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Nikfardjam M.S.P.,State Research Institute for Viticulture and Pomiculture | Nikfardjam M.S.P.,FVM Research Institute for Viticulture and Oenology | Gausz I.S.,FVM Research Institute for Viticulture and Oenology | Farkas V.,FVM Research Institute for Viticulture and Oenology
Mitteilungen Klosterneuburg

Musts and wines made from 'Cabernet Sauvignon' and 'Lemberger' grapes of the vintages 1992 to 2001 from the Hungarian wine regions Pécs, Szekszárd and Villány were analysed for their manganese content by means of AAS. Results showed that in 'Cabernet Sauvignon' weather conditions had a stronger impact on the final manganese content than in 'Lemberger'. Compared to values published in literature Hungarian red wines showed average concentrations. Mean manganese concentration of must from 'Cabernet Sauvignon' was 1.06 mg/l (n = 300), in 'Cabernet Sauvignon' wines the mean concentration was 1.35 mg/l (n = 300). Generally, 'Cabernet Sauvignon' musts from Pécs had slightly higher contents of manganese than must from Szekszárd or Villány. Mean manganese concentration of must from 'Lemberger' was 0.96 mg/l (n = 300), in 'Lemberger' wines the mean concentration was 1.24 mg/l (n = 300). 'Lemberger' musts from Villány generally showed higher manganese contents than from Pécs or Szekszárd. Daily intake of manganese regarded as being safe will not be exceeded by drinking two glasses (= 0.2 l) of 'Cabernet Sauvignon' or 'Lemberger' wine per day. Source

Czibulya Z.,University of Pecs | Kollar L.,University of Pecs | Pour Nikfardjam M.,State Research Institute for Viticulture and Pomiculture
Journal of Food Science

The effect of increased temperature on the color of red wines was studied due to its importance during storage and transport. The chemical reactions induced by elevated temperature were investigated by measuring the UV-VIS spectra. The temperature of the wines was increased from its common storage temperature (about 14 °C) to higher temperatures (t= 20 °C, 25 °C, 30 °C, 35 °C, and 40 °C) and the UV/VIS spectra were recorded during several hours. The spectral changes obtained indicate the presence of quasi-first-order chemical processes justifying determination of the activation energies using their temperature dependence. The determined decay values (Villányi Portugieser: EVPa,420 nm= 90.02 kJ/mol, EVPa,520 nm= 34.18 kJ/mol, EVPa,620 nm= 54.55 kJ/mol; half-life values of 46.5 d [25 °C] and 9.5 d [35 °C] at 420 nm; 4.67 d [25 °C] and 2.0 d [35 °C] at 520 nm; 9.5 d [25 °C] and 2.4 d [35 °C] at 620 nm; Bikatory wine: EBka,420 nm= 82.07 kJ/mol and half-life values of 41.35 d [25 °C] and 4.001 d [35 °C] at 420 nm) of these reactions highlight a considerable change in the quality of wines stored for a few hours at elevated temperatures. Depending on polyphenol composition the wines show different half-life with regard to their color stability and browning reactions. Higher polyphenolic content helps to stabilize the wine against detrimental temperature effects. © 2012 Institute of Food Technologists®. Source

Teszlak P.,University of Pecs | Kocsis M.,University of Pecs | Gaal K.,University of Pecs | Nikfardjam M.P.,State Research Institute for Viticulture and Pomiculture
Scientia Horticulturae

Different impacts of exogenous gibberellic acid (GA3) on water relation and CO2 gas exchange in grapevine leaves were studied on four varieties belong to various ecogeographical groups. GA3 treatment resulted in increasing cell wall rigidity in some cultivars and affected the linear correlation between elasticity modulus ('ε') and relative water content at the turgor loss point (RWCTLC). The response of cultivar 'Riesling' agreed with the hypothesis; GA treatment resulted in increasing 'ε' values ('ε'>12MPa), indicating decreased cell wall elasticity. According to pressure-volume analysis, osmotic potential at full turgor (Π100) in treated 'Sauvignon Blanc' vines was higher compared to the controls. Results of analysis demonstrated that the four varieties showed a negative linear correlation between apoplastic water content (AWSD%) and leaf water potential at the turgor loss point (ΨTLP) and a positive linear correlation between AWSD% and RWCTLP. Values of Ci and PN showed a positive exponential correlation; Ci values increased parallel with increasing net CO2 assimilation in a range between 10 and 24Pa of Ci both in control and treated vines. In each cultivar, intrinsic water use efficiency (WUEi) increased at reduced stomatal conductance. GA3 treatment resulted in favourable values of WUEi as expected for cultivar 'Kadarka' (group of convarietas pontica). WUEi was significantly (P<0.05) lower in the GA3 treated vines compared to the controls in most of the varieties irrespective of different ecogeographical groups. © 2013 Elsevier B.V. Source

Czibulya Z.,University of Pecs | Czibulya Z.,Janos Szentagothai Research Center | Horvath I.,University of Pecs | Kollar L.,Janos Szentagothai Research Center | And 4 more authors.

The temperature and pH dependence of the color stability of a Hungarian red wine (Portugieser variety from Villány, Southern Transdanubia, Hungary) was investigated. Results show that both color intensity and pH were decreased by increasing temperature due to the dissociation of several phenolic OH groups. However, wine color intensity was increased upon addition of HCl even in the presence of additional potassium ions. This leads to the conclusion that added potassium ions change the pH dependence, while the addition of calcium ions resulted in moderated change on the pH dependence of color intensity. Comparing the color changes induced by the temperature or the pH highlights that the change in color intensity is a result of complex processes and its temperature dependence cannot be described solely as the decrease of pH at elevated temperatures. © 2015 Elsevier Ltd. All rights reserved. Source

Nikfardjam M.P.,State Research Institute for Viticulture and Pomiculture | Maier D.,State Research Institute for Viticulture and Pomiculture
Food Chemistry

A reliable and simple method was developed for the completely automatised analysis of apple juice aroma compounds. In total 26 flavour compounds could be measured by headspace trap gas chromatography/mass spectrometry (GC/MS). We used the method to analyse 85 commercially available apple juices, of which 67 apple juices were not from concentrate. Our results show that apple juices not from concentrate are mainly characterised by flavour compounds responsible for fruity, ripe, and sweet aroma impressions, such as 1-butanol, 2-methyl-1-butanol, ethylbutyrate, and ethyl-2-methylbutyrate. On the contrary, apple juices made from concentrate were dominated by acetaldehyde, E-2-hexenal, 3-methyl-1-butanol, ethyl acetate, and hexanal, which are mainly responsible for sensory impressions, such as 'green, fresh, estery'. According to our data, neither of the single compounds nor indexes calculated thereof as suggested by some authors could be used for the reliable assessment of apple juice quality. Thus, these results suggest that sensory evaluation remains the ultimate mean to reliably assess apple juice quality. © 2010 Elsevier Ltd. All rights reserved. Source

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