Authors:R. Engel, L. Abrankó, É. Stefanovits-Bányai and P. Fodor
Vitamins form a heterogeneous chemical group having different stability. In foodstuffs some of them might be bound to matrix components. In the case of vitamin supplemented food products, since the vitamins are not strongly embedded in the matrix a general extraction method could be fit for purpose. The aim of this study was the simultaneous determination of the most common water-soluble vitamins, i.e. ascorbic acid (C), riboflavin (B
), niacin (B
), pyridoxine (B
), folic acid (B
) in enriched food products. Sample preparation based on the European Standard (CEN, 2003) was optimised for further LC-MS compatible chromatography. The separation of the vitamins was achieved by reversed-phase liquid chromatography. Detection was carried out with a photodiode array detector at four different wavelengths. The chromatographic method and the sample preparation were successfully applied for vitamin-enriched cereal, instant cacao powder and fruit juice samples.
Authors:L. Varga, R. Engel, K. Szabó, L. Abrankó, B. Gosztola, É. Zámboriné Németh and S. Sárosi
Ground ivy (Glechoma hederacea L.) is one of the prosperous plants for the food-industry as natural antioxidant. This fact led us to examine the chemical diversity of six ground ivy populations situated in different natural habitats and to analyse the effect of the harvesting time. Total phenolic content, chlorogenic acid, and rutin content, as well as the antioxidant capacity showed significant differences due to the harvest time. The highest total phenol content (115 mg g–1 GAE) and the strongest antioxidant activity (53.3 mg g–1 AAE) were measured in the population originated from Budapest (GLE 6), harvested in July. The highest chlorogenic acid (357 mg/100 g) and rutin (950 mg/100 g) contents were detected in the July harvested samples from the Soroksár Botanical Garden population (GLE 1). According to our results, the collection time has significant effect on the total phenolic content – first of all on the chlorogenic acid and rutin accumulation levels of ground ivy, while the influence of the habitat seems to be less important.
Authors:E. Farkas, B. Biró, K. Szabó, K. Veres, Zs. Csintalan and R. Engel
The terricolous species Cladonia foliacea (Cladoniaceae, lichenised Ascomycota) widely distributed in open, dry lowland steppe and rocky mountain grassland vegetation in Europe was chosen as a potential test organism for ecological experiments, since their thalli are producing cortical solar radiation-protective and UV screening pigment dibenzofuran usnic acid and medullary secondary substance depsidone fumarprotocetraric acid. Significant seasonal differences were found in the amounts of lichen secondary metabolites analysed by HPTLC and HPLC-PDA between summer and winter collected thalli in sandy grassland area in Hungary. The concentrations of usnic acid varied between 7.34 and 15.52 mg/g in summer collected samples and 13.90 and 21.61 mg/g in winter collected ones. A comparable amount (11.61±0.29 mg/g) was measured in pulverised samples. The concentrations of fumarprotocetraric acid varied between 0.60 and 3.01 mg/g in summer collected samples and 2.26 and 5.81 mg/g in winter collected thalli. A comparable amount (2.45±0.21 mg/g) was found in pulverised samples. The range of concentration values is comparable with data known from lichens. A higher amount of usnic acid is produced in winter probably to ensure sufficient protection also for summer. The fumarprotocetraric acid content of the medulla might contribute to the solar irradiation reflecting role of the pale lower surface lobes turning upwards in dry condition.