Authors:M. Nagy-Gasztonyi, E. Biekman and B. Krebbers
The combination of lactofermentation and enzyme-treatment (Rohament-PL as endo-polygalacturonase and the mixture of Rohament-PL and Rohalase 7069 as cellulase) of sliced carrot and orange juice resulted in a homogeneous product, with pleasant organoleptic features, after 18 h fermentation period. Two ways of inoculation were applied with Lactobacillus plantarum. The addition of Rohament-PL, even at 150 mg kg-1 concentration, simultaneous inoculation with Lactobacillusplantarum (circumstances: 28 °C, 80 r.p.m. shaking) promoted the growth of lactobacilli. By 42 h fermentation time LAB count increased up to 3.2-4.8´109 cm-3. Furthermore the surface colour of the samples was more intensive (higher L-, a- and b-values) than without Lactobacillus plantarum inoculation. The application of Rohament-PL (50-100 mg kg-1) resulted in a homogeneous carrot puree, the combination of Rohament-PL (150 mg kg-1) and Rohalase 7069 (150 mg kg-1) in the process gave a more fluid product, as proved by the lower specific viscosity values.
Authors:M. Nagy-Gasztonyi, Á. Kardos-Neumann and M. Takács-Hájos
Nitrate accumulation in plants is a natural phenomenon resulting from uptake of nitrate ion in excess of its reduction and subsequent assimilation. The water soluble nitrate content of various carrot and red beet varieties was measured as a function of irrigation and mineral supplement in three years. In the first year, the nitrate content increased in both roots (significant differences were found for three carrot and at three red beet cultivars) following the irrigation. The activity of nitrate-reductase in the leaves was also significantly higher after irrigation in three red beet varieties in 1998. The mineral supplement in most of the carrot varieties increased the nitrate content. In the third year, the impact of water supply showed various tendencies in nitrate accumulation in both vegetables. On the basis of results for three years, the conclusion was that the seasonal and varietal differences were also remarkable.
Authors:M. Nagy-Gasztonyi, Á. Kardos-Neumann and P. Á. Biacs
Blanching of vegetables before freezing has some advantages as well as a number of disadvantages. Process optimization involves measuring the rate of enzyme destruction, such that the blanching time is just long enough to destroy the indicator enzyme. Eventually, peroxidases were almost universally the enzymes of choice, as they are usually the most heat-stable enzymes found in vegetables and fruits, so by the time they are inactivated no other enzymes or micro-organisms remain. But there is no evidence that peroxidases are involved in deteriorative reactions in the food. The aim of this work was to improve blanching technology in Hungarian frozen food industry with special emphasis on broccoli treatment. Instead of peroxidases, lipoxygenases were chosen to determine the adequate blanching parameters. Usually, lipoxygenases accompany lipases, so lipase activity is measured, too. On the basis of model blanching experiments, the conclusion is that lipoxygenase could be used as indicator enzyme. Being less heat stable than peroxidase, this enzyme requires shorter heat treatment, hence its inactivation should result in minimum quality deterioration and economic loss.
Authors:R. Tömösközi-Farkas, M. Berki, M. Nagy-Gasztonyi, I. Wolf and Zs. Polgár
We have investigated the Total Glycoalcaloid (TGA), nitrite, and nitrate contents of some Hungarian and foreign potato cultivars in relation to the effect of different combination of fertilisers and green manure, late blight management strategies (none, programmed, or prediction based spraying), and irrigation regime for three years. The Hungarian cultivars have exotic potato species like S. acaule, S. demissum, S. stoloniferum, S. vernei, or S. tub. ssp. andigenum in their genetic background as sources of resistance genes. No effect of fertilisers or irrigation was found on the level of glycoalkaloids and nitrate contents, which were influenced mostly by the genotype and season. In conclusion, the absolute amount and the presence of different antinutritive components of potato tubers were influenced by the technology, genotype, and season in a complex manner. These results in general prove that ware potato production utilising intensive commercial agrotechnical practices and common cultivars is safe regarding the nitrate and TGA content of tubers.
Authors:É. Kónya, G. Bujdosó, M. Berki, M. Nagy-Gasztonyi and N. Adányi
Two Hungarian and two introduced walnut cultivars were examined as fresh samples and under storage. Some important compositional data were determined in order to evaluate the differences between the cultivars and the changes after storage. The cultivars’ oil contents were the same, but there was some difference in fatty acid composition; ‘Alsószentiváni 117’ had a higher mono-unsaturated fatty acid content than the others. Considering the oxidative stability, ‘Alsószentiváni 117’ contained good properties in all stages (induction time equals or higher than 10 h). Lower antioxidant capacity was measured in ‘Chandler’ samples compared to the others. ‘Alsószentiváni 117’ has higher α- and γ-tocopherol contents than the other cultivars studied. Two different drying methods were also compared in case of the Hungarian cultivars. The changes in compositional data showed no tendencies. We found that Hungarian cultivars were at least as valuable as the introduced ones.
Authors:Á. Halász, E. Horváth-Szanics, M. Nagy-Gasztonyi, J. Pauk and Gy. Hajós
Protein sets, enzyme activities and immune reactivity against wheat germ agglutinin in the albumin-globulin fractions of parent and herbicide resistant transgenic wheat lines were studied.Our results showed significantly increased amylase activities and increased immune reactivity against wheat germ agglutinin in the herbicide resistant transgenic wheat lines, investigated. The amylases and lectins belong to the plant food allergens; this explains why both scientists and consumers are interested in assessing the allergenic potential of plant proteins and the safety assessment of novel foods and GM foods in highlight of food safety. This paper is an important contribution to our database and the understanding of what is going on with genetic engineering of crop plants.
Authors:R. Tömösközi-Farkas, Zs. Polgár, M. Nagy-Gasztonyi, V. Horváth, T. Renkecz, K. Simon, F. Boross, Z. Fabulya and H. Daood
Anti-nutritive components in multi resistant potato cultivars were investigated in relation to conventional and organic farming for three years. Glycoalkaloids, nitrate, nitrite, asparagine, and glutamine contents of tubers were examined. Farming technology was found not to have an effect on the level of glycoalkaloids, which was influenced mostly by the genotype and season. Nitrogen fertilisation caused significant increase in nitrate, asparagine, and glutamine contents as compared to organic farming. Nitrite content was found to be more independent of farming technologies than nitrate. Tubers of cultivar Rioja had the lowest nitrate content irrespective of season or technology. In conclusion, the absolute amount and changes of different anti-nutritive components of potato tubers were influenced differently by the technology, genotype, and season in a complex manner. Organic farming had no effect on the glycoalkaloid content, but the nitrate levels had a tendency to be lower compared to conventional farming. This can be seen as a positive effect of organic farming.