Inulin addition improved probiotic survival in soy-based fermented beverage.

Currently, the growing demand for non-dairy functional foods leads to the constant development of new products. The objective of the present work was to obtain a soy-based fermented beverage employing the strains Lactiplantibacillus plantarum CIDCA 8327 or Lacticaseibacillus paracasei BGP1 and to analyze the effect of post-fermentation addition of inulin of low or high average polymerization degree on the bacterial resistance. Also, the antimicrobial and antioxidant activity of the fermented soy-based beverages were analyzed. The soy-based matrix was shown to be a suitable substrate for the growth of both lactic acid bacteria, and the fermented beverages obtained presented bioactive properties such us antioxidant activity and bactericidal effect against pathogen microorganisms. The addition of inulin after the fermentation process avoid the hydrolysis and so, preserve its polymerization degree and thus the potential prebiotic effect. The incorporation of inulin to the soy-based fermented beverages increased the bacterial count after 30 days of refrigerated storage up to 8.71 ± 0.15 and 8.41 ± 0.10 log CFU/mL for L. paracasei and L. planatrum respectively. The resistance to the gastrointestinal conditions of the strain L. paracasei BGP1 in the fermented beverage was improved up to 70% when inulin of high polymerization degree was added. Meanwhile the strain L. plantarum CIDCA 8327 showed a survival of 97 and 94% in the fermented beverage added with inulin of low or high polymerization degree, respectively. These results contribute to the development of non-dairy products containing inulin and probiotics and the diversification agri-based functional foods.

Water kefir: Factors affecting grain growth and health-promoting properties of the fermented beverage.

Nowadays, the interest in the consumption of healthy foods has increased as well as the homemade preparation of artisanal fermented product. Water kefir is an ancient drink of uncertain origin, which has been passed down from generation to generation and is currently consumed practically all over the world. Considering the recent and extensive updates published on sugary kefir, this work aims to shed light on the scientific works that have been published so far in relation to this complex ecosystem. We focused our review evaluating the factors that affect the beverage microbial and chemical composition that are responsible for the health attribute of water kefir as well as the grain growth. The microbial ecosystem that constitutes the grains and the fermented consumed beverage can vary according to the fermentation conditions (time and temperature) and especially with the use of different substrates (source of sugars, additives as fruits and molasses). In this sense, the populations of microorganisms in the beverage as well as the metabolites that they produce varies and in consequence their health properties. Otherwise, the knowledge of the variables affecting grain growth are also discussed for its relevance in maintenance of the starter biomass as well as the use of dextran for technological application.

"Physicochemical, immunomodulatory and safety aspects of milks fermented with Lactobacillus paracasei isolated from kefir".

The use of Lactobacillus paracasei strains isolated from kefir grains as starters for the development of functional dairy products was evaluated. The physicochemical and immunomodulatory properties of milks fermented with L. paracasei CIDCA8339, CIDCA83123 and CIDCA83124 were analyzed. The three strains produced bioactive metabolites during fermentation, since the fermented milk supernatants were able to downregulate >75% of the induced innate immune response in vitro. Although all strains presented absence of hemolytic activity and susceptibility to antibiotics, L. paracasei CIDCA8339 presented more attractive probiotic and technological properties. Mice consuming the fermented milk with L. paracasei CIDCA 8339 did not present significant modifications in sIgA levels or TNF-α, TGF-ß and IL-10 mRNA expression in ileum. Additionally, a decrease of INF-γ level in ileum and no microbiological translocation to liver and spleen was observed. These results demonstrate that L. paracasei CIDCA8339 represents a safe promising potential probiotic strain for the development of functional foods.

Inulin rich carbohydrates extraction from Jerusalem artichoke (Helianthus tuberosus L.) tubers and application of different drying methods.

In this study the operational extraction variables to obtain higher yields of inulin from Jerusalem artichoke tubers (JAT), as well as the optimal conditions to obtain a stable and dispersible powdered product by either spray or freeze drying, were studied. With this purpose, the powder yield, moisture content, water activity and flowability or products obtained by different experimental conditions were analyzed. Inulin rich carbohydrates (IRC) extraction was performed from lyophilized and ground tubers employing distilled hot water as solvent. It was proved that the solid:solvent ratio (S:S) was the critical variable in the extraction process, followed by temperature. Thus, the IRC extraction was optimal without ultrasound assistance, at 76°C, employing a S:S of 1:16, during 90min. In addition, the powder obtained by freeze-drying of the IRC extract showed advantages respect to powders obtained by spray-drying regarding the yield and considering that maltodextrin was not necessary as encapsulation agent. In another hand, spray drying process provided IRC powered materials with appropriate flow properties, and taking into account cost and time of production, this method should be considered as an alternative of freeze-drying.

Impact of growth temperature on exopolysaccharide production and probiotic properties of Lactobacillus paracasei strains isolated from kefir grains.

EPS-producing LAB are widely used in the dairy industry since these polymers improve the viscosity and texture of the products. Besides, EPS might be responsible for several health benefits attributed to probiotic strains. However, growth conditions (culture media, temperature, pH) could modify EPS production affecting both technological and probiotic properties. In this work, the influence of growth temperature on EPS production was evaluated, as well as the consequences of these changes in the probiotic properties of the strains. All Lactobacillus paracasei strains used in the study showed changes in EPS production caused by growth temperature, evidenced by the appearance of a high molecular weight fraction and an increment in the total amount of produced EPS at lower temperature. Nevertheless, these changes do not affect the probiotic properties of the strains; L. paracasei strains grown at 20 °C, 30 °C and 37 °C were able to survive in simulated gastrointestinal conditions, to adhere to Caco-2 cells after that treatment and to modulate the epithelial innate immune response. The results suggest that selected L. paracasei strains are new probiotic candidates that can be used in a wide range of functional foods in which temperature could be used as a tool to improve the technological properties of the product.

Biological activity of the non-microbial fraction of kefir: antagonism against intestinal pathogens.

Kefir is a fermented milk obtained by the activity of kefir grains which are composed of lactic and acetic acid bacteria, and yeasts. Many beneficial health effects have been associated with kefir consumption such as stimulation of the immune system and inhibition of pathogenic microorganisms. The biological activity of kefir may be attributed to the presence of a complex microbiota as well as the microbial metabolites that are released during fermentation. The aim of this work was to characterise the non-microbial fraction of kefir and to study its antagonism against Escherichia coli, Salmonella spp. and Bacillus cereus. During milk fermentation there was a production of organic acids, mainly lactic and acetic acid, with a consequent decrease in pH and lactose content. The non-microbial fraction of kefir added to nutrient broth at concentrations above 75% v/v induced a complete inhibition of pathogenic growth that could be ascribed to the presence of un-dissociated lactic acid. In vitro assays using an intestinal epithelial cell model indicated that pre-incubation of cells with the non-microbial fraction of kefir did not modify the association/invasion of Salmonella whereas pre-incubation of Salmonella with this fraction under conditions that did not affect their viability significantly decreased the pathogen's ability to invade epithelial cells. Lactate exerted a protective effect against Salmonella in a mouse model, demonstrating the relevance of metabolites present in the non-microbial fraction of kefir produced during milk fermentation.

Local Treatment with Lactate Prevents Intestinal Inflammation in the TNBS-Induced Colitis Model.

Lactate has long been considered as a metabolic by-product of cells. Recently, this view has been changed by the observation that lactate can act as a signaling molecule and regulates critical functions of the immune system. We previously identified lactate as the component responsible for the modulation of innate immune epithelial response of fermented milk supernatants in vitro. We have also shown that lactate downregulates proinflammatory responses of macrophages and dendritic cells. So far, in vivo effects of lactate on intestinal inflammation have not been reported. We evaluated the effect of intrarectal administration of lactate in a murine model of colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). The increase in lactate concentration in colon promoted protective effects against TNBS-induced colitis preventing histopathological damage, as well as bacterial translocation and rise of IL-6 levels in serum. Using intestinal epithelial reporter cells, we found that flagellin treatment induced reporter gene expression, which was abrogated by lactate treatment as well as by glycolysis inhibitors. Furthermore, lactate treatment modulated glucose uptake, indicating that high levels of extracellular lactate can impair metabolic reprograming induced by proinflammatory activation. These results suggest that lactate could be a potential beneficial microbiota metabolite and may constitute an overlooked effector with modulatory properties.

Lactate and short chain fatty acids produced by microbial fermentation downregulate proinflammatory responses in intestinal epithelial cells and myeloid cells.

The use of short chain fatty acids to modulate gastrointestinal inflammatory conditions such as ulcerative colitis has produced encouraging results either in animal models or also in clinical trials. Identifying the key cellular and molecular targets of this activity will contribute to establish the appropriate combinations/targeting strategies to maximize the efficacy of anti-inflammatory interventions. In the present work, we evaluated in vitro the interaction of lactate, acetate, propionate and butyrate on cells relevant for innate immune response of the gastrointestinal tract. All molecules tested regulate the production of proinflammatory cytokines by TLR-4 and TLR-5 activated intestinal epithelial cells in a dose response manner. Furthermore SCFAs and lactate modulate cytokine secretion of TLR-activated bone marrow derived macrophages and also TLR-dependent CD40 upregulation in bone marrow derived dendritic in a dose-dependent manner. Butyrate and propionate have been effective at concentrations of 1 to 5mM whereas acetate and lactate produced modulatory effects at concentrations higher than 20-50mM in different assays. Our results indicate that in concentrations similar to found in large bowel lumen, all SCFAs tested and lactate can modulate activity of relevant sentinel cell types activated by TLR signals. Modulatory activity was not inhibited by pertussis toxin treatment indicating that the effects are not related to Gi signaling. The use of these molecules in combined or separately as intervention strategy in conditions where epithelial or myeloid cells are main triggers of the inflammatory situation seems appropriate.