Electrochemical Biosensor Based on surfactant doped polypyrrole (PPy) matrix for lactose determination

Lactose biosensor based on surfactant doped polypyrrole (PPy) was developed. Galactose oxidase and β‐galactosidase was coimmobilized in PPy matrix during electropolymerization process with the presence of sodium dodecylbenzene sulphonic acid as surfactant. Bi‐enzyme entrapped PPy was characterized with Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and scanning electron microscopy (SEM). The response of the enzyme electrode was measured by CV in the range of ?0.1 to 1.0 V versus Ag/AgCl which was due to the electrooxidation of enzymatically produced H₂O₂. The effect of lactose concentration was investigated. Response time of biosensor was found to be 8–10 s (the time required to obtain the maximum peak current) and upper limit of the linear working portions was found to be 1.22 mM lactose concentration with a detection limit of (2.6 × 10^?6 M). The apparent Michaelis–Menten constant was found to be 0.117 mM lactose. The effects of interferents (ascorbic acid and uric acid) were determined. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40200.     

Recent developments in non-thermal processing for seafood and seafood products: cold plasma,pulsed electric field and high hydrostatic pressure

Seafood and seafood products (SSPs) are highly perishable foods due to their chemical composition (high moisture content and nutrients). They are regarded as highly sensitive to different processing technologies. SSPs are subjected to various processing conditions with intent to extend their shelf life, quality and minimal nutritional degradation. Recently developed non-thermal technologies (NTTs) have proved their efficacy in inactivation of microorganisms and enzymatic activities, enhancing the shelf life while maintaining the nutritional quality. Considering the significant impacts of NTTs on shelf life extension and maintaining quality parameters, it has attracted considerable interest by scientific communities and commercial applications in some cases. Thus, this article focuses on recent developments in the application of NTTs namely, cold plasma, pulsed electric field and high hydrostatic pressure as well as advantages and limitations of NTTs. In addition, their impacts on microbiological, physicochemical, quality and safety of SSPs are elucidated.     

Photoacoustic analysis and imaging techniques: Sound of light

An unusual form of imaging and analysis applications combines optics and acoustics to probe the features and behaviors of materials. The name of photoacoustic like all other techniques of spectroscopy reveals underlying its theoretical basis. Even if the prefix “photo” makes sense for a spectroscopy, acoustic may be initially amazing. Photoacoustic technique is extension of the photothermal effect, which is based on light beam hitting the sample and altering its thermal status. More precisely, photoacoustic effect is a transformation between light, heat, and sound caused by light absorption. After the successful formulation of general theoretical model, photoacoustic technique, which initially was only used for the analysis of gas samples, has been efficiently extended to analysis of condensed matters. Variety of samples, nondestructive analysis and imaging, depth profiling, high specificity and sensitivity, analysis of opaque samples are the most important advantages of photoacoustic technique. As of today, many researchers have performed in vitro and in vivo analysis and imaging application using photoacoustic technique; moreover, increasing number of companies are manufacturing biomedical imaging devices based on this effect. If the obstacles to experimental restrictions are removed, we will begin to hear the sound of light as more powerfully in many applications, particularly physics, materials science, and medicine.     

Effects of laurel and myrtle extracts on the sensory,chemical and microbiological properties of vacuum‐packed and refrigerated European eel (Anguilla anguilla) fillets

The effects of extracted natural antioxidant (laurel and myrtle) on the sensory, chemical (TVB‐N, TBARS, PV, FFA and pH) and microbiological (total viable count, psychrotrophic bacteria and Enterbacteriaceae counts) properties of vacuum‐packaged European eel (Anguilla anguilla) stored at 4 ± 1 °C were investigated. The TBARS values of myrtle were significantly lower than that of other groups. The peroxide value was low for European eel treated with myrtle and laurel extract. The FFA‐free fatty acid concentration increased from 0.44 (% oleic acid) (2.03) in the eel during 24 days of storage. The values of pH showed statistically significant (P < 0.05) changes for all groups. The myrtle significantly reduced bacterial growth in fillets (P < 0.05). The microbiological limit of 7 log cfu per gram did not exceed in the treated groups. Data showed that the extracts of myrtle and laurel contain substances that inhibit oxidation of lipids and growth of bacteria in European eel, indicating the potential value of these extracts to extend the shelf life of fish.     

Acrylic bone cements: Effects of the poly(methyl methacrylate) powder size and chitosan addition on their properties

The effect of the particle size of poly(methyl methacrylate) (PMMA) and the incorporation of chitosan (CH) on the mechanical and thermal properties and the biocompatibility of acrylic bone cements were investigated. Three groups of bone cements were prepared with different PMMA particles. Groups 1 (BC1) and 2 (BC2) contained ground and sieved PMMA with particle sizes in the ranges 50–150 μm and 1–50 μm, and group 3 (BC3) contained synthesized PMMA microspheres with a size of about 1 μm. The mechanical properties of the three groups were similar, but their curing properties were significantly affected. The presence of CH improved the mechanical and thermal properties. For the BC1 group, the compressive strength increased more than 10 MPa, and the curing temperature decreased 12°. The cement having the optimum properties (BC1) was applied to rats, where it enhanced the bone bonding ability, and bioactivity was observed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39662.     

Effects of ohmic heating for pre-cooking of meatballs on some quality and safety attributes

Effectiveness of ohmic treatment on some quality attributes of semi-cooked meatballs was studied. Meatball samples were semi-cooked by 15.26 V/cm voltage gradient and 0 s holding time at 75 °C. Although ohmic cooking significantly reduced the numbers of total mesophilic aerobic bacteria, mould-yeast, Staphylococcus aureus and completely eliminated Salmonella spp. from meatball samples (p < 0.05), it was not found efficient to inactivate all Listeria monocytogenes cells. Ohmic semi-cooking process was resulted at higher cooking yields, which were supported by high fat and moisture retention values in meatball samples. Metal levels (iron, chromium, nickel and manganese) of ohmically semi-cooked meatball samples were found below the upper level of dietary exposure levels. Ohmic cooking procedure was found to be safe in terms of PAH formation and mutagenic activity. Sensory evaluation showed that the overall acceptance of the semi-cooked meatball samples were good. These results demonstrate considerable potential for the application of ohmic process for semi-cooking of meatballs.