Petrov D.,University of Food Technologies
Applied Physics A: Materials Science and Processing | Year: 2011
Nanocrystalline gadolinium monoaluminate (GdAlO3) has been synthesized by sol-gel method after sintering the precursor gel at 950°C. The microstructural features have been proved by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray analysis (EDX). The XRD pattern confirms the formation of single-phase GdAlO3 while EDX shows that this nanomaterial is stoichiometric; the average size of the nanoparticles is 40 nm. X-ray photoelectron spectroscopy (XPS) has been used to study the chemical composition and bonding in the as-prepared samples. The binding energies of corelevel electrons in Gd, Al and O in GdAlO3 nanopowder have been found slightly shifted compared to the corresponding values of the same elements. The electron paramagnetic resonance (EPR) spectra at 9.23 GHz (X-band) and different temperatures indicate the existence of magnetically concentrated solid containing Gd3+ ions. Nèel temperature, TN = 3.993 K, effective Bohr magneton number, μeff = 8.18, and constant of magnetic exchange interaction, Jex =-0.069 cm-1, have been determined from DC magnetic susceptibilities measured in the range 2-300 K. © Springer-Verlag 2011.
Krastanov A.,University of Food Technologies
Biotechnology and Biotechnological Equipment | Year: 2010
Metabolomics is an emerging field of "omics " research that focuses on high-throughput characterization of small molecule metabolites in biological matrices. This review focuses on the recent trends and potential applications of metabolomics. We begin with an overview of metabolomic studies with amphasise on metabolomics workflow. The approaches of metabolomics are applied in the biological systems, including human, plants, and microorganisms. Thus the critical evaluation of the contribution that metabolomics has made to the environmental, plant and animal sciences, microbiology and food technology and science, was established.
Nikovska K.,University of Food Technologies
Emirates Journal of Food and Agriculture | Year: 2012
The rheological properties and oxidative stability of oil-in-water emulsions (O/W) with olive oil stabilized by soy protein isolate (SI) and whey protein isolate (WPI) were investigated. The emulsions were prepared at oil phase volume concentrations ranging from 30 to 70% v/v and emulsifier concentrations ranging from 4 to 8 wt%. The emulsions exhibited Newtonian or pseudoplastic behaviour at lower oil and emulsifier concentrations and plastic behaviour at higher concentrations. In addition, the emulsion stability against creaming over storage period was determined. It was established that the emulsions at lower oil concentration were less stable. The creaming stability correlated well with the viscosity of dispersive systems. The differences in the oxidation processes were evaluated by measuring the formation of primary and secondary oxidation products. It was shown that the emulsions with lower olive oil volume concentration were less stable than the emulsions with higher one. The bulk olive oil was more stable than the O/W emulsions both with SI and WPI.
Nikovska K.,University of Food Technologies
Advance Journal of Food Science and Technology | Year: 2010
The oxidative stability of walnut oil and oil-in-water (O/W) emulsions with walnut oil stabilized by soy protein isolate (SI) and Whey Protein Isolate (WPI) was evaluated. The food emulsions w ere more stable than walnut oil, as indicated by measuring the formation of primary and secondary oxidation products. It was shown that the emulsions with WPI had a better oxidative stability than the emulsions with SI, probably due to the ability of whey proteins to inactivate peroxil radicals. In addition, the basic rheological characteristics: apparent and plastic viscosities, yield stress, consistency coefficient, and flow behavior index of the evaluated O/W emulsions, were determined. The rheological behavior and flow curves were analyzed using a fitted power law and Herschel-Bulkley model. The emulsions with SI showed increased viscosity in comparison to WPI emulsions. Moreover, soy protein formed a continuous network, and emulsions were more stable to creaming. © Maxwell Scientific Organization, 2010.
Krastanov A.,University of Food Technologies |
Alexieva Z.,Bulgarian Academy of Science |
Yemendzhiev H.,University Professor Dr. Assen Zlatarov Burgas
Engineering in Life Sciences | Year: 2013
Phenol and its derivatives are one of the largest groups of environmental pollutants due to their presence in many industrial effluents and broad application as antibacterial and antifungal agents. A number of microbial species possess enzyme systems that are applicable for the decomposition of various aliphatic and aromatic toxic compounds. Intensive efforts to screen species with high-degradation activity are needed to study their capabilities of degrading phenol and phenolic derivatives. Most of the current research has been directed at the isolation and study of microbial species of potential ecological significance. In this review, some of the best achievements in degrading phenolic compounds by bacteria and yeasts are presented, which draws attention to the high efficiency of strains of Pseudomonas, Candida tropicalis, Trichosporon cutaneum, etc. The unique ability of fungi to maintain their degradation potential under conditions unfavorable for other microorganisms is outstanding. Mathematical models of the microbial biodegradation dynamics of single and mixed aromatic compounds, which direct to the benefit of the processes studied in optimization of modern environmental biotechnology are also presented. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.