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Background and objective: Consumer interests in probiotic foods have increased in recent decades. Food industries respond to these growing interests by developing innovative products and guaranteeing high production efficiency. Cereals, due to their prebiotic nature, are good fermentable substrates; from which, potentially functional foods could be achieved. The aim of this study was to verify effects of D-glucose addition on fermentation of rice, oat and wheat flours. Material and methods: Suspensions of 15% of cereals flours (rice, oat and wheat) in distilled water added with increasing glucose concentrations (2, 5, 7 and 10% w v-1) were fermented by Lactobacillus paracasei CBA L74 for 24 h. Then, pH, microbial growth and lactic acid production were assessed. Results and conclusion: Rice fermentation was not affected by glucose addition. For oat and wheat, addition of D-glucose increased bacterial concentration, as well as lactic acid production. In particular, the best growth was achieved by the addition of 2 and 5% of glucose. Furthermore, lactic acid concentration increased with increased glucose concentration. In conclusion, D-glucose addition seems to be unnecessary for the improvement of rice fermentation. On the contrary, oat and wheat fermentations need further available carbon sources for a better Lactobacillus growth and a higher lactic acid production. Conflict of interest: The authors declare no conflict of interest.

The concept of functional food has evolved throughout the years. These days we define a food to be functional when it confers a benefit to human health. Lactic acid fermentation is one of the most important and used food processing technologies to produce this type of food. Fermentation of Lactobacillus Paracasei CBA L74 - a homofermentative, gram positive probiotic - on rice flour suspension has been proved to be a successful route to produce functional foods. However, the process was characterized by high energy consumption, low air sparging and complex expensive metabolite separation. A research program has been developed to carry out L. Paracasei fermentation using a low viscosity medium based on rice flour suspension. Fractionation of rice flour suspension provided a medium characterized by low amounts of solids and nutrients at concentration high that support the microorganism growth. Fermentations were carried in a 1L batch reactor equipped with an agitation systems designed to provide uniform mixing. The composition of the medium; cells, glucose, protein, pH, metabolite production as well as L. Paracasei’ growth trend was analysed throughout the process. Fermentation on supernatant obtained from rice flour and water suspension through centrifugation were possible to produce a potential probiotic functional food with a good bacterial charge.

Coeliac disease is an increasingly recognised pathology, induced by the ingestion of gluten in genetically predisposed patients. Undigested gliadin peptide can induce adaptive and innate immune response that unleash the typical intestinal mucosal alterations. A growing attention is paid to alternative therapeutic approaches to the gluten-free diet: one of these approaches is the use of probiotics and/or postbiotics. We performed lactic fermentation of rice flour with and without pH control, using Lactobacillus paracasei CBA L74 as fermenting strain. We evaluated bacterial growth, lactic acid production during fermentation and gliadin peptide P31-43 entrance in CaCo-2 cells with and without pH control. When pH control was applied no differences were observed in terms of bacterial growth; on the contrary, lactic acid production was greater, as expected. Both samples could inhibit the P31-43 entrance in CaCo-2 cells but the effect was significantly greater for samples obtained when the pH control was applied.

The mathematical modeling of fermentation processes allows for the formulation of predictions about the kinetics of biomass growth and metabolite production as well as setting or verifying the best operative conditions in view of the economical convenience of the process. For this purpose, we performed a kinetic study of a rice flour fermentation process using Lactobacillus paracasei CBA L74 with and without pH control, the pH value was set to 5.8 under pH control. Monod, Logistic, and Contois models were proposed to describe the bacterial growth rate in both conditions. The best mathematical model, which was able to describe the experimental data obtained without pH control, was the Contois model, as the specific growth rate was influenced by both the glucose reduction (from 14.31 g/L to 10.22 g/L) and the biomass production (2 log growth) that occurred during fermentation. Conversely, when pH control was implemented, both Monod and Contois models satisfactorily described the specific growth rate trend. The estimated kinetic parameters confirmed that biomass production (2 log growth) and glucose consumption (from 14.31 g/L to 6.06 g/L) did not affect the microorganism’s growth capacity when the fermenting medium was maintained at an optimal pH. The lactic acid production rate described by the Luedeking–Piret model did not appear to be linked to growth in the absence of pH control while, on the other hand, this model was unsuitable for describing the experimental lactic acid concentration when pH control was applied. The kinetic modeling of lactic acid production and the percentage of added glucose in the protocol with controlled pH will be optimized in the future.

Cereals are becoming interesting substrates to be fermented to obtain new functional foods. For this reason, an enzymatic pretreatment of a wheat flour suspension using amylase was investigated in order to guarantee the feasibility to ferment a cereal-based substrate at a solid content higher than that used in past experimentations. Trials with and without amylase pretreatment, using a 52% w/v wheat flour water suspension, were carried out to evaluate the fermentation feasibility; mixing tests with a food dye were performed to verify the suspension homogeneity. The pretreated suspension, whose starch was hydrolyzed for about 80% by α-amylase, was then fermented (37°C, 24h) by Lactobacillus paracasei CBA-L74. Starting from pH value 5.75, microbial concentration 1.89 × 106 CFU/ml and lactic acid 0 mg/L, final values of 3.93, 3 × 108 CFU/ml and 6,251 mg/L were found after 24 hr of fermentation. The untreated suspension went to gelation and was impossible to ferment because its consistency was like a dough and the mixing system was not suitable to ensure mixing. Practical applications: The aim of the present study was the handling and the fermentation of cereal-based substrate at high solid content (52% w/v), through a preliminary amylase pretreatment. The fermentation of such a solid content could guarantee the production of a greater quantity of solid fermented matrix and this could considerably reduce drying times with greater productivity at a low cost.

Studies of the ability of probiotics to ferment cereal flours are necessary to obtain products with enhanced nutritional value. In this study, Lactobacillus paracasei CBA-L74 was used to ferment cereal aqueous mixtures containing both oat (7.5% w/v) and rice flours (7.5% w/v), with and without glucose, to understand whether glucose addition could have any effect on growth and metabolism. Viability, pH, metabolites production during fermentation (24 h, 37 °C) and substrates reduction were analysed. The strain showed good growth in the cereal aqueous mixture both with and without glucose addition, but suspensions prepared with glucose showed the best results. A bacterial concentration of 7 log CFU mL−1, a pH value of 4.70 and lactic acid production of 1250 mg L−1 were achieved when fermentation was performed without glucose addition, while in the presence of glucose, a t24 bacterial growth of 8 log CFU mL−1 was reached, with a pH value of 3.11 and lactic acid production of 6050 mg L−1., Food science, Food technology, Nutrition, Lactobacillus paracasei CBA L74, Fermented food, Rice flour, Oat flour, Glucose, Probiotics

The feasibility of developing a dry legume-based functional product using a fermentation process carried out on a 10% w/v navy bean suspension, in a lab-scale stirred batch reactor was studied. After soaking and cooking dried navy beans, the fermentation tests performed on the resulting medium using Lactobacillus paracasei CBA L74 showed a maximum bacterial count of 109 CFU/mL after 20 hr and a maximum lactic acid concentration of 1.9 g/L after 16 hr of process time. A freeze-drying process was conducted on the fermented bean suspension, showing a two-log microbial reduction and a bacterial viability in the resulting probiotic powder of 3.7 × 108 CFU/g.

Banana puree, due to its nutritional composition, is a good substrate for fermentation in the development of probiotic products. The production of banana puree mainly consists of three phases, i.e., raw material pretreatment, heat treatment, and the addition of anti-browning agents. In this study, we conducted three experimental protocols to evaluate the effect of ripeness grade, heat treatment, and ascorbic acid addition on fermentation performance. At the end of each protocol, the substrate was subjected to the fermentation process (37 °C, 48 h), and then measurements of pH reduction, microbial growth, and lactic acid production were used as markers in the analysis of fermentation performance. Ripe bananas produced better results than unripe bananas whose fermentation appeared to be inhibited. Therefore, ripe bananas were used to test the effect of two different heat treatments (sterilization (121 °C, 20 min) versus tyndallization (70 °C, 30 min, 37 °C, 30 min, 70 °C, 30 min)) on banana puree fermentation, and no significant differences were observed. Finally, 500 or 1000 ppm of ascorbic acid, normally used as an anti-browning agent, was added to ripe tyndallized bananas. No differences in fermentation results were observed between the two tested conditions, though values obtained for growth and lactic acid production were significantly lower than those from fermentation of banana puree without ascorbic acid.

Several recent reports describe a role of probiotics as a therapeutic approach for celiac disease (CD). Two undigested A-gliadin peptides, P31-43 and P57-68, are central to CD pathogenesis, inducing an innate and an adaptive immune response, respectively. They enter enterocytes and localize to vesicular compartment to induce their toxic/immunogenics effects. In this article, we tested the effect of probiotic Lactobacillus paracasei (LP) CBA L74 (International Depository Accession Number LMG P-24778), its supernatant and LP-fermented cereals on gliadin peptides, P31-43 and P57-68, entrance in Caco-2 cells. Both LP CBA L74 and its supernatant inhibit P31-43 (intensity of fluorescence; FI: 75%) and P57-68 (FI: 50%) entrance in Caco2 cells, indicating that this biological effect is due to some product included in LP CBA L74 supernatant. This effect was present also after fermentation of cereals. This study describes a novel effect of probiotics in the prevention of undigested gliadin peptides toxic effects.