Authors:Cs. Mohácsi-Farkas, G. Kiskó, L. Mészáros, and J. Farkas
Laboratory batches of fresh tomato juices were treated in several experimental trials by high hydrostatic pressure alone or in combination with various concentrations of oregano, thyme or dill seed oils. Lactic acid bacteria formed the dominating component of the spoilage microbiota during post-processing storage at 15 °C causing spoilage of the untreated samples within 4 days. One tenth of a percent oregano or thyme oils at least doubled the microbiological shelf life, while their respective concentrations of 0.5% alone, or 400 MPa 5-20 min high hydrostatic pressure treatment alone resulted in microbial stability for at least two weeks. Two hundred MPa for 10 min resulted only in an approx. 3 days delay of spoilage, whereas 0.1% thyme oil increased the efficiency of this moderate UHP-treatment, resulting in a microbiologically stable product for at least 3 weeks at the storage temperature applied.
Eight Lactobacillus, five Saccharomyces and one Streptococcus strains were chosen to perform mono and mixed culture fermentations, focusing on interaction investigation via agar diffusion and analysis of cell growth kinetics, both serving as selection criteria. Mixed culture fermentations with four lactic acid bacteria (Lb. bulgaricus, Lb. paracasei SF1, Lb. plantarum 2142, and Lb. casei Shirota) and four yeast strains (S. cerevisiae W66, S. cerevisiae WS34/70, S. cerevisiae W120, and S. carlsbergensis 843) were performed in wort with initial cell ratio of 1:1. It was determined that during fermentations, cell concentration of lactic acid bacteria exceeded that of yeasts by one order of magnitude. Three strain combinations (S. carlsbergensis with Lb. bulgaricus, Lb. 2142, and Lb. Shirota) were chosen for further fermentations. Basic behaviour of them in wort was studied in mono culture, which helped to determine interaction type between bacteria and yeast in mixed culture. It resulted in higher Lactobacillus cell concentration in mono cultural than in mixed culture fermentation, which refers to competition. Cell ratio was changed to 1:10 (lactobacilli:yeasts), to favour growth of yeast and avoid lower pH. Despite the higher initial concentration of yeast, results turned in favour of lactobacillus already at the 24th hour.
Authors:G. Horvath, G. Joo, G. Kekesi, I. Farkas, G. Tuboly, Z. Petrovszki, and G. Benedek
The goal was to develop a rat model for determination of the effects of intrathecally administered drugs on the peripherally induced pruritic behaviors. After chronic intrathecal catheterization, a serotonin derivative (5-methoxytryptamine: MeOT, 200 μg on both sides) was injected into the lower leg skin. After the first period (phase 0: 0–30 min) MeOT injection was repeated and opioid antagonist naltrexone (10 μg), NMDA receptor antagonists ketamine (10–100 μg), kynurenic acid (1–10 μg) or their combinations were injected intrathecally. The second observational period lasted for 60 min (phases I and II, 30–60 and 60–90 min, respectively). MeOT produced pruritic behavior with high degree of interindividual differences. The second MeOT injection caused an enhanced pruritic behavior in Phase I. Naltrexone decreased the pruritic activity, while neither doses of ketamine influenced the effects of MeOT. The higher doses of kynurenic acid resulted in notable decreases in the pruritic behavior. The combinations of naltrexone with ketamine or kynurenic acid produced a prolonged antipruritic effect. Our data suggest an important direction for the development of a new itch model in rats that focuses on the spinal mechanism of itching. Besides, the results revealed the role of the spinal opioid and NMDA receptors in this process.
Authors:H. G. Daood, R. Tömösközi-Farkas, and J. Kapitány
In the present work, bio and conventional forms of spice red pepper were analysed using various high performance liquid chromatographic (HPLC) systems for their carotenoid, tocopherol and vitamin C contents. The carotenoid pigment was fractionated into free xanthophylls, monoesters, carotenes and diesters with newly developed reversed phase HPLC, while a-, b- and g-isomers of vitamin E were separated by normal phase chromatography. Ion-pair chromatography on a C-18 column provided good separation and quantification of vitamin C. The peppers included new resistant varieties and hybrids that are essential for bio-production. It was found that crossing new disease-resistant varieties such as Kaldom and Kalorez with susceptible ones such as Rubin and SZ-20 produced resistant hybrids that contained higher levels of quality components compared to the parents, particularly when grown and cultivated under organic farming conditions.
Authors:S. Hornok, Renate Edelhofer, G. Földvári, Anja Joachim, and R. Farkas
In order to evaluate the seroconversion of horses to
in Hungary, blood samples were collected from 371 animals on 23 different locations of the country. The presence of antibodies to
was screened with a competitive ELISA. All 29 positive samples came from one region (the Hortobágy). The prevalence of infection did not show correlation with sexes, and reached 100% in the age group of 2–5 years.
-specific antibodies were demonstrated by IFAT in 6.74% of animals kept in 7 regions. The titres were low or medium level (1:40 to 1:160), indicating that the horses had previously been exposed to this piroplasm, but their infection must have been limited. The highest seropositivity rate was observed in the age group of 3–4 years, and males (stallions and geldings) were significantly more frequently infected than females. However, neither
could be identified in the peripheral blood samples of infected horses by PCR. Since most of the
-positive horses remained negative in the
IFAT, whereas seroconversion solely to
was detected in several regions of the country, serological cross-reaction between the two species can be discounted. This is the first serological evidence of horses being naturally infected with
, supporting the view that piroplasms are less host specific than previously thought.
Authors:A. Taczman-Brückner, Cs. Mohácsi-Farkas, Cs. Balla, and G. Kiskó
Applying antagonistic yeasts is one of the recent possibilities for controlling postharvest disease caused by blue mould (Penicillium expansum). In this work, antagonistic activity of several Kl. lactisstrains was tested against two strains of P. expansum. Three strains of Kl. lactiswere compared to three biocontrol yeasts: Metschnikowia pulcherrima, Sporobolomyces roseusand Pichia anomala. The investigations were carried out at 25 °C, 15 °C and 5 °C, applying different yeast cell densities and culture media. Statistical analysis showed no significant differences among the three Kl. lactisstrains. The inhibitory effect of the tested yeasts was different according to the applied mould strain temperature, culture medium and cell density. Application of antagonistic yeasts combined with reduced temperature enhanced the inhibitory effect. Direct relationship was observed between increasing cell density and the biocontrol efficiency of Kl. lactis. According to this work, Kl. lactisis a possible biocontrol agent.
Authors:G. Farkas, J.M. Rezessy-Szabó, F. Zákány, and Á. Hoschke
Fermentation trials were conducted in all-malt wort with mixed cultures of SaccharomycescerevisiaeWS 34/70 and one of two non-Saccharomycesyeast strains: Saccharomycodesludwigiiand Torulaspora delbrueckiiDSM 70607. Interactions were observed between the two yeasts during the alcoholic fermentation process started with eight different initial cell ratios ranging from 1:1 to 1:20 (Saccharomyces yeast : non-Saccharomyces yeast). Composition of the medium greatly affected the cell yield, degree of attenuation and ethanol concentration due to the maltose-negative characteristic of the non-Saccharomycesyeast strains. Starting cell ratios had less effect on the outcome of the fermentation experiments. S. cerevisiaelimited the growth of T. delbrueckiito a great extent, overgrowing it in the course of fermentation. On the other hand, S. cerevisiaedid not grow as dynamically in mixed culture with S. ludwigiias the composition of the medium would have suggested.
Authors:B. Fekete, G. Kiskó, É. Stefanovits-Bányai, and Cs. Mohácsi-Farkas
Fruits and vegetables are increasingly consumed as a part of healthy diets. They are routinely consumed raw, without any further antimicrobial processing. The aim of our studies was to determine radiation doses improving the microbial safety of fruits without diminishing quality parameters of these produce. Effects of low dose irradiation on the microbiota, antioxidant capacity, total polyphenol contents, firmness and sensory properties of pre-cut apple, orange and banana were investigated. Dose of 2.0 kGy was able to reduce considerably the microbiological contamination of fruits, apple, orange, banana, but microorganisms surviving the irradiation are able to recover and grow during refrigerated storage. Two kGy was an acceptable radiation dose for the treatment of these products, having no significant effect on the mentioned quality parameters.