This paper reports on the results obtained with the pulsed nuclear magnetic resonance (P-NMR) technique applied for determining fat content in fresh meat. The interfering moisture content of meat was removed by microwave drying and the dried residue was quantitatively transferred into the P-NMR tubes. The total analysis time was about 50 min. Experiments were performed with rendered pure pork, beef and goose fats, sunflower oil and with lean pork - fat and lean beef - tallow mixtures (batters). The regression (prediction) equations (intensity of P-NMR signal vs. fat content determined with the Soxhlet reference method) of the sunflower oil and fat samples did not differ appreciably. Consequently, contrary to the results obtained with the CW-NMR technique, the variability of the fatty acid composition of the examined fats and oil had no substantial effect on the regression (prediction) equations in this case. On the other hand, there was a considerable difference between the regression lines of the lean pork-fat and lean beef-tallow mixtures. Therefore, due to the interfering effect of the non-fat dry matter and the type of meat on the intensity of P-NMR signal, this technique can only have a restricted practical application in the in-line process control of fat content of meats.
Authors:M. Molnár, L. Hornyák, R. Nagy, E. Márki, and Gy. Vatai
Our experiments were based on a model solution containing five of the main pineapple aroma components. Both sweeping-gas pervaporation and vacuum-pervaporation methods were carried out. Measurements were performed at different temperatures and feed flow rates. The purposes of this study were to examine applicability of the two pervaporation methods in reference to the pineapple aroma recovery, the effects of the operating parameters on the process, and modelling the pervaporation process by resistance-in-series model. Higher enrichment could be reached with vacuum-pervaporation than the sweeping-gas method. The separation process is determined by the diffusion of compounds in the membrane, thus the resistance in the boundary layer at liquid side is negligible. Based on performed experiments, the pervaporation process can be applied in beverage industry for aroma recovery.
Authors:A. Szabó, A. Gyepes, Á. Nagy, L. Abrankó, and J. Győrfi
Vitamin D2 is essential for the human body and mushrooms are proved to be one of the best sources of it. In our experiment biologically active, pre-harvest white and cream type button mushrooms and oyster mushroom were treated with UVB light in order to increase their vitamin D2 level, by transforming their natural ergosterol content into vitamin D2. UVB lamps (operating on 312 nm) and six time periods of irradiation (15 to 90 min) were used. After three consecutive days of treatments the yield were measured and samples were taken for vitamin D2 analysis. Data showed considerable increase in vitamin D2 levels at every time period in each cultivar.
Authors:A. Nagy, L. Jędrychowski, É. Gelencsér, B. Wróblewska, and A. Szymkiewicz
In recent years, research related to studying the effect of gut microflora on the human health has become of major economic importance. The main objective of our study was to examine whether or not the orally administered Lactobacillusstrains (LB) as an oral adjuvant can improve the mucosal immune protectionviaan enhanced IgA secretion to a co-administered marker antigen ovalbumin (OVA). We adapted a murine (BALB/c) model to demonstrate beneficial adjuvant effects of probiotic LB strains. Orally sensitised mice with OVA, which were prefed with native or heat denatured (HD) Lactobacillus salivarius (Ls) or Lactobacillus casei (Lc) responded better or with the same efficiency to a vaccination with antigen (OVA) than mice that had been sensitised only with OVA or not sensitised at all. Antibody (IgA) responses in the gut were increased in response to vaccination with OVA in mice that had been prefed with native or heat denatured Ls or Lc followed by Ls or Lc and OVA feeding. In prefed groups, the OVA feeding alone primed for specific immune response, while adjuvanted OVA has increased the immune exclusion potential of the gut.
Authors:E. Nagy, I. Éliás, L. Körmendy, and J. Czeglédi-Jankó
Development of rapid methods is often needed for the in-line process control of the proximate composition (e.g. fat or moisture content) of meat in the meat processing plants. This paper reports on the continuous wave nuclear magnetic resonance (CW-NMR) technique applied for determining fat content in fresh meat. The interfering moisture content in meat was removed by microwave drying and the dried residue was transferred quantitatively into the NMR-tubes. The total analysis time was about 35 min. Experiments were performed with pork (with a fat content from 1.7% to 21%), beef (with a fat content from 1.0% to 16.1%), lard (rendered pork fat) and tallow (rendered beef fat) samples and with their combinations: lard-tallow, lard-lean pork, tallow-lean beef and lard-tallow-lean beef-lean pork. The regression (prediction) equations (NMR-signal vs. fat content determined with the Soxhlet reference method) of pork and beef did not differ significantly. However, there was a noticeable difference between the regression lines of pure lard and pure tallow. Moreover, the latter ones differed from the regression equations of pork, beef and of the various meat-fat combinations. The variability of the fatty acid composition of the fat also seems to influence the stability of the calibration curves, because the sensitivity of the CW-NMR signal to the fatty acid composition interferes with the quantitative determination of fat content in meat.
Authors:L. Mesarčová, S. Marcinčák, J. Nagy, P. Popelka, M. Bača, P. Jevinová, and D. Marcinčáková
Frozen fillets of Atlantic herrings (Clupea harengus) were used to evaluate the effect of glaze with or without addition of selected herbal extracts on lipid oxidation and sensory properties during 8 months of freezing storage under −14 °C. Fillets were divided into four groups: control non-glazed group, glazed group without addition of herbal extracts, and glazed groups with addition of hawthorn (Crataegus oxyacantha L.) extract (0.3%) and agrimony (Agrimonia eupatoria L.) extract (0.3%). The antioxidant activity and total phenolic content in hawthorn and agrimony extracts, and their effect on lipid deterioration expressed as thiobarbituric acid reactive substances were measured. The results showed that the herbal extracts of hawthorn and agrimony are effective antioxidants and good sources of total phenols. Significant influence of herbal extracts added into glaze on the extent of lipid oxidation changes has been obvious within 4 months storage of herring fillets under freezing conditions. Finally, positive influence of glaze and herbal extracts on organoleptic characteristics of fish fillets was found.
Authors:I. Rurik, E. Gyömörei, L. Biró, K. Nagy, A. Regöly-Mérei, and M. Antal
The aim of this study was to evaluate the nutritional status of elderly belonging to one primary care office. Twenty-seven men and 26 women, all over 60 years, were involved. Nutritional assessment, anthropometric measurements were performed, serum proteins, lipid and iron status and haematological parameters were determined. Energy and protein intake was sufficient, but the distribution of energy with a high fat and low carbohydrate was inadequate. Iron, copper, calcium, retinol and folate intake was lower, whereas sodium, ascorbic acid and cobalamin intake was higher than the Hungarian recommendation. The prevalence of obesity characterized by body mass index or waist circumference was higher in women than in men. The percentage of pathological levels of lipid parameters was also higher in women. No iron deficient erythropoesis was detected, but high serum ferritin concentration as a marker of body iron store was determined in some cases. General practitioners have possibilities to influence the nutritional habits of elderly, thereby reducing the incidence of obesity, cardiovascular diseases and stroke. Iron status of Hungarian elderly looks to be satisfactory, so supplementation without testing the iron status would be useless and harmful.
Authors:J. B.Nagy, J. N. Coleman, A. Fonseca, A. Destrée, Z. Mekhalif, N. Moreau, L. Vast, and J. Delhalle
Organic polymers -
carbon nanotubes nanocomposites are synthesized either by mechanical mixing of
the two components or by covalently linking the nanotubes to the matrix. The
various procedures will be overviewed and the determining factors will be
identified for the best mechanical properties of the composites. On the other
hand, it will be shown that for highest electrical conductivity much smaller
amounts of carbon nanotubes are needed if the nanotubes can be aligned. The
thermal conductivity of the nanocomposites will also be overviewed. Finally,
together with nanoclay particles, nanotubes are inducing remarkable flame
retardant properties in the nanocomposites materials.