Journal of Engineering & Processing Management (EPM)
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Synthesis, characterization and in vitro biological evaluation of the Schiff base derived from Benzidine and 1,3-Diphenyl-1,3-propanedione
Full text linkSchiff bases are organic compounds formed by the reaction of the primary amine with carbonyl compounds (aldehydes or ketones). These are mainly bi- or tridentate ligands capable of forming very stable complexes with transitional metals. They are used as catalysts in oxygenation, hydrolysis, electro-reduction and decomposition reactions. Many Shiff bases show significant anti-tumor and antimicrobial activity, which is why they are the subject of research by many scientists in the world. In this paper Schiff's base from benzidine and 1,3-diphenyl-1,3-propanedione was synthesized. To characterize the product, FTIR spectroscopy and stereo-microscopy were used. In order to determine biological activity, antibacterial, antifungal and antioxidant activity of the product was tested. The results showed that the interaction of benzidine and 1,3-diphenylpropandione results in a Schiff base showing antibacterial, antifungal and antioxidant activity
Determination and Application of Improved Kinetic Parameters for Simulation of Maleic Anhydride Synthesis in Industrial Fixed-Bed Reactor
Full text linkThe aims of this study were to determine improved kinetic parameters in five kinetic models for oxidation of n-butane into maleic anhydride in an industrial fixed-bed reactor, and to simulate the reactor performance. On the basis of the measured process parameters, inlet and outlet concentrations of n-butane were calculated and then used to fit the kinetic models. The industrial fixed-bed reactor was approximated by 10 continuous stirred tank reactors (CSTR) connected in series. Based on the calculated outlet concentration of n-butane from the industrial reactor, the outlet concentration of n-butane from the penultimate reactor was calculated. Then the concentrations of n-butane were calculated until the inlet concentration of n-butane in the first reactor was obtained. Kinetic parameters were determined by comparing the inlet concentrations of n-butane in the first reactor with the inlet concentration of n-butane obtained on the basis of the measured process parameters in the industrial fixed-bed reactor. Kinetic models with improved kinetic parameters showed better simulation results compared to kinetic models with the existing kinetic parameters. The best agreement of simulation results and measured values was achieved with application of the kinetic model 2 (Equations (2a-c)). The smallest deviations of numerical simulation in comparison with measured values of the outlet pressure of reaction mixture were 0.45, 0.75 and 0.75% for application of the kinetic model 3 (Equations (3a-c)). The percentage deviations of numerical simulation with improved kinetic parameters and the existing kinetic parameters in comparison with measured values of inside reactor temperature were in the range 0.90-5.36% and in the range 4.17-9.78% (kinetic model 2, Equations (2a-c)), respectively
An exploration of the effects of low-pressure plasma discharge on the physico-chemical properties of chia (Salvia hispanica L.) flour
Full text linkThis work explores the preliminary feasibility of employing the low-pressure cold plasma technology for the modification of the properties of chia flour. Chia flour was exposed to low pressure plasma in air for 5 min, 10 min, and 15 min, at two different power levels (40 W and 60 W). The oils extracted from untreated and treated chia flour were exhaustively characterized for fatty acid composition, nutritional value, and rancidity indices using thermal calorimetric methods (DSC/TGA). The results indicated a significant change in the colour of flour with an increase in lightness. Infrared and ultraviolet spectroscopy indicated changes in the tocopherol groups of the oil extracted from plasma treated chia flour. However, the oil extracted from plasma treated chia flour revealed a loss of conjugated dienes and formation of trans-fatty acids as seen in conventional hydrogenation of edible oils. DSC and TGA results revealed better oxidative stability of low-pressure plasma treated oils than control, which was linked to a relative increase of MUFA in the former
HOW DOES CRYOGENIC FREEZING AFFECT THE CALORIMETRIC PROPERTIES OF LIQUID EGG PRODUCTS?
Full text linkEggs are widely utilized because of their high nutrient value, coagulating, foaming, emulsifying and sometimes even colouring or flavouring facilities in food manufacturing. Production of processed egg products shows an increasing trend. Frozen products belong to first processing, their shelf life can increase up to 1 year. By freezing, a large reduction in microbial loss can be achieved. But different undesirable processes can occur. The effect of freezing on animal cells is highly dependent on freezing parameters. It has a different effect on egg subtituents. Egg yolk undergoes a gelation process while proteins can denaturate. In our study pasteurized liquid egg products (liquid egg white, liquid egg yolk and liquid whole egg) were frozen by dripping into liquid nitrogen. After that, a 14-day frozen storage experiment was carried out at -18°C. Before freezing and on the 1th, 7th and 14th days of storage experiment pH, dry matter content, colour and calorimetric properties (denaturation temperatures and enthalpy of denaturation) with differential scanning calorimetry were tested. For statistical analysis, one-way ANOVA (α = 0.05) was employed. In our experiment, we found no significant change in calorimetric properties of liquid egg white after freezing, but significant decreasing of enthalpy and denaturation temperatures of liquid egg yolk and liquid whole egg was identified. In contrast, frozen storage had a decreasing effect in all these products. Freezing caused a clearly visible colour change in LEW, a visible change in colour of LWE and a very clearly visible change in colour of LEY. In case of LEW and LEY changes increased to clearly visible 14 days. In conclusion, our results show that frozen storage had a greater effect on liquid egg products properties than freezing in liquid nitrogen
Biochemical changes in myofibrillar and sarcoplasmatic meat proteins at different freezing rates
Full text linkFreezing rate significantly affects the quality of frozen meat and its biochemical changes. The loss of water from the cellular structure, which, under normal conditions, acts as a mechanical barrier between protein chains, causes spontaneous interactions of proteins that result in their denaturation. In order to determine the content of myofibrillar and sarcoplasmic proteins in meat samples, the samples were frozen at rates of 0.40, 0.90, and 1.25 cm/h for a storage period of 15 days. Protein content was analyzed by capillary gel electrophoresis and high-pressure liquid chromatography. During the freezing process, the protein chains were found to be shortened so that myofibrillar proteins were between 20 and 50 kDa, whereas sarcoplasmic proteins were between 20 and 100 kDa at all the freezing rates mentioned. The results of the analysis also show that the total number of sarcoplasmic proteins (freezing rate 0.90 cm/h; 20 proteins) was lower than the total number of myofibrillar proteins (freezing rate 0.90 cm/h; 35 proteins), and the molecular weight for both types of protens was lower 50 kDa. Further research should be directed towards extending storage time
The Enzyme Immobilization: Carriers and immobilization methods
Full text linkStrategies based on the enzyme application are increasingly replacing the conventional chemical procedures because of their efficiency, quicker performance and environmental protection. However, natural enzymes can rarely be used in industry since their beneficial features can not endure the industrial conditions. Additional drawbacks of natural enzymes are their inhibition by reaction products and difficulty to be removed from the reaction mixture. The most promising technique to substantially improve the enzyme properties, such as activity, pH, thermal and organic-solvent stability, reusability and storage stability, in non-natural environments is by the enzyme immobilization. In this review we summarized different techniques used to immobilize enzymes to inert carriers. A wide variety of materials of both the organic and inorganic origin was used as carriers for the enzyme immobilization. We also summarized a class of new materials where the enzyme performance was enhanced by combining different classical materials and shaping in specific forms
Laser scattering, optical constants and connection to other material performances (Kerr constant, mobility/diffusion coefficient/electrophoresis and depolarization)
Full text linkScattering of optical photons from the view of parallel methods related to absorption, scattering, fluorescence, reflection with inclusion of the polarization states of laser beams from experiment and theory give many possibilities for obtaining indirect data on material, processes, and dynamics. As a method with minimal perturbations, if low power beams are involved, certain type of data is provided. In fundamental dependences of various material properties, many phenomenological and basic laws are covered. Several coupled variables, primarily with the processes of scattering, pointing out further possibilities for linking the obtained theoretical or experimental results were presented. By including simulations, this associates with biological environments / variables for properties equivalent to defined tissues, cells, and characteristics. Along with selected formalisms including Stokes vectors and scattering matrices, a biological cell as an object can be monitored in time and influence of various environments could be predicted. Connecting Kerr’s effect with depolarization and scattering makes the complete description of molecule possible. Angular scattering observation with experimental possibilities gives the fastest practical data. This enables interpretation of E. coli with the application of Stokes vector formalisms. A relatively small number of material constants for many simulation cases could give draft estimation, but the experiment depends on the measuring devices and samples. The necessary symmetries showing the size of the scattering centers are analyzed, with the scattering data for some liquids (known / less known). From measured data, depolarization could be calculated, and with refractive index (molar refraction) connection with Kerr effect/ birefringence for selected solutions and behavior of molecules could be monitored. From the experimental Rayleigh factors, cross section (apparent/ effective) and attenuation coefficients for pure liquids were calculated. An approach for the correct assessment of the measurement uncertainty in the process of calibration of polyethylene samples
Assessing the possibility of solidification and stabilization of pyrite cinder by using quicklime and fly ash
Full text linkThe aim of this study was to determine the possibility of using two low-cost binders, quicklime and fly ash for the solidification/stabilization (S/S) of pyrite cinder. Pyrite cinder, used in this study, represents a remnant from sulfuric acid production in fertilizer factory IHP “Prahovo” A.D. (Serbia), and has a very high toxic metal content. High contents and leachability of copper, lead and zinc make this waste material hazardous, representing an extraordinary risk to the environment. In order to determine the leaching behavior of the S/S mixtures, four single-step leaching tests were performed, each one having a different sort of leaching fluid (deionized water, inorganic and organic acidic solutions). X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analyzer (EDS) were implemented to elucidate the mechanisms responsible for immobilization of Cu, Pb and Zn. Overall, the test results indicated that S/S treatment using both quicklime and fly ash was effective in immobilizing these metals, especially when there is a higher share of binder present. Treated waste can be safe for disposal and even considered for “controlled utilization”. Furthermore, the use of fly ash for S/S treatment of pyrite cinder solves the disposal problems of two waste types, as it also represents a secondary industrial product
Influence of coffee blends and roasting process on the antioxidant activity of coffee
Full text linkThe aim of this paper is to develop specification for the production of roasted coffee with improved nutritional quality. In this sense, the influence of different coffee blends and temperatures of roasting on the antioxidant activity of coffee was examined. Also, the composition of some bioactive components in the analyzed samples was determined. Two Arabica coffees of different quality and Robusta coffee were used for preparation of coffee blends. Experimentally determined green coffee blends B1, B2 and B3 were roasted at 167°C, 171°C and 175°C for 25 minutes in order to establish the effect of temperature roasting on the antioxidant activity and the content of bioactive components in blends. Based on results of DPPH and ABTS test, coffee blends B3 and B2, roasted at 171°C, had the highest (P<0.05) antioxidant activity. Those coffee blends had higher content of Robusta coffee than coffee blend B1. Results of this research can provide opportunities for development roasted ground coffee with improved nutritive quality, which could ensure competitiveness of producers in the target market
EFFECTS OF MINIMAL PROCESSING AND VITAMIN C ENRICHMENT ON MICROBIOLOGICAL SAFETY AND VISCOSITY OF LIQUID EGG WHITE
Full text linkEmerging technologies, like High Hydrostatic Pressure, heat treatments on low temperatures, and ultra-sonication, have an increasing tendency in industrial application. Vitamin enriched foods, like eggs, are considered as functional foods, but for high retention of biologically active compounds adequate minimal processing technologies are needed. In our study vitamin C enriched liquid egg white was examined to meet consumer expectations. Several combinations of low temperature pasteurization (57 - 63°C, 5 – 7 min) and High Hydrostatic Pressure (350, 5 min) were used to provide microbiological stability of vitamin C enriched (1000 mg/L) liquid egg white. After enrichment and treatments, the samples were examined for mesophyll aerobe and Enterobacteriaceae cell counts and viscosity attributes. Our results show that microbiological stability is not significantly influenced by vitamin C enrichment, but the different parameters of heat treatments and HHP have a strong effect. Viscosity attributes (measured with Anton Paar MCR 92) analysed by Hershel-Bulkley models point out that higher pressure of HHP has a stronger influence on viscosity than the temperature of pasteurization. Our results show a great opportunity for industrial use of minimal processing technologies for liquid egg white