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Czibulya Z.,University of Pécs | Kollar L.,University of Pécs | Pour Nikfardjam M.,State Research Institute for Viticulture and Pomiculture
Journal of Food Science | Year: 2012

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®.


Porep J.U.,University of Hohenheim | Mattes A.,State Research Institute for Viticulture and Pomiculture | Pour Nikfardjam M.S.,State Research Institute for Viticulture and Pomiculture | Kammerer D.R.,University of Hohenheim | And 3 more authors.
Australian Journal of Grape and Wine Research | Year: 2015

The parameters commonly examined upon receival of grapes at wineries are insufficient for comprehensive quality assessment. Grape quality is mainly determined by the ripeness and phytosanitary status of the grapes and is indicated by changes in chemical composition. Thus, we have evaluated the feasibility of an on-line assessment for real-time analysis of crushed grapes by near infrared/visible (NIR/VIS) spectroscopy at production scale upon their receival. Methods and Results: Spectrometers were successfully integrated into the receival lines of two wineries during three vintages. The spectra of 1160 samples were collected. Calibration models were established for the spectral ranges of 450-850nm (VIS) and 1050-1650nm (NIR) by partial least squares regressions for ten relevant parameters. A global calibration model and more specific models relying on grape colour, vintage, winery and grape cultivar were established. The best performing models specific to individual cultivars resulted in a coefficient of determination of the validation (R2 val) of 0.767, 0.732 and 0.747 for relative density, fructose and glucose concentration; 0.787, 0.540, 0.877 and 0.862 for pH value, tartaric acid and malic acid concentration and titratable acidity; and 0.698, 0.777 and 0.574 for the grape rot indicators glycerol, gluconic acid and acetic acid, respectively. Conclusions: Models suitable for semi-quantitative prediction of parameters related to composition were established as being valuable for multifactorial, holistic assessment of the composition of grape deliveries. Specialisation of the calibration models bears the potential for further improvement, thus allowing comprehensive assessment of grape composition by NIR/VIS spectroscopy. Significance of the Study: On-line implementation of NIR/VIS spectroscopy was shown to be a promising tool for rapid and objective assessment of the composition of grapes upon receival at wineries, which may enable improved systems for payment and quality management. Further acceptance criteria may be developed and food safety may be improved by detecting and rejecting spoiled grapes potentially containing mycotoxins. © 2015 Australian Society of Viticulture and Oenology Inc.


Porep J.U.,University of Hohenheim | Mrugala S.,State Research Institute for Viticulture and Pomiculture | Pour Nikfardjam M.S.,State Research Institute for Viticulture and Pomiculture | Carle R.,University of Hohenheim | Carle R.,King Abdulaziz University
Food and Bioprocess Technology | Year: 2015

In general, vinification of sound grapes is an essential requirement for the production of high-quality wines. Grape rot, mainly caused by filamentous fungi, commonly impairs perceptual quality of wine; food safety may be affected due to the formation of biogenic amines and mycotoxins. Grape rot assessment by visual examination, taste or smell remains subjective. Other methods for grape rot quantification frequently lack specify, sensitivity or reproducibility. In contrast, ergosterol represents an objective and specific marker for filamentous fungal grape rot. In our study, we approved the suitability of ergosterol as a marker for grape rot of commercially harvested grapes, delivered to wineries under normal operating conditions. A total of 177 grape samples from five grape varieties was analysed by HPLC-UV for ergosterol content. Pinot Meunier showed the highest ergosterol contents up to 11.4 mg/kg. Mean ergosterol content for all varieties amounted to 2.3 mg/kg. About 20 % of the samples exceeded the limit of 3.0 mg/kg for sound grapes, and about 3.4 % were above the limit of 6.2 mg/kg indicating rotten grapes. Moreover, near-infrared/visible (NIR/VIS) spectroscopy has been applied as a rapid tool for online determination of ergosterol under industrial conditions. Calibration models were established and validated. Validation statistics for a dependent test set were coefficient of determination of the validation (R2val) of 0.726, root mean square error of prediction (RMSEP) of 0.84 mg/kg and ratio of prediction to deviation (RPD) of 2.0. At least semi-quantitative measurements of ergosterol in grape mashes upon delivery at wineries appeared feasible, thus enabling the objective detection of grape rot. Thereby, fair and incentive quality-based payment may be enabled; quality management and food safety may be improved. © 2015, Springer Science+Business Media New York.


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 | Year: 2012

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.


Kunsagi-Mate S.,University of Pécs | May B.,State Research Institute for Viticulture and Pomiculture | Tschiersch C.,State Research Institute for Viticulture and Pomiculture | Fetzer D.,State Research Institute for Viticulture and Pomiculture | And 3 more authors.
Food Research International | Year: 2011

The temperature-dependent transformation of π-π-stabilized stacked malvidin-catechin structures towards polymeric-type structures was studied by photoluminescence (PL) and anisotropy decay studies. The results show an immediate decrease of the anisotropy decay after elevating the temperature from 293. K to 303. K or 313. K, while only a very slow increase in the anisotropy decay could be observed when the samples were kept at these elevated temperatures for a longer time such as a few days. The slow polymerization of the malvidin-polyphenol system could be identified as the main process responsible for the change in optical properties by the comparison of the time-dependence of the anisotropy decay with the change observed in the PL intensity. Measurements were also conducted in red wines, where we observed similar results. This suggests a possibly broader relevance of our results for all systems, where anthocyanins and polyphenols are present in considerable concentrations. © 2010 Elsevier Ltd.


Teszlak P.,University of Pécs | Kocsis M.,University of Pécs | Gaal K.,University of Pécs | Nikfardjam M.P.,State Research Institute for Viticulture and Pomiculture
Scientia Horticulturae | Year: 2013

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.


Nikfardjam M.P.,State Research Institute for Viticulture and Pomiculture | Maier D.,State Research Institute for Viticulture and Pomiculture
Food Chemistry | Year: 2011

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.


Czibulya Z.,University of Pécs | Czibulya Z.,Janos Szentagothai Research Center | Horvath I.,University of Pécs | Kollar L.,Janos Szentagothai Research Center | And 4 more authors.
Tetrahedron | Year: 2015

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.

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