Authors:A. Mouwakeh, P. Radácsi, ZS. Pluhár, É. Németh Zámboriné, G. Muránszky, CS. Mohácsi-Farkas, and G. Kiskó
Nigella sativa L. (black cumin) is well known for its benefits in the field of traditional medicine. The aim of this study was to determine the chemical composition and investigate the antimicrobial activity of cold pressed oil (CO) and essential oil (EO) of Nigella sativa L. on food-borne pathogenic and spoilage bacteria. The microdilution method was used to determine the minimal inhibitory concentration (MIC) of Nigella sativa crude oil (CO) and essential oil (EO) against 4 Gram-positive (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, and Listeria monocytogenes) and 3 Gram-negative (Salmonella Hartford, Pseudomonas aeruginosa, and Escherichia coli) foodborne pathogenic and spoilage bacteria occurring in food products. Total fatty acid composition of CO was analysed by GLC, while the EO was analysed by GC-MS to detect its active compounds. The results showed that the major fatty acid of CO was palmitic acid (C16:0), as saturated fatty acid, however, linoleic acid (C18:2) was the main unsaturated fatty acid. The major compounds of the EO were p-cymene and thymoquinone. The inhibition on all tested bacteria of EO was 10 times higher than of CO, and the lowest concentration value was observed in case of Bacillus subtilis (0.003%). Hence, results reinforce the ambition to apply Nigella sativa oils in food as natural preservative.
Authors:J. Jakopič, N. Fajt, F. Štampar, and R. Veberič
To study the effect of the crop load on fruit quality of the cultivar ‘Fuji’ apple, in a two-year experiment, fruitlets were hand-thinned to six, eight, ten and in the second year, to twelve fruit per cm2 of the trunk cross-sectional area (TCSA). With increasing crop load, yield and the proportion of small fruits increased, but mean fruit weight decreased. However, the increase of TCSA and the number of flower clusters at return bloom were the lowest in high cropping trees. The highest percentage of total soluble solids was measured in the lightest cropping trees, which could be in correlation with the highest content levels of the sum of the analysed sugars, sucrose, sorbitol, malic and citric acids in the treatments with lowest crop load in the second year. The most intensive red colour of the fruit and the highest concentration of cyanidin-3-galactoside was observed in the treatment with eight fruit per cm2 TCSA. Different cropping of trees had no influence on phenolic compounds, such as the concentrations of catechin, epicatechin and chlorogenic acid. On the basis of yield efficiency, return bloom and detected fruit quality parameters cv. ‘Fuji’ apple has high yield potential.
This study describes the development and application of a mathematical model of the two-phase flow regime found in settling tanks. The phases present are water, the continuous medium, and solid, the dispersed phase. The performance of the model is assessed, applying it to two validation cases using solid suspensions as the working medium. These are; a settling tank measuring velocity and concentration. The calculations are presented for two different dispersed phase densities for the experimentally given density difference between the inlet and outlet. Computational Fluid Dynamics (CFD) simulations are employed to assess the effect of extended a baffle at the feed section of a full-scale sedimentation tank for the improvement of solids settling in potable water treatment in Slovakia. It is found that the baffle decreases the inlet re-circulation zone and enhances the settling of solids by directing them towards the bottom of the tank with high velocities. It is noteworthy that even small differences in the particle velocity can cause large changes in the percent of settled particles; in this work, the overall solids removal efficiency increased when using the baffle from 80% to 98% leading to a reduction of the effluent solids concentration of approximately 85%.
In the present study, fully developed laminar flow with forced convection heat transfer of Al2O3/water and TiO2/water nanofluids inside a vertical tube subjected by constant heat flux from the wall was numerically analyzed using Ansys Fluent release 17.2. In this work, the single-phase model was proposed to simulate the water and nanofluids heat transfer characteristics; spherical nanoparticles with a constant diameter equal to 30 nm are used. The study has been carried out on a Reynolds number with ranges (400-2000) and nanoparticles volume concentration up to 1.5%. the results show that the average Nusselt number for nanofluid is higher than that the base fluid (water) especially for TiO2/water nanofluid, the Nusselt number increased with increasing Reynolds number and volume concentration in all cases. The enhancement ratio for nanofluids compared to water at different volume friction was studied; the higher improvement is about 3.51% for TiO2/water nanofluid with 1.5% volume fraction. Moreover, a study for pressure drop along vertical tube was discussed.
Authors:E. Polonkai, E. Gyimesi, I. Kovács, A. Csillag, Gy. Balla, É. Rajnavölgyi, A. Bácsi, and S. Sipka
In this study, we examined the relationship between levels of lactoferrin (LF) and IL-17 in human serum and breast milk and the development of allergy in children. LF and IL-17 levels were determined by ELISA in healthy (n=19) and allergic mothers (n=21) on the 5th day after delivery. Two years later, information on breastfeeding and allergic outcomes was collected by questionnaires from parents of both groups and district child care nurses. Significantly higher concentrations of LF were found in the breast milk of allergic mothers compared to the healthy controls. At 2 years of age, only those three infants became allergic from the atopic group in whose starting breast milk samples a very high LF level (306 μg mg–1 protein) or simultaneously elevated concentrations of LF and IL-17 were measured. These findings indicate that the very early measurement of LF and IL-17 levels in the breast milk of allergic mothers may help to predict the allergy development in their infants.
Authors:G. Styevkó, Cs. Styevkó, Á. Hoschke, and Q. Nguyen
Glycosyltransferase activity of Pectinex ultra SP-L (from Aspergillus aculeatus) commercially available enzyme preparation was studied in mono- and bisubstrate systems using different donors (maltose, lactose, and sucrose) and acceptors (fructose, galactose, glucose, maltose, mannose, xylose, lactose, and sucrose). Oligosaccharides consisting of three monomers were detected in the cases of maltose, sucrose, and lactose as monosubstrates, thus this preparation should contain glucosyl-, fructosyl-, and galactosyl-transferase activity. Generally, yields of oligosaccharides synthesized were higher in bisubstrate systems maltose:sucrose, maltose:lactose, and sucrose:lactose than on monosubstrates. Use of maltose:sucrose bisubstrate resulted new oligosaccharide(s) (fructosyl-maltose or glucosyl-sucrose). The optimal ratio of substrates in the case of maltose:sucrose was determined to be 1:9. Increase of the dry content of the reaction mixture induced the transfer reaction. The highest oligosaccharide content was obtained at 60% (w/v) substrate concentration. In the case of the optimal ratio and dry content, 4.02% (w/v) oligosaccharide (DP3) concentration was achieved. These oligosaccharides may alter prebiotic and biochemical properties in food applications.
The efficiency of seven disinfectants (Divomil Forte, Nobactel, Domestos, SU 392, Buraton, Descosal, Cidex) was tested against Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 10231, Bacillus subtilis ATCC 6633, Aspergillus niger ATCC 16404. Surface test was used in order to evaluate the efficiency of disinfectants during the everyday sanitizing practice on special industrial surfaces. Test organisms represented pathogenic, spore forming bacteria, yeast and mould. Surface test was started with minimal concentration of agents and was not increased above the maximal concentrations, which were recommended by manufacturers in order not to corrode surfaces or risk the safety of use. Test organisms were inoculated on test areas and after drying inoculated surfaces were treated with disinfectants. Seven disinfectants were tested and four were effective against every test organism. (Buraton: 1%, Descosal: 1%, Cidex: 100%, SU 392: 75%.) Two disinfectants were ineffective against Aspergillus niger (Nobactel: 2%, Domestos: 2%) and 1 against Staphylococcus aureus and Aspergillus niger (Divomil Forte: 2%).
Authors:Z. Jrad, H. El Hatmi, I. Adt, T. Khorchani, P. Degraeve, and N. Oulahal
The aim of this study was to evaluate the antimicrobial activity of camel caseins and their hydrolysates by gastrointestinal proteolytic enzymes against 3 Gram-positive and 2 Gram-negative bacterial strains. Camel caseins (CN) were hydrolysed by successive action of pepsin and pancreatin. Hydrolysis of CN was checked by electrophoresis and gel filtration chromatography (GFC). Both techniques showed that CN was hydrolysed into peptides. Among the tested bacteria, a decrease of 19.3%±0.02 of E. coli XL1 blue cells growth was observed in the presence of undigested camel casein at a concentration of 20 mg ml−1. After successive hydrolyses by pepsin and pancreatin, camel milk casein hydrolysates still exhibited anti-bacterial activity against E. coli XL1 blue strain (19.73±0.01% growth inhibition under the same conditions). Gram-positive strain growth was not affected by intact camel CN, while, at the same concentration (20 mg ml–1), their hydrolysates slightly inhibited the growth of these bacteria. This suggests that antibacterial peptidic fragments of caseins were generated by pepsin and pancreatin.
Authors:M. Kizil, G. Kizil, M. Yavuz, and B. ÇeKen
The present study was designed to investigate the protective ability of the ethanol extracts of Achillea aleppica D.C. subsp. aleppica (AA), Achillea aleppica D.C. subsp. zederbaueri (Hayek) Hub.-Mor (AZ) and Achillea biebersteinii Afan. (AB) against the lipid peroxidation, protein oxidation and DNA damage induced by Fenton system. Ethanol extract of Achillea species were evaluated by quantifying the ability of different concentrations of plant extracts to supress Fe2+-induced lipid peroxidation in rat liver homogenates. The inhibition of lipid peroxidation by ethanol extracts of AA, AB and AZ was the result of their scavenging effect on Fe2+/ascorbate generated free radicals.The ability of AA, AZ and AB to prevent oxidative damage to bovine serum albumin (BSA) induced by Fe3+/H2O2 and ascorbic acid was investigated. The ethanol extracts of AA, AB and AZ at different concentrations (50–1000 μg ml−1) efficiently prevented protein oxidation induced by hydroxyl radical as assayed by protein oxidation markers including protein carbonyl formation (PCO). We have also investigated the effect of ethanol extracts of AA, AB and AZ on DNA cleavage induced by UV-photolysis of H2O2 using pBluescript M13+ plasmid DNA. These extracts significantly inhibited DNA damage induced by reactive oxygen species (ROS). Therefore, Achillea aleppica D.C. subsp. aleppica (AA), Achillea aleppica D.C. subsp. zederbaueri (Hayek) Hub.-Mor (AZ) and Achillea biebersteinii Afan. extracts may be useful in the food industry as effective synthetic antioxidants.
Authors:E. Bujna, F. Kukovics, Q. Nguyen, and J. Rezessy-Szabó
Production of phytase by Aspergillus niger F00735 strain in submerged fermentation was studied. The effects of various natural substrates with different phytate contents on secretion of extracellular phytase were investigated and the rice flour with about 5 mg g−1 of phytic acid was found to be the best one. The repression effect of high levels of phytic acid or inorganic phosphorous in fermentation medium (corn flour, wheat grit, soy flour, etc.) on production of phytase was also observed. The optimal concentration of rice flour as main carbon sourc e was determined in combination with sodium nitrate. The maximal activity (≈1500 U l−1, 1.5 times higher than using basal medium) was achieved on the 7th day in media containing 7.12% (w/v) rice flour and 0.86% (w/v) sodium nitrate. Supplementation of fermentation medium with different surfactants such as Tween series (20, 40, 60, 65, 80, 85) and Triton X-100 up to 0.1% (w/v) had no significant effects on the secretion of phytase enzyme, meanwhile at concentrations higher than 0.2% (w/v), decrease in enzyme activity was observed.