Search Results

You are looking at 21 - 26 of 26 items for

  • Author or Editor: Gy. Kiss x
  • All content x
Clear All Modify Search
Acta Alimentaria
Authors: Zs. Molnár, Sz. Bánvölgyi, Á. Kozák, I. Kiss, E. Békássy-Molnár, and Gy. Vatai

Concentration of raspberry (Rubus idaeus L.) juice by combination of membrane processes was investigated. The pre-treatment steps were crushing, enzyme treatment, pressing and clarification by microfiltration (MF). Ceramic tube MF membrane was used at low pressure and temperature (3.9 bar and 30 °C).Nanofiltration (NF) and reverse osmosis (RO) process with flatsheet membranes was studied to pre-concentrate the clarified and sterilized raspberry juice. The NF experiments were carried out at different flow-rates (400 l h−1 and 600 l h−1). Any significant effect of flow-rate was not experienced. Both pre-concentration processes were used at low temperature (30 °C) for a mild concentration of raspberry juice. For further concentration osmotic distillation (OD) was applied. The initial total soluble solid content of the raspberry juice was 8–10 °Brix, the final concentrate of OD was 70–80 °Brix.The membrane-, fouling- and the polarization layer resistance were determined in case of micro-, nanofiltration and reverse osmosis.The soft drinks, made from RO and OD concentrates, were compared with well-known conventional raspberry juice from trade. During the sensory analysis (the colour, odour, flavour, acid taste and general impression was evaluated) our juices were preferred by customers.The antioxidant capacity, total phenol, anthocyanin and acid content, the total cell count and the number of yeasts and moulds were determined in the permeate and retentate samples of the different filtration steps.

Restricted access
Acta Alimentaria
Authors: Sz. Bánvölgyi, T. Vatai, Zs. Molnár, I. Kiss, Ž. Knez, Gy. Vatai, and M. Škerget

Two novel technologies were applied in order to investigate concentration and formulation of anthocyanins for potential use in food industry. Integrated membrane process technology was applied for concentrating elderberry juice. In the first step, the juice was clarified by microfiltration, followed by a pre-concentration step with reverse osmosis. Finally, the juice was concentrated to the end concentration of 56 °Brix by osmotic distillation. The elderberry juice concentrate was formulated in a powderous form by a high-pressure process — Particles from Gas Saturated Solution (PGSS™) — using supercritical CO2. The applied carrier material was palm fat. The products with different anthocyanin-carrier ratios were measured for their colour properties (lightness, hue angle, and saturation). Colour stability was monitored for prolonged storage at different conditions (light/dark and ambient temperature/ refrigerator). The obtained powderous anthocyanin-palm fat products showed good colour stability, which gives good bases for potential applications in the future.

Restricted access

WCR adults generally lay their eggs in maize and their larvae feed almost exclusively on maize roots (Smith,1966,Branson and Ortman,1967,1971,Branson and Krysan,1981,Levine and Oloumi- Sadeghi,1991).For this reason,farmers have accepted growing maize in rotation with soybean to manage WCR larval populations without the use of soil insecticides.Recently,in Northwest Indiana and East Central Illinois in the USA,western corn rootworm has adapted to the above management system (Gerber et al., 1997).A portion of WCR eggs is laid in soybean and in other crops like alfalfa.This behavioral change increases the potential for survival of WCR larvae the following year since most soybean fields are rotated to maize.During the summers of 1996,1997,and 1998 field studies related to this behavioral shift were conducted in northwestern Indiana.Eleven pairs of maize/soybean fields were selected for the study.During these sampling periods,WCR beetles were present in both maize and soybean.Empirical observations show that there were higher numbers of females in soybean when compared to maize.

Restricted access

The aim of this paper was to find possible link between molecular and morphological similarities of 38 Hungarian white grape varieties. Three aspects of morphological and molecular similarity were assessed in the study: comparison of the ordered variety pairs, assessment of molecular and morphological mean similarity differences and separation of varieties into similar groups by divisive cluster analysis to define (DIANA). Molecular similarity was calculated from binary data based on allele sizes obtained in DNA analysis. DNA fingerprints were determined at 9 SSR loci recommended by the European GrapeGen06 project. Morphological similarity was calculated on the basis of quantitative morphological descriptors. Morphological and molecular similarity values were ordered and categorized after pairwise comparison. Overall correlation was found to be weak but case by case assessment of the variety pairs confirmed some coincidence of molecular and morphological similarity. General similarity position of each variety was characterized by Mean Similarity Index (MSI). It was calculated as the mean of n-1 pair similarity values of the variety concerned. Varieties were ordered and compared by the difference of the index. Five varieties had low morphological and high molecular MSI meaning that they share several SSR marker alleles with the others but seems relatively distinct according to the expression of their morphological traits. Divisive cluster analysis was carried out to find similar groups. Eight and twelve cluster solutions proved to be sufficient to distinct varieties. Morphological and molecular similarity groups partly coincided according to the results. Several clusters reflected parent offspring relations but molecular clustering gave more realistic results concerning pedigree.

Restricted access
Acta Alimentaria
Authors: R. Kiss, G. Szita, M. Herpay, Gy. Csikó, J. Pászti, T. Mag, P. Kovács, G. Kovács, J. Szita, P. Tóth, I. Szatmári, and S. Bernáth

The authors investigated the possibility of the presence of VTEC strains in improperly pasteurized milk samples. A total of 64 Escherichia coli strains were isolated from 135 pasteurized milk samples originating from the same producer. The examined isolates contained 29 haemolysin-, 9 colicin- and 5 aerobactin-producing strains, but the investigations concerning heat-resistant and heat-sensitive toxins gave negative results.Six O128-type E. coli strains exerted a cytotoxic effect on the VERO cell line; 5 of them contained H12 antigen, while one could not be typed. Four of the 6 verocytotoxin-producing strains belonged in phage group 20, one in phage group (2)3(7), and one in phage group 4; four strains were of B3, one of A1, and one of A1(A2) phage type.Because of a technical failure the milk was pasteurized at 69 °C for 15 s, which is 2 °C less than required. The results underline the importance of the appropriate pasteurization temperature, as otherwise the milk may contain verocytotoxin-producing E. coli, which is a potentially great hazard for public health.

Restricted access
Acta Biologica Hungarica
Authors: I. Grigorszky, Gy. Dévai, K. Kiss, B. Tóthmérész, M. Gligora, A. Plenkovic-Moraj, Koraljka Kraj, V. Béres, Cs. Schnitchen, G. Borics, and A. Nagy

Phosphatase enzymes are capable of releasing phosphate through cleavage of phosphoester bonds. The seasonal importance of this process was examined by using a model substrate paranitrophenylphosphate and the Michaelis-Menten equation to estimate the release rate of PO 4 -P from phosphomonoesters. The seasonal occurrence of phosphomonoesters and acid phosphatase activity was used to estimate the velocity of phosphate release from these compounds. Filter fractionation of phosphatase activity demonstrated that most activity (>60%) was in size fractions less than 0.45 μm. The release rates were highest in May and June (15 to 25 nmol L −1 min −1 ) during the Gonyostomum semen (Raphidophyta) bloom and decreased to less than 2 nmol L −1 min −1 in two weeks and remained low throughout the summer and the fall. Fractionation of 32 P-H 3 PO 4 labelled dissolved organic phosphorus showed this fraction to vary considerably through the year. Potential phosphate release declined through the summer and into the fall. Significance of the co-occurrence of phosphomonoesters and acid phosphatase activity maxima and Gonyostomum semen (Raphidophyta) bloom is discussed.

Restricted access