Search

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 consumption of vegetable oils has increased in recent years due to their nutraceutical properties. There is growing scientific research interest in the development of innovative, efficient and sustainable extraction techniques capable of separating lipid fractions from vegetal matrices. In this study, we introduce an innovative technique for extracting lipids from bilberry seeds that uses Norflurane, a hydrofluorocarbon, as the solvent under subcritical conditions. Preliminary extraction experiments were carried out using bilberry seeds in the waste material from the bilberry drupe valorization process. Different granulometric bilberry fractions were selected, suitably crushed, and sized prior to extraction. An extraction efficiency of 91% of the total lipid content was obtained for the ground fraction with grains 450−710 μm in size. The main fatty acids present in the lipid extracts were oleic, linoleic and α-linolenic acids. The ratio of unsaturated-to-saturated fatty acids was determined to be 11.63, with a ω6/ω3 ratio of 1.06.

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.

The present study analyses the performance of a scraped surface heat exchanger (SSHE) equipped with a new arrangement of blades to achieve higher thermal efficiencies than the conventional SSHE. This new design of exchanger, named here as scraped surface heat exchanger with alternate blades, A-SSHE, may be particularly suited to treat high viscous fluids, like food pastes. Experimental and numerical tests were carried out on an industrial scale A-SSHE used to heat hazelnut paste, an intermediate product widely used in Italian confectionery industry. Experimental tests include physical, chemical and rheological characterization of the hazelnut paste and the evaluation of the overall heat transfer coefficient as a function of rotational speeds and mass flow rates. Three-dimensional axial-symmetric CFD simulations of the A-SSHE were performed by using the software Fluent 6.2. For comparison, the same numerical tests were carried out for an equivalent SSHE with a conventional blades design (C-SSHE). Our studies show that the A-SSHE gives heat transfer coefficient values almost twice that of an equivalent C-SSHE, and that the numerical results are consistent with the experimental observations. The analysis of the fluid dynamics and of the thermal profiles suggests that the higher heat transfer efficiency of A-SSHE may be attributed to the occurrence of backmixing phenomena.