Authors:M. Nagy-Gasztonyi, Á. Kardos-Neumann and P. Á. Biacs
Blanching of vegetables before freezing has some advantages as well as a number of disadvantages. Process optimization involves measuring the rate of enzyme destruction, such that the blanching time is just long enough to destroy the indicator enzyme. Eventually, peroxidases were almost universally the enzymes of choice, as they are usually the most heat-stable enzymes found in vegetables and fruits, so by the time they are inactivated no other enzymes or micro-organisms remain. But there is no evidence that peroxidases are involved in deteriorative reactions in the food. The aim of this work was to improve blanching technology in Hungarian frozen food industry with special emphasis on broccoli treatment. Instead of peroxidases, lipoxygenases were chosen to determine the adequate blanching parameters. Usually, lipoxygenases accompany lipases, so lipase activity is measured, too. On the basis of model blanching experiments, the conclusion is that lipoxygenase could be used as indicator enzyme. Being less heat stable than peroxidase, this enzyme requires shorter heat treatment, hence its inactivation should result in minimum quality deterioration and economic loss.
Authors:P. Neumann, Z. Horváth, P. Nemes-Incze, G. Molnár, G. Vértesy and L. Biró
We studied the electrical transport properties of indium contacted graphene, few layer graphite (FLG) and bulk graphite samples under ambient conditions. Some of the contacted samples showed nonlinear transport characteristics. The initial electrical properties of the samples were changed reversibly by light illumination and irreversibly by argon ion irradiation. Ion irradiation modified the nonlinear I–V characteristics to quasi-linear ones in many cases. The resistance of a graphene sample showed positive temperature coefficient.
Authors:Zs. Szél, Á. Kardos-Neumann, P. Á. Biacs, E. Szalai-Mátray and A. Takáts
Diastase and glucose-oxidase activity was determined in 8 samples of Hungarian milkweed (Asclepias syriaca) honey and in 10 samples of Hungarian acacia (Robinia pseudoacacia) honey. The aim of the study was to compare diastase and glucose-oxidase activity of milkweed and acacia honey. Mean value for diastase was 16.28 diastase number (DN) (±2.53) in acacia honey and 24.48 DN (±5.07) in milkweed honey. Mean value for glucose-oxidase was 3.67 nmol unit g–1 (±3.31) in acacia honey and 8.24 (±4.21) in milkweed honey. The differences both in diastase and glucose-oxidase activities of the two honey types were statistically significant.
Authors:E. Horváth, P. L. Neumann, A. L. Tóth, É. Vázsonyi, A. A. Koós, Z. E. Horváth, P. Fürjes, C. Dücső and L. P. Biró
The deposition of
nanowires for interconnects in nanoelectronic devices werestudied
morphologically by scanning electron microscopy (SEM), atomic force microscopy
(AFM) and by in-situ resistance measurements. The deposition and basic
characterization of nanometer size tungsten wires by gas injection (GIS) and
focused ion beams (FIB) was carried out in-situ in a LEO 1540 XB workstation.
The I(V) measurement showed that the deposited W wires have ohmic
characteristic. The variation of the resistance during an ex-situ heating was
linear with a low thermal coefficient (4% of the pure metallic W).