Influence of starter cultures on polychlorinated biphenyls (PCBs) degradation in various media was tested in the frame of the thesis. The experiment was divided into three parts. In the first part liquid broths BHI (Brain Hearth Infusion Broth) and MRS (de Man, Rogosa and Sharpe) were used, as well as commercial starter cultures Texel DCM-1 and Texel LM-30. The eventual PCBs degradation in the meat emulsions was tested in the second part in which protein extracts obtained from the same starter culture were added to supplement the used Texel DCM 1 starter culture. Also the influence of heat treatment (core temperature 78 °C and 100 °C) on meat emulsions’ PCBs content was tested. In the third part, with the closest connection to real meat industry the PCBs degradation was followed during the dry fermented sausages drying/maturing process. Biostar Sprint and SM-181 were also used, besides the already mentioned starter cultures. A different extraction method was applied in each of the experiments, mainly due to differences in the media used. GC-ECD was used to determine PBCs concentration in liquid media and meat emulsions and GC-MS was used in dry fermented sausages. Statistically significant PCBs degradation with added starter cultures was proved in all the experiments. The highest PCBs degradation has been determined in the experiment with a Texel DCM-1 (Staphylococcus carnosus, Staphylococcus xylosus) starter culture in MRS nutrient medium. Meat emulsion followed in which maximal degradation was reached at core temperature 100 °C and with added starter. The lowest percentage of PCBs degradation was observed in dry fermented sausages samples, among which the sample with starter culture SM-181 (Lactobacillus sakei HJ-7, Staphylococcus xylosus DD-34) exhibited highest degradation rate.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 4488056Doctoral 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. We measured some morphometrical parameters (height and diameter, number of leaves, net mass). In different chicory cultivars grown with the addition of organic and/or mineral fertilisers following parameters were evaluated: individual phenolic compounds by means of HPLC, stable isotope composition of 15N and 13C and fatty acid composition. 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 phosphorus influenced 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 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 acid composition was determined by means of GCas fatty acid methyl esters (FAMEs). 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: 4487288The study material is divided into seven chapters, which deal with the situation in the viti-viniculture branch and winemaking industry in Slovenia, the importance of control and analytics of wine, wine yeast (technological, fermentation and aromatic characteristics), malolactic fermentation, sensory analysis of musts and wines, HACCP and possibilities of preserving the purity of smell and taste wine.
D.10 Educational activities
COBISS.SI-ID: 4444280Dr. Janez Hribar is a member of editorial board of Food Technology and Biotechnology since 2007.
C.04 Editorial board of an international magazine
The quality of honey is evaluated by legally defined parameters, which are not sufficient for a comprehensive assessment of its quality and authenticity. Honey frauds comprise also intentionally or unintentionally incorrect declaration of honey origin. Foods with labelled geographical origin, including honey, normally achieve a higher price. The unauthentic honey is therefore anyone with wrongly given geographical origin, and labelled with a protected designation, although not even been produced in that area. The subject of false declaration of geographical origin is often cheaper honey from non-European countries or honey labelled with the EU symbol of quality (PDO and PGI), although not justified to it. In this paper we present the results of multi-year research of Slovenian honey, which enabled development of a protocol for verifying the correctness of the declared geographical origin.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 4481144