnosus GG. The fermentation process resulted in a notable increase in microbial counts of LAB populations, production of organic acids, reduction of antinutritional factors such as tannins, and enhancement the bioavailability of some essential minerals. Post-fermentation analyses revealed a threefold increase in total phenolic content compared to the non-fermented extract. Antioxidant activity also showed a substantial enhancement, with L. plantarum 299V and P. acidilactici IRZ12B nearly doubling the DPPH inhibition percentage, while L. rhamnosus GG exhibited no improvement. Furthermore, antimicrobial activity varied among strains, with P. acidilactici IRZ12B and L. rhamnosus GG effectively inhibiting Y. enterocolitica growth, while all fermented samples significantly reduced S. enterica proliferation. These findings support the use of lactic acid bacteria fermentation as a bioprocess to improve the phytochemical profile of malva, with potential therapeutic applications. Furthermore, the optimized fermentation conditions could facilitate the incorporation of fermented malva as a functional ingredient in plant-based foods, aligning with the growing consumer demand for health-oriented products. Graphical Abstract

Commercial Saccharomyces cerevisiae starters are single-strain cultures widely used in winemaking to optimise the fermentation process and improve the organoleptic quality of wine. Unfortunately, the worldwide extensive use of a limited number of industrial strains led to the standardisation of the sensory properties, reducing the identity of wines. Therefore, the use of multi-strain S. cerevisiae starters can be an alternative tool to alter the sensory profile of wines, increasing the diversity of wine styles. However, this strategy may be interesting only if the overall fermentation kinetics is not affected. To date, there is a lack of information regarding the influence of multi-strain starters on the overall fermentation process in wine. In this context, killer toxins, affecting the viability of sensitive strains, can play a significant role. This study aimed to evaluate the effects of pairing eight wine strains of S. cerevisiae (two sensitive, three neutral and three killer) in co-fermentations compared to single-strain fermentations. Results evidenced that, among co-fermentations where the strain prevalence was significant, the killer strains constituted 79% to 100% of the total yeast population when co-inoculated with a sensitive one. However, in most of the cases, co-fermentations kinetics were similar to those of sensitive strains or worse than both strains. Thus, the presence of a killer strain alone is not sufficient to predict the overall fermentation progress, which is an essential information in winemaking. Interestingly, the neutral strain P304.4 was always prevalent, regardless of the second strain and, in most of the co-fermentations, the overall fermentation trend was similar to the P304.4 single-strain fermentation. Regardless of killer activity, our results suggest that the effect of strains on fermentative kinetics is still unpredictable, and further studies are needed to thoroughly explore strain to strain interactions in winemaking.