Effect of linear and branched fructans on growth and probiotic characteristics of seven Lactobacillus spp. isolated from an autochthonous beverage from Chiapas, Mexico.

The effect that the fructans of Cichorium intybus and Agave salmiana have on health, as well as on the growth of some Lactobacillus species, has been demonstrated. The aim of this work was to evaluate the effect of linear and branched fructans on the growth of seven strains and some probiotic characteristics. The molecular identification of seven strains was performed. Moreover, the growth, resistance to antibiotics and simulated gastrointestinal conditions were also evaluated when these microorganisms were grown in a culture medium containing agave and chicory fructans. The strains were identified as Lactiplantibacillus plantarum, Lactiplantibacillus pentosus, Lactiplantibacillus fabifermentans and Lactiplantibacillus paraplantarum. The results suggest that the seven Lactobacillus strains were able to grow using agave (branched) and chicory (linear) fructans. The linear and branched fructans statistically influenced the kinetic parameters. The specific growth rate varied between 0.270 and 0.573 h-1 and the generation time between 1.21 and 2.45 h for all strains and culture media. All strains showed a growth of 9 Log CFU/mL in all the culture media. Production of lactic, acetic, propionic, butyric, formic and succinic acid was influenced by linear and branched fructans (p < 0.05). All the strains survived simulated gastrointestinal conditions greater than 83%. The resistance of Lactobacillus against ciprofloxacin and rifaximin was significantly affected by linear and branched fructans, but survival to gastrointestinal conditions was not affected by the type of substrate. These results highlight the use of the seven strains, which have probiotic potential; therefore, these could be applied in several biotechnological products.

Effect of UV-B Radiation on Flavonoids and Phenols Accumulation in Tempisque (Sideroxylon capiri Pittier) Callus.

Tempisque (Sideroxylon capiri Pittier) is classified as a threatened species and has been reported with a high content of phenols and flavonoids in the leaves. The use of abiotic elicitors such as radiation has been reported due to the changes it produces in the metabolism of plants by activating their defense mechanisms and increasing the biosynthesis of bioactive compounds with antioxidant capacity such as phenols and flavonoids. Therefore, the aim of this work was to evaluate the effect of UV-B radiation on growth parameters and the synthesis of bioactive compounds in in vitro culture of tempisque callus. For the callus induction, we used thidiazuron (TDZ) and 2,4-dichlorophenoxyacetic acid (2,4-D) at 0, 0.5 and 1 mg/L. Calluses were exposed to UV-B radiation (0, 1, 2, 3 and 4 h/day) for two and four weeks. The highest callus formation index was obtained with TDZ and 2,4-D at 1 mg/mL. The greatest increase in the concentration of phenols and flavonoids was detected in the fourth week with 4 h of exposure per day. The highest concentrations of quercetin (230 µg/g dry weight), kaempferol (235 µg/g dry weight) and gallic acid (240 µg/g dry weight) were found in callus obtained from leaves explants.

Zinc Oxide Phytonanoparticles' Effects on Yield and Mineral Contents in Fruits of Tomato (Solanum lycopersicum L. cv. Cherry) under Field Conditions.

The use of phytonanoparticles in agriculture could decrease the use of fertilizers and therefore decrease soil contamination, due to their size being better assimilated in plants. It is important to mention that the nanofertilizer is slow-releasing and improves plant physiological properties and various nutritional parameters. The influence of soil and foliar applications of phytonanoparticles of ZnO with the Moringa oleifera extract under three concentrations (25, 50, and 100 ppm) was evaluated on the cherry tomato crop (Solanum lycopersicum L.). Synthesis of the phytonanoparticles was analyzed with ultraviolet-visible spectroscopy (UV-Vis) and infrared transmission spectroscopy with Fourier transform (FT-IR), as well as the analysis with the dynamic light scattering (DLS) technique. The morphometric parameters were evaluated before and after the application of the nanoparticles. The minerals' content of fruits was done 95 days after planting. Results showed that soil application was better at a concentration of 25 ppm of phytonanoparticles since it allowed the greatest number of flowers and fruits on the plant; however, it was demonstrated that when performing a foliar application, the fruit showed the highest concentrations for the elements Mg, Ca, and Na at concentrations of 511, 4589, and 223 mg kg-1, respectively.

Dielectric properties of Mexican sauces for microwave-assisted pasteurization process.

The dielectric properties and specifically the complex relative permittivity of foods are key elements for the design of pasteurization processes with high frequency electromagnetic waves. Mexican sauces are recognized worldwide for their flavor and nutritional properties. In this work, the complex permittivity of four of the most representative sauces of Mexican cuisine (chipotle chili, habanero chili, red and green sauce) is presented. The permittivity was measured with the open coaxial probe method at temperatures of 25, 40, 55, 70, 85 °C and in the frequency range of 500 MHz to 6 GHz. Additionally, moisture content, specific heat, viscosity, water activity, density and electrical conductivity are reported, these last three at 25 °C. Dielectric properties were affected by the sauce formulation. The loss factor of each sauce sample at any temperature presents significant changes in relation to the frequency. At 915 and 2,450 MHz, d ε ' ' d T > 0 , which would cause a thermal runaway effect or the uncontrolled rise in temperature in the sauces during the microwave pasteurization. At 5,800 MHz, d ε ' ' d T < 0 , which would give better control for microwave heating than at 915 and 2,450 MHz. At 915 MHz, the loss factor of all sauces is higher than at 2,450 and 5,800 MHz, therefore, more rapid heating can be produced. Moreover, at 915 MHz, microwaves exhibit higher penetration depth than at 2,450 and 5,800 MHz; therefore, at 915 MHz, the greatest uniform microwave dielectric heating would be achieved. Thus, 915 MHz is the frequency recommended for the studied sauces pasteurization. PRACTICAL APPLICATION: This work provides the dielectric properties of Mexican sauces at different temperatures and their penetration depths in the microwave range, which are key information for further microwave-assisted pasteurization process and for getting safer sauces for consumers. Moreover, this research supplies suggestions about what frequency for ISM (Industrial, Scientific and Medical) applications is the best for microwave-assisted pasteurization according to the penetration depth of the electromagnetic wave in the sauces and microwave dielectric heating speed of the sauces.

Changes in the physiological and biochemical state of peanut plants (Arachis hypogaea L.) induced by exposure to green metallic nanoparticles.

Different types of nanoparticles (NPs) are increasingly used in multiple sectors such as industry, medicine and agriculture. This application has increased the possibility of NPs accumulating and contaminating the environment. Plants are one of the essential building blocks of all ecosystems and the interaction between NPs and plants is an indispensable aspect of risk assessment. To understand the effects of NPs in agricultural systems, in the present study we investigated the effects of exposure of Ag, Cu and Cu/Ag phytonanoparticles in Arachis hypogaea L. plants at a physiological and biochemical level, for which NPs solutions were applied foliarly at concentrations of 250, 500, 750 and 1000 ppm for 48 days. Parameters such as leaf length, chlorophyll and concentration of phytohormones showed that phytonanoparticles could cause serious damage to plant growth and development. Plants exposed to phytonanoparticles showed an increase in total phenols, proline, PAL activity and antioxidant enzymes, this to mitigate the stress caused. The alteration in the composition and content of fatty acids in the peanut kernels after exposure to different NPs indicated that they could affect the yield and quality of crop. Therefore, it is necessary to investigate its potential impact on food quality. Statement of noveltyIn this manuscript, we report for the first time that green nanoparticles induced a lower degree of toxicity in plants compared to commercial nanoparticles.Our results indicate that the mechanisms by which peanut plants respond to the application of nanoparticles were an increase in the activity of phenylalanine ammonia-lyase and antioxidant enzymes. So far there are few studies on the effect of nanoparticles on plant hormones, our results revealed a significant decrease in indole-3 acetic acid and induced the synthesis of gibberellins. The modification in the composition and content of fatty acids in the peanut kernels indicated that the nanoparticles could affect the quality of the crop.