The combination of stable isotope and multi-elemental data for determination the geographical origin of lettuce (Lactuca sativa L.), sweet pepper (Capsicum annuum L.) and tomato (Solanum lycopersicum L.) was investigated, in order to reveal their country of origin at the scale of Central and Southern Europe and Mediterranean (Spain, Morocco, Italy, Slovenia, Austria, Greece). Samples were collected from the Slovenian market and subjected to stable isotope ratio (δ13C, δ15N, δ34S, δ18O) and elemental composition (P, S, Cl, K, Ca, Zn, Br, Rb, Sr) analyses. The discriminant analysis of obtained data proposed a distinction of most lettuce, sweet pepper and tomato samples, originated from different countries.
F.01 Acquisition of new practical knowledge, information and skills
COBISS.SI-ID: 30070823At a professional conference with international participation "News in the field of organic farming in 2016 in Maribor, we presented partial results of this project. Organic and biodynamic agriculrural practice affect the sensory properties which better as compared to conventional practice. Analysis of stable isotopes of nitrogen δ15N allows to differentiate vegetables grown using organic or biodynamic agricultural practice as compared to conventionally produced vegetables.
F.34 Consultancy
COBISS.SI-ID: 4626552In this review article we described the possibility to determine the geographical origin of fruits and vegetables according to analyses of stable isotopes (δ2H, δ13C, δ15N, δ18O, δ34S), elements (P, S, Cl, K, Ca, Zn, Br, Rb, Sr) and chemical parameters. Plant cell water originates from natural water cycle, hydrogen and oxygen stable isotopes are fractionated due to climatic conditions, higher values of δ2H and δ18O coincide with warmer climate. δ13C values exhibit environmental influences, however, δ13C values are strongly related to the photosynthetic pathway (C3, C4 and CAM). δ34S ratio and elemental content occur within large limits in particular soils. Chemical parameters per se (bioactive compounds like phenols, vitamin C, carotenoids, fatty acids, etc.) usually do not allow discrimination of geographical origin but may be included in multivariate analysis in combination with stable isotopes ratios and elemental content.
F.34 Consultancy
COBISS.SI-ID: 4756088The aim of doctoral thesis was to find out whether it is possible to distinguish between organic and conventional crops applying the analyses of antioxidant activity of total phenols, the content of δ13C and δ15N and minerals. The results of antioxidant activity and total phenol, on average, showed no statistically significant differences according to the type of farming, also the δ13C is not suitable for the separation between organic and conventional foods. Organically produced samples were achieving, on average, higher δ15N values than those produced by conventional production. This confirms the assumption that among the studied parameters, δ15N is the best parameter for distinguishing between organic and conventional foods.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 816503Doctoral thesis deals with the differences in the chemical composition of red, red-spotted and green chicory (Cichorium intybus L.) cultivars grown with different production methods (forced chicons, rosettes grown in pots). In five chicon cultivars from forcing in different nutrient solutions we obtained: total phenolic content, total flavonoids, antioxidative potential, mineral content and fatty acid profiles. The results showed significantly higher total phenolics and antioxidative potential in red chicory cultivars. The addition of potassium in the nutrient solution resulted in higher total phenolics and flavonoids, the addition of nitrogen increase only antioxidative potential. Multi-elemental analysis of chicons showed the content of the macro-minerals (P, Ca, K, Cl, S) and micro-minerals (Fe, Zn, Mn, Rb, Sr, Br). In rosettes grown in pots we identified the monomeric and oligomeric hydroxycinnamic acids and their derivatives (gallic, benzoic acid). We also confirmed the presence of some important flavonoids (quercetin, kaempferol, apigenin and luteolin). We further identified and quantified the chicoric, chlorogenic and caftaric acids. Fatty acids composition was determined by means of GC as fatty acid methyl esters (FAMEs). The analysis revealed the presence of α-linolenic, linoleic, palmitic, oleic and palmitoleic fatty acid, their content being influenced by agricultural production method. Predominant fatty acids were α-linolenic (n-3) and linoleic (n-6) fatty acids, with the favourable n-6/n-3 ratio (( 1). Stable isotope composition of 15N confirmed, that administration of organic fertilizers results in significantly higher δ15N values as compared to mineral fertilizers.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 4487288