Flavanols and their dimer procyanidins as well as methylxanthines are two groups of secondary metabolites that are present together in chocolate and green tea. Flavanols and procyanidins are desired compounds in food because of their potential for prevention of cardiovascular diseases. Methylxanthines have influence on the central nervous system increasing attention, physical performance and muscular recovery etc, however in high doses especially caffeine can cause shivering, wakefulness, heart beating and even delirium. HPLC is the most usable chromatographic technique for the separation of flavanols, procyanidins and methylxanthines. However, the separation of flavanols and dimer procyanidins needs about an hour on ordinary C18 columns despite of gradient elution. Therefore, the aim of our work was to develop a faster HPLC method for the separation of flavanols, procyanidins and methylxanthines in one run. lnstead of the ordinary RP column the core-shell column was used. Core-shell columns are a new generation columns with 2.6 or 2.7 µm particle sizes which give better resolution as well as shorter separation time and can be employed on the HPLC system. Mobile phases based on acetonitrile-water or methanol-water with addition of acetic or formic acid were tested. The flow rate and the temperature were also optimised. The baseline separation of five flavanols (epigallocatechin, catechin, epicatechin, epigallocatechin gallate, epicatehin gallate), three procyanidins (procyanidin B1, B2 and A2), three methylxanthines (theobromine, theophylline and caffeine) was achieved in 10 minutes on C18 Kinetex column (100 x 4.6 mm; 2.6 µm particle size; Phenomenex, Torrance, USA) by using acetonitrile and water with acetic acid in both solvents in gradient mode. The run time for routine analysis was extended to 5 more minutes for column elution and conditioning. The optimised HPLC method was used for analysing chocolate samples previously cleaned by solid-phase extraction.
E.02 International awards
COBISS.SI-ID: 4769818Fodder enriched with patented water soluble coenzyme Q10 increase chickens’ weight and the content of coenzyme Q10 in chicken meat, which improves its quality. In this way enriched meat is functional food and a good source for the preparation of other food products from chicken meat (e.g. pate, salami etc).
F.07 Improvements to an existing product
COBISS.SI-ID: 3909496Tutoring for postgraduate students. Breda Simonovska was a mentor of young researcher Vesna Glavnik, who received her PhD at the Biotechnical Faculty (University of Ljubljana).
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 6844793