Seasonal development of entomophthoralean unfection in colonies of
was evalauted on summer barley under conditions of south-western Slovakia in 2001 and 2002.
was infesting summer barley during both years, while
was only recorded in 2002. Further three cereal aphids,
, were also observed on summer barley. Complex of entomophthoralean fungi identified in cereal aphid colonies included four species,
as the most prevalent fungus during both years. Two parasitic fungi,
, were identified from
was predominant. Infection rate in
colonies was low, not exceeding 15% and 10% in 2001 and 2002, respectively. Only nine
individuals were killed with entomophthoralean fungi. The fungi were identified as
. No epizootics were observed in the aphid colonies. The fungi could not control development of the aphid populations since they did not appear until high host densities had been established in the crops.
For colouring of foods anthocyanins are widely used, which are present in great quantity in black elderberry (Sambucus nigra). Experiments were done to study the anthocyanin content of several varieties and candidates, from which the highest value was found in the Haschberg cultivar. Further experiments were performed with this cultivar to study the anthocyanin stability ofS. nigraunder different circumstances (heat-treatment at various pH and temperatures). Our results revealed that anthocyanins react sensitively to temperature and pH increase.
Authors:B. Szabó-Nótin, R. Juhász, J. Barta, and M. Stéger-Máté
The aim of the present study was to investigate whether apple pomace powder produced by a simple drying method is suitable for replacing pectin in bakery jam products. Rheological properties of bakery jams were tested by oscillatory tests using amplitude sweep method. Apple pomace addition decreased gel strength and stability of bakery jams, while 12-month storage increased the gel strength of samples. Based on our results, dried apple pomace powder seems to be suitable to replace pectin up to 40% without changing rheological properties of bakery jams.
Authors:M. Gyalai-Korpos, A. Fehér, Zs. Barta, and K. Réczey
The need to introduce promising bioethanol production technologies calls for advanced laboratory techniques to study experiment designs and to obtain their results in a quick and reliable way. Real time monitoring based on general principles of ethanol fermentation, such as effluent CO2 volume, avoids time consuming steps, long lasting analyses and delivers information about the process directly. A device based on the above features and capable for real time monitoring on parallel channels was developed by the authors and is described in this paper. Both for calibration and for fermentation, test runs were carried out on different days and channels. Statistical evaluation was based on the obtained data. According to the t-test (P=0.05) and Grubbs analysis, the calibration method is reliable regardless of the date of calibration. When evaluating the fermentation results by ANCOVA acceptable standard derivations were obtained as impact of channel (58.8 ml), date (82.1 ml) and incorporating all impacts (116.2 ml). The final ethanol concentrations calculated based on the gas volume were compared to ones determined by HPLC and an average difference of 10% was found. Thus, the device proved to be advantageous in monitoring fermentation.
Authors:M. Stéger-Máté, G. Ficzek, E. Kállay, G. Bujdosó, J. Barta, and M. Tóth
The variation of some compositional quality parameters in connection with ripening time in the case of four sour cherry varieties (
L. Mill.) was studied. Our aim was to optimize the harvest time on the basis of antioxidant capacity. The experiments were carried out in the Érd-Elvira orchards of the Research Institute for Fruitgrowing and Ornamentals (cultivars Érdi bőtermő, Kántorjánosi 3) and in orchards of the Agárd Frucht Ltd. in Agárd (cultivars Érdi jubileum, Maliga emléke). Anthocyanin, polyphenol and vitamin C contents as well as the water-soluble dry matter content of fruits were measured.According to the results of quality parameter measurements it can be stated, that in case of the studied cultivars the optimal picking time for industrial processing is the second picking. At this time the anthocyanin, polyphenol and water-soluble dry matter content of the cultivars are optimal. In general, at the end of the ripening period the fruits shrink, fruit weight and juiciness decreases as a consequence of water loss, therefore determining optimal harvest time for the desired utilization purpose is very important. According to our results, out of the four studied cultivars, Érdi jubileum has the highest values regarding anthocyanin and polyphenol contents.
Authors:B. Nótin, M. Stéger-Máté, R. Juhász, D. Jakab, J. Monspart-Sényi, and J. Barta
In this study the effect of drying temperature and pressure on the antioxidant capacity and phenolic compounds of black currant (Ribes nigrum L., cultivar Titania) was investigated. Samples were vacuum dried at 10 mbar at temperature 40, 50 and 60 °C until a wet content lower than 10% was reached. As control, atmospheric drying at 60 °C was also performed.During the drying processes the amount of total polyphenol, total anthocyanin, catechin and leucoanthocyanin as well as the antioxidant capacity (FRAP) were measured. The drying curves were also determined.The drying temperature affects the duration of the drying, the rate of water loss, and the remaining amount of antioxidant compounds. The amount of phenolic compounds decreased during drying. The amount of phenolic compounds decreased the least of all during atmospheric drying at 60 °C. Among vacuum drying technologies temperature level of 50 °C proved to be the best to preserve antioxidant phenolic compounds. Greater loss was observed when black currant was vacuum dried at higher temperature (60 °C) or at lower temperature (40 °C) for a longer time.